AAS Meeting #193 - Austin, Texas, January 1999
Session 60. Star Clusters in Galaxies
Oral, Thursday, January 7, 1999, 2:00-3:30pm, Room 9 (C)

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[60.05D] Star Clusters in Local Group Galaxies: M33

R. Chandar (JHU)

We have compiled the first unbiased, representative sample of star clusters in M33 from HST WFPC2 multiband images of twenty fields in this galaxy. The HST spatial resolution allowed us to penetrate the crowded, spiral arm regions of M33. The fields sample a variety of environments, from outer regions to spiral arms and central regions, as well as a range of galactocentric distances. We found 60 clusters in our fields, and measured integrated photometric properties and surface brightness profiles. By comparing the integrated photometry with evolutionary models and theoretical M/LV ratios, we find that the clusters formed continuously in M33 from ~4\times106 - 1010 years, and have masses between ~4\times102M\odot - 3\times105M\odot. There is a correlation between the ages and masses of our clusters, the oldest objects being the most massive. Clusters at all ages are found to have well relaxed density profiles which are reasonably well fit by King profiles. Core radii are smaller on average than those of Galactic globular clusters and LMC populous clusters at similar magnitudes.

In October we obtained WIYN HYDRA spectra of ~150 clusters in M33 at a dispersion of 1.6Å~pix-1, covering the wavelength range 3900-6600Å. Preliminary results of these cluster spectra will also be presented.

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