Journal of The Korean Astronomical Society (천문학회지)
- Volume 29 Issue spc1
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- Pages.49-51
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- 1996
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- 1225-4614(pISSN)
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- 2288-890X(eISSN)
AGES OF ELLIPTICAL GALAXIES FROM POPULATION SYNTHESIS MODELS
- LEE YOUNG-WOOK (Astronomy Program, Yonsei University) ;
- PARK JANG-HYUN (Korea Astronomy Observatoryi)
- Published : 1996.12.01
Abstract
New population synthesis models, with the effects of metallicity spread and the horizontal-branch (HB) morphology, provide a way to break the well-known age-metallicity degeneracy in the analysis of the integrated light of elliptical galaxies. Our models suggest that the far- UV radiation of these systems is dominated by a minority population of metal-poor, hot HB stars and their post-HB progeny, while the optical radiation is dominated by a metal-rich population. The systematic variation of UV upturn depends on the contribution from metal-poor, hot HB stars and their post-HB progeny, which in turn depends on the ages of old stellar populations in galaxies. Our result implies a prolonged epoch of galaxy formation, in the sense that more massive galaxies (in denser environments) formed first. Our models also suggest that the strenghth of H