Journal of The Korean Astronomical Society (천문학회지)

The Korean Astronomical Society (한국천문학회)
권호 표지

VELOCITY ANALYSIS OF M13 BY MAXIMUM LIKELIHOOD METHOD

  • Oh, K.S. (Department of Astronomy and Space Science, Chungnam National University) ;
  • Lin, D. N. C. (Institute of Astronomy, University of Cambridge, England and University of California Observatories/Lick Observatory, Board of Studies in Astronomy and Astrophysics, University of California)
  • Published : 1992.06.30
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Abstract

We present new approach to analysis of velocity data of globular clusters. Maximum likelihood method is applied to get model parameters such as central potential, anisotropy radius, and total mass fractions in each mass class. This method can avoid problems in conventional binning method of chi-square. We utilize three velocity components, one from line of sight radial velocity and two from proper motion data. In our simplified scheme we adopt 3 mass-component model with unseen high mass stars, intermediate visible stars, and low mass dark remnants. Likelihood values are obtained for 124 stars in M13 for various model parameters. Our preferred model shows central potential of $W_o=7$ and anisotropy radius with 7 core radius. And it suggests non-negligible amount of unseen high mass stars and considerable amount of dark remnants in M13.

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