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 (opens in new tab) of objects traveling at varying speeds and angles colliding with an Earth-like planet with a thin atmosphere.
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"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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