Star Clusters in the Nearby Late-Type Galaxy NGC 1311
de Grijs, Richard; Windhorst, Rogier A.; Eskridge, Paul B.; Jansen, Rolf A.; Mager, Violet A.; Anders, Peter
United States, United Kingdom, China, Netherlands
Abstract
Ultraviolet, optical and near-infrared images of the nearby (D ≈ 5.5 Mpc) SBm galaxy NGC 1311, obtained with the Hubble Space Telescope, reveal a small population of 13 candidate star clusters. We identify candidate star clusters based on a combination of their luminosity, extent, and spectral energy distribution. The masses of the cluster candidates range from ~103 Msun up to ~105 Msun, and show a strong positive trend of larger mass with increasing with cluster age. Such a trend follows from the fading and dissolution of old, low-mass clusters, and the lack of any young super-star clusters of the sort often formed in strong starbursts. The cluster age distribution is consistent with a bursting mode of cluster formation, with active episodes of age ~10 Myr, ~100 Myr, and {\ga}1 Gyr. The ranges of age and mass we probe are consistent with those of the star clusters found in quiescent Local Group dwarf galaxies.
Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract no. NAS5-26555.