Latest from Space.com in Astrophysics

Our Milky Way galaxy might be larger than we thought

chelseagohd@gmail.com (Chelsea Gohd) — Tue, 07 Jul 2026 20:00:00 +0000

Is the Milky Way even bigger than we thought? New observations have revealed that our galaxy's spiral arms could stretch farther and wider than we previously concluded.

The Milky Way's spiral structure was discovered over 175 years ago in 1850. But new information could completely change our understanding of our cosmic home. Astronomers have taken a new look at our Milky Way galaxy using data from NASA's Chandra X-ray observatory and the European Space Agency's XMM-Newton observatory and have pieced together new, precise measurements of the galaxy's spiral arms. And what they found is that its spiral arms stretch out farther than we once thought, a discovery that could change our understanding of our galaxy's structure.

"The differences are small, but any revision of these distances is important because they are so fundamental for understanding our galaxy," co-author Ilaria Fornasiero said in a statement. "For example, this could mean that astronomers have to revise estimates of the mass of the galaxy, because that affects how wide the arms stretch."

To make this new galactic measurement, researchers had to get a little creative with the data. They measured these cosmic distances by observing X-ray light scattered by the dust in the Milky Way's arms as it echoed out from around gamma-ray bursts, or the most powerful explosions across the universe that happen either when massive stars collapse or neutron stars collide and merge. These massive bursts of energy are happening far beyond our galaxy, but their X-ray light is so powerful that it can reach and bounce off of dust clouds in the Milky Way's arms.

This artist's concept shows where the Milky Way's spiral arms are now thought to extend to and how that compares to previous estimations. (Image credit: NASA/CXC/SAO/M.Weiss)

By studying the diameters of the rings of light as they expand away from these explosions and observing how and where they reflect off of the Milky Way's dust, the team was able to precisely point to where the galaxy's arms extend.

"This is a very direct way – relying only on geometry – to precisely measure distances to the Milky Way's spiral arms," lead author Beatrice Vaia, who led this research as a PhD student, said in the statement. "Most other methods rely on assumptions about how the Milky Way rotates, which become increasingly uncertain in the outer regions of our galaxy."

The team used the X-ray light from three different gamma-ray bursts to look at three of the Milky Way's spiral arms: the Perseus, the Outer, and the Outer-Scutum-Centaurus arms. According to these new measurements, both the Outer and the Outer Scutum-Centaurus arms are about ten percent more distant than was previously thought.

With this data, the team was also able to measure the thickness of the Milky Way's most distant arm, which they found to be about 3,500 light-years wide. By incorporating the arm's width, the team ensured that they were measuring the full extension of the arm and not just one particular dust cloud, further bolstering their findings.

This composite image shows X-ray rings created by a gamma-ray burst bouncing off of the dust clouds in the spiral arms of the Milky Way galaxy. (Image credit: X-ray: NASA/CXC/INAF/B. Vaia et al.; Optical: Pan-STARRS; Image processing: NASA/CXC/SAO/N.Wolk & P.Edmonds)

While it's interesting that the Milky Way's arms extend out a bit farther and wider than we previously thought, these new findings could have larger implications. Based on these new measurements, astronomers may have to reinvestigate our understanding of our galaxy's mass distribution, rotation and overall structure. This evolving understanding could ripple out and impact how we view not just the structure but the evolution of our galaxy and beyond.

But this study isn't one that can be replicated too easily. That's because gamma-ray bursts don't happen all of the time. Even more rare are bursts that we can see clearly through our galaxy.

"We’re relying on the universe to provide us with these events, and so far, over 25 years, we’ve only found a handful that we can use," co-author Andrea Tiengo of Scuola Universitaria Superiore IUSS Pavia said in the same statement. "That said, we will continue to be on the lookout for more."

This work was described in a new study published June 19 in the journal Astronomy & Astrophysics.

The Whirlpool Galaxy comes alive | Space photo of the day for May 13, 2026

chelseagohd@gmail.com (Chelsea Gohd) — Wed, 13 May 2026 14:00:00 +0000

A section of M51, also known as the Whirlpool Galaxy. (Image credit: ESA/Webb, NASA & CSA, A. Pedrini, A. Adamo (Stockholm University) and the FEAST JWST team)

The Whirlpool Galaxy sprawls across the cosmos in this striking new snapshot from NASA's James Webb Space Telescope (JWST).

The galaxy, formally known as M51 (Messier 51), stretches out its spiral arms, glowing brightly in the darkness of space. While the galaxy's many limbs have been spotted before by the Hubble Space Telescope and even amateur astronomers, this image captures a uniquely striking view of its galactic beauty.

What is it?

The Whirlpool Galaxy was captured in this image by JWST's Near-Infrared Camera (NIRCam), according to a statement. This is JWST's primary instrument for seeing the universe in near-infrared light, which is a range of the electromagnetic wavelengths just out of our eyes' reach.

By seeing in near-infrared, NIRCam was able to capture this incredible view of part of the Whirlpool Galaxy. Located in the constellation Canes Vanatici, the spiral galaxy is made up of long swirls of gas and dust speckled with stars.

Beyond being just a beautiful cosmic sight, the formations of dust and gas that comprise this galaxy are actually a star-forming region. Here, gases like hydrogen and dust are compressed, condensing into new stars.

Why is it incredible?

This image shows only a section of the incredibly expansive spiral galaxy. The galaxy's red and orange spiral arms bending outward can measure tens or even hundreds of light-years across.

The full galaxy measures an incredible 76,900 light-years across. While this is an enormous size for any object or region, our own Milky Way galaxy measures over 100,000 light-years in diameter. But size and distances get fairly massive when we're talking on a cosmic scale. The Whirlpool Galaxy is a whopping 31 million light-years away from our own, but it's still considered one of our closer neighbors.

Something that has made the Whirlpool Galaxy beloved is its visibility. With an apparent magnitude of +8.4, skywatchers and amateur astronomers using small telescopes or even just binoculars are able to spot the galaxy and its spiral shape.

Scientists found 10,000 possible exoplanets hiding in NASA data

chelseagohd@gmail.com (Chelsea Gohd) — Fri, 08 May 2026 13:00:00 +0000

Using NASA data and machine learning, scientists have found over 10,000 possible new planets in a single survey.

In a new study, researchers used machine learning to perform a sweeping survey of data from NASA's exoplanet-hunting Transiting Exoplanet Survey Satellite (TESS). As a result, they and uncovered exactly 10,091 candidate planets that had never been seen before. To clarify, when planets beyond our solar system (otherwise known as exoplanets) are first spotted, they are considered "candidates" until they can be confirmed as such with the right amount of evidence. Some of these candidates might not end up being planets after all — some could end up being other objects or even just "noise" in the data.

To date, humanity has discovered over 6,200 confirmed exoplanets, or planets outside of our solar system, according to NASA's Exoplanet Archive. But soon, thanks to all these new candidates, we could be adding a ton of worlds to the mix.

This major haul of exoplanet candidates, however, may beg the question: Why haven't these thousands of planets been seen before? In fact, TESS has been operational since 2018, and has been continuing on its extended mission since 2020.

Well, TESS operates by observing planets "transiting," or passing in front of, their stars. In other words, when an exoplanet is orbiting its star, at some point it will cross the face of the star from TESS' view. When this happens, the star appears to dim. TESS can measure that dimming, thereby revealing information about the planet passing in front of its star. Planets orbiting brighter stars are easier to spot because the transits are clearer.

However, this new study pulled data from fainter stars.

The survey actually looked at stars 16 times fainter than those typically targeted by TESS. Using machine learning, a type of artificial intelligence, the team surveyed over 83 million stars that were observed during TESS' first year of observations. Of these many millions of faint stars TESS looked at, 10,091 appeared to have transiting, planet-like objects never seen before.

An exoplanet drifts through the dark vastness of space. (Image credit: NASA/JPL–Caltech/Keith Miller (Caltech/IPAC).)

Jackpot

Of course, some of the 10,091 planet candidates might turn out to not be planets, so this research team wanted to start further testing to confirm these results. And in doing so, they were able to confirm one of the candidates: a planet called TIC 183374187 b. This world appears to be a hot Jupiter, a gas giant that orbits very close to its host star — which is why it's so hot — and has a mass similar to Jupiter's.

But besides confirming all the exoplanets spotted with this research, the team also intends to take things a step further. While this study used the first year of TESS data, the research team aims to continue with a follow-up study using TESS' second year of data, lead author Joshua Roth, a graduate researcher at Princeton University, told IFLScience.

This boom in exoplanet discovery comes just about 30 years since the first exoplanet to be confirmed, 51 Pegasi b, was found in 1995. With that first confirmation, scientists were able to definitively say what they had thought likely true for years — that planets exist around other stars outside of our solar system. Since then, NASA missions like TESS and Kepler have provided data that has grown the field tremendously.

Looking to the future, in addition to incorporating techniques like machine learning as this team has done, NASA's upcoming Nancy Grace Roman Space Telescope will continue to expand exoplanet science with its Coronagraph Instrument which will make direct observations of worlds beyond our cosmic neighborhood. Rather than increase the number of exoplanets discovered, this instrument will allow for more in-depth study of these worlds and their atmospheres. As of writing this article, that telescope is slated to launch no earlier than early September 2026.

And even farther into the future, NASA aims to expand the field yet again with its Habitable Worlds Observatory, which is currently being built.

This work was published April 28 in The Astrophysical Journal.

Astronomers spot 1st coronal mass ejection from an alien star — and that's bad news in the search for life

Robert Lea — Wed, 12 Nov 2025 16:01:00 +0000

Thanks to the European Space Agency (ESA) spacecraft XMM-Newton, astronomers have seen a powerful explosion of plasma erupting from a distant star for the first time. We have seen (and felt) plenty of these coronal mass ejections (CMEs) from the sun, but even though we have long thought other stars expel such powerful outflows of superheated gas and magnetic field, astronomers had never before spotted them in any convincing way.

This first extra-solar CME, which erupted from a red dwarf star, wasn't any run-of-the-mill stellar blast either. This CME was dense enough and carried enough energy to strip away the atmosphere of any closely orbiting planet, with the ejected material traveling at 5.4 million miles per hour (2,400 kilometers per second). That speed, around 3,500 times as fast as a Lockheed Martin F-16 jet fighter, is something that is only observed in around 1 in 2,000 CMEs from our sun.

The atmosphere-stripping potential of this outburst means the observation of this CME could help astronomers better refine which extrasolar planets, or exoplanets, orbiting distant stars are capable of supporting life.

"Astronomers have wanted to spot a CME on another star for decades," team member Joe Callingham of the Netherlands Institute for Radio Astronomy (ASTRON) said in a statement. "Previous findings have inferred that they exist, or hinted at their presence, but haven’t actually confirmed that material has definitively escaped out into space. We’ve now managed to do this for the first time."

The team's research was published on Wednesday (Nov. 12) in the journal Nature.

The discovery of this extra-solar CME was aided by the Low-Frequency Array (LOFAR) radio telescope, which is capable of detecting radio signals that are created by CMEs when they ripple through the outer layers of stars and emerge into interplanetary space. This creates a shock wave and an associated telltale burst of light in the radio wave region of the electromagnetic spectrum.

"This kind of radio signal just wouldn’t exist unless material had completely left the star’s bubble of powerful magnetism," Callingham said. "In other words, it's caused by a CME."

This extra-solar CME was first spotted in data from LOFAR thanks to a new data processing technique. XMM-Newton was then used to determine the temperature of the star that created it, its rotational speed, and its brightness in X-ray light. This revealed that this red dwarf, located around 130 light-years away, has around half the mass of the sun, but rotates around 20 times faster than our star and has a magnetic field around 300 times more powerful than the solar magnetic field.

"We needed the sensitivity and frequency of LOFAR to detect the radio waves," team member David Konijn, a PhD student at ASTRON, explained. "And without XMM-Newton, we wouldn’t have been able to determine the CME’s motion or put it in a solar context, both crucial for proving what we’d found. Neither telescope alone would have been enough – we needed both."

This research could also help us better understand the CMEs launched by the sun and how they drive space weather around Earth.

"XMM-Newton is now helping us discover how CMEs vary by star, something that’s not only interesting in our study of stars and our sun, but also our hunt for habitable worlds around other stars," said Erik Kuulkers, an ESA XMM-Newton Project Scientist. "It also demonstrates the immense power of collaboration, which underpins all successful science. The discovery was a true team effort, and resolves the decades-long search for CMEs beyond the sun."

CMEs and the search for life

The fact that the CME was fast and dense enough to strip away a planetary atmosphere also adds additional information to the criteria that define what a habitable planet is.

"This work opens up a new observational frontier for studying and understanding eruptions and space weather around other stars," Henrik Eklund, an ESA at the European Space Research and Technology Centre (ESTEC) in Noordwijk, The Netherlands, said. "We're no longer limited to extrapolating our understanding of the sun's CMEs to other stars. It seems that intense space weather may be even more extreme around smaller stars – the primary hosts of potentially habitable exoplanets. This has important implications for how these planets keep hold of their atmospheres and possibly remain habitable over time."

Currently, to be considered habitable, a planet has to sit in the zone around its star that is neither too hot nor too cold to support liquid water, known as the habitable or "Goldilocks" zone. But, if the star at the heart of that zone is particularly active and is throwing out violent and frequent CMEs, not even a stable orbit in the Goldilocks zone will help it sustain an atmosphere, and thus the conditions needed for life to prosper.

That is a significant discovery because red dwarf stars like this one are the most common stars in the Milky Way. Thus, more of these stars than was previously believed may be stripping their orbiting planets of their atmospheres.

Correction 11/12: The star is located around 130 light-years away, not 40 light-years away, and the estimated speed of the CME is only seen in 1 out of 2000 CMEs, not in 1 out of 20. This article has been updated to reflect that.

108 million degrees! Solar flares are far hotter than thought, study suggests

Sharmila Kuthunur — Thu, 11 Sep 2025 20:00:00 +0000

Our sun's fiery flares are even more extreme than scientists had thought, blasting particles to temperatures six times hotter than earlier estimates, according to new research.

Solar flares are colossal explosions in the sun's atmosphere that hurl out bursts of powerful radiation. These events are notorious for disrupting satellites, scrambling radio signals and potentially posing dangers to astronauts in space.

Now, a team led by Alexander Russell of the University of St. Andrews in Scotland reports that particles in the sun's atmosphere heated up by flares can reach a staggering 60 million degrees Celsius (108 million degrees Fahrenheit) — tens of millions higher than earlier predictions, which typically put such temperatures between 10 million and 40 million degrees Celsius (18 million to 72 million degrees Fahrenheit).

"This appears to be a universal law," Russell said in a statement. The effect has already been observed in near-Earth space, the solar wind and in simulations, he added, but until now, "nobody had previously connected work in those fields to solar flares."

Since the 1970s, astronomers have been puzzled by a strange feature in the light from solar flares. When split into colors using powerful telescopes, the telltale "spectral lines" of different elements look much broader, or blurrier, than theory predicts.

For decades, scientists chalked this up to the turbulence known to occur in the sun's plasma. Like the chaotic bubbling of boiling water, the swift, random motions of charged particles in plasma can, in theory, shift light in different directions as they move. But the evidence never fully matched up, the new study notes. Sometimes the broadening appeared before turbulence could form, and in many cases the shapes of the lines were too symmetrical to match turbulent flows, according to the paper.

In their new study, Russell and his team suggest a simpler explanation: the solar particles affected by flares are simply far hotter than previously thought.

Using experiments and simulations of magnetic reconnection — the snapping and realignment of magnetic field lines that powers flares — the researchers found that, while electrons may reach 10 million to 15 million degrees C (18 million to 27 million degrees C), ions can soar past 60 million degrees C (108 million degrees F). Because it takes minutes for electrons and ions (which are atoms or molecules with an electrical charge) to share their heat, this temperature gap lasts long enough to shape the behavior of flares, according to the study.

At such extreme temperatures, ions zip around so quickly that their motion naturally makes the spectral lines look wider, "potentially solving an astrophysics mystery that has stood for nearly half a century," Russell said in the statement.

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The finds are not merely an academic exercise; they also carry implications for predicting space weather. If scientists have been underestimating the energy stored in flare ions, forecasts of space weather may need to be revised. Improved models could give satellite operators, airlines and space agencies more accurate information and extra time to prepare for dangerous solar events, scientists say.

The research also calls for a new generation of solar models, ones that treat ions and electrons separately instead of assuming a single uniform temperature. This "multi-temperature" approach is already common in other plasma environments, such as Earth's magnetic field, but has rarely been applied to the sun, the study notes.

This research is described in a paper published earlier this month in The Astrophysical Journal Letters.

Astronomers discover strange new type of supernova: 'This is the first time we have seen a star that was essentially stripped to the bone'

Robert Lea — Thu, 21 Aug 2025 20:00:00 +0000

Astronomers have used a new type of extreme supernova in which a massive star was stripped right "down to the bone" to better understand the process of stellar life and death.

When other massive stars die in supernova explosions, astronomers detect strong signals of light elements like hydrogen and helium that existed at the surface of the star. However, in this supernova, designated SN2021yfj and located 2.2 billion light-years from Earth, this team found a different chemical signature. This contained traces of heavier elements like silicon, sulfur, and argon that originate from deeper within the progenitor star.

If dying stars have onion-like structures with lighter elements at their surfaces and heavier elements toward their iron cores as astrophysicists currently theorize, then this star must have somehow lost its outer layers, thus exposing inner silicon and sulfur-rich layers before it "went nova." This would not only confirm the layered structure of massive stars, but it also give stellar scientists a rare glimpse at the interior of a star prior to it exploding in a supernova.

"This is the first time we have seen a star that was essentially stripped to the bone," team leader and Northwestern University scientist Steve Schulze said in a statement. "It shows us how stars are structured and proves that stars can lose a lot of material before they explode. Not only can they lose their outermost layers, but they can be completely stripped all the way down and still produce a brilliant explosion that we can observe from very, very far distances."

SN2021yfj, first spotted in September 2021 by the Zwicky Transient Facility (ZTF), suggests that while our models of stellar life and death and star structure may be correct, they may not fully describe the explosive death throes of all stars.

"This event quite literally looks like nothing anyone has ever seen before," Northwestern University researcher and team member Adam Miller said. "It was almost so weird that we thought maybe we didn't observe the correct object. This star is telling us that our ideas and theories for how stars evolve are too narrow. It's not that our textbooks are incorrect, but they clearly do not fully capture everything produced in nature.

"There must be more exotic pathways for a massive star to end its life that we hadn't considered."

The team's research was published on Wednesday (Aug. 20) in the journal Nature.

A burning onion in space

The progenitor stars of supernovas are between 10 and 100 times as massive as the sun, but still generate their energy via the nuclear fusion of lighter elements to heavier elements at their cores.

Whereas the sun will die when it has finished fusing its core hydrogen to helium in around 5 billion years, more massive stars have the pressures and temperatures at their cores to fuse progressively heavier and heavier elements right up to iron. As this process unfolds, lighter elements continue to undergo nuclear burning in the outer shells of massive stars.

When the cores of massive stars are hearts of pure iron, they collapse, and a supernova is triggered, ripping away the outer layers. The collapsing iron core eventually becomes a neutron star, or in the case of the most massive stars, a black hole.

To obtain information about supernovas, astronomers look for the signatures of chemical elements using a process called spectroscopy. The team was able to gain a spectroscopic picture of SN2021yfj using the W.M. Keck Observatory in Hawaii.

"We thought we had fully lost our opportunity to obtain these observations," said Miller. "So, we went to bed disappointed. But the next morning, a colleague at UC Berkeley unexpectedly provided a spectrum. Without that spectrum, we may have never realized that this was a strange and unusual explosion."

An illustration of a gamma-ray burst erupting from a dense environment around a collapsing massive star (Image credit: NASA, ESA and M. Kornmesser)

This revealed that SN2021yfj stands apart from other supernovas because the layers that were ripped away during its explosive end went deeper than what has been seen in the deaths of other massive stars. Astronomers have seen elements as heavy as carbon or oxygen during other supernovas due to the prior loss of stars' outer hydrogen layers. However, no elements heavier than this, and thus from deeper within the progenitor stars, have been seen before.

"We saw an interesting explosion, but we had no idea what it was," Schulze said. "Almost instantly, we realized it was something we had never seen before, so we needed to study it with all available resources."

The spectrum of SN2021yfj didn't just contain traces of heavy elements; it was dominated by strong signals of heavy elements like silicon, sulfur and argon. Thus, it became evident very early in this investigation that there was something particularly extreme and violent about SN2021yfj.

"This star lost most of the material that it produced throughout its lifetime," Schulze explained. "So, we could only see the material formed during the months right before its explosion. Something very violent must have happened to cause that."

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What caused this particular supernova to be violent is still somewhat mysterious, with several possible scenarios including a massive pre-supernova eruption, unusually strong stellar winds, or even a companion star stripping outer material away from this dying star prior to its explosive death.

However, the team thinks the most likely explanation is multiple episodes of so-called "pair instability" during which nuclear fusion is reignited, causing powerful bursts of energy that blow away the outer shells of the star. This is akin to the massive star effectively ripping itself apart before its supernova death. The bright emission that allowed SN2021yfj to be spotted by the ZTF would have been caused by shells of ejected material catching up with and slamming into previously ejected shells.

"While we have a theory for how nature created this particular explosion," Miller concluded. "I wouldn't bet my life that it's correct, because we still only have one discovered example.

"This star really underscores the need to uncover more of these rare supernovae to better understand their nature and how they form."

Astronomers trace massive cosmic explosion back 12 billion years. 'This is the most distant event where we can directly see light escaping from around stars'

Robert Lea — Thu, 21 Aug 2025 15:00:00 +0000

Astronomers have used a newly discovered and still mysterious class of cosmic explosions to better understand the process of stellar life and death in the distant universe.

The blasts in question are Fast X-ray Transients (FXTs), recently discovered outbursts of X-rays that last for just a few minutes. The source of FXTs has been shrouded in mystery. Now, with the aid of the Einstein Probe X-ray space telescope, astronomers have tracked one FXT, designated EP240315A, back to its source after travelling towards Earth for 12 billion years.

"We've known that these unique explosions exist for some time, but it is only now, thanks to the new Einstein Probe mission, that we can pinpoint them in near real time," team member Peter Jonker, of Radboud University, said in a statement.

Occurring in galaxies located billions of light-years away and lasting anywhere from seconds to hours, FXTs have proved difficult to trace back to their sources. Despite this, astronomers have theorized that FXTs may occur when massive stars go supernova, collapsing and leaving behind black holes.

"This event is novel and interesting because only a handful of FXTs had been discovered until very recently, and their origin was a mystery, primarily because they had been found in archival observations," team member and University of Lancaster researcher Samantha Oates said in the statement. "By the time they were discovered, it was too late to perform follow-up of these transient X-ray objects at other wavelengths to get other information about what might be causing them."

The team thus perfected their mapping of EP240315A using the ATLAS optical telescope system, the Very Large Telescope (VLT) in northern Chile, and the Gran Telescopio Canarias, located in Spain.

"These observations show that this explosion happened when the universe was less than 10% of its current age - the light has been travelling to us for 12 billion years," team member Andrew Levan, of Radboud University, said. "The combination of the distance and the brightness means this explosion gave off more energy in a few seconds than the sun will over its entire life."

Are Fast X-ray Transients and Gamma-ray Bursts cousin cosmic explosions?

The extreme energy of the FXTs and data regarding blasts of energy called gamma-rays suggest that FXTs and gamma-ray bursts (GRBs) are, at least sometimes, related.

GRBs are the most powerful and violent explosions in the known universe, brief flashes of high-energy radiation that result from some of the universe's most explosive events, including the death of massive stars and the subsequent birth of black holes.

Unlike FXTs, GRBs have been studied by humanity for around half a century.

"A real question is whether all of the FXTs come from GRB-like systems, or if there is much more diversity," Jonker added. "Our paper shows that many of them might be gamma-ray bursts, but there are good reasons to think there is much more still to discover."

An illustration of a gamma-ray burst erupting from a dense environment around a collapsing massive star (Image credit: NASA, ESA and M. Kornmesser)

When the team looked at observations of EP240315A, collected by the VLT, they found that its source was surrounded by very little material. In particular, they noted a dearth of hydrogen in this region.

Hydrogen filters ultraviolet light, preventing it from effectively traversing the cosmos. When this FXT was launched, around 1.8 billion years after the Big Bang, hydrogen was bombarded by ultraviolet light, causing it to be ionized.

"Our observations show that perhaps 10% of the ultraviolet light created in the host galaxy of the FXT is escaping to ionize the universe," said team member Andrea Saccardi, the French Alternative Energies and Atomic Energy Commission (CEA) Saclay. "This is the most distant event where we can directly see light escaping from around stars.

"Galaxies like this are probably really important for reionization."

An illustration shows the Einstein Probe as it hunts cosmic X-rays. (Image credit: Chinese Academy of Sciences)

The FXT EP240315A was one of the first events detected by the Einstein Probe, which launched on Jan. 9, 2024.

"In the year since this first object, we have found and studied another 20 of these outbursts," Levan added. "They [FXTs] are living up to their promise as an exciting new way to explore both how stars end their lives, and also what the universe was like in the distant past."

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Oates explained that this research exemplifies how the Einstien Probe is revolutionizing the detection of FXTs and their further study.

"The Einstein Probe has opened up a new window on the universe, allowing us to probe the origin of these transient X-ray phenomena and widen our knowledge of the behavior associated with the deaths of massive stars," she concluded.

The team's research was published on Tuesday (Aug. 19) in the journal Nature Astronomy.

Why do the numbers that shape our universe exist at all?

Paul Sutter — Fri, 23 May 2025 16:15:36 +0000

There is a set of very special numbers, known as the fundamental constants of nature, that cannot be explained. Where do they come from? Finding out if they are, in fact, constant is the key to unlocking this enduring mystery.

Physics is a mathematical description of nature. We use models, equations and formulas to describe how systems work and predict how they'll behave in the future. This approach has proved enormously successful, explaining everything from the behavior of subatomic particles to the evolution of the entire universe.

But there are aspects of these equations that defy explanation. Any time we try to take a hypothetical model and connect it to the real world, we have to introduce special numbers. These numbers capture some aspects of nature that are left outside our equations. For example, if I want to predict the motion of a tossed ball, I have to know how strong gravity is. But there is no theory that explains why gravity has the strength it does. We can only measure that value independently and insert it into the equations.

Over the decades, physicists have compiled various lists of the most important fundamental constants. Generally, there are a little more than two dozen of them. They describe things like the strengths of the four forces of nature, the masses of the fundamental particles, and aspects of space-time, like the speed of light.

We have no idea where these numbers come from and why they have the values they do. One way to study them is to figure out if they are actually constant. If any of these numbers shift either in time or throughout space, that would be a major clue. Variations in the constants would tell us that they are not really fundamental and instead a reflection of our ignorance of a deeper theory of physics.

For example, if I knew nothing about how gravity works, I could still measure the acceleration of objects when near Earth. I could assign a "fundamental" constant to this number and measure it to be 9.8 meters per second squared. I could still predict the trajectories of tossed balls perfectly fine with this number in hand.

But careful observations would reveal that this acceleration isn't really constant. It can change depending on the elevation or even the location on Earth. This would tell me that there's something deeper going on — in this case, that there is a universal force of gravity.

Physicists and astronomers have attempted a variety of experiments to find variations in the constants. In the end, it requires an enormous amount of data to look for incredibly tiny shifts. Scientists can accomplish this either by examining a system for very long periods or looking deep into the cosmos. Either way, we can test to see if some constant or another has changed with time.

For example, astronomers have used measurements of distant quasars, which are incredibly bright sources of radio emission from the early universe. They have also studied the cosmic microwave background, which is the radiation emitted when the universe cooled from a hot plasma state billions of years ago.

An all-sky image of the cosmic microwave background, created by the European Space Agency's Planck satellite, that shows echoes of the Big Bang left over from the dawn of the universe. (Image credit: ESA/ LFI & HFI Consortia)

If constants like the speed of light, the strength of gravity, or even the mass of the electron were different way back when, then we should be able to see a subtle shift in the appearance of those astronomical objects. In other words, they should look different than they do in a universe where the constants really are constant.

Closer to home, physicists study vibrations of atoms, such as those used in atomic clocks, to look for deviations from pure constancy. No matter what, however, we have not observed any hints of anything other than pure uniformity. And these are incredibly precise measurements. For many of the constants, we've pinned their constancy down to no more than a 1-part-per-billion change in a year.

The physics of the universe appear to be fine-tuned for life. Why?

Paul Sutter — Wed, 21 May 2025 14:00:00 +0000

The fundamental constants of nature seem perfectly tuned to allow life to exist. If they were even a little bit different, we simply wouldn't be here. Given this grave existential fact, we are forced to ask a question: Why?

Our laws of physics contain several parameters with values that we cannot predict from theory alone. These are known as the fundamental constants. We can only go out and measure their values and then insert those values into our equations to make physics work. All told, there are about two dozen such numbers. They express such basic facts as the speed of light, the strength of the four fundamental forces, and the masses of elementary particles.

