The Small Blue Straggler Star Population in the Dense Galactic Globular Cluster NGC 6752
Abstract
We used high-resolution Hubble Space Telescope (HST)-WFPC2 and wide-field ground-based observations to construct a catalog of blue straggler stars (BSSs) that spans the entire radial extent of the globular cluster NGC 6752. The BSS sample is the most extensive ever obtained for this cluster. Although NGC 6752 is a high-density cluster with a large binary population, we found that its BSS content is surprisingly low: the specific number of BSSs is among the lowest ever measured in a cluster. The BSS distribution is highly peaked in the cluster center, shows a rapid decrease at intermediate radii, and rises again at larger distances. This distribution closely resembles those observed in M3 and 47 Tuc by Ferraro and coworkers. To date, BSS surveys covering the central regions with HST and the outer regions with wide-field CCD ground-based observations have been performed for only these three clusters. Despite the different dynamical properties, a bimodal radial distribution has been found in each. A detailed comparison of observed BSS luminosity and temperature distributions with theoretical models reveals a population of luminous, hot BSSs that is not easily interpreted.
Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS5-26555. Also based on Wide Field Imager observations collected at the European Southern Observatory, La Silla, Chile, within the observing program 62.L-0354 and 64.L-0439.- Publication:
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The Astrophysical Journal
- Pub Date:
- December 2004
- DOI:
- 10.1086/425492
- arXiv:
- arXiv:astro-ph/0409001
- Bibcode:
- 2004ApJ...617.1296S
- Keywords:
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- Stars: Binaries: Close;
- Stars: Blue Stragglers;
- Galaxy: Globular Clusters: Individual: NGC Number: NGC 6752;
- Stars: Evolution;
- Astrophysics
- E-Print:
- 29 pages, 10 figures, in press on ApJ