Blue straggler evolution caught in the act in the Large Magellanic Cloud globular cluster Hodge 11

Abstract

High-resolution {\sl Hubble Space Telescope} imaging observations show that the radial distribution of the field-decontaminated sample of 162 'blue straggler' stars (BSs) in the $11.7_{-0.1}^{+0.2}$ Gyr-old Large Magellanic Cloud cluster Hodge 11 exhibits a clear bimodality. In combination with their distinct loci in color--magnitude space, this offers new evidence in support of theoretical expectations that suggest different BS formation channels as a function of stellar density. In the cluster's color--magnitude diagram, the BSs in the inner 15$"$ (roughly corresponding to the cluster's core radius) are located more closely to the theoretical sequence resulting from stellar collisions, while those in the periphery (at radii between 85$"$ and 100$"$) are preferentially found in the region expected to contain objects formed through binary mass transfer or coalescence. In addition, the objects' distribution in color--magntiude space provides us with the rare opportunity in an extragalactic environment to quantify the evolution of the cluster's collisionally induced BS population and the likely period that has elapsed since their formation epoch, which we estimate to have occurred $\sim$4--5 Gyr ago.

13 pages, 4 figure, accepted by Astrophysical Journal Letters

References in corpus (8)

• Scaled solar tracks and isochrones in a large region of the Z-Y plane I. From the ZAMS to the TP-AGB end for 0.15 - 2.5 Mo stars
• Dynamical age differences among coeval star clusters as revealed by blue stragglers
• A Binary Origin for Blue Stragglers in Globular Clusters
• Calcium II Triplet Spectroscopy of LMC Red Giants. I. Abundances and Velocities for a Sample of Populous Clusters
• The radial distribution of blue straggler stars and the nature of their progenitors
• Another Non-segregated Blue Straggler Population in a Globular Cluster: the Case of NGC 2419
• The blue stragglers formed via mass transfer in old open clusters
• Photometry of Magellanic Cloud clusters with the Advanced Camera for Surveys - II. The unique LMC cluster ESO 121-SC03

Cited by in corpus (13)

• Gamma-ray burst progenitors
• The binary fractions in the massive young Large Magellanic Cloud star clusters NGC 1805 and NGC 1818
• Discovery of Extended Main Sequence Turn-offs in Four Young Massive Clusters in the Magellanic Clouds
• Consequences of Dynamical Disruption and Mass Segregation for the Binary Frequencies of Star Clusters
• The "dynamical clock": dating the internal dynamical evolution of star clusters with Blue Straggler Stars
• GAMA+KiDS: Empirical correlations between halo mass and other galaxy properties near the knee of the stellar-to-halo mass relation
• Probing the role of dynamical friction in shaping the BSS radial distribution. I - Semi-analytical models and preliminary N-body simulations
• An unexpected detection of bifurcated blue straggler sequences in the young globular cluster NGC 2173
• Model computations of blue stragglers and W UMa-type stars in globular clusters
• GalevNB: a conversion from N-BODY simulations to observations
• Non-homogeneous Behaviour of the Spatial Distribution of Macrospicules
• Blue straggler stars beyond the Milky Way: a non-segregated population in the Large Magellanic Cloud cluster NGC 2213
• Blue straggler stars beyond the Milky Way. III. Detection of evolved blue straggler candidates in Large Magellanic Cloud clusters