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Title: SPECTROSCOPY OF THE THREE DISTANT ANDROMEDAN SATELLITES CASSIOPEIA III, LACERTA I, AND PERSEUS I

We present Keck II/DEIMOS spectroscopy of the three distant dwarf galaxies of M31 Lacerta I, Cassiopeia III, and Perseus I, recently discovered within the Pan-STARRS1 3π imaging survey. The systemic velocities of the three systems (v {sub r,} {sub helio} = –198.4 ± 1.1 km s{sup –1}, –371.6 ± 0.7 km s{sup –1}, and –326 ± 3 km s{sup –1}, respectively) confirm that they are satellites of M31. In the case of Lacerta I and Cassiopeia III, the high quality of the data obtained for 126 and 212 member stars, respectively, yields reliable constraints on their global velocity dispersions (σ{sub vr} = 10.3 ± 0.9 km s{sup –1} and 8.4 ± 0.6 km s{sup –1}, respectively), leading to dynamical-mass estimates for both of ∼4 × 10{sup 7} M {sub ☉} within their half-light radius. These translate to V-band mass-to-light ratios of 15{sub −9}{sup +12} and 8{sub −5}{sup +9} in solar units. We also use our spectroscopic data to determine the average metallicity of the three dwarf galaxies ([Fe/H] = –2.0 ± 0.1, –1.7 ± 0.1, and –2.0 ± 0.2, respectively). All these properties are typical of dwarf galaxy satellites of Andromeda with their luminosity and size.
Authors:
;  [1] ; ; ; ; ; ;  [2] ;  [3] ;  [4] ;  [5] ; ;  [6]
  1. Observatoire Astronomique de Strasbourg, Université de Strasbourg, CNRS, UMR 7550, 11 Rue de l'Université, F-67000 Strasbourg (France)
  2. Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822 (United States)
  3. Max-Planck-Institut für Astronomie, Königstuhl 17, D-69117 Heidelberg (Germany)
  4. Department of Physics and Astronomy, University of California, Los Angeles, CA 90095-1547 (United States)
  5. Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)
  6. Institute for Astronomy, University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom)
Publication Date:
OSTI Identifier:
22364979
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal Letters; Journal Volume: 793; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; EMISSION SPECTROSCOPY; GALAXIES; HYDROGEN; IRON; LIMITING VALUES; LUMINOSITY; MASS; METALLICITY; STARS; VISIBLE RADIATION