SCYON Abstract

Received on October 14 2009

Globular clusters as laboratories for stellar evolution

Authors	Márcio Catelan (¹), Aldo A.R. Valcarce (¹), and Allen V. Sweigart (²)
Affiliation	(¹) PUC-Chile (²) NASA-GSFC
To appear in	Proceedings of IAU Symp. 266 (ed. R. de Grijs & J. R. D. Lepine)
Contact	mcatelan@astro.puc.cl
URL	http://arxiv.org/abs/0910.1367
Links

Abstract

Globular clusters have long been considered the closest approximation to a physicist's laboratory in astrophysics, and as such a near-ideal laboratory for (low-mass) stellar evolution. However, recent observations have cast a shadow on this long-standing paradigm, suggesting the presence of multiple populations with widely different abundance patterns, and -- crucially -- with widely different helium abundances as well. In this review we discuss which features of the Hertzsprung-Russel diagram may be used as helium abundance indicators, and present an overview of available constraints on the helium abundance in globular clusters.