PI: Bruce A. Twarog, University of Kansas, email@example.com
Address: Physics Department, 1251 Wescoe Hall Dr., Lawrence, KS 66045-7582, US
CoI: Barbara J. Anthony-Twarog, University of Kansas
CoI: Constantine Deliyannis, Indiana University
CoI: Andrew Szentgyorgyi, Smithsonian Astrophysical Observatory
Title: Probing Stellar Structure and Evolution via Li Abundances
Abstract: Tests of sub-photospheric stellar structure and evolution are few and far between. In addition to asteroseismology, color-magnitude diagram (CMD) morphology, and abundance anomalies among evolved stars, an increasingly valuable probe of stellar structure for lower mass main sequence and post-main sequence stars is the Li abundance. Building upon our recent work in NGC 3680 and NGC 6253, we propose to derive A(Li) for every probable member single star in NGC 2420 from the tip of the giant branch to 2.5 mag below the turnoff. NGC 2420 is one of very few metal-deficient open clusters with stars within observational reach on both sides of the Li-dip. The observations will allow mapping of convection along the giant branch for stars near the He-degenerate core boundary, better definition of the metallicity dependence of the Li-dip, and constraints on any depletion of Li among the cooler stars that populate the analogous Spite plateau within the halo.
National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360