Journal of The Korean Astronomical Society (천문학회지)

The Korean Astronomical Society (한국천문학회)
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SPATIAL DISTRIBUTION OF STARS AROUND SIX METAL-POOR GLOBULAR CLUSTERS IN THE GALACTIC BULGE

  • Chang, Cho-Rhong (Department of Astronomy, Yonsei University) ;
  • Kim, Jae-Woo (Center for the Exploration of the Origin of the Universe (CEOU), Department of Physics and Astronomy, Seoul National University) ;
  • Matsunaga, Noriyuki (Kiso Observatory, Institute of Astronomy, the University of Tokyo) ;
  • Han, Mihwa (Department of Astronomy, Yonsei University) ;
  • Ko, Jongwan (Korea Astronomy and Space Science Institute) ;
  • Chun, Sang-Hyun (Yonsei University Observatory) ;
  • Kang, Minhee (Department of Astronomy, Yonsei University) ;
  • Sohn, Young-Jong (Department of Astronomy, Yonsei University)
  • Received : 2013.09.18
  • Accepted : 2013.10.30
  • Published : 2013.12.31
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Abstract

Wide-field $JHK_s$ images obtained with the SIRIUS near-infrared camera of the IRSF 1.4m telescope are used to examine the tidal structures of the spatial stellar configuration around six metal-poor ([Fe/H]< -1.0) globular clusters located within 3 kpc from the Galactic center. The radial surface density profiles are obtained from the surface photometry of the cluster images and the star counting for the photometric data. For the star counting, candidates of cluster member stars are selected with an filtering algorithm in color-magnitude diagrams. We find that the six target clusters show tidal overdensity features in the radial surface density profiles. There is a break inside the tidal radius for each cluster, and the profile in the outer overdensity region is characterized by a power law. Two-dimensional density maps of all the clusters show distorted asymmetric stellar configurations in the outer region. In five out of the six target clusters, the overdensity features are likely to be associated with the effects of the Galaxy dynamical interaction and the cluster space motions. The observed tidal configurations of stars suggest that several metal-poor clusters in the Galactic bulge are possibly surviving remnants of mergers to build the old stellar system of the Galactic bulge.

Keywords

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