What's especially unnerving about these numbers is how carefully crafted they appear to be. If any were different, even by a tiny amount, our universe would be radically altered. For example, stronger gravity would make stars burn out faster, preventing the rise of solar systems and life-bearing planets like Earth. If the speed of light were faster or the electron were heavier, stars wouldn't even form in the first place. If Planck's constant were different, the cosmos would be totally unrecognizable.

It appears that we live on the knife-edge, where only the narrowest combination of values for the fundamental constants allow life, and especially conscious life, to arise.

This is the heart of the fine-tuning argument: that the universe appears to favor the existence of life. So why are we here?

One answer is to simply end the line of thinking right there. The constants are the way they are because if they were different, we wouldn't be here to observe it. This is called the anthropic argument: Life exists because otherwise, it would be impossible for life to exist.

Many physicists and philosophers consider this argument a little less than satisfying. While it does answer the question, we seem to have this nagging feeling that there's more to the story.

Another possibility is that there's more than one universe — that we live in a multiverse, with each different universe "sampling" different values of the constants. There are a few extremely hypothetical ideas in physics that can lead to the multiverse. One is through the concept of eternal inflation, where the very early universe never ended its period of rapid expansion and different portions of the overall multiverse "pinched off" to create their own bubble universes.

Another path to the multiverse comes from string theory, where extra spatial dimensions can twist up on themselves in a dizzying number of ways. Each possible arrangement would lead to new values of the physical constants, and even entirely new laws of physics. The range of possible combinations is known as the landscape, with our universe consisting of one point in that landscape.

In these multiverse-inspired ideas, there are a multitude of universes "out there" that don't support life — but this one does, so here we are. At the end of the day, it's still the anthropic argument, but at least it's one that explains how different values of the constants can be realized.

But there are issues with both of these ideas. Importantly, both are hypothetical and not supported by any available evidence. We don't know how regular inflation works and whether eternal inflation is even possible. Additionally, string theorists can't make the connection between a particular arrangement of the extra dimensions and the physics it generates, meaning we can't even make testable predictions.

—Why is gravity so weak? The answer may lie in the very nature of space-time

—Could we travel to parallel universes?

What's more, eternal inflation and string theory contain their own constants that are not "explored" by different iterations of the multiverse. For example, string theory assumes a certain number of extra dimensions — a number that is not predicted by the theory itself. And eternal inflation requires any number of extra, unknown parameters to make it work.

So no matter what, we can't yet escape some form of fundamental constant, or some form of knowledge about the universe that we can't explain from our theories themselves. I suppose we'll just have to keep digging.

James Webb Space Telescope discovers most distant and earliest Milky Way 'twin' ever seen. Meet dragon-galaxy Zhúlóng (image)

Robert Lea — Wed, 16 Apr 2025 13:22:43 +0000

Astronomers have discovered the most distant and thus earliest spiral galaxy ever seen, using the James Webb Space Telescope (JWST). This "twin" of the Milky Way existed just 1 billion years after the Big Bang, challenging our theories of galactic evolution.

Previously, it was believed that galaxies like ours would take billions of years to form distinct features like spiral arms, vast star-forming disks, and central bulges of densely packed stars. Yet, rather than being the expected chaotic galactic blob, those well-ordered features appear to be present in this galaxy, which is so distant that its light has taken 12.8 billion years to reach us.

"We named this galaxy Zhúlóng, meaning 'Torch Dragon' in Chinese mythology. In the myth, Zhúlóng is a powerful red solar dragon that creates day and night by opening and closing its eyes, symbolizing light and cosmic time," team leader Mengyuan Xiao of the University of Geneva (UNIGE) said in a statement. "What makes Zhúlóng stand out is just how much it resembles the Milky Way in shape, size, and stellar mass."

Another similarity between the Milky Way and this early cosmic dragon galaxy is the sizes of their stellar disks and the masses of those regions. Zhúlóng's disk spans around 60,000 light-years and has a mass of 100 billion times that of the sun. The Milky Way's disk is slightly wider at 100,000 light-years wide with a stellar mass estimated at around 46 billion solar masses.

A zoomed in image of Zhúlóng the most distant spiral galaxy ever seen as spotted by the JWST (Image credit: NASA/CSA/ESA, M. Xiao (University of Geneva), G. Brammer (Niels Bohr Institute), Dawn JWST Archive )

Zhúlóng was discovered in images collected during the JWST's ANORAMIC survey (GO-2514). This wide-area extragalactic program led by Christina Williams (NOIRLab) and Oesch (UNIGE) exploits a special mode of the $10 billion telescope called "pure parallel," which allows it to collect high-quality images of one object whilst also collecting data from other targets.

"This allows JWST to map large areas of the sky, which is essential for discovering massive galaxies, as they are incredibly rare," Williams said. "This discovery highlights the potential of pure parallel programs for uncovering rare, distant objects that stress-test galaxy formation models."

— This star burped after eating a planet — but the planet was really asking for it

— Scientists used JWST instruments 'wrong' on purpose to capture direct images of exoplanets

In the future, scientists could use the JWST and the Atacama Large Millimeter Array (ALMA), a collection of 66 radio telescopes located in the Atacama desert region of northern Chile, to further investigate the qualities of Zhúlóng.

This could reveal the formation history of this well-ordered galaxy, explaining how a "grand design" spiral galaxy came to exist in the early universe.

"This discovery shows how JWST is fundamentally changing our view of the early universe," Oesch said.

The team's research was published on wednesday (April 16) in the journal Astronomy & Astrophysics.

A gravitational war next door: The Large Magellanic Cloud is gradually destroying the Small Magellanic Cloud

Robert Lea — Fri, 11 Apr 2025 16:00:00 +0000

Two dwarf galaxies are waging war in the vicinity of our Milky Way and it looks like there is only one possible victor.

Using tips from the star-tracking Gaia spacecraft, scientists examined the motions of massive stars in the Small Magellanic Cloud (SMC) to find it is being ripped apart by the gravitational influence of its larger counterpart, the Large Magellanic Cloud (LMC).

The results spell disaster for the SMC, suggesting it may eventually be completely destroyed by this interaction. The SMC's loss is astronomers' gain, however, as this event can teach us more about galactic evolution.

"When we first got this result, we suspected that there might be an error in our method of analysis. However, upon closer examination, the results are indisputable, and we were surprised," team co-leader Kengo Tachihara of Nagoya University said in a statement. "The stars in the SMC were moving in opposite directions on either side of the galaxy, as though they are being pulled apart.

"Some of these stars are approaching the LMC, while others are moving away from it, suggesting the gravitational influence of the larger galaxy. This unexpected movement supports the hypothesis that the SMC is being disrupted by the LMC, leading to its gradual destruction."

Is the Small Magellanic Cloud doomed?

Thanks to the proximity of the SMC to our own galaxy, Tachihara and his colleagues were able to identify and track around 700 massive stars in the dwarf galaxy.

These stars, with over eight times the mass of the sun, burn through their nuclear fuel supplies more rapidly than smaller stars do. This means they have much shorter lifespans. While the sun is expected to burn hydrogen in its "main sequence" lifetime for around 10 billion years, massive stars can exhaust their nuclear fuel in just a few million years. After exhausting their fuel supplies, the stars erupt in supernova explosions, leaving behind neutron stars or black holes.

The velocities of massive stars in the SMC. Red arrows are stars moving toward the LMC, which is at the bottom left. Blue arrows are stars in the SMC moving away from the LMC (Image credit: Satoya Nakano)

In addition to discovering stars moving in opposite directions on different sides of the SMC, the team also found that the stars in this dwarf galaxy lacked rotational motion. This is surprising because massive stars are born from clouds of collapsing interstellar gas, which, as we have seen in the Milky Way, do rotate. Plus, massive stars usually share that rotational motion when they are young, as they have not yet "decoupled" themselves from their pre-natal cocoons.

This lack of rotating stars in the SMC hints that the interstellar gas in the dwarf galaxy may also not rotate. This could have implications for how we model the SMC and its interactions with the LMC and the Milky Way.

"If the SMC is indeed not rotating, previous estimates of its mass and its interaction history with the Milky Way and LMC might need to be revised," team co-leader Satoya Nakano, also of Nagoya University, said in the statement. "This could potentially change our understanding of the history of the three-body interaction between the two Magellanic Clouds and the Milky Way."

— Hidden monster black hole in the galaxy next door fired stars at us like million mph cosmic bullets

— NASA wants a 'Super-Hubble' space telescope to search for life on alien worlds

The new findings could help scientists better understand dynamic interactions between galaxies in general. Because the SMC and LMC share many characteristics with primordial galaxies in the early universe, such as the dearth of elements heavier than hydrogen and helium, this research could also help understand how the interactions of galaxies in the early universe shaped the cosmos as we see it today.

"We are unable to get a 'bird's-eye view' of the galaxy in which we live," Tachihara said. "As a result, the SMC and the LMC are the only galaxies in which we can observe the details of stellar motion.

"This research is important because it allows us to study the process of star formation in connection with the motion of stars throughout the galaxy."

The team's research was published on Thursday (April 10) in The Astrophysical Journal Supplement Series.

Watch SpaceX, NASA launch SPHEREx and PUNCH science probes tonight after multiple delays (video)

Monisha Ravisetti — Thu, 27 Feb 2025 10:00:50 +0000

Two NASA missions called "SPHEREx" and "PUNCH" could share a ride to space this evening (March 11) after multiple delays.

The agency had planned to launch both missions at the same time on Saturday (March 8) aboard a SpaceX Falcon 9 rocket, but SpaceX delayed the launch to complete vehicle checkouts. The next attempt, planned for March 10, was scrubbed due to poor weather and an undisclosed issue with one of the spacecraft.

SpaceX has now announced a new launch window starting at at 11:10 p.m. EDT on Tuesday, March 11 (0310 March 12 GMT). Liftoff will occur from Launch Complex 4E at Vandenberg Space Force Base in California. NASA has predicted a 40% chance of weather violation due to clouds, however. SpaceX has a backup opportunity at the same time on Wednesday (March 12) in case weather forces another delay.

A SpaceX Falcon 9 rocket carrying NASA’s SPHEREx and PUNCH missions is vertical on Space Launch Complex 4 East at Vandenberg Space Force Base in California on March 8, 2025. (Image credit: SpaceX)

SPHEREx — which stands for Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer — is a conical white spacecraft constructed to work as a sort of wide-angle version of the James Webb Space Telescope. It'll be working with information-rich infrared light wavelengths emanating from the distant universe just like the JWST does, but it will do so on a much wider scale.

The JWST can peer into the crevices of a faraway galaxy with remarkable resolution, for instance, while SPHEREx will be able to detect the other galaxies around the JWST's single target with its own stellar imaging capabilities.

Meanwhile, PUNCH — which stands for Polarimeter to Unify the Corona and Heliosphere — will be searching for secrets of solar dynamics. Made up of four satellites that'll be stationed around our planet, this mission is meant to help scientists understand how the sun's outer atmosphere, or corona, turns into the solar wind. This is important because the solar wind ricochets around the bubble our solar system sits within, known as the heliosphere; the edges of that bubble represent the barrier between our cosmic neighborhood and the rest of the universe.

Decoding how our sun operates in general can offer many benefits to humanity, but the most obvious probably has to do with space weather. Sometimes, for instance, bursts of plasma rip off the sun and turn into what are known as coronal mass ejections, or CMEs, that can barrel toward our planet. This happens relatively often, meaning a CME headed our direction doesn't mean we're in for doomsday, to be clear — but space weather resulting from such events can indeed affect things like our power grid and the health of astronauts in space.

On the left, an animation showing the SPHEREx space telescope. On the right, the PUNCH primary spacecraft (Image credit: NASA (Screenshot by Space.com))

— NASA's 'SPHEREx' infrared space telescope is launching this week. Here's why it's a big deal

— NASA's launching a new sun mission this month: 'PUNCH is going to see a total solar eclipse'

While waiting for these missions to launch, if you'd like to read more about each of them, you can check out our detailed explanations about how they work here.

The science of SPHEREx, for instance, provokes intriguing questions, such as why cosmic inflation occurred just after time began and how water arrived on Earth to support life as we know it. PUNCH's work and observing techniques will also be incredibly interesting, delving into how the property of light called "polarization" can tell us about the directions of different features within our solar wind chamber (including CMEs) and the way an "artificial solar eclipse" will be instrumental in the mission's success.

Editor's Update: This article was updated on March 11 to reflect the latest launch information for this mission.

NASA pauses work by key space science groups amid Trump executive orders

tmalik@space.com (Tariq Malik) — Mon, 03 Feb 2025 18:47:45 +0000

NASA has ordered a pause on all work by key planetary and astrophysics science committees due to recent executive orders by President Donald Trump.

In a series of memos sent from NASA headquarters late Friday (Jan. 31), the space agency directed the leaders of at least 10 planetary science assessment and analysis groups that cover a wide range of topics, from the exploration of the moon and solar system planets to "ocean worlds" like the icy moons of Saturn and Jupiter. According to SpaceNews, NASA's astrophysics assessment groups received similar memos, all of which cited a need to ensure the groups were in compliance with recent executive orders by Trump.

"As NASA continues to review and ensure compliance with presidential actions, we are requesting that you please pause all meetings and activities of Planetary Science Analysis/Assessment Groups," read one NASA memo to the Mercury Exploration Assessment Group, which was obtained by Space.com and was nearly identical to memos sent to other planetary science committees.

The memos cited six Trump executive actions, three of them aimed at ending diversity, equity and inclusion (DEI) programs in the federal government. Two others targeting so-called "gender ideology extremism," while another referred to "Unleashing American Energy" that roll back climate change-related executive orders by the Biden administration.

The pause order from NASA headquarters has already led to the cancellation of at least one planetary science meeting. The Mercury exploration group, known by the acronym MExAG was scheduled to hold its first in-person meeting this week from Feb. 4 to Feb. 6, but will no longer meet.

"We are forced, therefore, to cancel MExAG 2025," the Mercury committee's chair Carolyn Ernst, a planetary scientist with Johns Hopkins University Applied Physics Laboratory, wrote in a memo obtained by Space.com. "This turn of events is shocking and concerning, and is extra painful given the order comes four days before our first in-person meeting." Some committee members had already begun travel for the meeting, Ernst added.

The nearly three-day hybrid meeting was expected to include at up 200 scientists attending either in person of virtually, one scientist Ed Rivera-Valentin shared on the social media site Bluesky. It was expected to include a number of researchers connected to the BepiColombo Mercury mission run by the Japan Aerospace Exploration Agency and the European Space Agency. The probe just made its sixth flyby of Mercury on Jan. 8.

Lava and debris on Mercury's surface as seen by the ESA/JAXA BepiColombo mission on 8 January 2025 during its sixth flyby (Image credit: ESA/BepiColombo/MTM)

"The MExAG steering committee is heartbroken that our first in-person meeting was cancelled due to this," scientist Mallory Kinczyk wrote on Bluesky.

Vicky Hamilton, a planetary geologist with the Southwest Research Institute who chairs NASA's Mars Exploration Program Analysis Group, said in a memo to her committee that the group has stopped planning work for its own meeting scheduled for April.

"We will let everyone know as soon as we are able to resume work," she wrote in a memo obtained by Space.com.

NASA's assessment and analysis groups meet regularly to assess the latest discoveries and missions in their specific fields and report them back to the space agency's internal planetary science and astrophysics divisions. While they provide key insight into space science, the groups are not formal advisory committees overseen by the Federal Advisory Committee Act, according to SpaceNews. Many of the planetary science committees are overseen by the Lunar and Planetary Institute, which itself is managed by the Universities Space Research Association.

— Trump says he'd create a Space National Guard if elected

— Trump's space policy won't catch Europe off guard, ESA chief says

NASA's pause order to its analysis groups is one of several agency changes that have followed executive orders from the Trump administration.

The agency has begun restricting funding to programs related to diversity, equity and inequality, including to a Here to Observer program that connected students from underrepresented groups with NASA planetary science missions, according to SpaceNews.

SpaceNews also reported that the agency has removed a 2023 article about the NASA astronaut class of 1978, a team that included the agency's first Black, Asian-American and female astronauts, written by NASA's own history office. It appears to have been removed by Jan. 29, after being accessible as late as Jan. 25, SpaceNews added. You can still find the article on the Internet Archive.

Space.com has reached out to NASA headquarters for comment and will update this story if one is received.

Egg-shaped galaxies may be aligned to the black holes at their hearts, astronomers find

David Parkinson — Thu, 21 Nov 2024 18:00:00 +0000

Black holes don’t have many identifying features. They come in one color (black) and one shape (spherical).

The main difference between black holes is mass: some weigh about as much as a star like our Sun, while others weigh around a million times more. Stellar-mass black holes can be found anywhere in a galaxy, but the really big ones (known as supermassive black holes) are found in the cores of galaxies.

These supermassive behemoths are still quite tiny when seen in cosmic perspective, typically containing only around 1% of their host galaxy’s mass and extending only to a millionth of its width.

However, as we have just discovered, there is a surprising link between what goes on near the black hole and the shape of the entire galaxy that surrounds it. Our results are published in Nature Astronomy.

When black holes light up

Supermassive black holes are fairly rare. Our Milky Way galaxy has one at its centre (named Sagittarius A*), and many other galaxies also seem to host a single supermassive black hole at their core.

Under the right circumstances, dust and gas falling into these galactic cores can form a disk of hot material around the black hole. This “accretion disk” in turn generates a super-heated jet of charged particles that are ejected from the black hole at mind-boggling velocities, close to the speed of light.

When a supermassive black hole lights up like this, we call it a quasar.

How to watch a quasar

To get a good look at quasar jets, astronomers often use radio telescopes. In fact, we sometimes combine observations from multiple radio telescopes located in different parts of the world.

Using a technique called very long baseline interferometry, we can in effect make a single telescope the size of the entire Earth. This massive eye is much better at resolving fine detail than any individual telescope.

As a result, we can not only see objects and structures much smaller than we can with the naked eye, we can do better than the James Webb Space Telescope.

Black holes are millions of times smaller than galaxies, yet make jets that are pointed in the same direction as the entire galaxy. (Image credit: Optical image: NASA, ESA, R.M. Crockett (University of Oxford, U.K.), S. Kaviraj (Imperial College London and University of Oxford, U.K.), J. Silk (University of Oxford), M. Mutchler (Space Telescope Science Institute, Baltimore, USA), R. O'Connell (University of Virginia, Charlottesville, USA), and the WFC3 Scientific Oversight Committee. Top right: MOJAVE Collaboration, NRAO/NSF. Bottom right: Event Horizon Telescope / ESO (same as before) CC BY-SA)

When black holes light up

Supermassive black holes are fairly rare. Our Milky Way galaxy has one at its centre (named Sagittarius A*), and many other galaxies also seem to host a single supermassive black hole at their core.

When a supermassive black hole lights up like this, we call it a quasar.

How to watch a quasar

To get a good look at quasar jets, astronomers often use radio telescopes. In fact, we sometimes combine observations from multiple radio telescopes located in different parts of the world.

As a result, we can not only see objects and structures much smaller than we can with the naked eye, we can do better than the James Webb Space Telescope.

Supergiant star Betelgeuse may have a 'Betelbuddy'

Samantha Mathewson — Tue, 22 Oct 2024 19:00:01 +0000

Could the giant star Betelgeuse have a buddy? A Betelbuddy?

Betelgeuse, the second-brightest star in the constellation Orion, is a giant star whose strange dimming has sparked debate over when it will collapse and explode in a massive supernova. Now, however, researchers believe a companion star may be behind Betelgeuse's irregular changes in brightness.

A new study used computer models to simulate Betelgeuse's activity, suggesting that the object's periodic pulsing is likely caused by an unseen, orbiting companion star — or stellar-like object, at least. The researchers aptly nicknamed the proposed object "Betelbuddy," or more formally, Alpha Orionis B (Betelgeuse is technically known as Alpha Orionis).

"We ruled out every intrinsic source of variability that we could think of as to why the brightening and dimming was happening in this way," Jared Goldberg, lead author of the study and a research fellow at the Flatiron Institute's Center for Computational Astrophysics, said in a statement.. "The only hypothesis that seemed to fit is that Betelgeuse has a companion."

Betelgeuse is a red giant star that exhibits roughly 100,000 times the brightness of our sun and more than 400 million times the volume. According to the new models, a companion star could act like a snowplow, pushing light-blocking dust out of the way as it orbits Betelgeuse and, in turn, allowing it to appear temporarily brighter from our vantage point.

This companion star model helps explain the different patterns of pulsating light observed from Betelgeuse. The star exhibits two separate periods of brightening and dimming: one that pulses on a timescale a little longer than a year, and one that pulses on a timescale of about six years. As a variable star, one of these patterns is intrinsic to Betelgeuse, caused by the star's rhythmic expansion and contraction, and indicative of when it will become a supernova.

"If the star's fundamental mode is its long-scale heartbeat, then Betelgeuse could be ready to blow sooner than expected," according to the statement. "However, if its fundamental mode is its short-scale heartbeat, as several studies suggest, then its longer heartbeat is a phenomenon called a long secondary period."

A long secondary period can be triggered by something external to the star, including a companion. In this case, the researchers argue Betelbuddy could be another star with up to twice the sun's mass. However, further study is required to not only confirm Betelbuddy exists, but to also better understand the true nature of a possible companion star.

— Betelgeuse may be the result of a 'quiet' star merger

— Here's what the supergiant star Betelgeuse will look like when it goes supernova

"[Betelgeuse] has been the target of countless studies since the dawn of modern astrophysics," László Molnár, co-author of the study from the Konkoly Observatory at the HUN-REN Research Center for Astronomy and Earth Sciences in Hungary, said in the statement. "And yet there's still room to make significant new discoveries: in this case, a sunlike star hiding in plain sight, in the immense glare of a red supergiant. That is what excites me the most."

Their findings have been accepted for publication in the The Astrophysical Journal and are currently available to view as a pre-print on the arXiv.

How to watch 'Solar System' online and from anywhere – Brian Cox's five-part series

Tom Bailey — Mon, 07 Oct 2024 17:28:09 +0000

'Solar System': Key information

• UK: Watch for FREE on BBC iPlayer
• US: Watch on PBS Nova
• Away from home: Use a VPN such as NordVPN to watch your usual service from anywhere

After the success of TV shows such as "Planets" and "Adventures in Space and Time", Brian Cox is back with a new five-part series: "Solar System".

The popular physicist will set out to lift the lid on the "truly extraordinary" events unfolding daily on the planets and moons of our solar system.

"We are living through a golden age of exploration," Cox told the BBC. "As we speak, there are spacecraft in orbit around or on the surface of five of the eight planets in our solar system, and there are a host of new missions close to launch or en-route to their targets. As new data cascades in, we are building an ever more accurate picture of our solar system."

The first episode is entitled 'Volcano Worlds' and sees Cox examine the Volcanic activity on other planets, most notably Venus, where volcanoes abound and evidence grows that they are more active than previously thought.

How to watch 'Solar System' for free in the UK

How to watch 'Solar System' from anywhere

If you're a UK resident abroad, you can still watch "Solar System" for free on BBC iPlayer.

Downloading a VPN allows you to stream your favourite content from anywhere. These simple pieces of software can change your IP address, allowing you to access on-demand content or live TV just as you would at home.

BBC iPlayer doesn't work outside of the UK. A VPN solves that problem...

Important: we do not support or condone the illegal or malicious use of VPN services. Consuming pirated content that is paid-for is neither endorsed nor approved by Future Publishing.

How to watch 'Solar System' in the US

"Solar System" was produced for PBS and the BBC.

The five-part series airs on PBS on Wednesdays, beginning October 2 at 9pm Eastern Time / 8pm Central Time. The series will also be available for streaming at PBS Nova, NOVA on YouTube, and the PBS app.

Remember: Brits away from home can use NordVPN to access BBC iPlayer when traveling abroad. You'll need an iPlayer account (free) and a valid TV license.

Solar System official trailer

Ahead of the first episode, here's a teaser of what's in store...

"Solar System" (2024) episodes

Episode 1: Volcano Worlds
Professor Brian Cox journeys to the volcano worlds of the solar system and explore alien landscapes bursting with fire and ice.

Episode 2: Dark Worlds
Professor Cox explores the solar system’s hidden realms, between and beyond the planets, where countless worlds lie shrouded in darkness.

Episode 3: Storm Worlds
Professor Cox explores the storm worlds of the solar system and the weird weather that plays out in the atmospheres of distant planets and moons.

Episode 4: Ice Worlds
Professor Cox meets the dwarf planet where mountains of solid ice float across the surface.

Episode 5: Strange Worlds
Professor Cox visits an egg-shaped dwarf planet that shouldn’t really exist and a tiny moon that looks like a UFO.

"Solar System" FAQ

Who else appears in the "Solar System" TV series?

"Solar System" features a whole host of scientists including: Carly Howett from Oxford University; Lynnae Quick from NASA’s Goddard Space Flight Center; Veronica Bray Durfey from University of Arizona; Leigh Fletcher from the University of Leicester; James O’Donoghue from the University of Reading; James Dottin III from Brown University; Hakeem Oluseyi from George Mason University; Michael L. Wong from the Carnegie Institution for Science; Katherine de Kleer from the California Institute of Technology; George Dransfield from Birmingham University; David Grinspoon from NASA; Derrick Pitts from the Franklin Institute; Shannon MacKenzie from Johns Hopkins University; Abigail Fraeman from NASA’s Jet Propulsion Laboratory; Peter Gao from Carnegie Science; Alejandro Soto from the Southwest Research Institute; Jen Gupta from the University of Portsmouth; Sara T. Port, from the NASA Glenn Research Center; Amy Mlinar from the Planetary Science Institute.

Earth's upper atmosphere could hold a missing piece of the universe, new study hints

Paul Sutter — Wed, 03 Jul 2024 15:00:01 +0000

Earth may be swimming through an ocean of dark matter — and waves in that invisible ocean lapping against our planet's upper atmosphere may generate detectable radio waves that allow us to finally find this elusive component of the universe, according to new theoretical research.

A wealth of astrophysical and cosmological evidence points to the existence of dark matter, from the inexplicable rotation curves of certain galaxies to the growth of the largest structures in the universe. Attempts to explain this wide variety of observations with alternative formulations of gravity have failed, so the vast majority of astronomers think dark matter is some unknown form of matter that only rarely interacts with light or with normal matter.

But that is a very broad idea that encompasses a lot of possibilities. Dark matter may be made of massive particles, but searches for those kinds of particles have largely turned up empty. So an intriguing alternative is that dark matter is exceptionally light, either in the form of theoretical particles known as "axions" or as an exotic form of photon that carries a bit of mass.

With that incredible lightness — millions of times lighter than the lightest known particles — dark matter could act in very strange ways. In particular, instead of appearing as individual point-like bullets, the dark matter would behave more like large waves that slosh around the cosmos.

In a recent study published to the preprint server arXiv, physicists explored models of ultralight dark matter that wasn't entirely dark, allowing it to interact extremely rarely with normal matter. Most of the time, these interactions barely registered, producing nothing detectable. But in rare cases, the dark matter and normal matter interacted enough to produce a sizable amount of radio waves.

This would occur when the dark matter encountered a plasma and when the frequency of dark matter waves lined up with the frequency of plasma waves. When this happened, a resonance would occur, amplifying the interaction and producing radiation in the form of radio waves, the team’s models suggested.

The universe is no stranger to plasmas — all stars spew plasma into space in the form of stellar wind — so theorists had already explored the production of radio waves due to dark matter interacting with environments such as the solar corona or the interstellar medium. But in this new research, the scientists discovered an interaction point much closer to home: our planet's ionosphere.

Earth's ionosphere is the thin, hot layer of the upper atmosphere, and it consists of a loose collection of ionized (charged) particles — a plasma. It naturally has waves sloshing through it, and the researchers discovered that those waves can interact with waves of hypothetical dark matter that might be washing over Earth.

The radio waves produced by this interaction would be barely detectable. But the researchers found that by using a carefully tuned radio antenna to search for a specific frequency of radio waves over the course of a year, they might be able to detect these waves.

A star that exploded like a nuclear bomb is still raising questions half a century later

Keith Cooper — Wed, 12 Jun 2024 12:00:35 +0000

The aftermath of a thermonuclear explosion in a binary star system about 3,400 light years away has been witnessed by the Hubble Space Telescope.

HM Sagittae, or HM Sge for short, is what's known as a symbiotic system, in which a white dwarf is feeding off a companion red giant star. The stolen material forms an accretion disk swirling around the white dwarf. If too much material falls from the disk onto the white dwarf at once, the pressure and temperature becomes so great that a thermonuclear explosion detonates on the surface of the white dwarf.

Though this explosion isn't enough to destroy the white dwarf in a supernova, it does release enough energy to cause the system to brighten in what's termed a "nova."

Between April and September 1975, HM Sge went nova in the constellation of Sagitta, the Arrow. It brightened in the night sky by six magnitudes from magnitude +17 (visible only to telescopes with apertures larger than about 305mm/12 inches) to magnitude +10.5, at which point it became more easily visible to telescopes with smaller apertures equal to about 102mm/4 inches, allowing amateur astronomers to keep track of it. This brightening equates to an increase in luminosity of 250 times.

