Massive Binary Stars and Self-Enrichment of Globular Clusters

Robert G. Izzard, Selma E. de Mink, Onno R. Pols, Norbert Langer, Hugues Sana, Alex de Koter

Published 2013-02-04Version 1

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.