Looking for Companionship: Radial Velocity Follow-Up of Lithium-Rich Giants with ESPRESSO
Maryum Sayeed, Andrew R. Casey, Benjamin T. Montet, Melissa K. Ness, Adrian M. Price-Whelan, Daniel Huber, and Madeline J. Maldonado Gutierrez

TL;DR
This study investigates the binary fraction of lithium-rich red giants using high-resolution spectra, revealing diverse companions and suggesting potential formation mechanisms linked to stellar evolution and planetary interactions.
Contribution
First detailed radial velocity follow-up of lithium-rich giants with ESPRESSO, providing new insights into their companion types and formation scenarios.
Findings
27% of Li-rich giants have companions, including planets, brown dwarfs, and stars.
Li-rich giants with lower lithium abundance are more often in binaries.
Higher binary rate observed in giants with specific surface gravity ranges.
Abstract
Lithium-rich red giants have been a long-standing mystery in stellar astrophysics. A leading theory to explain these chemically peculiar and rare objects is interactions with a close companion. To investigate their companion fraction, we collected high-resolution spectra of 33 Li-rich red giants using ESPRESSO, and used The Joker constrain their orbital parameters. We find an overall companion rate of (9/33). Secondary masses reveal one planetary companion (), three brown dwarfs (), and five stellar-mass companions (). Our findings suggest that Li-rich red giants with lower lithium abundance () tend to be in binaries as compared to those with higher lithium abundance, and Li-rich red giants with have a higher companion rate than…
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Taxonomy
TopicsStellar, planetary, and galactic studies · Astronomy and Astrophysical Research · Educational Leadership and Practices
