Close pairs: keys to comprehension of star cluster evolution

Abstract

Abstract. In this review I first summarize why binaries are key objects in the study of stellar populations, to understand the evolution of star clusters and galaxies, and thus to understand the universe. I then focus on four specific topics:(i) the formation (through binaries) and evolution of very massive stars in dense clusters and the importance of stellar-wind mass loss. I discuss preliminary computations of wind mass-loss rates of very massive stars performed with the Munich hydrodynamical code and the influence of these new rates on the possible formation of an intermediate-mass black hole in the cluster MGG 11 in M82;(ii) the evolution of intermediate-mass binaries in a starburst with special emphasis on the variation of the supernova (SN) Ia rate (i.e., on the delayed time distribution of SNe Ia). A comparison with SN Ia rates in elliptical galaxies may provide important clues to SN Ia models as well as to the evolution of SN Ia progenitors; (iii) the evolution of double-neutron-star mergers in a starburst (i.e., the delayed time distribution of these mergers) and what this tells us about the suggestion that these mergers may be important production sites of r-process elements; (iv) the possible effect of massive binaries on the self-enrichment of globular clusters.

Multiple populations in globular clusters: the possible contributions of stellar collisions

“…There are indications that massive stars have a higher binary fraction than low mass stars in the field (Lada 2006) and so it may not be unreasonable to expect that interacting binary stars may have a significant impact on the mass lost from massive stars. Following suggestions by de Mink et al (2009), Vanbeveren (2010) goes as far to suggest that interacting massive binaries are responsible for all the pollution in globular clusters, not fast‐rotating massive stars or AGB stars.…”

The Stagnation of Contemporary Stellar Astronomy

“…The problem of current models is connected mainly with evolution of binary stars. During the post-AGB evolution the thermally pulsating asymptotic giant branch stars contribute about 60% of K-band light [16], but about 30% of them are binaries at Roche lobe overflow phase [17]. This is, however, usually ignored in most models of stellar population synthesis.…”