Blue straggler stars beyond the Milky Way. II. A binary origin for blue straggler stars in Magellanic Cloud clusters

Abstract

We have analyzed populations of blue straggler stars (BSSs) in 24 Magellanic Cloud star clusters using multi-passband Hubble Space Telescope images. We compiled a homogeneous BSS database, containing both traditional and evolved BSSs. We uncovered a sub-linear correlation between the number of BSSs in the cluster cores and the clusters' core masses, characterized by a power-law index of $0.51\pm 0.07$. For low stellar collision rates, the mass-normalized number of BSSs depends only weakly (or perhaps not at all) on the collision rate, implying that the binary-driven BSS formation channel dominates. Comparison with simulations suggests that stellar collisions contribute less than 20\% to the total number of BSSs formed. Further tests, including analysis of the BSS specific frequencies and their population numbers at larger cluster radii, suggest that binary interactions may be their main formation channel, hinting at an anti-correlation between a cluster's binary fraction and its core mass.

14 pages, 5 figures. Accepted for publication in ApJ

References in corpus (12)

• A Binary Origin for Blue Stragglers in Globular Clusters
• Dynamical Formation of Close Binaries in Globular Clusters II: Cataclysmic Variables
• Extended Main Sequence Turnoffs in Intermediate-Age Star Clusters: A Correlation Between Turnoff Width and Early Escape Velocity
• The radial distribution of blue straggler stars and the nature of their progenitors
• No Evidence for Significant Age Spreads in Young Massive LMC Clusters
• Blue straggler stars in dwarf spheroidal galaxies
• Binary coalescence from case A evolution -- mergers and blue stragglers
• Exploring the nature and synchronicity of early cluster formation in the Large Magellanic Cloud: II. Relative ages and distances for six ancient globular clusters
• Evidence of differential tidal effects in the old globular cluster population of the Large Magellanic Cloud
• The intermediate-age globular cluster NGC 1783 in the Large Magellanic Cloud
• Formation and Evolution of Blue Stragglers in 47 Tucanae
• Blue straggler stars beyond the Milky Way: a non-segregated population in the Large Magellanic Cloud cluster NGC 2213

Cited by in corpus (5)

• Stellar rotation and the extended main sequence turnoff in the open cluster NGC 5822
• Star density profiles of six old star clusters in the Large Magellanic Cloud
• Photometric Binaries in 14 Magellanic Cloud Star Clusters
• A binary-related origin mediated by environmental conditions for blue straggler stars
• Unveiling Bifurcated Blue Straggler Sequences in NGC 2173: Insights from Binary Evolution