🔭 A star swallows a super-Earth, a brown dwarf accomplice to the crime

A strange observation has recently caught the attention of astronomers: a star located 1,300 light-years away, named TOI-5882, displays a lithium abundance well above normal. This unusual peak could betray a cosmic crime: an exoplanet swallowed by its sun. Researchers have thus launched an investigation to understand what happened.

Lithium is a key clue. As a researcher from the University of Michigan explains, planets contain much more lithium than stars. If a star swallows a planet, its lithium abundance rises. That is exactly what scientists observe for TOI-5882, indicating it has devoured a rocky world.


But this star is not a red giant, which rules out the classic scenario of engulfment by stellar expansion. Another suspect has been identified: a companion brown dwarf. With a mass about 20 times that of Jupiter, this "failed star" would have disturbed the planet's orbit, sending it to its demise.

Astronomers acted like detectives at a crime scene. By analyzing the chemical composition of 62 similar stars, they found that TOI-5882 ranks in the 97th percentile for lithium abundance. This signal is robust, according to a researcher from the University of Wisconsin.

The data indicate that the missing planet was a super-Earth, with a mass between two times that of Earth and that of Neptune. Such engulfment events are extremely rare, as they occur over a few days to a few weeks. Astronomers must therefore reconstruct the scenario from these clues.

This study was published in The Astrophysical Journal. As one of the researchers explains, every clue counts to solve this cosmic mystery. One thing is certain: the star likely ate a planet, and the brown dwarf could be its accomplice.