Ever since it went nova, HM Sge hasn't been following the rules. Most novas simmer down after a few days; HM Sge remained at its peak brightness for years, until the mid-1980s, before it began to slowly fade, punctuated by more notable dimming events. Even now, it has only faded to about magnitude +12.

"In 1975 HM Sge went from being a nondescript star to something all astronomers in the field were looking at, and at some point the flurry of activity slowed down," said Ravi Sankrit of the Space Telescope Science Institute (STScI) in a statement.

"Symbiotic stars like HM Sge are rare in our galaxy, and witnessing a nova-like explosion is even rarer," added Steven Goldman, also of STScI, in the statement. "This unique event is a treasure for astrophysicists spanning decades."

Observations over the years with a multitude of telescopes have tried to get to the bottom of what is happening in HM Sge. Now, Goldman and Sankrit have attained new results with their team, based on 2021 Hubble Space Telescope observations and data collected with NASA's now-defunct SOFIA (Stratospheric Observatory for Infrared Astronomy), which featured an infrared telescope in the back of a Boeing 747 aircraft, in 2021 and 2022.

The onset of dimming with regard to the system in 1985 until now has been attributed at least partly to the behavior of the red giant star. It's what's called a Mira variable (after the prototype of the class, Mira — omicron Ceti — in the constellation of Cetus, the Whale) and endures periodic pulsations roughly every 534 days. The start of the system's dimming in the mid-1980s has been attributed to one of two things. It could either have been instigated by a larger-than-typical mass-loss event from the red giant linked to its pulsations, which would have created an outpouring of dust that blocks some of the light, or it could be the result of the 90-year, non-circular orbit of the white dwarf and red giant about one another taking them farther apart, reducing the amount of material flowing between the two. Currently, the separation between the two components of the system is approximately 40 astronomical units (AU), where 1 AU is defined by the average distance between Earth and our sun, 149.6 million kilometers (93 million miles). For comparison, Neptune is 30 AU from the sun.

Hubble's observations also revealed a strong emission line from ionized magnesium. This emission line was not present in spectra of HM Sge dating back to 1990, when the temperature of the white dwarf was 200,000 degrees Celsius ( about 400,000 degrees Fahrenheit). For strongly ionized magnesium to exist in large abundance, the temperature of the white dwarf must have risen in that time to 250,000 degrees Celsius (about 450,000 degrees Fahrenheit). This makes it one of the hottest white dwarfs known, despite the system fading in brightness overall. What is causing this rise in temperature is currently a mystery.

HM Sge, imaged by the Hubble Space Telescope. The nebulosity that surrounds the system is material puffed off by the red giant. (Image credit: NASA, ESA, Ravi Sankrit (STScI), Steven Goldman (STScI))

Furthermore, SOFIA was able to detect emission lines from water vapor in the disk for the first time in a symbiotic binary, and use its signal as a proxy for measuring the properties of the accretion disk. The water molecules appear to be moving at 29 kilometers (18 miles) per second, which is attributed to their speed flowing around the edge of the disk.

However, most of the emission lines in HM Sge's spectrum are weakening compared to 1990, showing that the system is slowly changing and evolving, possibly as the red giant and white dwarf move apart.

Goldman and Sankrit's team conclude that the HM Sge system settled down to a "new normal" quite quickly after the nova explosion 1975 with only a slow decrease in brightness on average over the years (there has been some up and down in brightness, both in optical and the infrared and not always at the same time, again attributed to the behavior of the red giant). The overall fading may continue at its slow pace for many more years, until the white dwarf and red giant come close again in their orbit, increasing the amount of material flowing between the two of them and sparking another nova.

Finally, the white dwarf is a preview of what fate has in store for the red giant companion. Both were once sun-like stars in a binary system, one star a little more massive than the other. The more massive star used up its nuclear fuel faster, and evolved into a red giant that eventually cast away its diffuse outer envelope to reveal its exposed, inert core — the white dwarf. The other star evolved a little more slowly, but is now following the same path as its sibling, first evolving into a red giant and then into a white dwarf after a million or so years.

The gravitational upheaval that the red giant's transformation will cause could draw the two white dwarfs close to one another. One day, if they collide, they will explode as a Type Ia supernova, but that won’t happen for hundreds of millions, or perhaps even billions, of years.

The findings from Hubble and SOFIA were published in The Astrophysical Journal.

Black holes are mysterious, yet also deceptively simple − a new space mission may help physicists answer hairy questions about these astronomical objects

Gaurav Khanna — Tue, 21 May 2024 13:00:05 +0000

Physicists consider black holes one of the most mysterious objects that exist. Ironically, they’re also considered one of the simplest. For years, physicists like me have been looking to prove that black holes are more complex than they seem. And a newly approved European space mission called LISA will help us with this hunt.

Research from the 1970s suggests that you can comprehensively describe a black hole using only three physical attributes – their mass, charge and spin. All the other properties of these massive dying stars, like their detailed composition, density and temperature profiles, disappear as they transform into a black hole. That is how simple they are.

The idea that black holes have only three attributes is called the “no-hair” theorem, implying that they don’t have any “hairy” details that make them complicated.

Hairy black holes?

For decades, researchers in the astrophysics community have exploited loopholes or work-arounds within the no-hair theorem’s assumptions to come up with potential hairy black hole scenarios. A hairy black hole has a physical property that scientists can measure – in principle – that’s beyond its mass, charge or spin. This property has to be a permanent part of its structure.

About a decade ago, Stefanos Aretakis, a physicist currently at the University of Toronto, showed mathematically that a black hole containing the maximum charge it could hold – called an extremal charged black hole – would develop “hair” at its horizon. A black hole’s horizon is the boundary where anything that crosses it, even light, can’t escape.

Aretakis’ analysis was more of a thought experiment using a highly simplified physical scenario, so it’s not something scientists expect to observe astrophysically. But supercharged black holes might not be the only kind that could have hair.

Since astrophysical objects such as stars and planets are known to spin, scientists expect that black holes would spin as well, based on how they form. Astronomical evidence has shown that black holes do have spin, though researchers don’t know what the typical spin value is for an astrophysical black hole.

Using computer simulations, my team has recently discovered similar types of hair in black holes that are spinning at the maximum rate. This hair has to do with the rate of change, or the gradient, of space-time’s curvature at the horizon. We also discovered that a black hole wouldn’t actually have to be maximally spinning to have hair, which is significant because these maximally spinning black holes probably don’t form in nature.

Detecting and measuring hair

My team wanted to develop a way to potentially measure this hair – a new fixed property that might characterize a black hole beyond its mass, spin and charge. We started looking into how such a new property might leave a signature on a gravitational wave emitted from a fast-spinning black hole.

A gravitational wave is a tiny disturbance in space-time typically caused by violent astrophysical events in the universe. The collisions of compact astrophysical objects such as black holes and neutron stars emit strong gravitational waves. An international network of gravitational observatories, including the Laser Interferometer Gravitational-wave Observatory in the United States, routinely detects these waves.

Our recent studies suggest that one can measure these hairy attributes from gravitational wave data for fast-spinning black holes. Looking at the gravitational wave data offers an opportunity for a signature of sorts that could indicate whether the black hole has this type of hair.

Our ongoing studies and recent progress made by Som Bishoyi, a student on the team, are based on a blend of theoretical and computational models of fast-spinning black holes. Our findings have not been tested in the field yet or observed in real black holes out in space. But we hope that will soon change.

LISA gets a go-ahead

In January 2024, the European Space Agency formally adopted the space-based Laser Interferometer Space Antenna, or LISA, mission. LISA will look for gravitational waves, and the data from the mission could help my team with our hairy black hole questions.

The LISA spacecrafts observing gravitational waves from a distant source while orbiting the Sun. (Image credit: Simon Barke/Univ. Florida, CC BY)

Formal adoption means that the project has the go-ahead to move to the construction phase, with a planned 2035 launch. LISA consists of three spacecrafts configured in a perfect equilateral triangle that will trail behind the Earth around the Sun. The spacecrafts will each be 1.6 million miles (2.5 million kilometers) apart, and they will exchange laser beams to measure the distance between each other down to about a billionth of an inch.

LISA will detect gravitational waves from supermassive black holes that are millions or even billions of times more massive than our Sun. It will build a map of the space-time around rotating black holes, which will help physicists understand how gravity works in the close vicinity of black holes to an unprecedented level of accuracy. Physicists hope that LISA will also be able to measure any hairy attributes that black holes might have.

With LIGO making new observations every day and LISA to offer a glimpse into the space-time around black holes, now is one of the most exciting times to be a black hole physicist.

Euclid telescope: A scientist tells us of his quest to understand the nature of dark matter and dark energy

Henk Hoekstra — Mon, 06 May 2024 14:00:02 +0000

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

Henk Hoekstra is a professor in observational cosmology at Leiden University.

On July 1st 2023, Euclid, a unique European space telescope was launched from Cape Canaveral. The launch was undoubtedly the highlight of my career as an astronomer, but witnessing the result of years of work being put on a rocket is not for the faint of heart. Following a perfect launch, Euclid swiftly arrived to its planned orbit, about 1.5 million km aways from Earth. From this distant vantage point, it has started sending back sharp images that will cover nearly one-third of the sky by the end of this decade.

Euclid is the next big step forward in our quest to try to understand the universe. Over the past century we have made tremendous progress. We have learned that the fusion of hydrogen into helium powers stars like our Sun, while most of the atoms in our bodies were forged in the cores of stars that have since exploded. We discovered that the Galaxy is one of many galaxies that trace enormous foam-like structures that permeate the cosmos.

We now know that the Universe started about 13.6 billion years ago with a "Big Bang" and has been expanding ever since.

Probing the universe’s black box

These are major achievements, but as we learned more, it also became clear that there is much that we do not understand. For instance, most of the mass is believed to be “dark matter”, a new form of matter that is not explained by the otherwise highly successful standard model of particle physics. The gravitational pull of all this matter should slow down the expansion of the universe, but about 25 years ago we found that it is actually speeding up. This requires an even more mysterious component. To reflect our ignorance – to date, no good physical explanation exists – we refer to it as “dark energy”. Combined, dark matter and dark energy make up 95% of the universe, but we do not understand their nature.

What we do know is that both dark components influence how large structures can form. The gravity from dark matter helps to pull together matter into galaxies or even larger objects. In contrast, dark energy pushes things apart, thus effectively counteracting the gravitational pull. The balance between the two evolves as the universe expands, with dark energy becoming ever more dominant. The details depend on the nature of the dark components, and comparison with observations allows us to distinguish between different theories. This is the main reason why Euclid was launched. It will map how the matter is distributed, and how this evolved over time. These measurements can provide the much-needed guidance that will lead to a better understanding of the dark side of the universe.

But how can we study the distribution of matter, if most of it is invisible dark matter? Fortunately, nature has provided a convenient way forward: Einstein’s theory of general relativity tells us that matter curves the space around it. Clumps of dark matter reveal their presence by distorting the shapes of more distant galaxies, just like waves on the surface of a swimming pool distort the pattern of tiles on the bottom.

Figure 1: Euclid image of the Perseus cluster of galaxies. The large, yellow galaxies are part of this massive clump of matter, but we can discern another 50,000 distant galaxies. (Image credit: ESA/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi, Fourni par l'auteur)

Figure 1: If we zoom in (right) we can see each galaxy with an amazing level of detail. Thanks to the large field-of-view we can observe such large structures for the first time with such high quality. (Image credit: ESA/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi, Fourni par l'auteur)

Gravitational lensing and its clues

Given the similarity with regular optical lenses – the physics is different, but the math is the same – the bending of light rays by matter is referred to as gravitational lensing. In rare cases the bending is so strong that multiple images of the same galaxy can be observed. Most of the time, however, the effect is more subtle, ever so slightly changing the shapes of distant galaxies. Nonetheless, if we average measurements for large numbers of galaxies, we can uncover patterns in their orientations that have been imprinted by the intervening distribution of matter, both regular and dark.

This “weak lensing” signal may not be that spectacular, but it does provide us with a direct way to map the distribution of matter in the universe, especially when combined with distances to the galaxies for which the shapes were measured. The potential of this technique was recognized in the early nineties, but it was also clear that the measurements would be challenging. Turbulence in the atmosphere blurs our view of the faint, small, distant galaxies that we want to use, while imperfections in the telescope optics inevitably change the observed shapes of galaxies. Hence, the astronomical community was skeptical about the technical feasibility. This was the situation when I started my PhD in 1995, when I embarked on a journey to prove them wrong.

An illustration of strong lensing (left) and how weak gravitational lensing distorts the observed shapes of a field of galaxies (center) if matter is in the foreground near the line-of-sight (right): The presence of matter between the background galaxies and us causes a coherent distortion in their shape and orientation. If done for a large part of the sky, such a distortion measurement carries valuable information about the distribution of matter across cosmic time. (Image credit: ESA/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi)

Over the years, using ever larger data sets collected with ground-based telescopes, we discovered and solved new problems. Basing myself on observations from the Hubble Space Telescope launched in 1990, my thesis work had already shown partially measuring shapes is far easier from space. However, until the arrival of Euclid, space telescopes could only observe tiny patches of sky: the James Webb Space Telescope (JWST), launched in 2021, sees the equivalent of a grain of sand at arm’s length. However, to really test the nature of dark energy we need to cover 6 million times more area. This is what led to Euclid, a unique telescope, designed to provide sharp images for 1.5 billion galaxies, as well as distance information to these. As figure 2 shows, in a single shot we observe an area larger than the full Moon.

These data are complemented by precise distances for about 25 million galaxies to map the distribution of distant galaxies in great detail.

Cosmology coordinator for Euclid

When I started my journey into this research field, dark energy had not been discovered, while few believed weak lensing would be a major tool to study the distribution of matter. How things have changed. The launch of Euclid is arguably the most spectacular demonstration of this. Since 2011 - when the project was still being considered by the European Space Agency (ESA) as part of its Cosmic Vision program - I have been as one of Euclid’s cosmology coordinators. This means I was responsible for establishing the main characteristics of the mission, in particular those pertaining to weak gravitational lensing. This included specifying how sharp the images should be, and how well we need to measure the shapes of galaxies. The work also involved frequent interactions with the European Space Agency (ESA) to clarify the science objectives and to figure out how to deal with new insights.

Figure 2: This picture shows Euclid’s field-of-view against the size of the full Moon. A single exposure is about 100x that of the Hubble Space Telescope, while its sharpness is almost the same. (Image credit: ESA/Euclid Consortium/NASA, image processing by J.-C. Cuillandre (CEA Paris-Saclay), G. Anselmi, Fourni par l'auteur)

Thanks to hard work by a large team of engineers and scientists, we managed to overcome the many technical hurdles. We continued our collaboration through a pandemic, only to lose our intended rocket because of the Russian invasion of Ukraine - Euclid was planned to launch on a Soyuz rocket. Remarkably, ESA quickly found a solution: a launch on a Falcon 9 by SpaceX. As a result, I found myself in Florida to witness what was arguably the culmination of all my research so far.

Euclid’s obstacle course

It has been a rollercoaster ride since. The first images taken in July were noisier than anticipated, due to sunlight that seeped into the camera. This would have been a serious problem, but the most likely culprit – a protruding thruster that reflected sunlight onto the back of the sunshield – was quickly identified, as was the solution. By rotating the spacecraft ever so slightly, the thruster could be placed in the shadow of the satellite. This, however, meant a complete overhaul of the planning of the survey.

The problems did not stop there. Radiation from the sun continuously pushes Euclid around a bit, which is compensated using thrusters that keep the telescope completely stable. Only then can we take the sharp pictures we need. However, energetic particles from the Sun interfered with the stabilizing system, causing the telescope to shake a little. This was solved with a software update. Most recently, the build-up of ice inside the telescope caused concern, but that problem was also successfully tackled.

Figure 3: Euclid image of IC 342, a spiral galaxy near the plane of the Milky Way. Euclid’s sensitive observations at near-infrared wavelengths, reveals many details in this galaxy. (Image credit: ESA, Fourni par l'auteur)

To provide the world a sense of its potential, a few “early release observations” of photogenic objects were issued in November. The one closest to my research is that of the Perseus cluster of galaxies (Figure 1). In addition to the large yellowish galaxies, which are part of this massive clump of matter, Euclid provides detailed images of another 50,000 galaxies. This level of detail is what I need for my research, but so far I only have 800 out of 25,000 such images! This has started: on February 15th 2024, Euclid started its main survey and in the next 2200 days it will keep photographing the sky. This vast amount of data will be a treasure trove for astronomers – and the whole world – for years to come. For instance, we can study in detail the structure of hundreds of nearby galaxies, such as IC 342 (Figure 3). These images are just a teaser of what the future will bring.

This article is the result of The Conversation’s collaboration with Horizon, the EU research and innovation magazine. In December, the authors published an interview with the magazine.

Read the original article at The Conversation.

The boiling surface of giant star Betelgeuse may be creating an illusion

Robert Lea — Tue, 12 Mar 2024 10:00:04 +0000

Recent observations of Betelgeuse, a star located in the constellation Orion, have created a mystery about the red supergiant. They suggest it is spinning much faster than a star its size should be able to.

Now, a team from the Max Planck Institute for Astrophysics, led by Ph.D. student Jing-Ze Ma, may have an explanation for why Betelgeuse appears to be spinning so utterly fast. Perhaps, the researchers say, it's actually an illusion created by the star's violently boiling surface.

Ma and colleagues think the star's bubbling surface could be mistaken for rotation — even by the most advanced telescopes. This mistake could lead to observers believing Betelgeuse, which is located between 500 to 600 light-years from Earth, appears to be rotating faster than should be possible for a star of such enormity.

"For most people, stars are just glowing dots in the sky. Our results highlight again that stars like Betelgeuse have such drastic boiling motions on the surface that we can see those motions in action in the telescopes," Ma told Space.com "As theorists, we are very excited that we can actually make predictions from our simulations that will be tested against observations in years to come."

Betelgeuse is an infamous red supergiant star that recently made headlines when its dimming led scientists to speculate that it may be about to explode.

"Most stars are just tiny points of light in the night sky. Betelgeuse is so incredibly large and nearby that, with the very best telescopes, it is one of the very few stars where we actually observe and study its boiling surface," Selma de Mink,
research coauthor and director at the Max Planck Institute for Astrophysics said in a statement. "It still feels a bit like a science fiction movie, as if we have traveled there to see it up close. And the results are so exciting."

Betelgeuse, Betelgeuse, Betelgeuse!

Betelgeuse is one of the brightest stars in the Northern Hemisphere over Earth, meaning it is well-studied for study — but, as observations of its dimming show, that doesn't mean it isn't capable of delivering surprises.

With a diameter greater than 620 million miles (1 billion kilometers), Betelgeuse is over 1,000 times larger than the sun, making it one of the largest stars in the known universe. If the sun and Betelgeuse were swapped, and the red supergiant was placed at the heart of the solar system, it would engulf Mercury, Venus, Earth, and Mars, with its atmosphere extending all the way out to the orbit of Jupiter.

Such massive stars are expected to have relatively sedate rotation speeds. This is because when stars "puff out" and expand during their red giant phase, the conservation of angular momentum suggests their rotation should slow. This is similar to an ice skater on Earth lowering and spreading out their arms to slow down their spins.

Yet, recent observations of Betelgeuse, particularly those made with the Atacama Large Millimeter/submillimeter Array (ALMA) located in Northern Chile, showed that Betelgeuse is rotating at around 11,200 miles per hour (5 kilometers per second). That's around eight times as fast as a Jet Fighter.

Comparing a non-rotating red supergiant with simulated observations and actual observations of Betelgeuse. (Image credit: MPA/Ma, Jing-Ze et al 2024)

An investigation with ALMA, an observatory comprised of 66 radio antennas that together form a single telescope, revealed that while half of Betelgeuse appears to be approaching Earth, the other appears to be receding. It was this so-called "dipolar radial velocity map" on the outer layer of Betelgeuse that scientists interpreted as rapid rotation.

This interpretation hinges on Betelgeuse being considered a perfectly round sphere, however — and this isn't the case, the new study's researchers point out. The surface of the red supergiant star is turbulent with boiling bubbles. Some of those bubbles, in fact, are as large as Earth's entire orbit around the sun. These bubbles, powered by a heat-transfer mechanism called convection, can rise and fall at speeds as great as 67,000 mph (30 km/s), around three times as fast as the Orion Spacecraft, the crew vehicle of the Artemis mission.

To analyze this precise, bubbly picture of Betelgeuse, the team developed a new post-processing computer package to simulate synthetic ALMA images and compare them with 3D radiation hydrodynamic simulations of nonrotating red supergiant stars. This revealed that a cluster of boiling bubbles rising on one side of Betelgeuse as another cluster falls on the other would create a dipolar radial velocity map. This convection would be blurred in actual ALMA observations, the team says, making it indistinguishable from rapid rotation.

In fact, the crew found that in around 90% of their simulations, Betelgeuse would be interpreted as rotating at tens of thousands of miles per hour because of this large-scale boiling on the red supergiant's surface. Should the team's modeling be wrong, however, there may be other explanations. For instance, it could indicate the red supergiant star engaged in some stellar cannibalism long ago.

"If Betelgeuse is rapidly rotating after all, then we think it must have been spun up after eating a small companion star that was orbiting it," de Mink added.

—Is the puzzling star Betelgeuse going to explode in our lifetime after all?

—Here's what the supergiant star Betelgeuse will look like when it goes supernova

The team will now use further observations of Betelgeuse to assess its rotational speed and better understand how its boiling surface affects such measurements, thus putting their model to the test.

"There is so much we still don’t understand about gigantic boiling stars like Betelgeuse. How do they really work? How do they lose mass? What molecules can form in their outflows? Why did Betelgeuse suddenly get less bright?" Andrea Chiavassa, research co-author and CNRS astronomer, said. "We are working very hard to make our computer simulations better and better, but we really need the incredible data from telescopes like ALMA."

The team's research was published in February in the Astrophysical Journal Letters.

NASA's new UVEX mission will explore the ultraviolet universe

andrew.w.jones@protonmail.com (Andrew Jones) — Wed, 21 Feb 2024 16:59:15 +0000

NASA has chosen its next Astrophysics Medium-Class Explorer mission.

The UltraViolet EXplorer (UVEX) will launch in 2030 to conduct an all-sky survey in ultraviolet light to bring new understanding of how stars and galaxies evolve.

The space observatory will be designed to be capable of quickly pointing toward ultraviolet light sources. This will allow it to capture violent cosmic events such as the explosions that follow gravitational waves from merging neutron stars, NASA officials said.

Related: What are gravitational waves?

It will also include an ultraviolet spectrograph for studying massive stars and stellar explosions.

"NASA's UVEX will help us better understand the nature of both nearby and distant galaxies, as well as follow up on dynamic events in our changing universe," said Nicola Fox, associate administrator, Science Mission Directorate at NASA Headquarters in Washington in a Feb. 13 statement announcing the mission's selection.

"This mission will bring key capabilities in near-and far-ultraviolet light to our fleet of space telescopes, delivering a wealth of survey data that will open new avenues in exploring the secrets of the cosmos," she added.

UVEX's observations — together with other ongoing and upcoming space survey missions, including the European Space Agency's Euclid and NASA's Nancy Grace Roman Space Telescope — will help astronomers build a map of the universe across a number of wavelengths of light.

"This new telescope will contribute to our understanding of the universe across multiple wavelengths and address one of the major priorities in astrophysics today: studying fleeting changes in the cosmos," said Mark Clampin, director of the Astrophysics Division at NASA Headquarters.

UVEX will have a two-year primary mission lifetime. SpaceNews reported that the launch date of 2030 represents a two-year delay to the mission, due to budgetary issues.

Orbital resonance — the striking gravitational dance done by planets with aligning orbits

cimpey@as.arizona.edu (Chris Impey) — Mon, 12 Feb 2024 19:00:01 +0000

Planets orbit their parent stars while separated by enormous distances – in our solar system, planets are like grains of sand in a region the size of a football field. The time that planets take to orbit their suns have no specific relationship to each other.

But sometimes, their orbits display striking patterns. For example, astronomers studying six planets orbiting a star 100 light years away have just found that they orbit their star with an almost rhythmic beat, in perfect synchrony. Each pair of planets completes their orbits in times that are the ratios of whole numbers, allowing the planets to align and exert a gravitational push and pull on the other during their orbit.

This type of gravitational alignment is called orbital resonance, and it’s like a harmony between distant planets.

I’m an astronomer who studies and writes about cosmology. Researchers have discovered over 5,600 exoplanets in the past 30 years, and their extraordinary diversity continues to surprise astronomers.

Harmony of the spheres

Greek mathematician Pythagoras discovered the principles of musical harmony 2,500 years ago by analyzing the sounds of blacksmiths’ hammers and plucked strings.

He believed mathematics was at the heart of the natural world and proposed that the Sun, Moon and planets each emit unique hums based on their orbital properties. He thought this “music of the spheres” would be imperceptible to the human ear.

Four hundred years ago, Johannes Kepler picked up this idea. He proposed that musical intervals and harmonies described the motions of the six known planets at the time.

To Kepler, the solar system had two basses, Jupiter and Saturn; a tenor, Mars; two altos, Venus and Earth; and a soprano, Mercury. These roles reflected how long it took each planet to orbit the Sun, lower speeds for the outer planets and higher speeds for the inner planets.

He called the book he wrote on these mathematical relationships “The Harmony of the World.” While these ideas have some similarities to the concept of orbital resonance, planets don’t actually make sounds, since sound can’t travel through the vacuum of space.

Orbital resonance

Resonance happens when planets or moons have orbital periods that are ratios of whole numbers. The orbital period is the time taken for a planet to make one complete circuit of the star. So, for example, two planets orbiting a star would be in a 2:1 resonance when one planet takes twice as long as the other to orbit the star. Resonance is seen in only 5% of planetary systems.

In the solar system, Neptune and Pluto are in a 3:2 resonance. There’s also a triple resonance, 4:2:1, among Jupiter’s three moons: Ganymede, Europa and Io. In the time it takes Ganymede to orbit Jupiter, Europa orbits twice and Io orbits four times. Resonances occur naturally, when planets happen to have orbital periods that are the ratio of whole numbers.

Musical intervals describe the relationship between two musical notes. In the musical analogy, important musical intervals based on ratios of frequencies are the fourth, 4:3, the fifth, 3:2, and the octave, 2:1. Anyone who plays the guitar or the piano might recognize these intervals.

Orbital resonances can change how gravity influences two bodies, causing them to speed up, slow down, stabilize on their orbital path and sometimes have their orbits disrupted.

Think of pushing a child on a swing. A planet and a swing both have a natural frequency. Give the child a push that matches the swing motion and they’ll get a boost. They’ll also get a boost if you push them every other time they’re in that position, or every third time. But push them at random times, sometimes with the motion of the swing and sometimes against, and they get no boost.

For planets, the boost can keep them continuing on their orbital paths, but it’s much more likely to disrupt their orbits.

Exoplanet resonance

Exoplanets, or planets outside the solar system, show striking examples of resonance, not just between two objects but also between resonant “chains” involving three or more objects.

The star Gliese 876 has three planets with orbit period ratios of 4:2:1, just like Jupiter’s three moons. Kepler 223 has four planets with ratios of 8:6:4:3.

The red dwarf Kepler 80 has five planets with ratios of 9:6:4:3:2, and TOI 178 has six planets, of which five are in a resonant chain with ratios of 18:9:6:4:3.

TRAPPIST-1 is the record holder. It has seven Earth-like planets, two of which might be habitable, with orbit ratios of 24:15:9:6:4:3:2.

The newest example of a resonant chain is the HD 110067 system. It’s about 100 light years away and has six sub-Neptune planets, a common type of exoplanet, with orbit ratios of 54:36:24:16:12:9. The discovery is interesting because most resonance chains are unstable and disappear over time.

Despite these examples, resonant chains are rare, and only 1% of all planetary systems display them. Astronomers think that planets form in resonance, but small gravitational nudges from passing stars and wandering planets erase the resonance over time. With HD 110067, the resonant chain has survived for billions of years, offering a rare and pristine view of the system as it was when it formed.

Orbit sonification

Astronomers use a technique called sonification to translate complex visual data into sound. It gives people a different way to appreciate the beautiful images from the Hubble Space Telescope, and it has been applied to X-ray data and gravitational waves.

With exoplanets, sonification can convey the mathematical relationships of their orbits. Astronomers at the European Southern Observatory created what they call “music of the spheres” for the TOI 178 system by associating a sound on a pentatonic scale to each of the five planets.

A similar musical translation has been done for the TRAPPIST-1 system, with the orbital frequencies scaled up by a factor of 212 million to bring them into audible range.

Astronomers have also created a sonification for the HD 110067 system. People may not agree on whether these renditions sound like actual music, but it’s inspiring to see Pythagoras’ ideas realized after 2,500 years.

