EDP Sciences
Free access
Volume 413, Number 2, January II 2004
Page(s) 563 - 570
Section Stellar clusters and associations
DOI http://dx.doi.org/10.1051/0004-6361:20031556

A&A 413, 563-570 (2004)
DOI: 10.1051/0004-6361:20031556

Metallicity estimates for old star clusters in M 33

Jun Ma, Xu Zhou and Jiansheng Chen

National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, PR China
(Received 18 February 2003 / Accepted 7 August 2003)

Using the theoretical stellar population synthesis models of BC96, Kong et al. (2003) showed that some BATC colors and color indices could be used to disentangle the age and metallicity effect. They found that there is a very good relation between the flux ratio of L8510/L9170 and the metallicity for stellar populations older than 1 Gyr. In this paper, based on the Kong et al. results and on the multicolor spectrophotometry of Ma et al. (2001, 2002a,b,c), we estimate the metallicities of 31 old star clusters in the nearby spiral galaxy M 33, 23 of which are "true" globular clusters. The results show that most of these old clusters are metal poor. We also find that the ages and metal abundance for these old star clusters of M 33 do not vary with deprojected radial position.

Key words: galaxies: individual: M 33 -- galaxies: evolution -- galaxies: star clusters

Offprint request: Jun Ma, majun@vega.bac.pku.edu.cn

SIMBAD Objects in preparation

© ESO 2004