STScI Preprint #1234

Mixing in Stars and the Evolution of the ³He Abundance

We first recall the observational and theoretical facts that constitute the so-called ³He problem. We then review the chemical anomalies that could be related to the destruction of ³He in red giants stars. We show how a simple consistent mechanism can lead to the destruction of ³He in low mass stars and simultaneously account for the low ¹²C/¹³C ratios and low lithium abundances observed in giant stars of different populations. This process should both naturally account for the recent measurements of ³He/H in galactic HII regions and allow for high values of ³He observed in some planetary nebulae. We propose a simple statistical estimation of the fraction of stars that may be affected by this process.

Status:

Appeared in: Space Sci. Rev. 84:199-206, 1998

Affiliations:

¹) Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
²) Laboratoire d'Astrophysique de Toulouse, CNRS UMR 5572, 14, av. E.Belin, 31400 Toulouse, France