What happens when neutron stars collide? Astronomers may finally know

Robert Lea — Tue, 24 Oct 2023 16:59:40 +0000

Scientists have used advanced computer modeling to determine the shape of a kilonova, an emission of light that follows the collision and merger of two neutron stars. Extraordinarily, the team discovered that rather than being shaped like smooth, homogeneous spheres or flattened, disk-like explosions, the kilonovas they simulated were filled with "blobs," or "bubbles."

"This is a significant step forward in the theoretical understanding of what’s going on in neutron star mergers," Stuart Sim, co-author of a study on the findings and a physicist at the University of Belfast, told Space.com.

Determining what goes on during a neutron star collision also has important implications close to home. That's because it's believed that the turbulent environments that give rise to kilonovas are the only sites in the universe suitable to forge elements heavier than lead — including the gold that we use for jewelry here on Earth. It is hoped that studying kilonovas could reveal more about this process.

"Kilonovas are the light signals from neutron star mergers, which are the origin of about half of all nuclei heavier than iron. Almost all of the platinum and gold that exists today was created from neutron star mergers," Luke Shingles, lead author of the research and a scientists at the Facility for Antiproton and Ion Research told Space.com. "The 3D structure seems to be very important, and it might be necessary to have a kind of foamy structure with small clumps and bubbles, rather than a smooth ellipsoid type of shape that many people were assuming.

"If our model is a good one, then we also know the full pattern of elements that were created in these types of events."

Why neutron star collisions are a unique laboratory for physics

It is hardly surprising that collisions between neutron stars generate such violent conditions, considering these stellar remnants consist of the densest material in the known universe.

That's because neutron stars are born when massive stars run out of the fuel necessary for nuclear fusion processes in their cores, and can therefore no longer generate the outward push that has supported them against the inward push of gravity for billions of years. Then, as the star's core collapses, the outer layers of the star are ejected, resulting in a body with a mass between one and two times that of the sun with a width of around 12 miles (20 kilometers) — a neutron star.

This resulting neutron star is so dense that if a teaspoon's worth of it could be brought to Earth, it would weigh about 10 million tons — that's 30 times as heavy as the Empire State Building in New York City.

As such, neutron star mergers make for a unique laboratory where it is possible to study things it would be impossible to simulate here on Earth, meaning research like the team's new study is vital far beyond astrophysics.

"In terrestrial experiments, you can never encounter matter that is as dense as neutral star matter," Sim added. "So there are fundamental questions that kind of relate to aspects of particle physics and quantum chromodynamics, and they are relevant to determining just how dense neutron star matter actually is and how neutron star matter will respond to this dynamical process of being squished together."

Just like the real thing

What the team did find surprising, however, was just how closely their computer-generated models fit real-life observations of a kilonova known as AT2017gfo, created by the clash between two neutron stars sitting about 130 million light-years away from us in the galaxy NGC 4993.

Shingles explained whyAT2017gfo was the only real choice for comparison to the team's advanced simulations. "It is the only one that has been very well observed and for which we have really good spectra taken every few hours," he said. "There are other objects that people think are probably kilonovas but haven’t really enough observations to see in great detail what kilonovas look like."

As for the unexpected bubbliness of the kilonova observed in the simulations, Sim stated that while this is the result of complicated physics and it isn't fully understood yet, what seems to be causing the strange structure is matter ejected during the clash between neutron stars.

"As two neutron stars come together, there are various different mechanisms that cause materials to be expelled," Sim continued. "The particular category of mechanism that we've been most looking at here is as they're starting to push together, material kind of gets 'spurted out' along the axis. As they squash in from the sides, this ejected stuff kind of comes up and goes down."

That stuff then interacts with other particles created by the collision, which can change the composition of the ejected matter.

Another thing that defied the team's expectations was the lack of heavy elements in their models. Sim explained that the team found an abundance of "mid-periodic table" elements, like strontium, but an absence of things like gold and platinum.

"That's a bit of a surprise. It's telling us about nucleosynthesis that's actually going on. And it's suggesting that these things are producing a lot of these sorts of medium elements," Sim said. "But we don’t yet have really definitive evidence of the very heaviest ones. It's very likely the case that the heavy elements are there, but they're just harder to directly identify in this particular object. That's something that we're going to be continuing to work on."

Looking at kilonovas from all angles

Astronomers have learned lots about the universe − but how do they study astronomical objects too distant to visit?

Luke Keller — Fri, 20 Oct 2023 17:00:00 +0000

This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.

Luke Keller is a Professor of Physics and Astronomy at Ithaca College and has received funding from NASA.

NASA's OSIRIS-REx spacecraft flew by Earth on Sept. 24, 2023, dropping off its sample of dust and pebbles gathered from the surface of near-Earth asteroid Bennu.

Analysis of this sample will help scientists understand how the solar system formed and from what sorts of materials. Scientists will begin their analysis in the same facility that analyzed rocks and dust from the Apollo lunar landings.

As an astronomer studying how planets form around distant stars, I felt excited watching the broadcast of that Bennu sample descending to the Utah desert – and a little envious. Those of us who study distant young solar systems can’t send robotic spacecraft to get a closer look at them, let alone grab a sample for laboratory analysis. Instead, we rely on remote observations.

But what astronomers can measure using telescopes is not what we really want to know – instead, we calculate the properties we're interested in studying by observing and interpreting apparent properties from afar.

Astronomers' tools

Asteroids are like fossils – they're composed of rocky material from the formation and early evolution of a solar system and they are preserved nearly unchanged. That’s how the pristine Bennu samples will help astronomers learn about our solar system’s formation.

Over the past several decades, astronomers have learned that disks of gas and dust called protoplanetary disks orbit young stars. Observing these disks – located many light years outside our solar system – can help astronomers understand the early planet formation process, but they’re too distant to send a sample-return mission like OSIRIS-REx to directly measure what the dust and asteroids in these systems are made of.

Left to right: Three images of protoplanetary disks TW Hydrae (Atacama Large Millimeter Array, ALMA), HD 135344B (European Southern Observatory, ESO) and 2MASS J16281370 (Hubble Space Telescope, HST). (Image credit: NASA/Goddard/University of Arizona and NASA/Robert Markowitz)

All that astronomers like me can do is observe those distant regions of the universe remotely, using telescopes here on Earth or in orbit near Earth. But even with limited tools and techniques, we’ve still managed to learn quite a bit about them.

Distance and luminosity

The closest protoplanetary systems are a few hundred light years from the sun, but we can’t directly measure distances that large. Instead, we have to determine distance indirectly using precise measurements of parallax – small changes in the apparent position of the star caused by our changing perspective as Earth orbits the sun.

Once we know their distances from Earth, we can determine another essential physical property of protoplanetary disks: Their luminosities and the luminosities of their stars.

Luminosity is an object’s power output measured in watts. The luminosity of a star like our sun is in the hundreds of trillions of trillions of watts. Just as sunlight influences weather and the chemistry of planetary atmospheres in our solar system, the luminosity of a young star directly affects the material in its protoplanetary disk. Luminosity can alter the size and composition of dust particles that will later form asteroids and planetary cores.

But brightness does not directly indicate luminosity. The measured brightness of a star or any luminous object decreases with the square of its distance from us. We measure the apparent brightness of a star, or how bright it looks in a digital image, and then calculate its luminosity from this observed brightness and the star's distance.

Color and temperature

Luminosity also depends on temperature – warmer objects are usually more luminous – but we can't directly measure the temperatures of distant systems. Astronomers determine temperature using precise measurements of the apparent color of a star and of the gas and dust orbiting in its planet-forming disk.

The color images of celestial objects that you see from observatories like the Hubble or James Webb space telescopes are composites of multiple images taken through a series of colored filters.

Instruments like the near-infrared spectrograph on the James Webb Space Telescope enable precise measurements of apparent color used to determine the temperature and chemical composition of a star-forming region. The visible colors assigned to infrared wavelengths indicate atomic hydrogen (blue), molecular hydrogen (green) and hydrocarbons (red). A combination of the three images produces a color composite. (Image credit: NASA, ESA, CSA, STScI, Webb ERO Production Team)

For astronomers, colors are numbers describing the brightness of an object at a particular wavelength compared with its brightness at another wavelength. Warmer objects emit more blue light relative to red light, so their color looks more blue and the corresponding number is smaller. Astronomers measure color in even more detail by passing starlight through a small prism installed in the telescope’s camera. This prism disperses the light into a spectrum.

The spectrum of light from a star and its surrounding material isn’t a smooth rainbow of color. Sharp bright and dark features in the spectra indicate the presence and relative abundances of atoms, molecules and even minerals. These chemical elements emit or absorb light in unique and recognizable combinations of colors.

Measurement and interpretation

Can you see a theme emerging? Astronomers can measure only a handful of apparent properties: brightness, color, position in the sky, shape, angular size and how each of these changes with time. These are the same properties each of us measures with our senses to navigate our surroundings in everyday life. They’re nothing exotic or special.

— Dramatic sampling shows asteroid Bennu is nothing like scientists expected

— Evidence for 'Planet 9' may actually show our theory of gravity is incomplete

And yet everything astronomers know about distant solar systems and their formation we have derived from measurements of these familiar and unremarkable apparent properties. The rich and detailed descriptions that we've come to expect in astronomy and astrophysics come from applying our understanding of chemistry and physics to these measurements.

The arrival of the Bennu sample is exciting because it is "real." In the coming months and years, scientists will examine this dust to inform our studies not only of asteroids and interplanetary dust, but also of interstellar dust in solar systems farther afield. I am eager to see what these new details will teach us about cosmic dust, some of the primary building blocks of planets everywhere.

This article is republished from The Conversation under a Creative Commons license. Read the original article.

The views expressed are those of the author and do not necessarily reflect the views of the publisher.

Atomic clocks on Earth could reveal secrets about dark matter across the universe

Robert Lea — Fri, 01 Sep 2023 19:00:01 +0000

Scientists are using atomic clocks to investigate some of the universe's greatest mysteries, including the nature of dark matter, in a laboratory. In the process, they say they're bringing cosmology and astrophysics "down to Earth."

The project, which is a collaboration between the University of Sussex and the National Physical Laboratory (NPL) in the U.K., uses the ticks of these incredibly precise clocks to hunt for hitherto unknown ultra-light particles.

These particles could be connected to dark matter, the mysterious substance that makes up an estimated 85% of all matter in the universe but remains effectively invisible to us because it does not interact with light or, more precisely, electromagnetic radiation. Scientists believe most galaxies are enveloped by a cloud of dark matter, but its presence can only be inferred by the effect it has on gravity.

"Our universe, as we know it, is governed by laws of physics, so gravity is governed by general relativity and particle physics by the Standard Model of particle physics," Xavier Calmet, project leader and a professor of physics at the University of Sussex, told Space.com. "We call deviations from these laws 'breakdown in physics' — basically, that is a synonym for new physics beyond our current understanding of the universe."

This new physics could be used to explain the nature of dark matter, something that doesn't fit within the Standard Model.

"One of the biggest mysteries is the nature of dark matter. We know that it is out there, we see its impact in our universe, but we don't have a valid explanation within the Standard Model of particle physics," Calmet continued. "There must be new physics, but we do not know how to describe these new particles and how they couple to regular matter."

How can "new physics" be spotted with atomic clocks?

According to established laws of physics, clocks should tick at a constant rate, but physics beyond the Standard Model's scope would result in tiny charges in atomic energy levels. This should affect the rate at which clocks tick, but the variation would be so small it could only be spotted with an incredibly precise clock — and that's where atomic clocks come in.

"Atomic clocks bring cosmology and astrophysics down to Earth, enabling searches for ultra-light particles that could explain dark matter in a laboratory," Calmet said.

Atomic clocks measure time using atoms with two potential energy states. When atoms absorb energy, they go to a higher energy state. Then, they eventually release this energy and drop back down to their lower ground state.

In atomic clocks, groups of atoms are prepared by placing them in a higher energy state using microwave energy, and the characteristic and consistent rates at which they vibrate between states — their resonance frequencies — are used to precisely measure time.

So, for example, all atoms of cesium resonate at the same frequency, meaning the standard measure of a second can be defined as 9,192,631,770 cycles of cesium. Because this cycling per second occurs with far less variation than, say, the swinging of a pendulum, this makes atomic clocks incredibly precise.

"It has been recently realized that dark matter could be made of ultra-light particles that interact extremely weakly with regular matter," Calmet explained. "If that is the case, dark matter would essentially behave as a classical wave that interacts with electrons and protons. This dark matter wave would give some small kicks to these particles."

Calmet added that these ultra-light dark matter particle kicks to the building blocks of the atom would lead to a time variation in fundamental constants of the universe, such as the fine-structure constant or "alpha" — a measure of how strong particles couple via the electromagnetic force — and the mass of the proton.

"Because atomic clocks are amazingly precise devices, they would be able to detect these kicks and thus discover ultra-light dark matter," he continued. "By comparing two clocks, one sensitive to changes in alpha and the other one less sensitive to changes in alpha, we can obtain a limit on the time variation of this fundamental constant and thus set constraints on ultra-light particles."

— Researchers dig deep underground in hopes of finally observing dark matter

— Is dark matter fuzzy? Ultracold state of matter sheds light on dark matter candidate

Calmet thinks the technique could potentially also be used to investigate another problematic aspect of the universe for physicists: Dark energy, the unknown force that is driving the accelerating expansion of space.

While Calmet acknowledges that dark energy is more likely explained by the cosmological constant, a form of energy that acts almost in opposition to gravity to stretch the fabric of space and push apart galaxies, there is a small chance it could be connected to an ultra-light particle. In this vein, future clocks could also be sensitive to that particle and its associated wave.

"While the clocks have not discovered new physics at this stage, we were able to develop a new theoretical framework to probe generic new physics with clocks and were able to derive the first model-independent limits on physics beyond the standard model within this approach," Calmet concluded. "We are creating a new field at the interface of atomic, molecular, and optical physics and traditional particle physics.

"These are exciting results!"

These results are set to be published in a future edition of the New Journal of Physics.

NASA selects four astrophysics missions for further study

andrew.w.jones@protonmail.com (Andrew Jones) — Fri, 19 Aug 2022 15:08:54 +0000

Four astrophysics mission proposals to study stars, galaxies and some of the most violent explosions in the universe have been selected for further study by NASA.

The selected missions are competing for funding as part of NASA’s Explorers Program and were announced by the agency on Thursday, Aug. 18. The Explorers Program focuses on small to medium-sized missions that can make a big science impact but also can be built and launched in a much shorter timeframe than large, expensive missions.

Two Astrophysics Medium Explorer missions and two Explorer Missions of Opportunity will now move into the mission concept study phase. NASA will evaluate the concepts before selecting one Mission of Opportunity and one Medium Explorer in 2024. The chosen pair of missions will then prepare for launches in 2027 and 2028.

The two Medium Explorer teams will each receive $3 million for a nine-month mission concept study. These are:

— UltraViolet EXplorer (UVEX). The mission would survey the whole sky in ultraviolet light to provide new insights into galaxy evolution and the lifecycle of stars. The spacecraft would seek to capture light from the explosion that follows a burst of gravitational waves caused by merging neutron stars, as well as study massive stars and stellar explosions. The principal investigator is Fiona Harrison at Caltech in Pasadena, California.

— Survey and Time-domain Astrophysical Research Explorer (STAR-X). The spacecraft would use sensitive wide-field X-ray and ultraviolet telescopes to study supernova explosions and active galaxies. Deep X-ray surveys would map hot gas trapped in distant clusters of galaxies. Combined with infrared observations from NASA’s upcoming Roman Space Telescope, these observations would trace how massive clusters of galaxies built up over cosmic history. The principal investigator is William Zhang at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

The two Mission of Opportunity teams will each receive $750,000 to conduct their own nine-month concept study. These are:

— Moon Burst Energetics All-sky Monitor (MoonBEAM). The spacecraft would operate in the so-called halo orbit between Earth and the moon, meaning it would be able to see almost the whole sky at any time, watching for bursts of high-energy gamma rays from distant cosmic explosions. MoonBEAM would then rapidly alert other telescopes so they can study the source. The principal investigator is Chiumun Michelle Hui at NASA’s Marshall Space Flight Center in Huntsville, Alabama.

— A LargE Area burst Polarimeter (LEAP). LEAP would be mounted on the International Space Station to study gamma-ray bursts from the energetic jets launched during the formation of black holes after the explosive death of a massive star, or in the merger of objects such as neutron stars, and black holes. The principal investigator is Mark McConnell at the University of New Hampshire in Durham.

— Gamma-ray bursts might be much rarer than we thought, study suggests

— The heaviest neutron star ever observed is shredding its companion

The costs for medium explorer missions are capped at $300 million each, excluding the cost of launch. NASA Mission of Opportunity costs are capped at $80 million each.

“NASA’s Explorers Program has a proud tradition of supporting innovative approaches to exceptional science, and these selections hold that same promise,” Thomas Zurbuchen, associate administrator for NASA’s Science Mission Directorate, said in a statement.

“From studying the evolution of galaxies to explosive, high-energy events, these proposals are inspiring in their scope and creativity to explore the unknown in our universe.”

Explorers is NASA's longest-running program and aims to provide regular opportunities for launch of space science missions. The first mission dates back to Explorer 1 in 1958, which discovered the Van Allen radiation belts surrounding Earth. More than 70 U.S. and cooperative international scientific space missions have been part of the program.

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Search for habitable exoplanets included in China's upcoming space missions

brett.tingley@futurenet.com (Brett Tingley) — Mon, 04 Jul 2022 18:19:54 +0000

The Chinese Academy of Sciences (CAS) has selected candidates for its next round of space missions, which are projected to launch between 2026 and 2030.

Out of the 13 missions proposed, it is expected that between five and seven will be chosen for launch, SpaceNews reported.

The new missions will be part of CAS's third Strategic Priority Program (SPP III) project, also known as the New Horizons Program (The program has no relation to NASA's New Horizons mission.). A description of each of the 13 candidates was published in a paper in the Chinese Journal of Space Science on June 28, 2022.

Three of the proposed missions will conduct astrophysics and astronomy research:

The Enhanced X-ray Timing and Polarimetry, or eXTP mission, aims to "study the state of matter under extreme conditions of density, gravity and magnetism" and search for gravitational wave and neutrino sources.
The Discovering the Sky at the Longest Wavelength (DSL) mission would put a small constellation of satellites into lunar orbit, where they could be shielded from terrestrial interference and study undiscovered areas of the electromagnetic spectrum that could reveal signals from the earliest ages of the cosmos.
The DArk Matter Particle Explorer-2 (DAMPE-2) would follow up on the DAMPE mission launched in 2015 and search for evidence of dark matter.

Four of CAS's 13 potential missions are heliophysics efforts:

The Chinese Heliospheric Interstellar Medium Explorer (CHIME).
The SOlar Ring (SOR) mission proposes using a trio of spacecraft orbiting at one astronomical unit (AU) — the same distance at which Earth circles the sun — to collect data on the sun and the inner heliosphere.
The Solar Polar-orbit Observatory (SPO) would study the poles of the sun while in a high-inclination orbit.
The Earth-occulted Solar Eclipse Observatory (ESEO) is designed to orbit at the Earth-Sun Lagrange Point 2, to study the sun's inner corona. (NASA's James Webb Space Telescope also orbits at Earth-Sun L2.)

Four of the potential missions are aimed at studying Earth and other members of our solar system:

The E-type Asteroid Sample Return (ASR) would explore the asteroid 1989 ML and return samples from it back to Earth.
The Venus Volcano Imaging and Climate Explorer (VOICE) mission is aimed at studying the geological and atmospheric processes occurring on Venus.
The low-Earth orbit Climate and Atmospheric Components Exploring Satellites (CACES) proposes gathering a wealth of data about Earth's climate and atmosphere.
The Ocean Surface Current multiscale Observation Mission (OSCOM) would use satellite Doppler radar to study oceanographic dynamics and energetics.

Finally, two missions would search the cosmos for habitable exoplanets:

The Closeby Habitable Exoplanet Survey (CHES) would use micro-arcsecond relative astrometric techniques to study 100 sun-like stars within 33 light-years of Earth.
The Earth 2.0 (ET) mission would specifically seek Earth-size exoplanets that have similar orbits around sun-like stars using a seven-telescope instrument orbiting at Earth-Sun L2.

– China will launch a big space telescope in 2023 to investigate distant galaxies

– China to launch Tianwen 2 asteroid-sampling mission in 2025

Each of the 13 proposed New Horizons Program missions will be assessed by a CAS committee on criteria such as budgetary requirements, technological readiness level and how quickly the required technologies could be manufactured ahead of China’s 15th Five-year plan, which begins in 2026. The New Horizons Program also includes funding for research projects that would support future science missions.

Email Brett at BTingley@Space.com or follow Brett on Twitter at @bretttingley. Follow us on Twitter @Spacedotcom or on Facebook.

20 trailblazing women in astronomy and astrophysics

Elizabeth Howell — Tue, 08 Mar 2022 16:26:01 +0000

From discovering planets to following comets, women all over the world play a crucial role in astronomy.

While it's hard to pick the definitive list of women who have contributed to our understanding of the cosmos, these 20 women (mostly from modern times) will give you a sense of some of the scientific knowledge they contribute.

Caroline Herschel (1750-1848)

Caroline Herschel is the first woman credited with discovering a comet. (Image credit: Michelle Bridges / Alamy Stock Photo)

Caroline Herschel is the first woman credited with discovering a comet and is also the first to receive honorary membership with Britain's prestigious Royal Society. Herschel's childhood passions included music, and she sang as a soprano in several performances in her early 20s.

But with her older brother, William, it was Herschel's enthusiasm in astronomy that she is best remembered for. Herschel at first polished mirrors and did other assistant tasks for her brother. She helped her brother with compiling a 20-year survey of the night sky, including 2,500 new nebulae and star clusters that were eventually compiled into the "New General Catalogue."

Herschel also observed the sky on her own, using a small Newtonian telescope. Among her discoveries were the open cluster NGC 2360, Andromeda Galaxy's companion nebula NGC 205 and a comet. In 1787, King George III gave her official employment as William's assistant, granting her a modest salary. Among her later career achievements was cross-indexing an existing star catalog compiled by John Flamsteed, including contributing 550 stars not included by Flamsteed.

Maria Mitchell (1818-1889)

Maria Mitchell discovered a comet in 1847 using a telescope. (Image credit: The Picture Art Collection / Alamy Stock Photo)

Maria Mitchell is best remembered for discovering a comet using a telescope in 1847, an achievement that garnered her a gold medal from the King of Denmark. Mitchell is usually cited as the first professional female astronomer in the United States.

Mitchell's work in astronomy began in her childhood. By age 12, she had helped her father calculate the exact position of their house by using a solar eclipse. Only two years later, she rated ship chronometers for professionals; chronometers were instruments that measured time in challenging conditions involving motion or local weather variations.

Mitchell's 1847 discovery of a comet came on the roof of the bank where her family lived, and where her father was the head cashier. She worked at the Nantucket Atheneum as a librarian between 1836 and 1856, resigning from that post to focus on travel and astronomy studies. By 1865, she was an astronomy professor at Vassar College.

Other notable career achievements include working for the U.S. federal government on an ephemeris of Venus, founding the Association for the Advancement of Women, and becoming the first woman member of the American Academy of Arts and Sciences, among others.

Annie Jump Cannon (1863-1941)

Annie Jump Cannon is renowned for her approach to classifying and examining stars. (Image credit: Harvard-Smithsonian Center for Astrophysics )

Annie Jump Cannon is renowned for her approach to classifying and examining stars, including the famous O, B, A, F, G, K or M classification for stellar objects.

She began her career as one of a few dozen female "computers" (mathematicians) hired by Edward Charles Pickering, director of the Harvard College Observatory. Cannon and her colleagues spent their time examining photographic plates of stars, giving them specialized knowledge of the sky considered too tedious for men of the day.

Cannon studied physics and astronomy at Wellesley College, as well as advanced studies in astronomy at Wellesley and Radcliffe College (affiliated with Harvard). Her work with the Pickering computer group included classifying stars with her women colleagues; Cannon alone classified more than 350,000 stars in her career and supplemented other women's work in our understanding of stellar spectra.

Other career contributions by Cannon included publishing nine volumes of the Henry Draper Catalog between 1918 and 1924, creating the Harvard Catalogue of Variable Stars, and receiving numerous awards. She finally received staff status at Harvard in 1938.

Henrietta Swan Leavitt (1868-1921)

Henrietta Swan Leavitt discovered a relationship between the period of a star's brightness cycle to its absolute magnitude. The discovery made it possible to calculate their distance from Earth. (Image credit: Harvard-Smithsonian Center for Astrophysics )

Henrietta Swan Leavitt is best remembered for discovering the relationship between period and luminosity in Cepheid variables, which are stars that fluctuate predictably in luminosity (inherent brightness). Cepheids are used as standard distance markers in astronomy, allowing scientists to estimate distances to galaxies and other faraway objects.

Leavitt was educated at both Oberlin College and the Harvard-affiliated Radcliffe College. She started her astronomy career at the Harvard College Observatory under Edward Charles Pickering, the same employer of Annie Jump Cannon. Like Cannon, Leavitt's job was to analyze photographic plates; by examining thousands of these images, she found that some stars have a consistent luminosity during fluctuations.

Leavitt, unfortunately, received little credit for her work during her lifetime, with most of the glory going to director Harlow Shapley (who used Leavitt's work to chart distances in the Milky Way). After her death, however, other astronomers came to recognize her work. For example, the American astronomer Edwin Hubble used Leavitt's information to help him compute the distance to the Andromeda Galaxy, which is the closest large galaxy to the Milky Way.

Cecilia Payne Gaposchkin (1900-1979)

Cecilia Payne Gaposchkin was the first woman to be awarded a PhD in astronomy at the Harvard-affiliated Radcliffe College. (Image credit: Science History Images / Alamy Stock Photo)

While not well recognized in her lifetime, Cecilia Payne-Gaposchkin made numerous contributions to astronomy. She was the first woman to be awarded a PhD in astronomy at the Harvard-affiliated Radcliffe College. Her thesis focused on how the line patterns she saw in the spectra of stars could be related to physical conditions on those stars, which is fundamental work still underlying much of our understanding of stars today.

Harvard's Harlow Shapley and Princeton University's Henry Norris Russell both acknowledged her thesis as groundbreaking but disagreed with Payne-Gaposchkin's (correct) hypothesis that hydrogen is the main component of most stars. Working against the scientific consensus of the day, Payne-Gaposchkin downplayed the discovery to get her work published. Her hydrogen discovery was eventually validated, however, along with her later insight that helium is also a principal component of star formation.

Payne-Gaposchkin elected to remain at Harvard after completing her doctorate but was unable at first to get a professorship due to being a woman. Instead, she continued at less recognized positions while publishing numerous books about stars, variable stars and galactic structure. She finally was awarded the first woman professorship at Harvard in 1956, even attaining department chair (another first for a woman).

Helen Sawyer Hogg (1905-1993)

Helen Sawyer Hogg is best remembered for researching variable stars in globular clusters. (Image credit: D. Gordon E. Robertson/Wikimedia Commons/CC BY-SA 3.0)

Helen Sawyer Hogg comfortably straddled the world of science and the challenge of popularizing science. The Canadian astronomer is best remembered for researching variable stars in globular clusters (clusters of older stars), but many Canadians remember her for a long-standing astronomy column she had in the Toronto Star between 1951 and 1981.

Hogg received her Ph.D. from Radcliffe College in 1931, electing to move to Canada afterward with her astronomer husband, Frank Hogg. The couple worked at the Dominion Astrophysical Observatory in Victoria, British Columbia until 1935, before moving to the David Dunlap Observatory, situated just north of Toronto.

Throughout her career, Hogg accumulated expertise in globular clusters and variable stars and was highly cited in her own time. Hogg became an adjunct full professor in the astronomy department of the University of Toronto in 1957 and studied more than 2,000 variable stars by her career's end, providing fundamental information about the age of the Milky Way galaxy. She was the founding president of the Canadian Astronomical Society in 1971 and received Canada's highest civilian honor, the Order of Canada, in 1976.

Margaret Burbidge (1919-2020)

Margaret Burbidge's contributions to astronomy included probing the nature of stars and contributing to instrument development on the famed Hubble Space Telescope. (Image credit: Fairfax Media Archives / Contributor)

Margaret Burbidge's contributions to astronomy included probing the nature of stars and contributing to instrument development on the famed Hubble Space Telescope. She was most famous for her work showing how stars create heavier elements over time, and how stars send those elements through the universe.

Burbridge led a four-person team in the 1950s that examined how reactions occur within stars, backed up by astronomical observations and theoretical computations. A colleague later won the Nobel Prize for this team's research. Burbridge, often researching alongside her husband Geoffrey, worked on other fundamental parts of astronomy such as the masses and rotations of spiral galaxies like the Milky Way and the redshifts to quasars (extremely luminous objects in the universe).

Later accolades include becoming the first female president of the International Astronomical Union's commission on galaxies, director of the Royal Greenwich Observatory in London and president of the American Astronomical Society. Her lifelong passion for astronomy was encouraged in childhood, including parental gifts of a telescope and a chemistry set.

