3He in stars of low and intermediate mass

Abstract

We follow the evolution of 3He in stars of mass 0.8 -- 10 M (solar units) for Pop. I and II compositions from the main sequence until advanced stages on the AGB. Under standard assumptions we confirm earlier results of more restricted investigations that low-mass stars up to 5 M are net producers of 3He. We show that the inclusion of additional mixing due to diffusion beneath the convective envelope simultaneously leads to observed carbon isotope anomalies observed in globular cluster Red Giants and to a strong reduction of 3He, such that stars exhibiting such anomalies will have destroyed 3He contrary to the standard picture.