Discovery and analysis of three faint dwarf galaxies and a globular cluster in the outer halo of the Andromeda galaxy

N. F. Martin, R. A. Ibata, M. J. Irwin, S. Chapman, G. F. Lewis, A. M. N. Ferguson, N. Tanvir, A. W. McConnachie

Research output: Contribution to journalArticlepeer-review

Abstract

We present the discovery of three faint dwarf galaxies and a globular cluster in the halo of the Andromeda galaxy (M31), found in our MegaCam survey that spans the southern quadrant of M31, from a projected distance of ~50 to ~150kpc. Though the survey covers 57 deg2, the four satellites lie within 2° of one another. From the tip of the red giant branch (RGB), we estimate that the globular cluster lies at a distance of 631 +/- 58kpc from the Milky Way and along with a ~100kpc projected distance from M31 we derive a total distance of 175 +/- 55kpc from its host, making it the farthest M31 globular cluster known. It also shows the typical characteristics of a bright globular cluster, with a half-light radius of 2.3 +/- 0.2pc and an absolute magnitude in the V band of MV,0 = -8.5 +/- 0.3. Isochrone fitting reveals that it is dominated by a very old population with a metallicity of [Fe/H] ~ -1.3. The three dwarf galaxies are revealed as overdensities of stars that are aligned along the RGB tracks in their colour-magnitude diagrams. These satellites are all very faint, with absolute magnitudes in the range -7.3
Original languageEnglish
Pages (from-to)1983-1991
JournalMonthly Notices of the Royal Astronomical Society
Volume371
Issue number4
DOIs
Publication statusPublished - 1 Oct 2006

Keywords

  • galaxies: dwarf: galaxies: formation: galaxies: individual: And XI: galaxies: individual: And XII: galaxies: individual: And XIII: galaxies: structure
  • galaxies: dwarf
  • galaxies: formation
  • galaxies: individual: And XI
  • galaxies: individual: And XII
  • galaxies: individual: And XIII
  • galaxies: structure

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