The Active Chromospheres of Lithium-rich Red Giant Stars*

Abstract We have gathered near-infrared zyJ -band high-resolution spectra of nearly 300 field red giant stars with known lithium abundances in order to survey their He i ? 10830 absorption strengths. This transition is an indicator chromospheric activity and/or mass loss giants. The majority our sample reside the clump or horizontal branch based on V ? J , M color–magnitude diagram, and Gaia T eff log( g ) values. Most target are Li-poor sense having normally low Li abundances, defined here as log ? (Li) < 1.25. Over 90% these weak features. However, more than half 83 Li-rich (log > 1.25) strong absorptions. These large lines signal excess stars; there almost no indication significant loss. giants may also a higher binary fraction stars, astrometric data. It appears likely that both residence present past interaction play roles Li–He connection established this survey.