As tragic as it is, the devouring of a planet by its parent star is a common occurrence throughout the universe, and it doesn’t necessarily end in doom. Using computer simulations, a team of astrophysicists has found that planets not only survive star devouring, but also drive stellar evolution.
Models of planetary system formation show that many planets typically end up being swallowed by their parent stars. It’s just a matter of orbital dynamics, where new planets randomly interact with the protoplanetary disk around the young star, throwing the planets into chaotic orbits, some of which are thrown out of the system entirely, and others that send them to their parent star. Another cannibalization opportunity occurs near the end of a star’s life, when the star becomes a red giant, which also affects the system’s gravitational dynamics and may send planets into the parent star’s atmosphere.
But surprisingly, when this happens, the planet doesn’t necessarily die. Astronomers have discovered many strange systems throughout the Milky Way, where planets have survived their entry into stars. For example, some white dwarf systems are closely surrounded by giant planets, which are too close for planets to form naturally. The atmospheres of some stars contain surprisingly heavy elements, a sign of a rocky object falling. There are also stars that spin too fast and are accelerated by falling planets.
All systems may be the result of a star eating a planet, affecting the further evolution of the star. But can planets really survive in the atmosphere of a star? Teams of astrophysicists use stellar computer simulations to solve problems, tracking the evolution and fate of the various planets that might fall into the star. Study planets of various masses and brown dwarfs in the simulation, supporting that planets can survive being swallowed.
In some cases, planets can orbit and survive for thousands of years within the atmosphere of a star. This motion throws off stellar material, thinning the outer edges of the atmosphere. In other cases, orbital energy exchanges raise the temperature of the star’s atmosphere, making it appear brighter than normal.
But in order to survive after swallowing, the planet itself must be relatively large, at least the mass of Jupiter, and asteroids like the Earth cannot survive. If the planet is large enough, it can speed up stellar evolution, causing the star to end its life quickly, freeing the planet from its deadly embrace.
(This article is sponsored by Taipei Planetarium Authorized to reprint; first image source: Pixabay)
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