Sun-like star TOI-5882 caught eating a planet, lithium excess signals engulfment, University of Michigan
A sun-like star 1,300 light-years away appears to have eaten one of its own planets. University of Michigan astronomers found a lithium excess in TOI-5882 that points to a swallowed super-Earth to Neptune-mass world, possibly nudged in by its brown dwarf companion.
Astronomers have found fresh evidence of a star consuming one of its own planets, about 1,300 light-years from Earth. A team led by Brooke Kotten at the University of Michigan detected an unusually high amount of lithium in the spectrum of TOI-5882, a sun-like star, and published the finding in The Astrophysical Journal. The lithium signal matters because the element is abundant in planets but is rapidly destroyed in the hot interiors of stars, so a sudden excess at the surface is a recognized fingerprint of recent planetary engulfment. The researchers estimate the star swallowed a world somewhere between super-Earth and Neptune in mass. TOI-5882 was already on astronomers' radar because of a massive companion, a brown dwarf more than 20 times the mass of Jupiter that orbits the star but never grew large enough to ignite as a star of its own. That companion may have played a role in the planet's demise by gravitationally kicking it onto a spiraling path inward until the star absorbed it. Observations of systems like this one help researchers understand how planets can be lost over a star's lifetime. Sources: University of Michigan, phys.org, The Astrophysical Journal.