천문학회보 (The Bulletin of The Korean Astronomical Society)
- 제36권2호
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- Pages.67.1-67.1
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- 2011
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- 1226-2692(pISSN)
THE EFFECT OF HELIUM-ENHANCED STELLAR POPULATIONS ON THE ULTRAVIOLET-UPTURN PHENOMENON OF EARLY-TYPE GALAXIES
- Chung, Chul (Department of Astronomy, Yonsei University) ;
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Yoon, Suk-Jin
(Department of Astronomy, Yonsei University) ;
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Lee, Young-Wook
(Department of Astronomy, Yonsei University)
- 발행 : 2011.10.05
초록
Recent observations and modeling of globular clusters with multiple populations strongly indicate the presence of super helium-rich subpopulations in old stellar systems. Motivated by this, we have constructed new population synthesis models with and without helium-enhanced subpopulations to investigate their impact on the UV-upturn phenomenon of quiescent early-type galaxies. We find that our models with helium-enhanced subpopulations can naturally reproduce the strong UV-upturns observed in giant elliptical galaxies assuming an age similar to that of old globular clusters in the Milky Way. The major source of far-UV (FUV) flux, in this model, is relatively metal-poor and helium-enhanced hot horizontal branch stars and their progeny. The Burstein et al. (1988) relation of the FUV - V color with metallicity is also explained either by the variation of the fraction of helium-enhanced subpopulations or by the spread in mean age of stellar populations in early-type galaxies.
키워드