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When worlds collide: Stunning 3D simulation shows what happens in giant planetary crashes (video)

New 3D supercomputer simulations show the early stages of planetary collisions, demonstrating what may happen to an Earth-like planet struck by a giant object. 

Planets evolve over billions of years, as bits of dust and gas clump together. However, planetary formation can be easily disrupted by impacts from other celestial objects. Such collisions can cause a wide range of consequences for young planets, such as atmospheric loss, the 3D simulations suggest. 

Using a supercomputer called Cosmology Machine (COSMA), researchers from Durham University and the University of Glasgow, both in the U.K., simulated more than 100 different scenarios of objects traveling at varying speeds and angles colliding with an Earth-like planet with a thin atmosphere.

Related: How did the solar system form?

A 3D simulation showing the impact (inset) and aftermath (main picture) of a giant planetary collision.  (Image credit: Jacob Kegerreis/Durham University)

"We know that planetary collisions can have a dramatic effect on a planet's atmosphere, but this is the first time we've been able to study the wide varieties of these violent events in detail," Jacob Kegerreis, lead author of the study and an astronomer at Durham University, said in a university statement. "In spite of the remarkably diverse consequences that can come from different impact angles and speeds, we've found a simple way to predict how much atmosphere would be lost."

The simulations suggest a slow, grazing impact causes less atmospheric loss than a fast, head-on collision. In fact, according to the statement, a direct hit could destroy not just a planet's entire atmosphere but even some of its mantle as well, the layer beneath a planet's crust. 

Earth's moon is believed to have formed about 4.5 billion years ago following a grazing impact of a small planet about the size Mars with Earth. The debris from this impact accumulated in orbit around Earth to form our moon. The new simulations suggest that this event may have stolen between 10% and 50% of early Earth's atmosphere. 

"At the moment, it appears that the amount of atmosphere a planet loses due to these collisions depends upon how lucky or unlucky they are in terms the type of the impact they suffer," Vincent Eke, co-author of the study and a cosmologist at Durham University, said in the statement.

Their findings, published on July 15 in the Astrophysical Journal, offer insight on planet formation in the early universe, as well as the aftermath of giant impacts. 

"This [research] lays the groundwork to be able to predict the atmospheric erosion from any giant impact, which would feed in to models of planet formation as a whole," Kegerreis said in the statement. "[These models] in turn will help us to understand both the Earth's history as a habitable planet and the evolution of exoplanets around other stars."

Next, the researchers plan to run additional simulations to show what happens during planetary collisions with objects of various masses and compositions. 

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  • rod
    Interesting 1:23 video here. The article stated "Planets evolve over billions of years, as bits of dust and gas clump together. However, planetary formation can be easily disrupted by impacts from other celestial objects. Such collisions can cause a wide range of consequences for young planets, such as atmospheric loss, the 3D simulations suggest. "

    Protoplanetary disks used in accretion models do not last *billions of years*, others reading may get this impression. Also synestia phase of matter after giant impacts I did not see reported or in the video simulation. 'Researchers propose new type of planetary object', https://phys.org/news/2017-05-planetary.html
    Reply
  • JPL-ACE
    Admin said:
    New 3D supercomputer simulations show the early stages of planetary collisions, demonstrating what may happen to an Earth-like planet struck by a giant object.

    When worlds collide: Stunning 3D simulation shows what happens in giant planetary crashes (video) : Read more
    Need a much slower playback speed. But great video. Some very interesting dynamics. Are these videos available on youtube?
    Reply
  • Torbjorn Larsson
    Seems we are all fascinated by the resolution here! What was most interesting to me is not the loss but the retention, which the last part with contrast colors showed well. As I have started to suspect from rapid planetary formation models, the mantle mixing is not primarily from the original Tellus crust of a complex process of core formation and later "grain rain". The video show the lower mantle as exogenous material from the core of am outer system planetesimal Theia. I'm not sure if it explains the primordial volatile leakage that we see from these deep regions, but assuming a planetary disk centered impactor distribution for Theia it could possibly explain the equatorial distributed masses https://en.wikipedia.org/wiki/Large_low-shear-velocity_provinces , https://phys.org/news/2020-06-scientists-unexpected-widespread-earth-core.html ].


    Reply
  • Torbjorn Larsson
    rod said:
    Interesting 1:23 video here. The article stated "Planets evolve over billions of years, as bits of dust and gas clump together. However, planetary formation can be easily disrupted by impacts from other celestial objects. Such collisions can cause a wide range of consequences for young planets, such as atmospheric loss, the 3D simulations suggest. "

    Protoplanetary disks used in accretion models do not last *billions of years*, others reading may get this impression. Also synestia phase of matter after giant impacts I did not see reported or in the video simulation. 'Researchers propose new type of planetary object', https://phys.org/news/2017-05-planetary.html

    Good catch! Seems the author mashed together the two different evolution processes (atmosphere evolution, with or without impcats) and early planet formation.

    I think synestias never became much popular among planetary scientists, and the videos may show why, they don't happen for feasible impact velocities and they aren't necessary to explain the impact outcome.
    Reply
  • rod
    FYI, this simulation model is important and the article here refers to atmospheric loss during a giant impact event. "Earth's moon is believed to have formed about 4.5 billion years ago following a grazing impact of a small planet about the size Mars with Earth. The debris from this impact accumulated in orbit around Earth to form our moon. The new simulations suggest that this event may have stolen between 10% and 50% of early Earth's atmosphere. "

    Here is the NASA ADS Abstract and arXiv PDF report. 'Atmospheric Erosion by Giant Impacts onto Terrestrial Planets: A Scaling Law for any Speed, Angle, Mass, and Density', https://ui.adsabs.harvard.edu/abs/2020arXiv200704321K/abstract
    "1. INTRODUCTION Terrestrial planets are thought to form from tens of roughly Mars-sized embryos that crash into each other after accreting from a proto-planetary disk (Chambers 2001). At the same time, planets grow their atmospheres by accreting gas from their surrounding nebula, degassing impacting volatiles directly into the atmosphere, and by outgassing volatiles from their interior (Massol et al. 2016). For a young atmosphere to survive it must withstand radiation pressure of its host star, frequent impacts of small and medium impactors, and typically at least one late giant impact that could remove an entire atmosphere in a single blow (Schlichting & Mukhopadhyay 2018)."

    These studies indicate that the proto-Earth could lose 60% of its early atmosphere too. Some impacts remove all of the early atmosphere. How the proto-Earth continued to gain an atmosphere after the postulated giant impact with Theia is not clear to me, consider that the gas in the accretion disk is now depleted by the time of Theia impact. Growing the proto-Earth to its present mass and size needs explaining too. Other simulations get very different results when using low mass stars like red dwarfs. 'Ejection of close-in super-Earths around low-mass stars in the giant impact stage', https://ui.adsabs.harvard.edu/abs/2020arXiv200714039M/abstract, "Earth-sized planets were observed in close-in orbits around M dwarfs. While more and more planets are expected to be uncovered around M dwarfs, theories of their formation and dynamical evolution are still in their infancy. We investigate the giant impact growth of protoplanets, which includes strong scattering around low-mass stars..."

    A rich area of study with enormous kinetic energies and the potential for much destruction of proto-planets and the proto-Earth too :)
    Reply