The radial distribution of blue straggler stars and the nature of their progenitors

Abstract

The origin of blue straggler stars (BSS) in globular clusters (GCs) is still not fully understood: they can form from stellar collisions, or through mass transfer in isolated, primordial binaries (PBs). In this paper we use the radial distribution of BSS observed in four GCs (M3, 47Tuc, NGC6752 and omega Cen) to investigate which formation process prevails. We find that both channels co-exist in all the considered GCs. The fraction of mass-transfer (collisional) BSS with respect to the total number of BSS is around ~0.4-0.5 (~0.5-0.6) in M3, 47Tuc, and NGC6752. The case of omega Cen is peculiar with an underproduction of collisional BSS. The relative lack of collisional BSS in omega Cen can be understood if mass segregation has not yet driven to the core a sizeable number of PBs, which dominate stellar collisions through three- and four-body processes. The spatial distribution of BSS provides strong hints to their origin: the BSS in the cluster outskirts form almost exclusively from mass transfer in PBs, whereas the BSS found close to the cluster core most likely have a collisional origin.

9 pages, 5 figures, MNRAS, in press, matches the published version

References in corpus (1)

• Discovery of Carbon/Oxygen depleted Blue Straggler Stars in 47 Tucanae: the chemical signature of a mass-transfer formation process

Cited by in corpus (12)

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• A Panchromatic Study of the Globular Cluster NGC 1904. I: The Blue Straggler Population
• The Blue Straggler Population of the Globular Cluster M5
• A Correlation between Blue Straggler and Binary Fractions in the core of Galactic Globular Clusters
• Blue straggler stars in dwarf spheroidal galaxies
• The surprising external upturn of the Blue Straggler radial distribution in M55
• Oscillating Blue Stragglers, gamma Doradus stars and eclipsing binaries in the open cluster NGC2506
• The Blue Straggler population in the globular cluster M53 (NGC5024): a combined HST, LBT, CFHT study
• Tidal Interactions of Red Giants with Environment Stars in Globular Clusters
• Effects of stellar collisions on star cluster evolution and core collapse