Study of the Helium Enrichment in Globular Clusters

TL;DR

This study investigates helium enrichment in globular clusters, specifically M3, and finds that recent high-precision observations do not support the presence of significant helium enhancement.

Contribution

The paper provides observational evidence against the hypothesis of helium enrichment in M3, challenging previous suggestions about stellar populations in globular clusters.

Findings

Helium enrichment is not supported in M3 by high-precision data.

Blue horizontal branch stars in M3 do not show signs of helium enhancement.

The results question the idea of multiple stellar populations with different helium levels in M3.

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.