SED, Metallicity and Age of Halo Globular Clusters in M33

Jun Ma, Xu Zhou, Jiansheng Chen, Hong Wu, Zhaoji Jiang, Suijian Xue, Jin Zhu

Published 2002-01-28Version 1

In this paper we study the properties of ten halo globular clusters in the nearby spiral galaxy M33. CCD images of M33 were obtained as a part of the BATC Colour Survey of the sky in 13 intermediate-band filters from 3800 to 10000{\AA}. By aperture photometry, we obtain the spectral energy distributions (SEDs) of these globular clusters. We estimate the ages of our sample clusters by comparing the photometry of each object with theoretical stellar population synthesis models for different values of metallicity. Our results suggest that eight of the ten sample halo globular clusters have ``intermediate'' ages, i.e. between 1 and 8 Gyrs.