Stars, Star Clusters, and Dust in NGC 3077

Abstract

Images obtained with the CFHTIR camera on the Canada-France-Hawaii Telescope are used to investigate the near-infrared photometric properties of the star-forming M81 group galaxy NGC 3077. The spectral-energy distribution (SED) of the near-infrared light within 10 arcsec of the nucleus is consistent with the 2um light being dominated by hot young (log(t_{yr}) < 6.8) stars reddened by A_V = 3 - 4, with A_V < 8 mag in some regions. A population like that near the center of NGC 205 likely contributes only a modest fraction of the light near 2um. A number of candidate star clusters are detected in and around NGC 3077. The specific frequency of globular clusters falls within the range measured in nearby dEs. The candidate young clusters have photometric masses that are similar to those of compact young clusters in other active star-forming systems, and SEDs consistent with ages log(t_{yr}) < 6.6. Based on the masses and ages of the young clusters, it is estimated that the star formation rate in NGC 3077 was at least 0.25 - 0.50 solar masses per year during the past few million years.