The Chemical Evolution of Helium in Globular Clusters: Implications for the Self-Pollution Scenario

We investigate the suggestion that there are stellar populations in some globular clusters with enhanced helium (Y ∼ 0.28 to 0.40) compared to the primordial value. We assume that a previous generation of massive Asymptotic Giant Branch (AGB) stars have polluted the cluster. Two independent sets of AGB yields are used to follow the evolution of helium and CNO using a Salpeter initial mass function (IMF) and two top-heavy IMFs. In no case are we able to produce the postulated large Y ∼ 0.35 without violating the observational constraint that the CNO content is nearly constant. Subject headings: stars: AGB and post-AGB stars: chemically peculiar stars: abundances Galaxy: globular clusters: general H. G. Thode Fellow at the Origins Institute