Nancy Grace Roman (1925-2018)

Nancy Grace Roman is best remembered for being the first chief of astronomy in the Office of Space Science at NASA Headquarters. (Image credit: NASA)

Nancy Grace Roman is best remembered for being the first chief of astronomy in the Office of Space Science at NASA Headquarters, and the first woman to hold an executive position at the space agency. Her managed projects include the world-famous Hubble Space Telescope, earning her the nickname, "Mother of Hubble."

Roman used to gaze at the sky with her mother, at night, to learn about the constellations, the northern lights and the local fauna and flora. She started an astronomy club at age 11 and elected to go into astronomy in high school, rationalizing that she could always teach the subject if she wasn't accepted as a researcher.

She received her bachelor's degree from Swarthmore College in 1946 and finished her doctorate at the University of Chicago, attempting to complete her thesis under an unsupportive supervisor. The department told her to leave without completing the degree, but she persisted and finished in 1949.

From there, she worked at Yerkes Observatory under the University of Chicago but left after realizing it was unlikely she would receive tenure. She subsequently studied radio astronomy at the U.S. Naval Research Laboratory before moving to NASA. The Nancy Grace Roman Space Telescope is named in her honor.

Vera Cooper Rubin (1928-2016)

Vera Rubin's principal contribution to astronomy was showing that galaxies are mostly made of dark matter. (Image credit: The Washington Post / Contributor)

Vera Rubin's principal contribution to astronomy was showing that galaxies are mostly made of dark matter, which is a substance that we cannot sense directly with current-day instruments. Rubin came to this conclusion after examining star spectra in the Andromeda Galaxy to figure out their individual velocities, using the Kitt Peak Observatory in the mountains of southern Arizona.

The idea of dark matter preceded Rubin, as Swiss astronomer Fritz Zwicky first proposed it in 1933 following an analysis of Coma Cluster galaxies. Zwicky said the galaxies should have come apart ages ago, but that dark matter (a poorly understood substance) is keeping them together. His work was dismissed at first, but Rubin helped show that 80% of our universe is made of dark matter and dark energy.

Rubin's interest in astronomy started in childhood when her father helped her build a cardboard telescope and her mother convinced a local librarian to let the young Rubin borrow adult science books. Rubin was the sole woman astronomy graduate from Vassar College in 1948 and was refused admission at Princeton because they did not accept female students. Rubin instead pivoted to Cornell and Georgetown Universities for graduate studies.

Rubin's other work included being the first woman to observe at the Palomar Observatory, pioneering research in the little-studied field of galaxy rotation, and taking on a permanent position at the prestigious Carnegie Institution in Washington D.C. She received the National Medal of Science in 1993, but was passed over for a Nobel. The Large Synoptic Survey Telescope (LSST) was renamed for Vera Rubin in January 2020.

Carolyn Shoemaker (1929-2021)

Shoemaker was the co-discoverer of Comet Shoemaker-Levy 9 in 1993. (Image credit: Gene Shoemaker/USGS)

Shoemaker is best remembered as being the co-discoverer of Comet Shoemaker-Levy 9 in 1993, a small solar system body that eventually collided with Jupiter. It was pioneering work showing how crucial Jupiter is in directing the paths of comets and asteroids in our solar system. Shoemaker's observing team included her husband, Gene, and David Levy. She holds the record for most comet discoveries by an individual, with at least 32 to her credit (along with 800 asteroids).

Shoemaker was not interested in astronomy growing up, having studied history and political science at Chico State College. She became more passionate about geology after meeting her husband, Gene; Gene was heavily involved in lunar geology missions and training for the Apollo astronauts in the 1960s.

Much of Shoemaker's work in searching out comets took place while comets were still being imaged by photographic plates. She would use a stereoscope to manually flip back and forth between the plates to search for changes. At her peak, her discovery rate was roughly 100 search hours per comet find. She also served as a field assistant to Gene and the two collaborated on many comet and asteroid discoveries; Shoemaker continued this work after Gene died in a car crash in 1997. At age 90 in 2019, her astronomy research was still receiving notice in Arizona news media.

Jocelyn Bell Burnell (1943-present)

Jocelyn Bell Burnell discovered the first radio pulsars in a team in 1967. (Image credit: Colin McPherson / Contributor)

Jocelyn Bell Burnell discovered the first radio pulsars in a team in 1967. Then a graduate student at the University of Cambridge in England, she spotted an odd signal in data collected by a radio telescope that she and her thesis supervisor, Antony Hewish, put together. Bell Burnell and her colleagues joked the pulse, which repeated every 1.3 seconds, was of alien origin, naming it Little Green Man-1. But more of these sources were discovered across the sky, suggesting a more natural origin.

Eventually, researchers figured out the signals are coming from swiftly rotating neutron stars, which are the cosmic leftovers of huge stars that exploded in supernovas. The objects were called "pulsars", a combination of the words "pulsing" and "quasar" (bright galactic nuclei). Pulsars have been used for numerous types of studies in the decades since, including testing Albert Einstein's theory of general relativity. Bell Burnell never received Nobel credit for her work, although other team members did.

In 2018, Bell Burnell received a Special Breakthrough Prize in Fundamental Physics, receiving $3 million that she planned to use in part to hire newer astronomy researchers. The award was given in recognition of her pulsar discovery and more than 50 years of scientific leadership in the decades since.

Jill Tarter (1944-present)

Jill Tarter is a noted radio astronomer and former director of the Center for the Search for Extraterrestrial Intelligence (SETI). (Image credit: Photo by Juan Naharro Gimenez/Getty Images)

Jill Tarter is a noted radio astronomer best known for her work as the former director of the Center for the Search for Extraterrestrial Intelligence (SETI). While she retired from the position in 2012, she continues her advocacy in astronomy and SETI. The fictional character Ellie Arroway in "Contact" (book in 1985, movie in 1997) is based on Tarter.

Tarter signed on to the SETI search in the 1970s after reading about "Project Cyclops", a 1971 NASA report describing a procedure to use Earth-based radio telescopes to look for signs of intelligence line up to 1,000 light-years away from Earth. She helped create the center in 1984, allowing SETI searches to continue even after Congress refused NASA funds for SETI work in 1993.

The Allen Telescope Array near San Francisco is the main signal-scanning tool for SETI, and Tarter elected to leave her director position in favor of ongoing fundraising efforts after SETI temporarily shut down the array in 2012 due to budget problems from a former partner, the University of California, Berkeley. In 2017, science journalist Sarah Scoles published a biography of Tarter and a history of SETI: "Making Contact: Jill Tarter and the Search for Extraterrestrial Intelligence."

Margaret Joan Geller (1947-present)

Margaret Joan Geller examines how galaxies are distributed in the universe, and where they come from. (Image credit: Wikimedia Commons/CC BY-SA 4.0)

Margaret Joan Geller, of the Harvard-Smithsonian Center for Astrophysics, is best known for examining how galaxies are distributed in the universe, and where they come from. She is also devoted to public engagement, including creating two award-winning films: "Where the Galaxies Are" and "So Many Galaxies...So Little Time."

Geller received her undergraduate degree from the University of California, Berkeley and her Ph.D. in physics in 1975 from Princeton University. Her career honors include a MacArthur Fellowship, the Newcomb-Cleveland Prize of the American Association for the Advancement of Science and the National Academies of Science Watson Medal, among numerous accolades.

"Dr. Geller's long-range scientific goals are to discover what the universe looks like and to understand how it came to have the rich patterns we observe today," her biography page states

Carolyn Porco (1953 to present)

Carolyn Porco is a planetary scientist and leader of the Cassini mission, which orbited Saturn between 2004 and 2017. (Image credit: ROBYN BECK / Staff)

Carolyn Porco is a planetary scientist best known for being the leader of the Cassini mission, which orbited Saturn between 2004 and 2017. Her specialty is examining Enceladus, a spurting icy moon orbiting the planet. She also was an imaging scientist on the Voyager missions to the outer solar system in the 1980s and is an associate member of the New Horizons mission that flew by Pluto in 2015 and is still active in the Kuiper Belt.

Porco looked at Saturn in detail at age 13, standing on a rooftop in the Bronx using a friend's telescope. She told Space.com in 2005 that her interest in space came from exploring topics such as Eastern philosophy, religion and existentialism that "turned my sights from inwards to outwards." She did her undergraduate astronomy degree at the State University of New York and her doctorate at the California Institute of Technology.

Even in her doctorate, Porco was intimately involved with space exploration, helping out the Voyager imaging team because they "didn't have enough hands or scientists to work on all of it," she told Space.com. She especially focused on the rings of giant planets on Voyager and leveraged that experience in her application for the Cassini mission.

Heidi B. Hammel (1960 to present)

Heidi Hammel is a planetary scientist who has worked on numerous missions. She is currently working as an interdisciplinary scientist with the James Webb Space Telescope team. (Image credit: NASA/Bill Ingalls)

Heidi Hammel is a planetary scientist who has worked on numerous missions. One of her latest roles is as an interdisciplinary scientist with the James Webb Space Telescope, a NASA flagship mission that is exploring everything from exoplanets to the early days of the universe. Her work as a planetary astronomer spans numerous missions, including observations with the Gemini, Hubble, Spitzer and Keck telescopes.

Hammel received her undergraduate degree from the Massachusetts Institute of Technology and her Ph.D. in physics and astronomy from the University of Hawaii. She did a post-doctoral position at NASA's Jet Propulsion Laboratory, then was a principal research scientist at MIT in the Department of Earth, Atmospheric, and Planetary Sciences. In 1998, Hammel joined the Space Science Institute, where today she is a senior research scientist.

Hammel's numerous awards include the 1996 Urey Prize from the American Astronomical Society for her outstanding achievement in planetary science, as well as the AAS/DPS 2002 Sagan Medal for her outstanding communication as an active planetary scientist to the general public. In her biography, she says that public education by scientists "is one of the most important things" these researchers can do.

Andrea M. Ghez (1965 to present)

Andrea Ghez was the fourth woman to be awarded the Nobel Prize in Physics. (Image credit: Stefanie Keenan / Contributor)

Andrea Ghez is an astronomer who became the fourth woman to be awarded the Nobel Prize in Physics in 2020. Ghez shared part of the prize (which was awarded to three scientists) "for the discovery of a supermassive compact object at the center of our galaxy," the Royal Swedish Academy of Sciences said.

Ghez wanted to be a ballerina when she grew up, until the age of four, her biography states. Then she saw Apollo 11 land on the moon in 1969, putting the first two astronauts on the moon. She first changed her career plans to become the first female astronaut, then changed again to become an astrophysicist. For pursuing these various dreams, she credits the encouragement of her mother and a high school chemistry teacher.

She graduated from the Massachusetts Institute of Technology with a bachelor of physics, then received a PhD from the California Institute of Technology. Her commitment to education began at Caltech when she convinced her adviser to teach undergraduate courses in Physics. She joined the teaching staff at the University of California, Los Angeles and is today head of the UCLA galactic center group.

While Ghez's studies are wide-ranging, it was her studies of a massive black hole called Sagittarius A* that got her the Nobel Prize. Her team found that an object that weighs four million solar masses is within our galaxy's center, and created telescopic methods to examine the object through the dense gas and dust in that region.

Beth A. Brown (1969 to 2008)

Beth Brown is best known for her contributions to astronomy, along with helping women and minorities pursue astrophysics careers. (Image credit: NASA)

Beth Brown is best known for her contributions to astronomy, along with helping women and minorities pursue astrophysics careers. Her most recent position was NASA Goddard Space Flight Center's assistant director for science communications and higher education, in the science and exploration directorate. Brown died unexpectedly at the age of 39, due to a pulmonary embolism.

Born in Roanoke, Virginia, Brown's childhood interests included "Star Trek", astronomy and science fiction. She was the valedictorian of her high school and graduated from Howard University summa cum laude with a bachelor's degree in astrophysics. She was the first African-American woman to pursue graduate studies in astronomy at the University of Michigan, receiving her Ph.D. there in 1998. Her dissertation concerned X-ray observations of elliptical galaxies using the Röntgen Satellite.

Post-graduation, Brown's other positions included Goddard postdoctoral fellow and Goddard astrophysics fellow. In between her research, she conducted planetarium shows, spoke on popular science topics and performed other activities geared to public outreach.

Sandra Faber (1944 to present)

President Barack Obama awards Sandra Faber with the National Medal of Science at the White House, on Feb. 1, 2013. (Image credit: Jewel Samad/AFP/Getty)

Sandra Faber's father was an engineer, and her mother was a housewife. At first, she was hesitant to study astronomy, however, because she felt the scientists there were "impossibly distant", in the sense that you had to be as smart as Einstein to pursue the career. She credits her public school teachers for encouraging her to pursue science nonetheless.

She received an undergraduate physics degree from Swarthmore College and her doctorate from Harvard University. After graduating, she spent her entire career at the University of California, Santa Cruz. She is professor emerita at that institution and astronomer emerita of the University of California Observatories, among other positions.

Faber's numerous discoveries include finding a relation between the luminosity of galaxies to the velocity of stars inside those galaxies, which is known today as the Faber-Jackson relation after the co-discoverers. She advocated for the building of the 10-meter Keck Telescope in Hawaii and led the construction of one of its biggest spectrographs. She also contributed to the testing and commissioning of the Wide-Field Camera for the Hubble Space Telescope.

Faber has dozens of honors and awards, among them the Alfred P. Sloan Foundation Fellowship in 1977, the Bart J. Bok Prize from Harvard in 1978, and Science Digest's 100 Best American Scientists Under 40 in 1984. In 2013, U.S. President Barack Obama presented her with the National Medal of Science.

Barbara A. Williams (current-day astronomer)

Barbara A. Williams was the first African-American woman to achieve a Ph.D. in Astronomy, in 1981 (Image credit: Scott Williams via Astronomers of the African Diaspora)

Barbara A. Williams was the first African-American woman to achieve a Ph.D. in Astronomy, in 1981. She received her education at the University of North Carolina, and a master's degree and doctorate in radio astronomy at the University of Maryland.

Following earning her doctorate, she took a position at the National Radio Astronomy Observatory to study groups of galaxies in radio wavelengths and has researched at places such as the NASA Goddard Space Flight Center.

Williams' groundbreaking research includes examining neutral atomic hydrogen emissions to study several galaxies, and looking at the role of atomic gases within galaxy groups, among other topics. Today she is based at the University of Delaware and is an active member of the International Astronomical Union.

What is Astrophysics?

Ariel Balter — Fri, 14 Jan 2022 17:22:12 +0000

Astrophysics is a branch of space science that applies the laws of physics and chemistry to seek to understand the universe and our place in it.

The field explores topics such as the birth, life and death of stars, planets, galaxies, nebulae and other objects in the universe. It has two sibling sciences, astronomy and cosmology, though the lines between these branches can blur.

In the most rigid sense:

Astrophysics creates physical theories of small to medium-size objects and structures in the universe.

Astronomy measures the positions, luminosities, motions and other characteristics of celestial objects.

Cosmology covers the cosmos' largest structures and the universe as a whole.

More: 20 trailblazing women in astronomy and astrophysics

In practice, the three fields form a tight-knit family.

Ask for the position of a nebula or what kind of light it emits, and an astronomer might answer first. Ask what the nebula is made of and how it formed and an astrophysicist could pipe up. Ask how the data fit with the formation of the universe, and a cosmologist would probably jump in. Or they might all chime in to explore all three questions.

Astrophysics at NASA

Astrophysicists seek to understand the universe and our place in it.

At NASA, the aims of its astrophysics work are "to discover how the universe works, explore how it began and evolved, and search for life on planets around other stars," according to NASA's website.

NASA states that its astrophysics work grapples with three main questions:

It began with Isaac Newton

Isaac Newton (Image credit: Science Photo Library)

While astronomy is one of the oldest sciences, theoretical astrophysics began with Isaac Newton.

Prior to Newton, astronomers described the motions of "heavenly bodies," as they were then called, using complex mathematical models without a physical basis. Newton showed that a single theory, describing what we now know as gravity, simultaneously explains the orbits of moons and planets in space and the trajectory of a cannonball on Earth. This added to the body of evidence for the (then) startling conclusion that the "heavens" and Earth are subject to the same physical laws.

Perhaps what most separated Newton's model from previous concepts, however, is that his theory was predictive as well as descriptive. Based on aberrations in the orbit of Uranus, astronomers predicted the position of a new planet, which was then observed and named Neptune.

Milestones in astrophysics

Cecilia Payne Gaposchkin (Image credit: Science History Images / Alamy Stock Photo)

We can't directly interact with distant cosmic objects, but we can observe the radiation they emit, and much of astrophysics has to do with studying this radiation and working to explain the mechanisms behind it.

The first ideas about the nature of stars emerged in the mid-19th century from the blossoming science of spectral analysis, an essential mainstay in the space sciences which means observing the specific frequencies of light that particular substances absorb and emit when heated.

Early spectroscopy provided the first evidence that stars contain substances also present on Earth. Spectroscopy has revealed that some nebulae are purely gaseous, while some contain stars. This later helped to cement the idea that some nebulae were not nebulae at all — they were other galaxies!

In the early 1920s, American astronomer and astrophysicist Cecilia Payne discovered, using spectroscopy, that stars are predominantly hydrogen (at least until their old age). By studying the spectra of stars, astrophysicists were also able to determine the speed at which they move toward or away from Earth.

The sound a vehicle emits is different whether it's moving toward us or away from us, and light has a similar effect because of something called the Doppler shift in which the spectra of stars change whether they are moving toward or away from us. In the 1930s, by combining the Doppler shift and Einstein's theory of general relativity, Edwin Hubble provided solid evidence that the universe is expanding. This is also predicted by Einstein's theory, and together form the basis of the Big Bang Theory.

In the mid-19th century, physicists Lord Kelvin (William Thomson) and Gustav Von Helmholtz speculated that gravitational collapse could power the sun, but eventually realized that energy produced this way would only last 100,000 years. Fifty years later, Einstein's famous E=mc² equation gave astrophysicists the first clue to what that energy source might be (although it turns out that gravitational collapse does play an important role).

As the fields of nuclear physics, quantum mechanics and particle physics grew in the first half of the 20th century, it became possible to formulate theories for how nuclear fusion could power stars. These theories describe how stars form, live and die, and they successfully explained the observed distribution of different types of stars, their spectra, luminosities, ages and other characteristics.

According to the Big Bang Theory, the first stars were almost entirely hydrogen. The nuclear fusion process that energizes them smashes together hydrogen atoms to form the heavier element helium. In 1957, the husband-and-wife astronomer team of Margaret and Geoffrey Burbidge, along with physicists William Alfred Fowler and Fred Hoyle, showed how, as stars age, they produce heavier and heavier elements, which they pass on to later generations of stars in ever-greater quantities.

It is only in the final stages of the lives of more recent stars that the elements making up the Earth, such as iron (32.1 percent), oxygen (30.1 percent) and silicon (15.1 percent) are produced. Another of these elements is carbon, which together with oxygen makes up the bulk of the mass of all living things, including us. This is why you might've heard astrophysics say that we are all made of stardust, seeing as we are carbon-based lifeforms.

Astrophysics as a career

If you dream of studying the stars, know that becoming an astrophysicist requires years of observation, training and work. But you can start at whatever age by doing things like joining an astronomy club, attending local astronomy events, taking free online courses in astronomy and astrophysics and keeping up with news in the field (you can even do that on a website like Space.com).

If you continue to pursue the career, most start with a related undergraduate college degree and eventually work towards graduate degrees or a doctorate degree in astrophysics. Many then take on a post-doctoral position in astrophysics.

Astrophysicists can work for the government, university labs and, occasionally, private organizations.

A few additional tips for pursuing a career in astrophysics:

Take math and science classes all through high school: Make sure to take a wide variety of science classes. Astronomy and astrophysics often blend elements of biology, chemistry and other sciences to better explore a wide variety of phenomena in the universe. Also, keep an eye out for any school clubs, volunteer work, summer jobs or internships available in math or science.

Pursue a bachelor's degree in math or science: While a bachelor's degree in astrophysics is a good route, there are many other paths that could lead you to the field. You can study computer science, for example, which is important in analyzing data. If you're considering this option, speak with your high school guidance counselor or university to find out what degree programs will be best for you.

Take on research opportunities: Many universities have labs in which students participate in research — and sometimes even get published. Agencies such as NASA also offer internships for undergraduate students.

Complete a graduate degree or doctorate in astrophysics: While some have graduate degrees, most astrophysicists have doctoral degrees, according to the U.S. Bureau of Labor Statistics.

Back in 2015, planetary astrophysicist Natalie Hinkel did a lengthy interview with Lifehacker that gave readers a glimpse into the rewards and challenges of being an astrophysics researcher. She described the long number of years she has put into doing her research, the frequent job switches, the work hours and what it's like to be a woman in the field. She also shared interesting insights about her day-to-day work, surprising to some readers is that little of her time is actually spent at a telescope.

"I spend the vast majority of my time programming. Most people assume that astronomers spend all of their time at telescopes, but that's only a very small fraction of the job, if at all. I do some observations, but in the past few years I've only been observing twice for a total of about two weeks," Hinkel told Lifehacker.

"Once you get the data, you have to reduce it (i.e. take out the bad parts and process it for real information), usually combine it with other data in order to see the whole picture, and then write a paper about your findings. Since each observation run typically yields data from multiple stars, you don't need to spend all of your time at the telescope to have enough work," she said.

Additional reporting by Elizabeth Howell, Space.com contributor. This page was updated Jan. 13 by Space.com senior writer Chelsea Gohd.

Additional resources

5 space missions to look forward to now that the James Webb Space Telescope has launched

Paul Sutter — Sun, 26 Dec 2021 12:59:31 +0000

The James Webb Space Telescope was a decade late and $10 billion over budget, but it has finally launched.

Now that the telescope is in space, what's next for astrophysics done from beyond Earth's surface? Here are five future missions to get excited about.

Nancy Grace Roman Telescope

This telescope — named after Nancy Grace Roman, NASA's first chief astronomer — was originally called the Wide-Field Infrared Space Telescope, or WFIRST. Its main purpose is to map large swaths of the universe to study dark energy.

(The original name is also a clever play on words: In the mathematical equations that cosmologists use to describe dark energy, its equation of state, or relationship between pressure and density, is represented by "w." Because the point of the mission is to study dark energy, "w" comes first — hence the name WFIRST.)

Expected to launch in 2027, the Nancy Grace Roman Space Telescope will survey millions of galaxies, building a map of our cosmological neighborhood. Astronomers hope to use the distribution of galaxies to tease out the evolution of dark energy. As a bonus, the instrument will also use gravitational microlensing — tiny changes in background starlight — to discover potentially millions of exoplanets.

An artist's impression of NASA's Nancy Grace Roman Space Telescope, formerly known as the Wide Field Infrared Survey Telescope (WFIRST). (Image credit: NASA)

LUVOIR

The James Webb Space Telescope is like a souped-up version of the Hubble Space Telescope. It's so big that it can't even fit into a single rocket fairing without a really complicated, origami-like folding of its mirror segments.

The Large Ultraviolet/Optical/Infrared Surveyor (LUVOIR) is even bigger, with a mirror diameter of about 50 feet (over 15 meters). Astronomers hope this general-purpose telescope could achieve a variety of astronomical science objectives, such as observe the cloud tops of Jupiter with a 15-mile (25 kilometers) resolution and hunt for biosignatures in the atmospheres other planets.

LUVOIR is only in the design phase and is competing with other observatories for priority funding. But if it goes through, the mega space telescope will launch sometime in the 2030s.

HabEx

Finding habitable planets is a pretty hot topic in astronomy. The discovery of an Earth 2.0 would be a gold mine, helping us understand how common life is in the universe, and maybe even heralding a discovery that we're not alone. To do that, astronomers search for near copies of Earth — planets with similar masses and compositions to our home world orbiting sunlike stars at just the right distance to allow for liquid water.

But finding the planet is only the beginning; we need to study its atmosphere, looking for biosignatures, which are chemical byproducts of life. An abundance of oxygen, for example, might be a sign that photosynthesis is active on that world, and a lot of methane might show us that there are bacteria-like organisms there.

The Habitable Exoplanet Imaging Mission (HabEx) hopes to do just that. Although it, too, is competing for funding, proponents hope to launch HabEx in 2035. What makes HabEx shine is its star shade, a massive flying disc that would block the light of individual stars, allowing the telescope to directly image exoplanets.

LISA

The Laser Interferometer Space Antenna (LISA) is a space-based gravitational wave observatory. Led by the European Space Agency, it will target gravitational wave sources that ground-based detectors can't, like colliding supermassive black holes and the mergers of compact objects within our own galaxy. LISA is a formation of three satellites, all orbiting the sun together while maintaining a separation of about 1.5 miles (2.5 million km).

By continually bouncing lasers between them, the satellites can measure any slight changes to their distance, especially if gravitational waves come washing through. The observatory is targeted for launch in 2034.

DARE

There was a time before stars. The first few hundred million years after the Big Bang were appropriately named the "Dark Ages." This era has not been observed with any telescope … because, well, it was dark.

But floating through that darkness were tendrils of neutral hydrogen. Neutral hydrogen gives off a very particular sort of radiation, emitting light at precisely 2.1 centimeters (0.83 inch). That radiation has sailed through the universe over all these eons and today, 13 billion years later, has redshifted to have a wavelength of around 2 meters (6.6 feet).

That's in the radio spectrum, which means any attempts to detect this sort of radiation are overwhelmed by our terrestrial radio chatter. So that's where the Dark Ages Radio Explorer (DARE) comes in.

DARE is currently in the design phase, and proponents hope to launch it sometime in the next few years. It's a relatively simple observatory, basically a car antenna in space, but its location will be unique: It will orbit the moon. The far side of the moon is the only known place in the inner solar system known to be free of human-generated radio interference. It's the quietest place nearby, and the best place to hunt for the cosmic Dark Ages.

Learn more by listening to the "Ask A Spaceman" podcast, available on iTunes and askaspaceman.com. Ask your own question on Twitter using #AskASpaceman or by following Paul @PaulMattSutter and facebook.com/PaulMattSutter. Follow us on Twitter @Spacedotcom and on Facebook.

30 years and $10 billion later, the James Webb Space Telescope is finally on the launch pad

mbartels@space.com (Meghan Bartels) — Fri, 24 Dec 2021 16:42:55 +0000

NASA and the astronomy community have poured $10 billion and more than two decades into just one piece of machinery. Now they are facing the moment of truth.

NASA's James Webb Space Telescope, also known as Webb or JWST, is finally in French Guiana, perched atop its rocket, ready to bid farewell to Earth and begin the long trek out to space. It has overcome loose screws, testing missteps, a Congressional cancellation, a pandemic and even the small risk of being hijacked by pirates on its way to the launch site. The project is so vast that it has shaped the agency as much as the agency has shaped it.

"You can't do this every five years," Michael Turner, a theoretical cosmologist at the Kavli Institute for Cosmological Physics at the University of Chicago, told Space.com. "It just convulses the agency, and that's exactly what they should be doing every once in a while."

Of course, the goal has been more to convulse science than NASA itself. Specifically, JWST has a truly massive mirror compared to other space telescopes, and the observatory will specialize in studying infrared light, which will give scientists an opportunity to look into the early days of the universe. Those two capabilities combined represent a huge step forward from existing space telescopes.

But infrared light is particularly difficult to observe because it doubles as heat. So JWST has been given an unprecedented sunshield and the observatory will be sent to a spot called Earth-sun Lagrange point 2, or L2, 1 million miles (1.5 million kilometers) farther away from the sun than Earth.

Scientifically, it's all very exciting, but in terms of engineering, it's incredibly hard. When designs for JWST solidified, NASA had never built anything like it before. "When you're doing something for the first time, it's really hard to predict how long it's going to take and how much it's going to cost," Elizabeth Frank, who was a planetary scientist working on NASA missions before becoming chief scientist at First Mode, an engineering company, told Space.com.

The Hubble Space Telescope, a smaller telescope but the key predecessor in scale to JWST, had a safety mechanism built in: Thanks to its orbit around Earth and its careful design, astronauts could visit the spacecraft and tend to its instruments. Not so for JWST.

And JWST's mirror is too big to launch in one piece, so for the first time on a space telescope, it must align 18 different segments to form one perfectly smooth surface.

And the five-layer sunshield that must unfurl in space? Nothing like it has flown before.

Getting a spacecraft to L2, that's been done, but only by much smaller missions, like NASA's Wilkinson Microwave Anisotropy Probe that operated from 2001 to 2010 and the European Space Agency's Planck mission to map the cosmic microwave background.

And there's no way to simplify JWST and get science results of the same magnitude. "If it weren't complicated, if it weren't at L2, if it hadn't had a sunscreen to keep it nice and cool, you couldn't do all the transformational stuff," Turner said.

An animation shows the orbit of the James Webb Space Telescope around Lagrange point 2, or L2. (Image credit: NASA)

An ever-growing project

When the astronomy community began toying with ideas for what is now known as JWST in the 1990s, NASA leadership led by then-administrator Dan Goldin encouraged going bigger and bolder.

