Photometric Binaries in 14 Magellanic Cloud Star Clusters

Abstract

Binary stars play a major role in determining the dynamic evolution of star clusters. We used images collected with the Hubble Space Telescope to study fourteen Magellanic Clouds star clusters that span an age interval between $\sim 0.6$ and $2.1$ Gyr and masses of $10^4-10^5$ M${}_{\odot }$. We estimated the fraction of binary systems composed of two main-sequence stars and the fraction of candidate blue-straggler stars (BSSs). Moreover, we derived the structural parameters of the cluster, including the core radius, the central density, the mass function, and the total mass. We find that the fraction of binaries with a mass ratio larger than 0.7 ranges from $\sim$7%, in NGC1846, to $\sim$20%, in NGC2108. The radial and luminosity distribution can change from one cluster to another. However, when we combine the results from all the clusters, we find that binaries follow a flat radial trend and no significant correlation with the mass of the primary star. We find no evidence for a relation between the fractions of binaries and BSSs. We combined the results on binaries in the studied Magellanic Cloud clusters with those obtained for 67 Galactic globular clusters and 78 open clusters. We detect a significant anti-correlation between the binary fraction in the core and the mass of the host cluster. However, star clusters with similar masses exhibit a wide range of binary fractions. Conversely, there is no evidence of a correlation between the fraction of binaries and either the cluster age or the dynamic age.

16 figures, 18 pages, accepted for publication in Astronomy and Astrophysics

References in corpus (6)

• The Dartmouth Stellar Evolution Database
• Dynamical age differences among coeval star clusters as revealed by blue stragglers
• The fraction of binary systems in the core of thirteen low-density Galactic globular clusters
• Photometric binaries, mass functions, and structural parameters of 78 Galactic open clusters
• Differential reddening in the direction of 56 Galactic globular clusters
• The dynamical origin of multiple populations in intermediate-age clusters in the Magellanic Clouds

Cited by in corpus (8)

• Hubble Space Telescope survey of Magellanic Cloud star clusters. Binaries among the split main sequences of NGC 1818, NGC 1850, and NGC 2164
• Exploring the formation environment of multiple stellar populations in Globular Clusters through binary systems
• On the original composition of the gas forming first-generation stars in clusters: insights from HST and JWST
• A deep HST view of the open cluster NGC2158: binaries, mass functions, and M-dwarf discontinuity
• The Origin of Young Stellar Populations in NGC 1783: Accretion of External Stars
• Unveiling Bifurcated Blue Straggler Sequences in NGC 2173: Insights from Binary Evolution
• The Small Magellanic Cloud through the lens of the James Webb Space Telescope : binaries and mass function within the galaxy outskirts
• Rubin Data Preview 1: Extending the View of Unresolved Binary Stars in 47 Tucanae