The blue straggler population of the old open cluster Berkeley 17

Abstract

Blue Straggler Stars (BSSs) are observed in Galactic globular clusters and old open clusters. The radial distribution of BSSs has been used to diagnose the dynamical evolution of globular clusters. For the first time, with a reliable sample of BSSs identified with Gaia DR2, we conduct such an analysis for an open cluster. We identify members, including BSSs, of the oldest known Galactic open cluster Berkeley 17 with the Gaia DR2 proper motions and parallaxes. We study the radial distribution of the BSS population to understand the dynamical evolution of the cluster. We select cluster members to populate the colour magnitude diagram in the Gaia filters. Cluster parameters are derived using the brightest members. The BSSs and giant branch stars are identified, and their radial distributions are compared. The segregation of BSSs is also evaluated with respect to the giant branch stars using the Minimum Spanning Tree analysis. We determine Berkeley 17 to be at $3138.6_{-352.9}^{+285.5}$ pc. We find 23 BSS cluster members, only two of which were previously identified. We find a bimodal radial distribution of BSSs supported by findings from the MST method. The bimodal radial distribution of BSSs in Berkeley 17 indicates that they have just started to sink towards the cluster center, placing Berkeley 17 with globular clusters of intermediate dynamical age. This is the first such determination for an open cluster.

arXiv comment6 pages, 6 figures, Accepted for publication in Astronomy and Astrophysics

References in corpus (30)

• Astropy: A Community Python Package for Astronomy
• Gaia Data Release 2. Summary of the contents and survey properties
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Gaia Data Release 2: The astrometric solution
• Estimating distances from parallaxes IV: Distances to 1.33 billion stars in Gaia Data Release 2
• A new generation of PARSEC-COLIBRI stellar isochrones including the TP-AGB phase
• Gaia Data Release 2: Photometric content and validation
• Global survey of star clusters in the Milky Way II. The catalogue of basic parameters
• A Gaia DR2 view of the Open Cluster population in the Milky Way
• Improving PARSEC models for very low mass stars
• Using the minimum spanning tree to trace mass segregation
• Dynamical age differences among coeval star clusters as revealed by blue stragglers
• Gaia Data Release 2: Properties and validation of the radial velocities
• The age of the oldest Open Clusters
• Two distinct sequences of blue straggler stars in the globular cluster M30
• Blue straggler production in globular clusters
• The Gaia astrophysical parameters inference system (Apsis). Pre-launch description
• Morphology of Galactic Open Clusters
• The Blue Straggler Population of the Globular Cluster M5
• The Unique Na:O Abundance Distribution in NGC 6791: The First Open(?) Cluster with Multiple Populations
• Multiwavelength photometry in the Globular Cluster M2
• BVI photometry of the very old open cluster Berkeley 17
• Reanalysis of nearby open clusters using Gaia DR1/TGAS and HSOY
• Deep multi-telescope photometry of NGC 5466. I. Blue Stragglers and binary systems
• UBVI CCD Photometry of the Old Open Cluster Berkeley 17
• Mock Observations of Blue Stragglers in Globular Cluster Models
• Blue Straggler Stars in Galactic Open Clusters and the effect of field star contamination
• A chemical study of M67 candidate blue stragglers and evolved blue stragglers observed with APOGEE DR14
• Disintegration of the Aged Open Cluster Berkeley 17
• The central Blue Straggler population in four outer-halo globular clusters

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• A study of the blue straggler population of the old open cluster Collinder 261
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