From there, the ignominy JWST has faced over its ballooning budgets and ever-more-delayed launch may have been a little inevitable. "The more you try to do with one spacecraft, the more inherent technical complexity there is within the spacecraft," Frank said.

And as JWST became ever more ambitious, NASA became ever more determined to make sure nothing could go wrong.

"If you have a large, complicated mission, you're going to demand high reliability because it's so expensive and you have so much riding on it," Frank said. "But to mitigate the risk of failure, you really need a lot of time and labor, and it's not the materials that drive the cost of missions, it's actually labor." That's particularly true of aspects like project management and system management, that are key for staying on track, she noted.

NASA's fear of failure also perhaps contributed to JWST's troubled image, as engineers tested it every way they could. "That's why you build in all the tests, because when it's that complicated, something's gonna go wrong," Turner said.

Those tests caused delay after delay as engineers caught and caused issues in the observatory that needed to be fixed. "It turns out there's no such thing as a smart accident," Turner said. "They all involve stupid things. All mistakes are stupid retrospectively."

A moment of reckoning

The tangle came to a head in 2011.

While substantial parts of the observatory were in the late stages of assembly, the project was still deep in debt and far from the launch pad. "People knew there was a problem, but no one wanted to say it," Turner said of NASA and JWST leadership. "They'd gotten themselves in trouble."

Congress lashed out. The House of Representatives produced a budget proposal that would have ended work on the observatory, although by the end of budget negotiations the telescope survived. Turner, who was among the astronomers who stepped in to argue the telescope's case during the crisis, said that the very vision that saw JWST spiral out of control may also have saved the mission.

"They really picked the right mission, and so during the darkest days, it was still worthy of doing," he said. "It wasn't one of those things, 'You know it would've been great if we could have done that, but it's getting pretty tough out there; let's just quit.'"

It could have gone a very different way, as astronomers are well aware. Physicists learned that the hard way in 1993, when Congress canceled construction on the Superconducting Super Collider (SSC) in Texas $2 billion into the project. "That is such a blemish on American science," Turner said. "It has colored a field: That dark cloud of SSC still lives over the field of high-energy physics and it left a blemish on American science."

Even JWST's immediate predecessor had faced a similar crisis. Hubble launched in 1990 and began gathering data only for astronomers to realize that an error in the mirror left the observatory's vision blurry. Software workarounds and crewed servicing missions eventually rescued the beleaguered telescope, but there was no guarantee.

"That's the scary part here: There were a lot of people who just left Hubble when it had the problems," Turner said. "The really tough ones — this is the grit side — said, 'Well, there must be some way we can fix this.'"

Risky business

Hubble survived and became an icon; today, JWST is perched atop its rocket, ready to launch. But it hasn't been a journey without casualties.

In the course of the observatory's development, NASA was forced to reallocate some $1.4 billion from other projects to JWST, William Russell of the federal government's Government Accountability Office said during a House hearing held on Dec. 1.

"Budgetary discipline is important, particularly with these big projects. When they bleed, the rest of science hemorrhages," Turner said. "A small overrun for them kills other projects, so you've got to go in realistic."

And as astronomers have poured so much into making JWST a reality, Frank argued that there must be an opportunity cost in terms of missions that have gone unbuilt. "What missions haven't we launched because JWST just sucked up the budget for as long as it has? What could we have done with 10 $1 billion missions instead?" Frank said. "It's easy to say things in retrospect, but I think these are important questions."

If anything goes wrong as JWST launches, deploys and eventually begins operations — well, that's the nightmare scenario on countless fronts.

"I think it's really, really challenging to put so many of your science eggs in one basket," Frank said. Scientists who have built their research programs to cater to the data that JWST has promised "see their careers literally at stake on the launch pad right now," she said.

Into the future

Some observers also worry that the woes of JWST will loom over future mission proposals. JWST has led NASA to be more diligent about requiring pragmatic mission schedules and budgets. But whether the experience has soured the agency entirely on such massive projects remains to be seen.

It might depend on how JWST fares in space. "Success brings success and failure brings failure," Robert Smith, a historian at the University of Alberta who has compared JWST and SSC as "megascience" projects, said during a webinar held on Dec. 9 by the National Air and Space Museum. "I think it absolutely needs to work if there is going to be a successor."

That's reflected in the new 10-year plan for astronomy released in November, he said. That report looked ahead to big space telescope projects but emphasized that the technology involved should be incorporated into smaller missions first to reduce risk. Smith called it a "shadow of JWST hang[ing] over quite a lot of that report."

Frank also worries that a failure at such a scale could imperil NASA's reputation, particularly because the agency relies on public funding. "The challenge that NASA has is being able to succeed and do good science and develop technology while minimizing blowback from people who may be unsupportive of failure," Frank said. "NASA has to be a good steward of taxpayer funding, and taxpayers are going to negatively react if they are perceived to not be good stewards."

That's a very different situation than, say, SpaceX faces. She noted that the company leans into its failures with videos of rockets blowing up. "They can kind of make fun of their own failures and use it in a way that works to their advantage, whereas NASA probably doesn't have the freedom to do that," Frank said.

She argued that the agency's culture shapes the projects it operates. "There needs to be a set of incentives that make people think, 'If I don't figure out a cost-effective solution to this problem, there's a real chance this mission could be canceled." She also noted NASA's work to pursue missions of a whole range of sizes, including smaller missions on which the agency might accept some risk of failure.

But it's important that NASA succeeds, and that it tackles the most ambitious projects, Turner said. "No one else could have pulled off JW[ST], and it's important for all of American science, not just astronomy, that this country can still do things that just dazzle," he said.

He argued that the importance stretches beyond science as well. "The world is a mess," Turner said. "The lesson I take away is we are a really good species when we put our mind to it. When we all come together, choose a good goal and work hard together, we can really do amazing things and we need to be reminded of that every once in a while."

For him, he said, JWST's launch, even or perhaps especially after all its twists and turns, is one of those amazing things. "Can't we take some of those skills and solve some other problems as well?"

Email Meghan Bartels at mbartels@space.com or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.

Massive simulation of the universe probes mystery of ghostly neutrinos

Paul Sutter — Mon, 06 Dec 2021 11:00:44 +0000

Paul M. Sutter is an astrophysicist at SUNY Stony Brook and the Flatiron Institute, host of "Ask a Spaceman" and "Space Radio," and author of "How to Die in Space." Sutter contributed this article to Space.com's Expert Voices: Op-Ed & Insights.

How do you test theories of the universe? By building gigantic supercomputers and simulating the evolution of the cosmos.

A team of Japanese scientists has built the largest-ever cosmic simulation to include tiny "ghost" particles called neutrinos. To explore one of physics' biggest unsolved mysteries, the researchers used a whopping 7 million CPU cores to solve for the evolution of 330 billion particles and a computational grid of 400 trillion units.

By far the most important form of matter in the universe is dark matter. We're not sure what it is or what it's made of, but we do know that there's a lot of it. It makes up about 80% of all matter. Baryonic matter — the stuff that makes up stars, planets and the rich variety of the entire periodic table — makes up just a small fraction of all the matter in the universe.

Related: Where did all the baryons go?

Dark matter forms the backbone of the cosmos. Billions of years ago, there were no structures in the universe. All of the matter — dark or otherwise — was smoothly distributed, and not lumpy at all. There simply weren't very many variations in density from place to place. Overall, it was a pretty boring universe.

But with time, the universe became more interesting. There were tiny density differences, seeded from microscopic quantum fluctuations in the early seconds of the Big Bang. Places with slightly higher density had slightly more gravity, and that's where dark matter began to pool together. As those early structures budded, they attracted even more material. Over billions of years, this process emptied out vast regions of the cosmos — now known as cosmic voids — pulling all the matter into an extensive network of clusters, walls and filaments.

And then there are neutrinos, extremely tiny particles that have barely any mass. Indeed, they make up less than 0.1% of all the mass in the universe. But these minuscule particles have an outsize influence on the evolution of structures. They are fast — really fast — capable of traveling at nearly the speed of light. This incredible speed dampens the formation of large structures, such as galaxies and clusters.

Whereas dark matter wants to keep piling up through gravity, neutrinos go too fast to settle down in one spot. And although neutrinos have very little mass, they still have some mass. They can use their gravity to weakly influence the behavior of dark matter, thus preventing it from clumping as tightly as it normally would.

In other words, the universe is a little smoother than it would be without neutrinos.

Mysteries of the universe

Finding the masses of the three known neutrino "flavors" — electron neutrinos, muon neutrinos and tau neutrinos — is a major unsolved problem in modern physics. But ironically, we can measure the masses of these tiny particles by mapping the largest structures in the universe.

To try to understand the nature of dark matter and the role of neutrinos in shaping cosmic evolution, cosmologists often turn to computer simulations. If you change the neutrino mass just a bit in the simulations, it will change how the neutrinos influence the formation of structures over billions of years. So by measuring those same structures, you can get an understanding of neutrino mass.

These simulations usually encompass a small fraction of the real universe and start with a set of dark matter "particles," with each particle representing a certain amount of dark matter — for example, a single blob with a mass millions of times the mass of the sun. The simulations then position these particles as they would be in the early universe. The simulations track how those particles evolve through their mutual gravity, giving rise to the giant structures we see today.

This is an approximation technique, because the true behavior of dark matter is represented by a limited number of particles, but it works very well for dark matter. Simulating neutrinos is much more difficult because of their ridiculous speed. It's difficult to follow their behavior within the simulation because they can move from one side of the simulation to the other in a short amount of time. So the simulations can't keep up with how the neutrinos are acting and how they're influencing dark matter.

A matter of computation

So maybe we shouldn't bother trying to approximate the behavior of neutrinos. To correctly follow the evolution of neutrinos and account for their fast behavior requires solving an incredibly complex equation. Solving this equation — called the Vlasov equation, after Russian physicist Anatoly Vlasov — however, requires immense computational resources.

So a team of Japanese scientists did just that: They used 7 million processors on the Fugaku supercomputer to trace the evolution of dark matter and the influence of neutrinos on the formation of structures. The researcher used 330 billion particles to represent dark matter and a computational grid of 400 trillion components to represent neutrinos, in the largest simulation of its kind.

And while it may not have solved the mystery of neutrinos' mass, the simulation does pave the way for more of its kind. In essence, this simulation was a proof-of-concept to show that we can now include neutrinos in simulations more accurately than ever before. Armed with this new technology, future simulations will open a window into the role of neutrinos in the universe and perhaps even reveal a key to unlocking their mass.

The team's paper was posted recently on the preprint server arXiv, and you can see the simulation here.

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Astronomers target habitable exoplanets, black holes and inclusivity as top priorities for next decade

mwall@space.com (Mike Wall) — Thu, 04 Nov 2021 15:13:03 +0000

We now have a rough sketch of what the next decade could bring in astronomy and astrophysics.

Today (Nov. 4), the U.S. National Academies of Sciences, Engineering, and Medicine released a "decadal survey" laying out scientific priorities and funding recommendations for the next 10 years of astronomy and astrophysics research.

The document, called "Pathways to Discovery in Astronomy and Astrophysics for the 2020s," identifies three top-line items the disciplines should concentrate on: the discovery and study of habitable exoplanets, the exploration of black holes and neutron stars as windows to the early universe, and a better understanding of the origin and evolution of galaxies. It also stresses the importance of making astronomy a more inclusive and diverse field.

"This report sets an ambitious, inspirational and aspirational vision for the coming decade of astronomy and astrophysics," Fiona Harrison, co-chair of the National Academies' steering committee for the survey, said in a statement.

"In changing how we plan for the most ambitious strategic space projects, we can develop a broad portfolio of missions to pursue visionary goals, such as searching for life on planets orbiting stars in our galactic neighborhood — and at the same time exploit the richness of 21st-century astrophysics through a panchromatic fleet," added Harrison, who chairs the division of physics, mathematics and astronomy at the California Institute of Technology in Pasadena.

An influential document

The National Academies prepares decadal surveys for a variety of fields, including planetary science and Earth science. As the name suggests, they come out every 10 years or so; the last astronomy and astrophysics decadal — "New Worlds, New Horizons in Astronomy and Astrophysics" — was released in 2010. (The new report was delayed by nearly a year by the coronavirus pandemic and a government shutdown; it was supposed to be released in January 2021.)

A lot of work goes into these documents, which are drawn up by prominent researchers in the fields that they cover. The newly released survey, for example, is 614 pages long.

"'Pathways to Discovery in Astronomy and Astrophysics for the 2020s' drew from the astronomical community through hundreds of white papers, town hall meetings and the advice of 13 sub-panels over several years to produce its recommendations," National Academies representatives wrote in the statement.

Decadal surveys are incredibly influential; government agencies such as NASA and the National Science Foundation (NSF) rely on them to decide how to allocate funding and other resources. For example, the 2001 astronomy and astrophysics decadal identified the Next Generation Space Telescope as the highest-priority mission to develop over the next 10 years. That ambitious observatory, now known as the James Webb Space Telescope, is scheduled to launch from French Guiana on Dec. 18.

In 2010, "New Worlds, New Horizons" flagged the Wide-Field Infrared Survey Telescope (WFIRST) and the Large Synoptic Survey Telescope (LSST) as especially important projects. And both are now progressing toward operation, though not without some drama. WFIRST, now known as the Nancy Grace Roman Space Telescope, is scheduled to lift off no later than May 2027, and the ground-based LSST, now called the Vera C. Rubin Observatory, will open its eyes in 2022 or 2023, if all goes according to plan.

Three areas of focus, and a new 'Great Observatories' program

The newly released survey identifies three "priority areas" that should receive special attention and investment over the coming decade.

One, called "Pathways to Habitable Worlds," is a program designed to help discover and characterize Earth-like exoplanets, with the goal of eventually capturing photos of such worlds and analyzing their atmospheric composition.

The second, "New Windows on the Dynamic Universe," describes an intensified effort to study black holes and neutron stars with a diversity of instruments on the ground and in space, including gear that detects gravitational waves. Gaining a better understanding of these exotic, superdense objects could shed considerable light on the very early universe, the report's authors wrote.

The third focus area, "Unveiling the Drivers of Galaxy Growth," aims to revolutionize scientists' understanding of galaxy formation and evolution, "from the nature of the tenuous cosmic webs of gas that feed them, to the nature of how this gas condenses and drives the formation of stars," the decadal survey states.

To help achieve these and other ambitious goals, the survey recommends the establishment of a "Great Observatories Mission and Technology Maturation Program" — a callback to NASA's Great Observatories program, which launched four powerful space telescopes from 1990 to 2003, starting with the iconic Hubble Space Telescope.

The new Great Observatories effort "would provide significant early investments in the co-maturation of mission concepts and technologies, with appropriate decadal survey input on scope, and with checks and course corrections along the way," according to the new decadal.

The survey also recommends that this program's first mission should be an infrared/optical/ultraviolet (IR/O/UV) space telescope with a primary mirror about 19.7 feet (6 meters) across. That's about 2.5 times wider than Hubble's mirror and roughly the same size as that of Webb, which is optimized to view the cosmos in infrared light.

This envisioned space telescope could search for biosignatures in the atmospheres of about 25 potentially habitable exoplanets and be ready for launch in the early 2040s, the survey determined. And its mission could be mounted for about $11 billion, if all goes well — roughly the same price tag as Webb, whose total cost is about $10 billion.

The goals of this proposed IR/O/UV space telescope are broadly similar to those of two concept missions that NASA has been developing since 2016 — the Large Ultraviolet Optical Infrared Surveyor (LUVOIR) and the Habitable Exoplanet Observatory (HabEx).

There are two potential LUVOIR variants, which would boast primary mirrors 49.2 feet (15 m) and 26.2 feet (8 m) wide, respectively. HabEx's primary mirror would be 13 feet (4 m) across.

The IR/O/UV space telescope recommended by the decadal is a middle ground between those options: it would be more capable than HabEx and could be developed more quickly and cost-effectively than either LUVOIR version, according to the document.

Other Great Observatories would follow the new IR/O/UV space telescope in relatively quick succession, if the vision laid out in the new decadal comes true. Five years after work on that first scope gets underway, "the survey recommends commencing mission and technology maturation of both a far-IR and an X-ray large strategic mission, both scoped to have implementation costs in the $3 billion to $5 billion range," the new report states.

The decadal survey also recommends making key investments in huge ground-based telescopes — especially the Giant Magellan Telescope, which is currently being built in the Chilean Andes, and the Thirty Meter Telescope, which is slated to be constructed in Hawaii but has met with opposition in the state.

Such investments would ideally be made "as components of a coordinated U.S. Extremely Large Telescope Program (ELT) program," the survey states. "These observatories will create enormous opportunities for scientific progress over the coming decades and well beyond, and they will address nearly every important science question across all three priority science areas."

Making astronomy and astrophysics more inclusive

The decadal also stresses that more investment is needed to support research facilities, early-career scientists and important activities such as data archiving.

Both astronomy and astrophysics are male-dominated fields, with representation of minoritized groups lower than that of society at large — a situation that the new report would like to help change.

"Funding to support diverse faculty in university astronomy and astrophysics programs should be increased," the survey states.

"Among other steps, the report recommends NASA, NSF and the U.S. Department of Energy (DOE) ensure their policies treat harassment and discrimination as forms of scientific misconduct, and invest in workforce diversity at the division and directorate levels — as well as consider including the diversity of project teams and participants as a criterion when awarding funding," it adds. "NSF and NASA should implement funding for traineeship and postdoctoral fellowships to develop diverse and inclusive excellence."

Mike Wall is the author of "Out There" (Grand Central Publishing, 2018; illustrated by Karl Tate), a book about the search for alien life. Follow him on Twitter @michaeldwall. Follow us on Twitter @Spacedotcom or Facebook.

Our universe might be a giant three-dimensional donut, really.

Paul Sutter — Wed, 21 Jul 2021 11:00:48 +0000

Imagine a universe where you could point a spaceship in one direction and eventually return to where you started. If our universe were a finite donut, then such movements would be possible and physicists could potentially measure its size.

"We could say: Now we know the size of the universe," astrophysicist Thomas Buchert, of the University of Lyon, Astrophysical Research Center in France, told Live Science in an email.

Examining light from the very early universe, Buchert and a team of astrophysicists have deduced that our cosmos may be multiply connected, meaning that space is closed in on itself in all three dimensions like a three-dimensional donut. Such a universe would be finite, and according to their results, our entire cosmos might only be about three to four times larger than the limits of the observable universe, about 45 billion light-years away.

A tasty problem

Physicists use the language of Einstein's general relativity to explain the universe. That language connects the contents of spacetime to the bending and warping of spacetime, which then tells those contents how to interact. This is how we experience the force of gravity. In a cosmological context, that language connects the contents of the entire universe — dark matter, dark energy, regular matter, radiation and all the rest — to its overall geometric shape. For decades, astronomers had debated the nature of that shape: whether our universe is "flat" (meaning that imaginary parallel lines would stay parallel forever), "closed" (parallel lines would eventually intersect) or "open" (those lines would diverge).

That geometry of the universe dictates its fate. Flat and open universes would continue to expand forever, while a closed universe would eventually collapse in on itself.

Multiple observations, especially from the cosmic microwave background (the flash of light released when our universe was only 380,000 years old), have firmly established that we live in a flat universe. Parallel lines stay parallel and our universe will just keep on expanding.

But there's more to shape than geometry. There's also topology, which is how shapes can change while maintaining the same geometric rules.

For example, take a flat piece of paper. It's obviously flat — parallel lines stay parallel. Now, take two edges of that paper and roll it up into a cylinder. Those parallel lines are still parallel: Cylinders are geometrically flat. Now, take the opposite ends of the cylindrical paper and connect those. That makes the shape of a donut, which is also geometrically flat.

While our measurements of the contents and shape of the universe tell us its geometry — it's flat — they don't tell us about the topology. They don't tell us if our universe is multiply-connected, which means that one or more of the dimensions of our cosmos connect back with each other.

Look to the light

While a perfectly flat universe would extend out to infinity, a flat universe with a multiply-connected topology would have finite size. If we could somehow determine whether one or more dimensions are wrapped in on themselves, then we would know that the universe is finite in that dimension. We could then use those observations to measure the total volume of the universe.

But how would a multiply-connected universe reveal itself?

A team of astrophysicists from Ulm University in Germany and the University of Lyon in France looked to the cosmic microwave background (CMB). When the CMB was released, our universe was a million times smaller than it is today, and so if our universe is indeed multiply connected, then it was much more likely to wrap in on itself within the observable limits of the cosmos back then. Today, due to the expansion of the universe, it's much more likely that the wrapping occurs at a scale beyond the observable limits, and so the wrapping would be much harder to detect. Observations of the CMB give us our best chance to see the imprints of a multiply connected universe.

The team specifically looked at the perturbations — the fancy physics term for bumps and wiggles — in the temperature of the CMB. If one or more dimensions in our universe were to connect back with themselves, the perturbations couldn't be larger than the distance around those loops. They simply wouldn't fit.

As Buchert explained to Live Science in an email, "In an infinite space, the perturbations in the temperature of the CMB radiation exist on all scales. If, however, space is finite, then there are those wavelengths missing that are larger than the size of the space."

In other words: There would be a maximum size to the perturbations, which could reveal the topology of the universe.

Making the connection

This image from the Planck satellite reveals the cosmic microwave background, the oldest light in our cosmos. This CMB image shows temperature fluctuations that correspond to regions of slightly different density. (Image credit: ESA/Planck Collaboration)

Maps of the CMB made with satellites like NASA's WMAP and and the ESA's Planck have already seen an intriguing amount of missing perturbations at large scales. Buchert and his collaborators examined whether those missing perturbations could be due to a multiply-connected universe. To do that, the team performed many computer simulations of what the CMB would look like if the universe were a three-torus, which is the mathematical name for a giant three-dimensional donut, where our cosmos is connected to itself in all three dimensions.

"We therefore have to do simulations in a given topology and compare with what is observed," explained Buchert. "The properties of the observed fluctuations of the CMB then show a 'missing power' on scales beyond the size of the universe." A missing power means that the fluctuations in the CMB are not present at those scales. That would imply that our universe is multiply-connected, and finite, at that size scale.

Physicists get close to taming the chaos of the 'three-body problem'

Charlie Wood — Sun, 09 May 2021 11:28:45 +0000

Physicists have spent centuries grappling with an inconvenient truth about nature: Faced with three stars on a collision course, astronomers could measure their locations and velocities in nanometers and milliseconds and it wouldn't be enough to predict the stars' fates.

But the cosmos frequently brings together trios of stars and black holes. If astrophysicists hope to fully understand regions where heavenly bodies mingle in throngs, they must confront the "three-body problem."

While the result of a single three-body event is unknowable, researchers are discovering how to predict the range of outcomes of large groups of three-body interactions. In recent years, various groups have figured out how to make statistical forecasts of hypothetical three-body matchups: For instance, if Earth tangled with Mars and Mercury thousands of times, how often would Mars get ejected? Now, a fresh perspective developed by physicist Barak Kol simplifies the probabilistic "three-body problem," by looking at it from an abstract new perspective. The result achieves some of the most accurate predictions yet.

"It does really well," said Nathan Leigh, an astronomer at the University of Concepción in Chile who is involved in testing the new model. "I think Barak's [model] right now is the best one."

What is the volume of chaos?

In this NASA animation, two neutron stars collide, ending in a kilonova. When two cosmic objects are involved, physicists can easily work out the likely outcome of a mash-up. (Image credit: NASA)

When gravity draws two objects together, the potential outcomes are simple. The objects might zoom by each other, or they might enter into an elliptical orbit around a shared center of mass. Isaac Newton was able to write down brief equations capturing these motions in the 1600s.

But if one star approaches a pair of stars already orbiting each other, all bets are off. The intruder might zoom by in a predictable way. Or it could enter the fray, initiating a period of furious loops and swerves that might last for moments or years. Eventually, the furor always subsides when one of the three stars is thrown clear of the other two. One of two scenarios will follow: If the third wheel has enough energy, it escapes, leaving the pair to live in peace. Or if it doesn't, that third object will zip away only to fall back toward the pair again and launch another episode of mayhem.

Famed mathematician Henri Poincaré showed in 1889 that no equation could accurately predict the positions of all three bodies at all future moments, winning a competition sponsored by King Oscar II of Sweden. In this three-body case, Poincaré had discovered the first instance of chaos, a phenomenon whose outcome can effectively disconnect from how it began.

Since perfect predictions for individual three-body events are impossibles, physicists turned toward statistical forecasts. Given general information about the three bodies, such as their energy and their collective spin, what could one say about the odds that, for example, the lightest one would eventually get kicked out?

To ponder this problem, physicists have abandoned the familiar backdrop of 3D space and moved to an abstract arena known as "phase space." In this expansive new realm, each spot represents one possible configuration of the three stars: That's a 3D position, a 3D velocity and a mass for each of the three bodies — an unchanging21-dimensional space, all told. A specific three-body event (such as one star flying toward a pair) starts at some point in phase space and traces out a path as it evolves from one configuration to another.

In this framework, physicists have been able to use chaos to their advantage. For a chaotic system, there is not just one possible outcome, but many. That means that if you let the three-body system evolve over time, it will explore every possible chaotic path, eventually reaching every nook and cranny of some chaotic region of its phase space. For the three-body problem, scientists can calculate, statistically, where each body might end up by precisely computing the volume inside its phase space that represents chaotic motion.

Physicists have used requirements such as conservation laws to cut the whole phase space down to a simpler "playground" of eight dimensions. But precisely defining the (also eight-dimensional) chaotic region within that has been a challenge, in part because three co-orbiting bodies can hop between chaotic and regular motion (by temporarily kicking out a body). Various groups have visualized the volume of the chaotic space in different ways, culminating in a definitive model by Nicholas Stone, of the Hebrew University of Jerusalem, and Leigh in 2019 that eliminated past assumptions to build the most accurate and mathematically rigorous three-body model to date.

"You can't do it better than we did it," said Leigh, who is also affiliated with the American Museum of Natural History in New York. "The only thing you can do is come up with a different model."

This theory "has made a huge dent in solving [the statistical three-body model]"
Viraj Manwadkar

A leaky chaos balloon

That's exactly what Kol, also of the Hebrew University of Jerusalem, has done. Stone and Leigh and previous groups have focused on the boundary of that chaotic region, a place where three-body systems transition from chaos to regular motion by kicking out one body.

Kol, at the Hebrew University of Jerusalem, in contrast, studies a metaphorical "hole" in the chaotic volume, where such a transition is more likely to take place. The longer a three-body system bounces around inside the chaotic region, the more likely it is to find such a hole, ejecting a member and escaping chaotic motion. The nature of this exit or exits, Kol believes, tell you everything there is to know about the statistical three-body problem.

Stone and Leigh's previous approach imagined the chaotic region as "a balloon and the entire surface is a little leaky and it has the same leakiness everywhere," Stone said. "Barak [Kol]'s approach is saying that 'No, the balloon has discrete holes and some patches that are leakier than others.'"

Kol captures the shape of the exits from the chaotic balloon in a mysterious function called chaotic absorptivity — the odds that a calm stellar couple with a certain energy will go chaotic if you fire a third star at them (as opposed to the pair immediately rebuffing the newcomer). Using this function and Kol's framework, one can, in principle, answer any statistical question about the whole phase space in all of its multidimensional glory, such as when a trio will eject a member (on average), the odds it will fly away with a certain speed, and the range of possible shapes for the orbit of the remaining pair. His theory was published April 1 in the journal Celestial Mechanics and Dynamical Astronomy.

This theory "has made a huge dent in solving [the statistical three-body model]," said Viraj Manwadkar, a researcher at the University of Chicago helping to test the model. "It has simplified [the problem] greatly."

Who gets the boot?

So far, Kol's ideas seem promising. In a not-yet-peer reviewed paper posted to the preprint database arXiv in January, Manwadkar, Kol, Leigh and Alessandro Trani of the University of Tokyo held a battle royale to see how Kol's theory held up against other statistical three-body forecasts.

They ran millions of simulations of mashups between trios of stars of different masses to see how often each star got kicked out of the group. When the stars have the same mass, the unpredictability of chaotic motion guarantees that each individual has a one-third chance of getting the boot — no fancy models required.

But as the masses skew, a pattern emerges: Lighter stars are easier to eject.When the three bodies have 10-sun (10 times the mass of the sun), 15-sun and 20-sun masses, for instance, the 10-sun star gets kicked out in 78% of the simulations. Kol's theory nailed that forecast, while rival theories predicted the lightweight's ejection to take place between 70% and 87% of the time. The new framework does even better as the masses get more lopsided.

"Those predictions are beautifully accurate," Stone said.

From digital stars to astrophysics

Dark matter could be made of black holes from the beginning of time

tcm2020@gmail.com (Tom Metcalfe) — Mon, 05 Apr 2021 17:50:18 +0000

Dark matter, the mysterious substance that exerts gravitational pull but emits no light, might really consist of vast concentrations of ancient black holes created at the very start of the universe, according to a new study.

