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The Unique Properties of omega Centauri Seen Through Stroemgren Eyes

M. Hilker·T. Richtler
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Abstract

A revised metallicity calibration of the Stroemgren (b-y),m_1 diagram, based on a sample of globular cluster and field red giant stars, is presented. This new calibration has been used to determine Stroemgren metallicities ([Fe/H]_phot) for more than 1400 red giants in omega Centauri. Most of the stars belong to a metal poor ([Fe/H]_phot = -1.7 dex), old population. A second more metal rich ([Fe/H]_phot = -0.9 dex) population is found to be about 3 Gyr younger and more centrally concentrated than the old one. The CN-rich stars do not seem to follow the radial distribution of the metal rich population.

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M. Hilker, T. Richtler. 1999-10-20. The Unique Properties of omega Centauri Seen Through Stroemgren Eyes. https://arxiv.org/abs/astro-ph/9910370

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