The age-mass relation for chromospherically active binaries: III. Lithium depletion in giant components

TL;DR

This study investigates lithium abundances in evolved components of chromospherically active binary systems, revealing lithium excesses that are independent of age and linked to stellar rotation and angular momentum transfer.

Contribution

It demonstrates that lithium abundance in giant components of CABS is unaffected by age and correlates with stellar rotation, highlighting angular momentum transfer effects.

Findings

Many giants show lithium excesses regardless of mass or evolutionary stage.

Li abundance is independent of age in giant CABS components.

Lithium overabundances are related to stellar rotation and angular momentum transfer.

Abstract

We present a study of the lithium abundances of a sample of evolved components of Chromospherically Active Binary Systems. We show that a significant part of them have lithium excesses, independently of their mass and evolutionary stage. Therefore, it can be concluded that Li abundance does not depend on age for giant components of CABS. These overabundances appear to be closely related to the stellar rotation, and we interpret them as a consequence of the transfer of angular momentum from the orbit to the rotation as the stars evolve in and off the Main Sequence, in a similar way as it happens in the dwarf components of the same systems and in the Tidally Locked Binaries belonging to the Hyades and M67.