Aguilera-Gómez, C., Chanamé, J. & Pinsonneault, M. H.
2020, ApJ, 897,20
https://ui.adsabs.harvard.edu/abs/2020ApJ…897L..20A/abstract
The Lithium-6 (6Li) abundance is often used as a diagnotic for substellar companion engulfment acting in 7Li-rich giants, as the relative 6Li and 7Li abundances are expected to be different if the enrichment were to come from internal production or from engulfment. In this work, we model the 6Li and 7Li abundances of different giants after the engulfment of a substellar mass companion. Given that 6Li is more strongly affected by Galactic chemical evolution than 7Li, 6Li is not a good discriminant at low metallicities, where it is expected to be low in both star and planet. For higher metallicities, 6Li increases significantly after the engulfment of a companion. However, at metallicities close to solar and higher, the 6Li signal does not last long in the stellar surface. As such, a detection of 6Li in such stars could hint towards a recent engulfment event. We conclude that 6Li should not be used to reject the hypothesis of engulfment in a 7Li-enriched giant or to support a particular 7Li-enhancement mechanism.