That conclusion comes from an analysis of the gravitational waves, or ripples in space-time, produced by two distant collisions between black holes and neutron stars.

The ripples — labeled GW190425 and GW190814 — were detected in 2019 by the Laser Interferometer Gravitational-Wave Observatory (LIGO) in Washington and Louisiana, and the Virgo Interferometer near Pisa, Italy. A previous analysis suggested the ripples were produced by collisions between black holes between 1.7 and 2.6 times the mass of our sun and either a smaller neutron star or a much larger black hole.

But that would make one of the objects in each collision what astrophysicists call a solar-mass black hole, with roughly the mass of the sun.

"Solar-mass black holes are quite mysterious, as they are not expected from conventional astrophysics," such as the star explosions, or supernovas, that crush larger stars into black holes, study lead author, Volodymyr Takhistov of the University of California, Los Angeles, told Live Science in an email.

Instead, the authors propose in the study, published Feb. 16 in the journal Physical Review Letters, these solar mass black holes may be "primordial" black holes created during the Big Bang. Or they might have formed later when neutron stars were transmuted into black holes — either after swallowing up primordial black holes, or after absorbing certain proposed types of dark matter, the mysterious matter that exerts gravitational pull does not interact with light, Takhistov said.

Primordial black holes

Primordial black holes, if they exist, were likely created in vast numbers in the first second of the Big Bang about 13.77 billion years ago. They would have come in all sizes — the smallest would have been microscopic and the largest tens of thousands of times the mass of our sun..

Calculations show the smallest would have "evaporated" by now, by emitting quantum particles through a process known as Hawking radiation, so that only primordial black holes with masses greater than 10^11 kilograms — about the mass of a small asteroid — would still exist today.

If they did exist, these ancient black holes could make up the immense halos of "dark matter" that fringe galaxies, some astrophysicists think.

The researchers wanted to learn if they could distinguish primordial black holes from black holes that had formed from neutron stars, the glimmering remnants of supernovas left behind when their parent stars exploded after using up all their hydrogen in nuclear fusion reactions.

Astrophysicists have calculated that stars smaller than about five times the mass of the sun collapse to leave behind a neutron star of ultra-dense matter, with roughly the mass of our sun packed into a ball the size of a city, Live Science reported.

In this theory, the intense gravity of some neutron stars would have continuously attracted particles of dark matter; eventually their gravity would have become so great that the neutron star and dark matter would have collapsed together into a black hole, the new study suggests.

An alternative proposed by the study is that a neutron star might have attracted and merged with a small primordial black hole, which then settled at the neutron star’s centre of gravity and fed off the surrounding matter until only the black hole remained.

Gravitational waves

Takhistov and his colleagues reasoned that black holes transmuted from neutron stars would have to follow the same mass distribution of the neutron stars they originated from, which depends on the sizes of their parent stars.

Taking that into account, they looked at the data from the 50 or so gravitational wave detections made to date, and found that just two — GW190425 and GW190814 — involved objects with the right masses to be primordial black holes, the study authors wrote.

The research is not conclusive: it's still possible those two collisions involved neutron stars of the masses detected, or black holes transmuted from neutron stars of those sizes. But the mass distribution of neutron stars theorized to exist in the universe makes that unlikely, the authors wrote.

"Our work advances a powerful test to understand their origin and relation with dark matter," Takhistov said. "In particular, this test demonstrates that black holes significantly heavier than about 1.5 solar-masses are very unlikely to be 'transmuted' black holes from neutron star disruptions."

In 'The Disordered Cosmos,' a physicist explores how physics and society intersect

mbartels@space.com (Meghan Bartels) — Mon, 15 Mar 2021 11:25:50 +0000

Theoretical physics is supposed to be about pure, crisp ideas. But physics is done by humans, and human society brings messiness to any endeavor.

That reality means that every aspect of physics is marked by the social constraints of who is allowed to do physics in harmony with their identity and who is not. Chanda Prescod-Weinstein, a theoretical physicist at the University of New Hampshire, tackles the implications of that reality in her new book, "The Disordered Cosmos: A Journey into Dark Matter, Spacetime, and Dreams Deferred" (Bold Type Books, 2021). (Read an excerpt from "The Disordered Cosmos.")

Space.com sat down with Prescod-Weinstein to discuss her new book, the state of physics and how to dream up a better world. This interview has been edited for length and clarity.

The Disordered Cosmos: A Journey into Dark Matter, Spacetime, and Dreams Deferred
Bold Type Books, 2021 | $24.99 on Amazon
From a star theoretical physicist, a journey into the world of particle physics and the cosmos -- and a call for a more just practice of science.View Deal

Space.com: Could talk a bit about your research on axions as a dark matter candidate?

Chanda Prescod-Weinstein: The axion is a hypothetical particle that actually was first theorized to solve a problem in the standard model that has nothing to do with dark matter. And it was realized soon after people started playing with this idea that it could also solve the dark matter problem, potentially.

When I started working on the axion, it was taken seriously as a dark matter candidate, but really, I feel like most of the people who were working on it from a theoretical point of view, at the point in time that I started with were in Europe.

It's interesting to see how the axion has evolved socially over the last seven years. After the announcement by the Large Hadron Collider that there was no evidence for supersymmetry, a lot of people who had been thinking about supersymmetry started looking around for what other viable dark matter candidates there were that dreams of finding it hadn't yet been crushed, and so a lot of people turned to the axion. So now it's like this really hot, happening field.

Space.com: Can you talk a bit about how the book came to be and what you wanted to pull into it?

Prescod-Weinstein: I had been writing a lot online … [my agent] said, "You already have this body of work that certain audiences aren't seeing. Let's get it to a different audience." The original idea was that it would be an essay collection, and clearly the book became more than that and developed a throughline that kind of evolved as I wrote it. …

I think I'm naturally a holistic thinker who likes to draw connections between the things that interest me. For me, it's a very natural thing that I started thinking about, like, how is this chapter connected to this one? … I really started to think, there are clear themes here and those themes are readily organizable. That was how the four phases came about, is that I realized that they were really reflecting these different ways of looking at physics and the doing of physics.

What I think of the book as, it's a holistic look at the doing of physics. It's kind of like taking physics and rotating it and looking at where the symmetries are, but also where the asymmetries are.

Chanda Prescod-Weinstein (Image credit: Chanda Prescod-Weinstein)

Space.com: There's this beautiful phrase you write, "I wanted to be normal, but I felt I had to be extraordinary." Could you talk a little bit more about that?

Prescod-Weinstein: The book remains an essay collection of personal essays, that I would strongly argue, at the end of the day, aren't memoir, but certainly use my story as a springing point for exploring ideas about how science should be done and how science is currently done. We have this saying in the Black community that you have to be 200%, because people are going to assume that because you're Black, that you're less competent that you're just gonna have to work 200% harder to get half as far.

I think that's something that we're all taught as kids, and we're not taught that because people are trying to abuse us or anything like that. Our families are trying to prepare us for a world that doesn't accept us as human in the same way.

If we're thinking about things that motivate me, I want Black children to have childhood. And you can't have a childhood in the same way white children have childhood if at the very beginning you're having to say to your kids, like, "Look, I know at schools they're telling you that the police are there to protect you, but they're not," — if you're already having to do this kind of like double thinking.

And so there is an element of like, I just want to be and not have to spend a lot of time fighting to make space for myself, fighting to make space for others, I want other people to just be able to be so I don't have to fight for them, they don't have to fight for themselves. So that's definitely one element.

Queerness and queer theory is like, a huge throughline in the book. Because so much of what queer theory teaches us is that we're always going to be on the edge of normal, pushing what that even means. Blackness can be framed as a queer way of being, and my experience as a queer person can inform how I am negotiating the world as a Black person.

I want everybody to be able to push those boundaries in a way that is safe and uplifting and nourishing, rather than in a way that feels like you're allowing yourself to get stabbed over and over again and you're just saying yourself, it's just a flesh wound. And you know, to be able to make Monty Python references and be like, "Yes, I also like Monty Python."

Space.com: And that's actually a great segue to my next question, which was going to be what was the most joyful part of the book for you to write?

Prescod-Weinstein: I had a lot of fun hiding the Dear Mama part from my mom. [The afterword of the book is addressed directly to her mother, Margaret Prescod.] My mom didn't know about that until October, when I had like a week before the copyedits had to be returned. … I sent it to my mom and I was like, "You have a week to tell me if you have a problem with us before nothing can be done about it."

I was really excited to surprise my mom with that. It was fun, having this secret from my mom. I really felt like she put so much of herself into making me and therefore the book possible that I wanted to make sure that part of the book turned around, and said, "You are in this." And it was fun and exciting to be able to do that for my mom.

Space.com: In the final chapter, you write about your vision of physics and on building a physics that's grounded in Black feminism. For you, what are the principles that would make up that vision?

Prescod-Weinstein: I think what I do toward the end of the book is signposting, rather than definitive statements like, "This is how it's gotta be." Because my hope is that it starts a conversation where we start articulating, as members of a community together, how do we have this conversation with each other?

I think we have much to learn from queer theory and from some of the discussions that trans theorists have been having about what does liberation look like as a trans person? … There are lots of different ways to be trans in the world, there are lots of different ways to relate to gender or lack thereof in the world. So I definitely think that part of it has to be unpacking how we saddle ourselves with the burden of having to fit into slots. Another signpost there is mutual aid. Prison abolition, I think, is tied up in pretty much everything that I talked about. I don't spend a lot of time talking about prison abolition, but for me, it's an undercurrent.

Something that my mom said to me many times when I was growing up, she's a women's and caretakers' rights campaigner, is that when money went into the hands of women — and I think now she would say caretakers — when money and resources go into the hands of caretakers in the community, the entire community benefits. So one very clear theme there is that we put resources into the hands of the people who do caretaking, and then we allow them to do the kind of caretaking that involves saying, like, have you looked at the sky, and thought about your place in the universe? We allow people to have that kind of room to have that care for each other, for themselves?

We can talk about diversity in science until we're blue in the face. But until we're talking about the conditions that we live in, we're not really having a real conversation about how we make change happen.

Space.com: That makes me think of that phrase that comes up so often, "Space is for everyone."

Prescod-Weinstein: Yeah. I love the idea that space is for everyone.

I think the International Dark-Sky Association is actually one of the most important scientific organizations out there, because they're really attending to what is our ecosystem in relation to the night sky? That is an astronomy question, it's an ecological question, it's a sociological question.

But I think that we have to take that seriously. It's great if a park gets designated as a dark sky park and I'm so glad that there's an organization that's working with national parks and with cities to address light pollution. But then the question I still have, is how do we get people to those national parks? How does everyone get to Joshua Tree in a way that's sustainable for Joshua Tree and for the actual Joshua trees but is also nourishing for us, spiritually, not in a supernatural sense, but in like the very human spiritual sense.

Space.com: That story in the book is so lovely. What do you give a little bit of a sort of teaser version of it?

Prescod-Weinstein: One of the stories that I tell in the book is my mom driving me to Joshua Tree to see I think it was Comet Hyakutake. To this day, I still have questions about how my mom paid for the gas to do that. That's not a simple expedition from Los Angeles.

It was one of my first times seeing a proper night sky. … It was one of my first hints that there was something wildly different about growing up in Los Angeles and growing up somewhere that didn't have the problems of pollution that we have in Los Angeles.

Space.com: Could you talk a little bit about the op-ed in Scientific American that you recently co-authored about James Webb and why naming a telescope for him is problematic, and then talk a bit about Harriet Tubman and her role in how you think about space?

Prescod-Weinstein: The op-ed is about what is called the next-generation Hubble Space Telescope, set to launch later this year. It's named after James Webb, who was a State Department official in the late 1940s and early '50s who played a very big role in the development of psychological warfare as a Cold War tool and then in the 1960s. And it is clear from historical records that he, like many of his contemporaries and pretty much everyone who was working in the presidential administrations of the time, was involved in the development of anti-LGBT policy that would eventually become hardwired government policy under Eisenhower. …

Under Kennedy, he became NASA administrator, so he's remembered in the astro community for his contribution to leading NASA through the Apollo program, etc. So he was not a scientist, nonetheless, the telescope is named after him. We essentially say in this op-ed that there's no reason the telescope should be named after someone whose legacy is, at best, complicated.

Let's let looking at the sky be part of our future, and what that guy stood for just be part of our past.

We propose at the end that rather than naming the telescope after someone like him, why not Harriet Tubman? There's an autobiography of Harriet Tubman — she couldn't read or write, so we're relying on maybe unreliable third parties — where she talks about using the North Star to escape to freedom. We know that there are other documented instances of people of her era using the North Star to run to freedom.

Harriet Tubman represents like everything that anyone has gotten right on this continent in the last 500 years. So why not literally put her up amongst the stars? I can't think of a more powerful use of astronomical information then using it to escape violent chattel slavery. If science does nothing else, that is what we should use scientific information for — liberation. So I want to send that message up into the sky. Why not put her out there with the stars that represented freedom?

It's going to be an incredible telescope, it's going to give us such incredible information, and I just love the idea of Harriet Tubman being associated with it. I don't know what's going to happen with the name, I don't know if it's possible to change it, if we do change it whether they will pick Harriet Tubman.

Space.com: Science people don't always want to talk about the social side of science, and your book really tackles that head on. Could you give the pitch for reading your book to someone who is coming from that perspective of, "I just want to focus on the science"?

Prescod-Weinstein: I just want to focus on the science, too! At the end of the day, the book is about how do we get to the point of being able to just enjoy science?

I, too, would like life to be simple; it is not. Some of us have the freedom to be like, "I'm going to look away," and some of us don't have the freedom to look away. In some sense, this book exists because people make the choice to look away and do nothing when they could do something to make the world better.

You can buy "The Disordered Cosmos" on Amazon or Bookshop.org.

Email Meghan Bartels at mbartels@space.com or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.

Book excerpt: 'The Disordered Cosmos'

Chanda Prescod-Weinstein — Mon, 15 Mar 2021 11:25:29 +0000

In theoretical physics, as in all human endeavors, identity matters.

And physics can be a hostile place to those who don't match the traditional template of a physicist. That reality is inseparable from the field itself, theoretical physicist Chanda Prescod-Weinstein argues in her new book, "The Disordered Cosmos: A Journey into Dark Matter, Spacetime, and Dreams Deferred" (Bold Type Books, 2021).

The book touches on everything from the smallest of particles to the largest of oppressive systems in a sweeping exploration of the complex nature of astrophysics.

(Read an interview with Chanda Prescod-Weinstein about the book.)

Chapter 4: The biggest picture there is

When people ask me what I do, I say that I'm a particle cosmologist. I tell them, "I use math to figure out the history of spacetime." It's my job to fill in the details about important events on the cosmological timeline — in other words, to tell a cosmological story using math. I have work to do because we still don't have a good sense of how the story begins, although as I described in "In the Beginning," we have filled in a lot of the timeline between then and now. What I love about this work is that this is the biggest picture there is: spacetime and its (dis)contents. It also feels like being the keeper of a deeply human impulse. To borrow a word from the Indigenous communities that my Black ancestors probably come from, I am a griot of the universe — a storyteller. And although I am the first Black woman to hold a tenure-track faculty position in theoretical cosmology, I am certainly not the first Black woman to be a griot of the universe.

(Image credit: Chanda Prescod-Weinstein)

Indeed, every community, including those of my African ancestors, has a cosmology. My way of studying the universe — through the analytic frameworks that I have mostly inherited from the Euro-American imperialists and settlers who kidnapped my ancestors from Africa and enslaved them — is not the only one. It is not the cosmology of my maternal ancestors. It's not quite the cosmology of my paternal ancestors either. Although my father is white in most global contexts, he is also an Ashkenazi Jew of Eastern European heritage — the kind of people who come from the shtetl, the village, not urban Western Europe like Einstein. Their cosmology is the Biblical Genesis, not the general relativity that I grew up to become an expert in. Cosmology is a deeply human impulse — we have always wanted to have a sense of where we came from and why we are here. It happens to be that because of where I grew up and my own personal tastes, I study one particular perspective on this, and here I hope to sketch out this picture for you in a way that will help you feel some of my enthusiasm for it.

The way professionalized physicists understand the cosmic timeline is something like this: in the beginning, there may have been no beginning. The spacetime that humanity calls its universe may in fact be one bubble of an infinite number of bubbles, all of which may be inaccessible to us except for the one we're in. It's not clear how we will prove, with physical or observational evidence, that this is true or not true. But currently, a large swath of my professional community leans toward believing that this is true. Perhaps there was no real big bang. So, in the beginning, we are maybe just talking about our single bubble, and before that bubble was a second old and certainly before there were any Standard Model particles wandering around, it likely underwent a rapid expansion where spacetime grew faster than the speed of light — because as we currently understand things, spacetime is the only phenomenon in the universe that can break the universal speed limit. This time period is called inflation, and it was first proposed by one of my research mentors at MIT, the wonderful Alan Guth. There's much we don't understand about inflation, including what exactly set it off. It didn't last very long — less than tenths of a fraction of a second — and when it was over, the universe continued to expand, albeit much more slowly.

Inflation is a vaguely contested idea. I say vaguely because there is a small but incredibly vocal minority of people who can quite reasonably be classed as "inflation haters." In the last five years especially, there has been an uptick in the number of editorials appearing in the pages of respected publications like Scientific American and Nature that challenge the centrality of inflation to our standard cosmology, even going so far as to say it's not real science because it's not testable. Essentially, this argument hinges on the fact that while we have generally worked out what inflation does and how it does it, we still don't know any details about the particle that would cause inflation to happen, and it is easy to write down different models of inflation that all essentially accomplish the same thing. Accusations sometimes fly around in the science press and the blogosphere about how inflation is completely untestable. I always shrug a little about these kinds of objections because while inflationary theory does face real challenges, it's also the case that it's hard to explain observational data without it. It's our best possible model and that fact alone means it merits continued excavation and theoretical experimentation. As my other MIT adviser — theoretical physicist and historian David Kaiser — would probably say, the evidence for inflation also continues to be strong. But before I can explain what evidence we have, I need to get further ahead in the timeline.

Every physicist and astronomer, no matter their field, knows the basics of inflation, which is that spacetime rapidly expanded. What isn't widely discussed is what happens after the end of the inflationary era — less than a tiny fraction of a second after our spacetime first came into being. Currently it seems likely that the inflaton, the particle field that drives inflation, transferred the remains of its energy to other particles, and those particles multiplied in number. We also know that inflation should have significantly cooled down the universe. We know, too, this time from actual experimental and observational data, that in order for the rest of structure formation — galaxies, stars, us — to occur, the universe needed to reheat. But we don't know how. This question has been one of two dominant drivers behind my research in the last few years: How do you reheat a phenomenal cosmic banquet after inflation has flash-frozen it — without going too far? This is a question of general interest to cosmologists, as well as people working on technical issues in quantum field theory in curved spacetimes (particle physics at the interface with gravity). I happen to fall into both categories, so this is fun for me.

This article has been adapted from The Disordered Cosmos: A Journey into Dark Matter, Spacetime, and Dreams Deferred by Chanda Prescod-Weinstein. Copyright © 2021. Available from Bold Type Books, an imprint of Perseus Books, LLC, a subsidiary of Hachette Book Group, Inc.

You can buy "The Disordered Cosmos" on Amazon or Bookshop.org.

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SpaceX secures contract to launch NASA's SPHEREx astrophysics mission

chelseagohd@gmail.com (Chelsea Gohd) — Fri, 05 Feb 2021 22:59:51 +0000

SpaceX will be launching an astrophysics mission into Earth's orbit for NASA.

NASA has selected the spaceflight company to launch the SPHEREx mission (short for Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer), NASA's Jet Propulsion Laboratory (JPL) in California announced Thursday (Feb. 4).

The 329-lb. (178 kilograms) craft will hitch a ride to space aboard SpaceX's Falcon 9 rocket, set to launch as early as June 2024, from Space Launch Complex 4E at Vandenberg Air Force Base in California. The launch will be managed by NASA's Launch Services Program at the agency's Kennedy Space Center in Florida. Still, NASA JPL remains in charge of overall project management, systems engineering, integration, testing and mission operations for the mission, agency officials said in a statement.

SPHEREx is a space observatory and the latest medium-class craft under NASA's Explorers program of astrophysics missions. NASA's other medium-class craft within this set of missions includes the planet-hunting craft TESS (Transiting Exoplanet Survey Satellite) and ICON (The Ionospheric Connection Explorer), which studies Earth's ionosphere — the region in our planet's atmosphere where Earth weather meets space weather.

The probe is set to spend two years scanning the skies in near-infrared light, completing a full survey every six months.

This light isn't visible to us humans with the naked eye, but it can allow the craft to peer out and observe far-off galaxies. With data from the craft, scientists aim to conduct an all-sky survey measuring the unique signatures of more than 300 million galaxies across the universe and 100 million stars inside our Milky Way galaxy, ultimately creating a unique sky map.

The craft won't just be mapping out these distant destinations, however, it will also be searching for signs of water and organic molecules in stellar nurseries — star-forming regions rich with interstellar gas and dust — and in the disks of material swirling around stars, where planets could form. By searching for water and organic molecules, which make life as we know it possible on Earth, scientists could explore habitability much farther from home.

"This amazing mission will be a treasure trove of unique data for astronomers," Thomas Zurbuchen, associate administrator for NASA's Science Mission Directorate, said in a 2019 NASA statement. "It will deliver an unprecedented galactic map containing 'fingerprints' from the first moments in the universe's history. And we'll have new clues to one of the greatest mysteries in science: What made the universe expand so quickly less than a nanosecond after the big bang?"

This mission will cost NASA about $98.8 million, including this launch service with SpaceX, in addition to other "mission-related costs," according to NASA JPL. The mission is funded by the Astrophysics Division of NASA's Science Mission Directorate, which is located at NASA headquarters in Washington, D.C.

Email Chelsea Gohd at cgohd@space.com or follow her on Twitter @chelsea_gohd. Follow us on Twitter @Spacedotcom and on Facebook.

Ghostly circles in the sky can't be explained. And astronomers are excited.

Ray Norris — Tue, 15 Dec 2020 19:48:49 +0000

In September 2019, my colleague Anna Kapinska gave a presentation showing interesting objects she’d found while browsing our new radio astronomical data. She had started noticing very weird shapes she couldn’t fit easily to any known type of object.

Among them, labeled by Anna as WTF?, was a picture of a ghostly circle of radio emission, hanging out in space like a cosmic smoke-ring. None of us had ever seen anything like it before, and we had no idea what it was. A few days later, our colleague Emil Lenc found a second one, even more spooky than Anna’s.

Anna and Emil had been examining the new images from our pilot observations for the Evolutionary Map of the Universe (EMU) project, made with CSIRO’s revolutionary new Australian Square Kilometre Array Pathfinder (ASKAP) telescope.

EMU plans to boldly probe parts of the Universe where no telescope has gone before. It can do so because ASKAP can survey large swathes of the sky very quickly, probing to a depth previously only reached in tiny areas of sky, and being especially sensitive to faint, diffuse objects like these.

I predicted a couple of years ago this exploration of the unknown would probably make unexpected discoveries, which I called WTFs. But none of us expected to discover something so unexpected, so quickly. Because of the enormous data volumes, I expected the discoveries would be made using machine learning. But these discoveries were made with good old-fashioned eyeballing.

Hunting ORCs

Our team searched the rest of the data by eye, and we found a few more of the mysterious round blobs. We dubbed them ORCs, which stands for “odd radio circles”. But the big question, of course, is: “what are they?”

At first we suspected an imaging artefact, perhaps generated by a software error. But we soon confirmed they are real, using other radio telescopes. We still have no idea how big or far away they are. They could be objects in our galaxy, perhaps a few light-years across, or they could be far away in the Universe and maybe millions of light years across.

When we look in images taken with optical telescopes at the position of ORCs, we see nothing. The rings of radio emission are probably caused by clouds of electrons, but why don’t we see anything in visible wavelengths of light? We don’t know, but finding a puzzle like this is the dream of every astronomer.

We know what they aren't

We have ruled out several possibilities for what ORCs might be.

Could they be supernova remnants, the clouds of debris left behind when a star in our galaxy explodes? No. They are far from most of the stars in the Milky Way and there are too many of them.

Could they be the rings of radio emission sometimes seen in galaxies undergoing intense bursts of star formation? Again, no. We don’t see any underlying galaxy that would be hosting the star formation.

Could they be the giant lobes of radio emission we see in radio galaxies, caused by jets of electrons squirting out from the environs of a supermassive black hole? Not likely, because the ORCs are very distinctly circular, unlike the tangled clouds we see in radio galaxies.

Could they be Einstein rings, in which radio waves from a distant galaxy are being bent into a circle by the gravitational field of a cluster of galaxies? Still no. ORCs are too symmetrical, and we don’t see a cluster at their centre.

A genuine mystery

In our paper about ORCs, which is forthcoming in the Publications of the Astronomical Society of Australia, we run through all the possibilities and conclude these enigmatic blobs don’t look like anything we already know about.

So we need to explore things that might exist but haven’t yet been observed, such as a vast shockwave from some explosion in a distant galaxy. Such explosions may have something to do with fast radio bursts, or the neutron star and black hole collisions that generate gravitational waves.

Or perhaps they are something else entirely. Two Russian scientists have even suggested ORCs might be the “throats” of wormholes in spacetime.

From the handful we’ve found so far, we estimate there are about 1,000 ORCs in the sky. My colleague Bärbel Koribalski notes the search is now on, with telescopes around the world, to find more ORCs and understand their cause.

It’s a tricky job, because ORCS are very faint and difficult to find. Our team is brainstorming all these ideas and more, hoping for the eureka moment when one of us, or perhaps someone else, suddenly has the flash of inspiration that solves the puzzle.

It’s an exciting time for us. Most astronomical research is aimed at refining our knowledge of the Universe, or testing theories. Very rarely do we get the challenge of stumbling across a new type of object which nobody has seen before, and trying to figure out what it is.

Is it a completely new phenomenon, or something we already know about but viewed in a weird way? And if it really is completely new, how does that change our understanding of the Universe? Watch this space!

This article is republished from The Conversation under a Creative Commons license. Read the original article.

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Chinese Long March 11 rocket launches satellites to hunt gravitational waves

Elizabeth Howell — Mon, 14 Dec 2020 23:23:35 +0000

China has successfully launched a pair of satellites into space to learn more about gravitational waves, or echoes in space-time from huge mergers or cosmic events.

The Gravitational Wave High-energy Electromagnetic Counterpart All-sky Monitor (GECAM) mission launched at 3:14 p.m. EST on Dec. 9 (2014 GMT Wednesday or 4:14 a.m. local time Thursday, Dec. 10) from the Xichang Satellite Launch Center in the southwestern Sichuan province.

The 330-pound (150-kg) twin satellites each entered their planned orbit of roughly 375 miles (600 kilometers) in altitude at opposite sides of the Earth, according to the China Aerospace Science and Technology Corp. and Science magazine.

"The launch of these scientific satellites will enable our country to make important breakthroughs in exploring the extreme universe, solar activities and the relationship between the sun and the Earth," Wang Chi, head of the Chinese Academy of Sciences' National Space Science Center, said in an interview with the state-run news channel CCTV, according to a translation.

China has successfully launched a pair of satellites into space to learn more about gravitational waves, or echoes in space-time from huge mergers or cosmic events. (Image credit: VCG/VCG via Getty Images)

From their orbits, the satellites will monitor the entire sky for events that generate gravitational waves, which could include cosmic confluences such as neutron stars merging or black holes coming together, Science said.

The Chinese satellites have an advantage over existing observatories searching for gamma rays, or bursts of energy from these collisions, because their view is not obscured, the magazine added. By contrast, NASA's Swift Observatory and the Fermi Gamma-ray Space Telescope both have only partial views of the sky.

The new mission launched on a Long March 11 rocket developed by the China Aerospace Science and Technology Corp., and the launch was the 355th mission of the Long March series, Chinese state sources said.

Last week, China also successfully docked the ascent module of its Chang'e-5 moon-landing spacecraft with an orbiter spacecraft, as part of larger mission to return samples from the lunar surface. The moon mission was performed by the China National Space Administration, while the new gravitational waves mission is under the science-focused National Space Science Center.

The Chang'e 5 sample-return spacecraft is now headed back to Earth for a landing later this week.

Follow Elizabeth Howell on Twitter @howellspace. Follow us on Twitter @Spacedotcom and on Facebook.

A 'tsunami' for astrophysics: New Gaia data reveals the best map of our galaxy yet

Megan Gannon — Thu, 03 Dec 2020 19:56:17 +0000

Astronomers were hit today (Dec. 3) with a huge wave of data from the European Space Agency's Gaia space observatory.

Those researchers can now explore the best-yet map of the Milky Way, with detailed information on the positions, distances and motion of 1.8 billion cosmic objects, to help us better understand our place in the universe.

"Gaia data is like a tsunami rolling through astrophysics," said Martin Barstow, head of the physics and astronomy department at the University of Leicester, who is part of Gaia's data processing team. He was speaking at a virtual news conference held today, at which another Gaia researcher, Giorgia Busso of the Leiden Observatory in the Netherlands, also told reporters that this data has produced "a revolution" in many fields of astrophysics, from the study of galactic dynamics like stellar evolution to the study of nearby objects like asteroids in the solar system.

