Massive Binary Stars and Self-Enrichment of Globular Clusters

TL;DR

This paper proposes that massive binary stars significantly contribute to the self-enrichment of globular clusters by ejecting processed material that forms subsequent stellar generations, explaining observed abundance patterns.

Contribution

It introduces the idea that massive binary stars are a key source of enriched material in globular clusters, expanding understanding of their chemical evolution.

Findings

Massive binary stars can eject nuclear-processed material.

Short-period binaries are more common, increasing material ejection.

Ejected matter can remain within clusters for star formation.

Abstract

Globular clusters contain many stars with surface abundance patterns indicating contributions from hydrogen burning products, as seen in the anti-correlated elemental abundances of e.g. sodium and oxygen, and magnesium and aluminium. Multiple generations of stars can explain this phenomenon, with the second generation forming from a mixture of pristine gas and ejecta from the first generation. We show that massive binary stars may be a source of much of the material that makes this second generation of stars. Mass transfer in binaries is often non-conservative and the ejected matter moves slowly enough that it can remain inside a globular cluster and remain available for subsequent star formation. Recent studies show that there are more short-period massive binaries than previously thought, hence also more stars that interact and eject nuclear-processed material.