Study of the Helium Enrichment in Globular Clusters

Abstract

Globular clusters (GCs) are spheroidal concentrations typically containing of the order of 10^5 to 10^6, predominantly old, stars. Historically, they have been considered as the closest counterparts of the idealized concept of "simple stellar populations." However, some recent observations suggest than, at least in some GCs, some stars are present that have been formed with material processed by a previous generation of stars. In this sense, it has also been suggested that such material might be enriched in helium, and that blue horizontal branch stars in some GCs should accordingly be the natural progeny of such helium-enhanced stars. In this contribution we show that, at least in the case of M3 (NGC 5272), the suggested level of helium enrichment is not supported by the available, high-precision observations.

4 pages, 2 figures. To appear in the proceedings of IAU Symp. 262 (ed. G. Bruzual & S. Charlot)

References in corpus (8)

• The ACS Survey of Galactic Globular Clusters. III. The Double Subgiant Branch of NGC 1851
• The ACS Survey of Galactic Globular Clusters: M54 and Young Populations in the Sagittarius Dwarf Spheroidal Galaxy
• The double Subgiant Branch of NGC 1851: the role of the CNO abundance
• The fraction of second generation stars in Globular Clusters from the analysis of the Horizontal Branch
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• Constraints on Helium Enhancement in the Globular Cluster M3 (NGC 5272): The Horizontal Branch Test