2015/04/27 by Lesley A. Simanton, Rupali Chandar, Bradley C. Whitmore · 11 citations
Physics and Astronomy · #Astronomy and Astrophysical Research #Cluster (spacecraft) #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy cluster #Globular cluster #Luminosity #Luminosity function #Milky Way #Spiral galaxy #Star cluster #Stellar, planetary, and galactic studies #astro-ph.GA
paper · pdf · doi:10.1088/0004-637x/805/2/160
published in The Astrophysical Journal 805(2), 160 (IOP Publishing) · 12 pages, 15 figures; Accepted to ApJ; Introductory level video description of the paper available at https://www.youtube.com/watch?v=SydJJq6cMMo
arxiv created 2015/04/27 · openalex publication_date 2015/05/29 · arxiv updated 2015/06/03 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/06
We present a new photometric catalog of 326 candidate globular clusters (GCs) in the nearby spiral galaxy M101, selected from B , V , and I Hubble Space Telescope Advanced Camera for Surveys images. The luminosity function (LF) of these clusters has an unusually large number of faint sources compared with GCLFs in many other spiral galaxies. Accordingly, we separate and compare the properties of "bright" ( ) versus "faint" ( ; one magnitude fainter than the expected GC peak) clusters within our sample. The LF of the bright clusters is well fit by a peaked distribution similar to those observed in the Milky Way (MW) and other galaxies. These bright clusters also have similar size ( r eff ) and spatial distributions as MW GCs. The LF of the faint clusters, on the other hand, is well described by a power law, with , similar to those observed for young and intermediate-age cluster systems in star forming galaxies. We find that the faint clusters have larger typical r eff than the bright clusters, and have a flatter surface density profile, being more evenly distributed, as we would expect for clusters associated with the disk. We use the shape of the LF and predictions for mass-loss driven by two-body relaxation to constrain the ages of the faint clusters. Our results are consistent with two populations of old star clusters in M101: a bright population of halo clusters and a fainter, possibly younger, population of old disk clusters.