Bulletin of the Korean Space Science Society (한국우주과학회:학술대회논문집(한국우주과학회보))

The Korean Space Science Society (한국우주과학회)
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Star Formation Histories of the Globular Clusters with Multiple Stellar Populations

  • Joo, Seok-Joo (Center for Space Astrophysics and Department of Astronomy, Yonsei University) ;
  • Lee, Young-Wook (Center for Space Astrophysics and Department of Astronomy, Yonsei University) ;
  • Yoon, Suk-Jin (Center for Space Astrophysics and Department of Astronomy, Yonsei University) ;
  • Han, Sang-Il (Center for Space Astrophysics and Department of Astronomy, Yonsei University)
  • Published : 2009.10.15
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Abstract

Recent observations for the Galactic globular clusters (GCs) have shown that a number of GCs have characteristic features of multiple stellar populations, such as multiple main-sequences (MSs), splits in sub-giant branch (SGB), bimodal and/or extended horizontal branches (HBs). Based on the population synthesis models, we investigate star formation histories of the GCs with multiple populations, $\omega$ Cen, M54, NGC 1851, NGC 6388, NGC 6441, and NGC 2808, by comparing synthetic model color-magnitude diagrams (CMDs) with observations. We adopt most up-to-date Yonsei-Yale (Y2) stellar evolutionary tracks and isochrones from MS to post-HB, as well as improved color-temperature transformations from the recent stellar atmosphere libraries. Our models show that the observed features can be naturally explained by assuming the presence of helium-enhanced subpopulations.

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