TOI-5882 Shows 98.4th-Percentile Lithium, Suggesting It Engulfed a 9-95 Earth-Mass Planet
Updated
Updated · spacedaily.com · Jul 26
TOI-5882 Shows 98.4th-Percentile Lithium, Suggesting It Engulfed a 9-95 Earth-Mass Planet
1 articles · Updated · spacedaily.com · Jul 26
Summary
Astronomers reported that TOI-5882, a roughly 4-billion-year-old early subgiant, has an unusually strong lithium signal that old stars normally destroy, making it a candidate case of planet engulfment.
Against 61 matched subgiants from the GALAH survey, TOI-5882 ranked in the 98.4th percentile for both lithium line strength and inferred abundance after younger contaminating stars were screened out.
Models indicate the excess could come from swallowing about 9 to 95 Earth masses of planetary material — roughly a super-Earth to Neptune — during a brief evolutionary stage when lithium can survive in the outer envelope.
A surviving 22-Jupiter-mass brown dwarf on a 7-day orbit could have destabilized an inner planet over billions of years, but the authors say the case remains unproven because it rests mainly on one chemical clue.
The study rules out youth, internal lithium production and exotic external sources as likelier explanations; confirming engulfment will require finding additional rocky-planet chemical fingerprints beyond lithium.