Photos: Gaia spacecraft to map Milky Way galaxy

Gaia launched in December 2013 to map the galaxy in unprecedented detail. The $1 billion spacecraft orbits the Lagrange-2, or L2, point, a spot about 1 million miles (1.5 million kilometers) away from Earth, where the gravitational forces between our planet and the sun are balanced and the view of the sky is unobstructed. Gaia can measure about 100,000 stars each minute, or 850 million objects each day, and can scan the whole sky about once every two months.

The latest trove of data improves upon the precision and scope of the two previous Gaia data sets, which were released in 2016 and 2018. For example, compared to the 2018 data, which included measurements for 1.7 billion objects, the 2020 data improves by a factor of two the accuracy of the data points for proper motion, or the apparent change in the position of a star as viewed from our solar system.

"It really gives us an insight into how the Milky Way lives," Nicholas Walton, an astronomer at the University of Cambridge who is part of Gaia's science team, said at the same science and news conference. "We're talking about billions of stars, which really gives us the ability to probe at a meaningful level the whole population of the Milky Way, similar to what you'd want to do with studying people."

Walton said the cosmic census would be like having trackers on every person in the U.K. to map their location and monitor their health. "If everyone's got a tracker, we could tell you if they're sweating or not. It's a bit like that with the stars here: We can tell you which ones are sweating, which ones are active, which ones are dormant, which ones are going to die, which ones are going to explode."

Data from Gaia has already been used across a wide range of applications over the past four years. The mission has helped researchers find the corpse of a galaxy that the Milky Way cannibalized 10 billion years ago, spot 20 hypervelocity stars unexpectedly zooming toward the galactic center, and identify about 1,000 nearby stars where hypothetical extraterrestrials would be able to see signs of life on Earth.

Closer to home, the spacecraft has allowed scientists to find previously unknown asteroids, and its precise data even allowed NASA to make a crucial, last-minute adjustment to the path of its New Horizons probe in 2018 to successfully swing past the icy rock Arrokoth, the most distant and primitive object in the solar system ever visited by a spacecraft.

So far, some 1,600 studies have been published based on Gaia data, Barstow said. More will surely result from today's newly released material, now available on ESA's website, and by the time the briefing for scientists and reporters ended, Walton said he expected a lot of scientists were already poring over it: "I think a lot of astronomers would have left this broadcast to go work on the data."

This image shows the paths of 40,000 stars located within 326 light-years of our solar system over the next 400,000 years based on measurements and projections from the European Space Agency's Gaia spacecraft. (Image credit: ESA/Gaia/DPAC; CC BY-SA 3.0 IGO. Acknowledgement: A. Brown, S. Jordan, T. Roegiers, X. Luri, E. Masana, T. Prusti and A. Moitinho.)

Some of the new Gaia data has already been used to make discoveries. One group of researchers led by scientists at the Dresden University of Technology measured how our solar system is accelerating inside the Milky Way, using as reference points Gaia's 1.6 million newly observed quasars, which are so far away they appear fixed in space, like galactic lighthouses.

The solar system was measured to be very slightly accelerating, as predicted by theorists, toward the galactic center. Busso said this barely perceptible acceleration only became observable in this newly released Gaia data because "the precision of the measurements increased hugely."

These super precise tests of the way masses are distributed and accelerated are essential for "probing the limits of fundamental physics," Gerry Gilmore, an astronomer at the University of Cambridge and a Gaia scientist, said during the event. Such measurements might help scientists understand the nature of the dark matter that we know is lurking throughout the universe.

"Even our own sun is moving so fast that our whole Milky Way would fly apart if it wasn't held together by the dark matter, and we've got no idea what the dark matter is," Gilmore said. "The hope is that by continuing experiments along the line that we're doing — and making them more precise, and doing them on different scales — we'll be able to see if there are different types of dark matter."

The third Gaia data set was set to be released in 2022, but the mission scientists decided to release preliminary data now so astronomers could use it sooner, with at least two more data sets to be released in the coming years. The spacecraft will operate until at least 2022, but its mission may be extended until 2025.

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Why black holes are the scariest things in the universe

Chrisy Impey — Sat, 31 Oct 2020 12:21:54 +0000

Halloween is a time to be haunted by ghosts, goblins and ghouls, but nothing in the universe is scarier than a black hole.

Black holes – regions in space where gravity is so strong that nothing can escape – are a hot topic in the news these days. Half of the 2020 Nobel Prize in Physics was awarded to Roger Penrose for his mathematical work showing that black holes are an inescapable consequence of Einstein’s theory of gravity. Andrea Ghez and Reinhard Genzel shared the other half for showing that a massive black hole sits at the center of our galaxy.

Black holes are scary for three reasons. If you fell into a black hole left over when a star died, you would be shredded. Also, the massive black holes seen at the center of all galaxies have insatiable appetites. And black holes are places where the laws of physics are obliterated.

I’ve been studying black holes for over 30 years. In particular, I've focused on the supermassive black holes that lurk at the center of galaxies. Most of the time they are inactive, but when they are active and eat stars and gas, the region close to the black hole can outshine the entire galaxy that hosts them. Galaxies where the black holes are active are called quasars. With all we’ve learned about black holes over the past few decades, there are still many mysteries to solve.

Death by black hole

Black holes are expected to form when a massive star dies. After the star's nuclear fuel is exhausted, its core collapses to the densest state of matter imaginable, a hundred times denser than an atomic nucleus. That’s so dense that protons, neutrons and electrons are no longer discrete particles. Since black holes are dark, they are found when they orbit a normal star. The properties of the normal star allow astronomers to infer the properties of its dark companion, a black hole.

The first black hole to be confirmed was Cygnus X-1, the brightest X-ray source in the Cygnus constellation. Since then, about 50 black holes have been discovered in systems where a normal star orbits a black hole. They are the nearest examples of about 10 million that are expected to be scattered through the Milky Way.

Black holes are tombs of matter; nothing can escape them, not even light. The fate of anyone falling into a black hole would be a painful "spaghettification," an idea popularized by Stephen Hawking in his book "A Brief History of Time." In spaghettification, the intense gravity of the black hole would pull you apart, separating your bones, muscles, sinews and even molecules. As the poet Dante described the words over the gates of hell in his poem Divine Comedy: Abandon hope, all ye who enter here.

A hungry beast in every galaxy

Over the past 30 years, observations with the Hubble Space Telescope have shown that all galaxies have black holes at their centers. Bigger galaxies have bigger black holes.

Nature knows how to make black holes over a staggering range of masses, from star corpses a few times the mass of the Sun to monsters tens of billions of times more massive. That’s like the difference between an apple and the Great Pyramid of Giza.

The fate of anyone falling into a black hole would be a painful "spaghettification," an idea popularized by Stephen Hawking in his book "A Brief History of Time."

Just last year, astronomers published the first-ever picture of a black hole and its event horizon, a 7-billion-solar-mass beast at the center of the M87 elliptical galaxy.

It’s over a thousand times bigger than the black hole in our galaxy, whose discoverers snagged this year's Nobel Prize. These black holes are dark most of the time, but when their gravity pulls in nearby stars and gas, they flare into intense activity and pump out a huge amount of radiation. Massive black holes are dangerous in two ways. If you get too close, the enormous gravity will suck you in. And if they are in their active quasar phase, you’ll be blasted by high-energy radiation.

How bright is a quasar? Imagine hovering over a large city like Los Angeles at night. The roughly 100 million lights from cars, houses and streets in the city correspond to the stars in a galaxy. In this analogy, the black hole in its active state is like a light source 1 inch in diameter in downtown LA that outshines the city by a factor of hundreds or thousands. Quasars are the brightest objects in the universe.

Supermassive black holes are strange

Something huge ripped the skin off this star before it died

Rafi Letzter — Thu, 08 Oct 2020 11:17:15 +0000

A giant star died, blasting its guts out into space. But before the star detonated, some stellar thief had already stolen the giant's skin. Now, astrophysicists think they've identified the culprit: another star blasting its own guts out nearby.

Supernovas are fairly common in space. Most very large stars end their lives as stellar explosions. When they die, hot clouds of gas spread across space. Those clouds are full of the heavy atoms the stars fused into being in the nuclear engines of their bellies. But usually there's hydrogen — the element that stars initially fuse into helium to get their engines started — in the clouds too: These simple, single-proton atoms remain in the outer skin of the star, where pressure and heat never got high enough to fuse them together into heavier elements. It's unspent fuel, in other words. Sometimes, however, that skin vanishes. Usually gravity from a nearby star —— such as a binary twin in the same system — strips that outer envelope of hydrogen away. Sometimes, however, it's not clear where all the hydrogen-rich skin went. For a long time, that was the case for the supernova remnant Cassiopeia A (Cas A). But not anymore.

In a new paper, researchers describe a scenario that could produce a solitary, "stripped-envelope" supernova like Cas A's. Their story, like most skinless supernova tales, begins with two sibling stars in a tight binary orbit around one another. Critically, these siblings were born at the same time in the same place and at nearly the same mass. As a result, the two stars would also live for similar lengths of time, become swollen red giants in their old age, and die in short succession, one after the other.

If Cas A's sibling went first, that first supernova would have effectively sandblasted the surviving big red supergiant (in other words, Cas A), just as Cas A was nearing the end of its own life.

The researchers, a team at the ARC Center of Excellence for Gravitational Wave Discovery (OzGrav) in Melbourne, Australia, simulated how this would work.

"Snapshots" from the simulation show how a supernova blast could strip off a star's outer layer. (Image credit: Ryosuke Hirai)

Their simulations showed between 50% and 90% of the surviving star's outer skin of hydrogen gets blasted away in the wind of the first supernova, as long as the two stars orbit very close together.

"This is enough for the second supernova of the binary system to become a stripped-envelope supernova, confirming that our proposed scenario is plausible," lead study author Ryosuke Hirai, an OzGrav astrophysicist, said in a statement.

It's also possible for the first supernova to rip off just some of its sibling's envelope, causing that star to be in an unstable state; in this scenario, the instability leads to more hydrogen being expelled from the star before it goes supernova. The star would react like it had just been shot with a shotgun, convulsing and losing fuel to space before its demise, the simulations showed.

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If this version of star death happens, it's likely rare, the researchers wrote — occurring in just 0.35% to 1% of supernovas.

And the scenario hasn't been confirmed, though the researchers think it might apply to two other known supernovas, RX J1713.7-3946 and G11.2-0.3.

But Cas A is the most exciting example for a simple reason: The simulation predicts that there should still be a signature of that envelope lost in the first supernova: a puff of hydrogen-rich gas drifting through space 30 to 300 light-years away from the supernova remnant. And in the case of Cas A, they found one such puff, just 50 light-years away — precisely fitting what their model predicted.

Originally published on Live Science

What happens if black holes fall into wormholes? A new way to find out.

cqchoi@sciwriter.us (Charles Q. Choi) — Tue, 11 Aug 2020 12:02:34 +0000

Astronomers think they might be able to detect black holes falling into wormholes using ripples in spacetime known as gravitational waves, but only if wormholes actually exist and such a scenario ever happened, a new study finds.

According to Einstein, who first predicted the existence of gravitational waves in 1916, gravity results from the way in which mass warps space and time. When two or more objects move within a gravitational field, they produce gravitational waves that travel at the speed of light, stretching and squeezing space-time along the way.

Gravitational waves are extraordinarily difficult to detect because they are extremely weak, and even Einstein was uncertain whether they really existed and if they would get discovered. After decades of work, scientists reported the first direct evidence of gravitational waves in 2016, detected using the Laser Interferometer Gravitational-Wave Observatory (LIGO).

Black holes vs. wormholes

Gravitational-wave observatories have detected more than 20 giant collisions between extraordinarily dense and massive objects such as black holes and neutron stars. However, more exotic objects may theoretically exist, such as wormholes, the collisions of which should also produce gravitational signals that scientists could detect.

Wormholes are tunnels in spacetime that, in theory, can allow travel anywhere in space and time, or even into another universe. Einstein's theory of general relativity allows for the possibility of wormholes, although whether they really exist is another matter.

In principle, all wormholes are unstable, closing the instant they open. The only way to keep them open and traversable is with an exotic form of matter with so-called "negative mass." Such exotic matter has bizarre properties, including flying away from a standard gravitational field instead of falling toward it like normal matter. No one knows if such exotic matter actually exists.

In many ways, a wormhole resembles a black hole. Both types of objects are extraordinarily dense and have powerful gravitational pulls for objects their size. The main difference is that no object can theoretically get back out after entering a black hole's event horizon — the threshold where the speed needed to escape the black hole's gravitational pull exceeds the speed of light — whereas any object entering a wormhole could theoretically reverse course.

Assuming wormholes might exist, scientists investigated the gravitational signals generated when a black hole orbits a wormhole for a new paper, which has not yet been peer-reviewed. The researchers also explored what might happen when the black hole enters one mouth of the wormhole, exits out the wormhole's other mouth into another point in space-time, and then — assuming the black hole and wormhole are gravitationally bound to one another — falls back into the wormhole and emerges out the other side.

No escape

In computer models, the researchers analyzed the interactions between a black hole five times the mass of the sun and a stable traversable wormhole 200 times the mass of the sun with a throat 60 times wider than the black hole. The models suggested that gravitational signals unlike any seen up to now would occur when the black hole journeyed into and out of the wormhole.

When two black holes spiral closer to one another, their orbital speeds increase, much like spinning figure skaters who draw their arms closer to their bodies. In turn, the frequency of the gravitational waves rises. The sound these gravitational waves would produce is a chirp, much like when one increases the pitch rapidly on a slide whistle, since any increase in frequency corresponds to an increase in pitch.

If one watched a black hole spiral into a wormhole, one would see a chirp much like two black holes meeting, but the gravitational signal from the black hole would quickly fade as it radiated most of its gravitational waves on the other side of the wormhole. (In contrast, when two black holes collide, the result is a giant burst of gravitational waves.)

If one watched a black hole emerge from a wormhole, one would see an "anti-chirp." Specifically, the frequency of gravitational waves from the black hole would decrease as it moved farther away from the wormhole.

As the black hole keeps journeying in and out each mouth of the wormhole, it would generate a cycle of chirps and anti-chirps. The length of time between each chirp and anti-chirp would shrink over time until the black hole got stuck in the throat of the wormhole. Detecting this kind of gravitational signal might support the existence of wormholes.

"Though wormholes are very, very speculative, the fact that we might have the ability to prove or at least give credibility to their existence is pretty cool," study co-author William Gabella, a physicist at Vanderbilt University in Nashville, told Space.com.

In this scenario, eventually the black hole would stop falling in and out of the wormhole and settle near its throat. The consequences of such a finale depend on the completely speculative properties of the exotic matter found in the wormhole's throat. One possibility is that the black hole has effectively increased the mass of the wormhole and the wormhole may not possess enough exotic matter to keep stable. Maybe the resulting disruption in space-time causes the black hole to convert its mass to energy in the form of an extraordinary amount of gravitational waves, Gabella said.

As long as a wormhole has a greater mass than any black hole it encounters, it should remain stable. If a wormhole encounters a larger black hole, the black hole may disrupt the wormhole's exotic matter enough to destabilize the wormhole, causing it to collapse and likely form a new black hole, Gabella said.

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It remains uncertain what might happen if a black hole only clipped the edges of a wormhole, with part of the black hole entering a wormhole's mouth with the rest staying outside it. "I suspect that there would be some crazy behavior at the black hole event horizon giving rise to even more gravitational waves and more energy loss," Gabella said. Such a collision may also disrupt the wormhole's exotic matter, "leading to an unstable wormhole," he added.

Future research can explore the interactions between a wormhole's exotic matter and any normal matter entering the wormhole, as well as more complex scenarios, such as what might happen if the wormhole is spinning, Gabella said. Other research directions could investigate how gravitational waves interact with both the normal and exotic matter in these scenarios, as well as "the variety of orbits that might occur between wormholes and you name it," he added.

The scientists detailed their findings online July 17 in a study they plan to submit to the journal Physical Review Letters. The research was detailed on the preprint site arXiv.org.

Follow Charles Q. Choi on Twitter @cqchoi. Follow us on Twitter @Spacedotcom and on Facebook.

Book excerpt: 'How to Die in Space' on the beauty and danger of nebulas

Paul Sutter — Tue, 21 Jul 2020 18:48:26 +0000

Sure, space looks pretty, but just because it sparkles doesn't make it welcoming.

Because, as astrophysicist Paul Sutter realized when he began thinking about phenomena he wanted to write about to share his field with readers, high-energy astrophysics is pretty brutal up close. Dying stars, black holes, the vacuum of space, even unknown dangers like hostile aliens — those fascinating-but-brutal scenarios became the beastly specimens catalogued in his new book, "How to Die in Space: A Journey Through Dangerous Astrophysical Phenomena" (Pegasus Books, 2020).

In the excerpt below, Sutter (whose writing you may recognize as a frequent contributor to Space.com) introduces planetary nebulas and explains why, while they're a perennial star of Hubble Space Telescope images, they're best admired from a distance. (Read an interview with Paul Sutter about the book.)

How to Die in Space: A Journey Through Dangerous Astrophysical Phenomena

Pegasus Books, 2020 | $27.95 on Amazon

Join Paul Sutter in a brilliant and breathtakingly vivid tour of the universe, describing the physics of the dangerous, the deadly, and the scary in the cosmos.
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Excerpt from Chapter 7: Planetary Nebulas

We've come to an interesting place in our journey through the galaxy.

We've broken out of our home solar system after dodging rogue asteroids, evading circuitry-frying coronal mass ejections from the sun, and simply accepting the flood of tiny cosmic rays constantly bombarding our delicate flesh.

Once we reached interstellar distances, we've seen stars born from clouds of vicious turbulence, and we encountered our first truly exotic creatures of this everlasting night that we call outer space: the black holes.

Paul Sutter (Image credit: Paul Sutter?Pegasus Bookes)

Those black holes are tombstones.

Markers. Memories of what once was. Almost-forgotten remnants of the past. The black holes of our galaxy used to be stars, shining with heat and light and warmth. Dead, gone now, generations ago. Their fusion finished, their hydrogen depleted, their spirit withered.

The stars of our universe will die, one by one. And those deaths are, to a number, nasty.

Many of the hazards that we're about to explore and explain will come from the variety of ways that stars can end their lives, and turn into other, far less pleasant, things.

Needless to say, it won't be pretty.

And when it comes to stars, everybody wants to go out with a bang. Make a big deal out of it. Sadly, not everybody can shine as brightly, as intensely, as ferociously as a supernova. Don't fret, eager explorer, we'll get to supernovas and other overly powerful explosions soon enough. It's best we start small, with weaker explosions and their consequences, and work out way up to the big leagues. Wouldn't want to get ahead of ourselves.

The Earth's own sun will die someday. Best to accept that fact now, deal with it, internalize it. When the moment comes you don't want to be caught off guard, your eggs half boiled, your grilled cheese sandwich only toasted on one side. We'll use the sun as a textbook lesson, so you won't be caught unawares in an unfamiliar system, so you won't pick a star to call home that will go giant on you in a thousand years.

A Hubble Space Telescope view of a planetary nebula called NGC 1501. (Image credit: ESA/Hubble & NASA; acknowledgement: Marc Canale)

All stars die. Some, the very largest, go out in a tremendous flash of energy, turning themselves inside out to light up the universe. Others, the smallest, slowly fade, never quite sputtering out, never making a scene, spending a trillion years tending to a weak fire.

The middle ones, like the sun, have the most miserable fates. Before they finally die, they become red and bloated, spewing out their innards through the local system. Spasm after spasm, they slowly lose themselves, leaving only a faint dying heart behind.

It's in these later years when they're most dangerous, when their violence overwhelms them, reducing any hapless inner planets to cinders.

Every year, old stars fade while new ones light up. A continuous cycle in the galaxy. Beautiful and poetic, really, except for the fact that when these stars go they cause mayhem and destruction for anybody unfortunate enough to live within their influence.

You can buy "How to Die in Space" on Amazon or Bookshop.org.

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'How to Die in Space' explores the dangers of astrophysics

mbartels@space.com (Meghan Bartels) — Tue, 21 Jul 2020 18:47:00 +0000

Life on Earth can seem pretty hazardous, but if you ask astrophysicist Paul Sutter, it's still safer than anywhere else in the universe.

Sutter, a frequent Space.com contributor, explores all the dangers the universe has on offer in his new book, "How to Die in Space: A Journey Through Dangerous Astrophysical Phenomena" (Pegasus Books, 2020).

From solar flares to wormholes, black holes to dark matter and supernovas to hostile aliens, Sutter touches on a host of astrophysical threats, both known and theoretical. (Read an excerpt from "How to Die in Space.") Sutter sat down with Space.com to share some highlights from writing the book. This interview has been edited for length and clarity.

How to Die in Space: A Journey Through Dangerous Astrophysical Phenomena

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Join Paul Sutter in a brilliant and breathtakingly vivid tour of the universe, describing the physics of the dangerous, the deadly, and the scary in the cosmos.
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Space.com: How did this book come about?

Paul Sutter: I wanted to write this book because I wanted to talk about some really cool astrophysics like stars blowing up, and stars being born and exotic stuff from the earliest moments of the formation of the universe. But as I was writing, as I was researching, I realized that, wow, this is all pretty high-energy stuff. It's all pretty nasty.

As cool as it is, I would hate to actually visit it, because there's a good chance I would die. And that became the genesis for the thread for the entire book: that the universe may be beautiful, but it's actually very, very dangerous.

Space.com: How did you decide which topics to include in the book?

Sutter: I knew from the start that I wanted to take a kitchen-sink approach to this, where I wanted to touch on as many different topics as possible because it's an amazing universe out there and there's a lot going on.

Each one of the topics I could dig down and write an entire book on, but I did want to make it high-level, I wanted to include a lot of things and show the connections between things, how certain kinds of forces and particles operate in very, very different ways and very similar ways throughout the universe to produce the amazing variety of dangers in the universe.

Space.com: What was your favorite topic to write about and why?

Sutter: Oh, picking a favorite topic is like picking a favorite kid, which you do, but you don't tell anyone about. It was really, really fun, I will admit, to write the chapter on wormholes and explain how wormholes don't actually work and they're a very, very bad idea, and generally should be avoided. It was also really fun to explore all the nuanced ways that stars die, and how each one is beautiful in its own way and tragic in its own way, and of course, dangerous in its own way.

video:

Space.com: Are there any topics you considered including that didn't make the cut?

Sutter: I think I managed to get everything in, even if something doesn't get its own chapter. When I ran across something cool, I worked it into some chapter. So at least there's some broad overview of everything.

Space.com: What do you hope readers take away from the book?

Sutter: I hope readers have a lot of fun, I hope readers learn a lot about the universe, and I hope readers stay at home.

Space.com: Can you expand on that?

Sutter: The very first chapter in the book starts with the vacuum of space and how it can immediately kill you in a very grotesque way, and it gets worse from there. So, I encourage everyone to enjoy our universe from a very safe distance.

Space.com: Are there any particularly fun tidbits you stumbled on while researching and writing the book?

Sutter: I've written about wormholes, I've talked about wormholes before but one of the reasons I really enjoyed writing that chapter is, as I read paper after paper on wormholes stretching back, from the 1970s until the present day, I was amazed at how hard physicists have been working to try to get wormholes to work and how nature just won't let us and you can see the frustration in the history of the articles and it was fun to share that frustration.

Paul Sutter (Image credit: Paul Sutter?Pegasus Bookes)

Space.com: And that's in the last section of the book, the one about speculative threats. Could you talk a bit about that section in general?

Sutter: That was a very fun section to write because so much of the book was known or largely known. Of course, we have questions about everything, we haven't figured out everything about how the universe works, but we generally know what powers say, a solar flare or a supernova. And then we get to the speculative threats.

If we were doing an intergalactic voyage, I felt compelled to talk about some of these things that we're not sure if they exist, we're not sure if they are going to be threats, we're not sure if you're going to encounter them. And so it gave me a chance, an opportunity to give a little bit more fun, to get a little bit more whimsical, to talk about aliens, to talk about cosmic strings, to talk about jumping into a wormhole and explore that this is real research, this is real science, but it is very hypothetical right now.

Space.com: What do you hope readers take away from that section?

Sutter: What I hope people get out of the speculative threats is to recognize and appreciate that we live in a very large, very old, very mysterious universe and that, yes, we've learned a lot in astrophysics and cosmology and astronomy. But we have a lot more still left to learn, and the universe is very much capable of surprising us.

Space.com: What are you excited about right now in space?

Sutter: As I state in the beginning of the book, anything that I write about could change in a moment's notice. I am personally very excited for the upcoming James Webb Space Telescope, which will launch one of these days, I guess, and will tell us a lot about the formation of stars and the formation of planets.

I'm very excited by exoplanet-hunting missions and the possibility of life outside the Earth. I'm very excited for things like LIGO and the continued detection of gravitational waves and getting more and more understanding about how black holes work and don't work and stretch the limits of known physics.

Basically, everything that's happening in astrophysics, I'm excited [for] in some form.

You can buy "How to Die in Space" on Amazon or Bookshop.org.

Email Meghan Bartels at mbartels@space.com or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.

Google doodle celebrates female Turkish astrophysicist Dilhan Eryurt

mbartels@space.com (Meghan Bartels) — Mon, 20 Jul 2020 14:45:22 +0000

It's the 51st anniversary of the Apollo 11 moon landing, the Google Doodle program is celebrating by commemorating the scientific legacy of Turkish astrophysicist Dilhan Eryurt.

Eryurt lived from 1926 to 2012, studied in Turkey, and worked at, among other institutions, NASA's Goddard Space Flight Center in Maryland and the University of California, according to a brief biography compiled by a group of astrophysicists.

Eryurt's research focused on stellar astrophysics, in particular of main-sequence stars like our sun. You can read some of her publications here.

In the Google Doodle, Eryurt is shown looking out on a sky full of stars, as well as a few planetary bodies, including the moon, and a Saturn V rocket, a nod to her time at NASA during the Apollo program.

In the late 1970s, she was also one of a group of scientists who encouraged the Turkish government to establish a national observatory, according to a paper recounting the history of astronomy in Turkey.

The project broke ground in 1991 and made its first observations in 1997.

Email Meghan Bartels at mbartels@space.com or follow her on Twitter @meghanbartels. Follow us on Twitter @Spacedotcom and on Facebook.

Origin of 'Mirach's Ghost' perplexes black hole scientists

Rafi Letzter — Sat, 18 Jul 2020 13:21:10 +0000

About 10 million light-years from Earth, a blurry galaxy named Mirach's Ghost may help unravel a dark mystery: where the largest black holes in the universe came from. But this ghostly galaxy has also deepened the mystery surrounding these objects' births.

A black hole is a singularity, a region in space-time where matter has gotten too dense to sustain itself, and collapsed into a formless point. Supermassive black holes (SMBHs) are cosmic monsters, often weighing billions of times the mass of our sun, as compared to the mass of heavy stars that form ordinary black holes. They sit at the centers of large galaxies, sucking up gas and whipping stars around with their immense gravities. There's one at the center of the Milky Way and an even larger one at the center of the Virgo A galaxy that astronomers have photographed. But it's still not clear how these mammoth objects formed.

Physicists think there are two possibilities: Maybe SMBHs are ancient features of the universe, objects that directly collapsed out of the hot mass streaming through space after the Big Bang. Or perhaps they formed like every other black hole in the universe: as a result of the detonations of dying stars. If the latter explanation were correct, SMBHs would have started small and picked up additional mass over the course of eons by gobbling up dust and other stars.

"The problem is that in either case most black holes have grown significantly since their birth, swallowing up clouds of gas and dust that swirl around them," said Timothy Davis, an astrophysicist at Cardiff University in Wales. "This makes them heavier and makes it difficult to determine the mass they began their lives with."

So Davis and his colleagues went looking for the smallest SMBHs they could find.

These small-supermassives, he told Live Science, "have not had the chance to consume large amounts of material in their past, [so in studying them we are] getting close to revealing how SMBHs must have looked when they were formed."

The researchers studied the SMBH at the center of the galaxy "Mirach's Ghost" (so named because from Earth the galaxy looks like an apparition near the star Mirach), using a new technique to determine its mass.

Relying on data from the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, the researchers measured the speed of carbon monoxide gas as it swirled toward the SMBH at the center of the Mirach's Ghost galaxy.

"Just like water going around a plug-hole, this gas goes faster and faster as it approaches the black hole," Davis said.

That swirling is a product of the black hole's mass, so the speed of the swirling — precisely measured — can tell researchers how much the black hole weighs. ALMA's images, with a resolution of 1.5 light-years (very detailed for such a distant object), made that possible. This SMBH, they found, has a mass less than 1 million times that of our sun — a baby by SMBH standards. Based on estimates of how much it has grown since its birth, it likely weighed less than 500,000 times the mass of our sun when it was born, Davis said.