Perseus I: A Distant Satellite Dwarf Galaxy of Andromeda

Nicolas F. Martin, Edward F. Schlafly, Colin T. Slater, Edouard J. Bernard, Hans-Walter Rix, Eric F. Bell, Annette M. N. Ferguson, Douglas P. Finkbeiner, Benjamin P. M. Laevens, William S. Burgett, Kenneth C. Chambers, Peter W. Draper, Klaus W. Hodapp, Nicholas Kaiser, Rolf-Peter Kudritzki, Eugene A. Magnier, Nigel Metcalfe, Jeffrey S. Morgan, Paul A. Price, John L. TonryRichard J. Wainscoat, Christopher Waters

Research output: Contribution to journalArticlepeer-review


We present the discovery of a new dwarf galaxy, Perseus I/Andromeda XXXIII, found in the vicinity of Andromeda (M31) in stacked imaging data from the Pan-STARRS1 3π survey. Located 27.°9 away from M31, Perseus I has a heliocentric distance of 785 ± 65 kpc, compatible with it being a satellite of M31 at 374^{+14}_{-10}\,kpc from its host. The properties of Perseus I are typical for a reasonably bright dwarf galaxy (MV = -10.3 ± 0.7), with an exponential half-light radius of rh = 1.7 ± 0.4 arcmin or r_h = 400^{+105}_{-85}\,pc at this distance, and a moderate ellipticity (\epsilon = 0.43^{+0.15}_{-0.17}). The late discovery of Perseus I is due to its fairly low surface brightness (\mu _0=25.7^{+1.0}_{-0.9} mag arcsec-2), and to the previous lack of deep, high quality photometric data in this region. If confirmed to be a companion of M31, the location of Perseus I, far east from its host, could place interesting constraints on the bulk motion of the satellite system of M31.
Original languageEnglish
JournalAstrophysical Journal Letters
Publication statusPublished - 1 Dec 2013


  • galaxies: individual: Perseus I Andromeda XXXIII
  • Local Group


Dive into the research topics of 'Perseus I: A Distant Satellite Dwarf Galaxy of Andromeda'. Together they form a unique fingerprint.

Cite this