Globular clusters as laboratories for stellar evolution

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.

12 pages, 6 figures. Invited review, to appear in the proceedings of IAU Symp. 266 (ed. R. de Grijs & J. R. D. Lepine)

References in corpus (14)

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• The fraction of second generation stars in Globular Clusters from the analysis of the Horizontal Branch
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• Hot Horizontal Branch stars in omega Centauri: clues about their origin from the cluster Color Magnitude Diagram

Cited by in corpus (4)

• The second and third parameters of the Horizontal Branch in Globular Clusters
• Effects of Helium Enrichment in Globular Clusters I.Theoretical Plane with PGPUC stellar evolution code
• Multiple populations within globular clusters in Early-type galaxies Exploring their effect on stellar initial mass function estimates
• UV bright red-sequence galaxies: a comparative study between UV upturn and UV weak systems