S316p.54 — Sleuthing Helium in Cluster Red Giants

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Aug 10th at 6:00 PM until 7:30 PM

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Author(s): Andrea K. Dupree1, Eugene Avrett1, Graeme Smith2, Jay Strader3

Institution(s): 1. Harvard-Smithsonian Center for Astrophysics, 2. Lick Observatory, 3. Michigan State University

A prediction is tested that a second generation of stars in globular clusters contains an enhanced abundance of helium. We report a near-infrared study of helium in red giants of the globular cluster Omega Centauri. In this cluster, the presence of helium is found to be associated with increased abundances of [Na/Fe] and [Al/Fe]. A realistic quantitative calculation of the helium line profile formed in the chromosphere of the red giants indicates that the element helium is enhanced by ≧0.17 dex in Omega Cen, signaling that high temperature H-burning has occurred in a previous generation of stars. The Helium transition at 1.08μ also offers a sensitive probe of the presence of stellar winds.