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Astron. Astrophys. 335, 573-582 (1998)

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On some properties of very metal-rich stars

N. Mowlavi 1, G. Meynet 1, A. Maeder 1, D. Schaerer 2 and C. Charbonnel 3

1 Geneva Observatory, CH-1290 Sauverny, Switzerland
2 Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
3 Laboratoire d'Astrophysique de Toulouse, CNRS - UMR 5572, 14 av. E. Belin, F-31400 Toulouse, France

Received 30 September 1997 / Accepted 6 April 1998

Abstract

An analysis of some properties of stellar models as a function of metallicity Z (and helium content Y) is presented, with special attention to those stars with metallicities higher than twice or three times solar.

It is shown that the stellar properties as a function of Z are mainly determined by the effects of the opacities at sub-solar metallicities, and by the effects of the mean molecular weight and stellar mass loss at higher metallicities. As a result, very metal-rich stars ([FORMULA]) exhibit properties that deviate from what is expected from the known characteristics at lower metallicities. In particular, they are more luminous and hotter than those at [FORMULA] due to the effect of the mean molecular weight. They have main sequence lifetimes much shorter (60% shorter at [FORMULA] than at [FORMULA]) than those at solar metallicity due to their lower initial hydrogen content. Finally, the high mass loss rates at high metallicities affect significantly the population synthesis of massive stars in very metal-rich regions. An analysis of expected Wolf-Rayet and supernovae populations in such conditions is briefly presented.

Key words: stars: evolution – stars: general – stars: Hertzsprung-Russell(HR) diagram – Galaxy: center – stars: Wolf-Rayet

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© European Southern Observatory (ESO) 1998

Online publication: June 18, 1998
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