Massive stars, globular clusters and elliptical galaxies

TL;DR

This paper explores the potential role of fast rotating massive stars in producing helium-rich populations in globular clusters and elliptical galaxies, linking stellar evolution to observed phenomena like the UV-upturn.

Contribution

It proposes that fast rotating massive stars are a key source of He-rich stars in globular clusters and may explain the UV-upturn in elliptical galaxies.

Findings

He-rich stars are linked to fast rotating massive stars.

He-rich populations may be responsible for the UV-upturn.

Fast rotation influences early stellar evolution in galaxies.

Abstract

Globular clusters as $\omega$ Cen and NGC 2808 appear to have a population of very He-rich stars. From a theoretical point of view, one expects the presence of He-rich stars in all globular clusters showing an oxygen-sodium (O-Na) anticorrelation. In this paper, we briefly recall how fast rotating massive stars could be the main source of the material from which He-rich stars have formed. We speculate that the UV-upturn phenomenon observed in all elliptical galaxies might be due to He-rich stars. If this hypothesis is correct then fast rotating massive stars may have played in the early evolutionary phases of these systems a similar role as the one they played in the nascent globular clusters.