Abstract

The post-main sequence stellar evolution can have catastrophic consequences for orbiting planets. With the expansion of the star’s envelope during the red giant branch, some exoplanets are likely engulfed, producing changes in the surface chemical composition of the star. There are no clear chemical signatures that are unequivocally associated with this event, but enhancement of light elements that should be depleted on the surface of red giants can be considered indicators of engulfment. In this talk, I will discuss lithium as a signature of accretion of substellar companions in red giant branch stars. Although identifying individual engulfment events during the red giant evolutionary phase can be complicated, the death of a low-mass star provides new opportunities to study engulfment. Metals in the atmosphere of white dwarfs are signs of accretion of smaller planetary bodies. Thus, I will also show how these polluted white dwarfs offer a novel means to study the composition of rocky exoplanets and understand if they retain the same composition as the material from which they formed.