Program: GN-2016B-Q-35

Red giant stars show a large dispersion in lithium abundances with A(Li) spanning several orders of magnitude. Stellar mixing processes determine how severely Li is depleted and whether Li is re-synthesized, but models have still not established which processes dominate for different stellar masses and at different times. Understanding the natural variation in A(Li) is crucial to being able to identify stars with external Li pollution, such as from the engulfment of a planet or brown dwarf. Asteroseismology has recently provided the ability to measure accurate masses for red giants and to discriminate between first ascent and red clump stars. We propose to measure A(Li) in a sample of 85 red giants in the Kepler field with such asteroseismic measurements. A subset of our sample comprises 25 known fast rotators. Fast rotation is an expected signature of engulfment. Measuring A(Li) for these stars will constrain the role that mass, evolutionary stage, and rotation play on the final Li content of red giants and may uncover outliers that suggest external Li pollution.