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Dusty alien planets could be more likely to harbor life, study suggests

A visualization showing computer simulations of three terrestrial exoplanets, depicting winds (arrows) and airborne dust (color), with an M-dwarf host star in the background.
A visualization showing computer simulations of three terrestrial exoplanets, depicting winds (arrows) and airborne dust (color), with an M-dwarf host star in the background.
(Image: © Denis Sergeev/University of Exeter)

Dusty alien planets might have a better chance at harboring life, a new study suggests.

Scientists studying the potential habitability of alien worlds look at a number of key factors, including temperature and composition (is it a rocky planet? Is it gaseous?). But in a new paper, scientists explore one often overlooked variable that could indicate whether life could exist on an exoplanet: dust. 

Now, we know that dust plays a role in climate here on Earth and also on Mars. According to this new study from researchers at the University of Exeter in the U.K., the Met Office (the U.K.'s national weather service) and the University of East Anglia in Norwich, England, planets with significant amounts of airborne mineral dust could be habitable within a greater range of distance from their star. This creates a wider window of exoplanets that might be capable of harboring life. 

Related: 10 exoplanets that could host alien life

In this study, researchers looked at M-dwarf planets, exoplanets which orbit close to cooler stars smaller than our sun. These planets usually orbit their stars in synchronous rotation, so there is a permanent day side of the planet facing the star and a permanent night side facing away. They performed a number of simulations of terrestrial planets and, using climate models, showed how the presence of substantial amounts of airborne mineral dust on the planet affected it. 

They found that dust would cool the hot day side of such an exoplanet and would warm its cold night side. 

"On Earth and Mars, dust storms have both cooling and warming effects on the surface, with the cooling effect typically winning out," Ian Boutle, lead author of this study from the Met Office and the University of Exeter, said in a statement

"But these 'synchronized orbit' planets are very different. Here, the dark sides of these planets are in perpetual night, and the warming effect wins out, whereas on the dayside, the cooling effect wins out. The effect is to moderate the temperature extremes, thus making the planet more habitable,"

However, while dust might be a key factor in some planets' habitability, it also complicates scientists' ability to observe these planets. "Airborne dust is something that might keep planets habitable, but also obscures our ability to find signs of life on these planets. These effects need to be considered in future research," co-author Manoj Joshi, a professor at the University of East Anglia said in the same statement. 

This research included work from undergraduate physics students, aiming to not only expand our understanding of exoplanet habitability, but to also support early-career researchers. 

"To be able to involve undergraduate physics students in this, and other projects, also provides an excellent opportunity for those studying with us to directly develop the skills needed in such technical and collaborative projects," co-author Nathan Mayne, a professor at the University of Exeter, said in the statement. 

This work was published June 9 to the journal Nature Communications. 

Email Chelsea Gohd at cgohd@space.com or follow her on Twitter @chelsea_gohd. Follow us on Twitter @Spacedotcom and on Facebook.

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  • rod
    The space.com article stated, "In this study, researchers looked at M-dwarf planets, exoplanets which orbit close to cooler stars smaller than our sun. These planets usually orbit their stars in synchronous rotation, so there is a permanent day side of the planet facing the star and a permanent night side facing away. They performed a number of simulations of terrestrial planets and, using climate models, showed how the presence of substantial amounts of airborne mineral dust on the planet affected it. They found that dust would cool the hot day side of such an exoplanet and would warm its cold night side."

    Class M stars with exoplanets are very interesting. This site, http://exoplanet.eu/ , shows 4270 exoplanets. I ran MS SQL query and found 245 listed for host stars with 0.1 to 0.5 solar masses. Some large property differences too, average mass about 6.6 Mjup. I ran the same query using this site, https://exoplanetarchive.ipac.caltech.edu/index.html The site shows 4164 exoplanets. 247 listed for 0.1 to 0.5 solar mass stars with average mass 1.85 Mjup. Some interesting properties from both sites for orbital periods, distances from host star and orbital eccentricity. Forecasting the weather on Earth can be difficult, looking at these exoplanets around smaller stars and forecasting the weather is interesting :)
    Reply
  • dfjchem721
    Abiogenesis, the origin of life from inanimate chemicals, is believed to have occurred on earth in deep oceans, near thermal vents, and well away from atmospheric variables. The energy source was from the earth's core, where radionuclide decay, and the heat of formation, provided a long term source of heat for production of chemicals essential to kick-start life. This internal heat also kept the aqueous milieu at the appropriate temperature over extended periods, in order for life to arise.

    So in its earliest phase, life could have arisen on earth without any atmosphere (dusty or not), and indeed even without the sun. The atmosphere and the sun would have been critical for the continuation of life long term, and its further evolution, providing both cover from high intensity sunlight, yet allowing in some light for photosynthesis to evolve. It is not likely that photosynthesis evolved from the get-go. The molecular mechanisms for trapping sunlight (aka the photosynthetic reaction center) to convert into chemical energy are likely too complex for the simplest life forms to develop. After some period, when life forms grew more complex and had more avenues to evolve into, such complex mechanisms could then arise.

    On the other hand, surface life on a dusty planet seems more likely to arise than one exposed to direct, intense light. So perhaps the optical density of an atmosphere would play a vital role in the later course of evolution on a habitable planet, one that had first undergone sub-surface abiogenesis. Clearly (no pun), the atmosphere at some point likely clarifies, like it did on earth, in order for the most advanced life forms to arise. But they won't become very advanced if they could not see into the cosmos and attempt to determine what those many lights in the sky are all about...........
    Reply
  • rod
    FYI, it is good in science to define constraints on various models used. Exoplanets that orbit close to their parent stars can also undergo atmosphere destruction and loss, when the star is young. How four newborn exoplanets get cooked by their sun, "Scientists from the Leibniz Institute for Astrophysics Potsdam (AIP) examined the fate of the young star V1298 Tau and its four orbiting exoplanets. The results show that these recently born planets are roasted by the intense X-ray radiation of their young sun, which leads to the vaporization of the atmospheres of these planets. The innermost planets could be evaporated down to their rocky cores, so that there is no atmosphere left. "

    This loss of atmosphere is reported in the TRAPPIST-1 system too. Seven-Planet Star Hides Age, Might Be Deadly, "The star with seven exoplanets puts out enough high-energy radiation to tear away the inner planets’ atmospheres in a few billion years. The world is abuzz over the little star TRAPPIST-1, the ultracool M dwarf with seven potentially rocky exoplanets..."
    Reply
  • rod
    For V1298 Tau report, see https://phys.org/news/2020-06-newborn-exoplanets-cooked-sun.html, the other reference link is oops :)
    Reply