Star Clusters in the Nearby Late - Type Galaxy NGC 1311 1 Paul

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 ∼10 up to ∼10 M⊙, 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 &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. Department of Physics and Astronomy, Minnesota State University, Mankato, MN 56001 Department of Physics and Astronomy, University of Sheffield, Sheffield S3 7RH, United Kingdom National Astronomical Observatories, Chinese Academy of Sciences, Beijing, P.R. China Sterrenkundig Instituut, Universiteit Utrecht, NL-3508 TA Utrecht, The Netherlands School of Earth & Space Exploration, Arizona State University, Tempe, AZ 85287 Department of Physics and Astronomy, Arizona State University, Tempe, AZ 85287 Observatories of the Carnegie Institution of Washington, Pasadena, CA 91101