A new faint milky way satellite discovered in the Pan-STARRS1 3π Survey

Benjamin P.M. Laevens, Nicolas F. Martin, Rodrigo A. Ibata, Hans Walter Rix, Edouard J. Bernard, Eric F. Bell, Branimir Sesar, Annette M.N. Ferguson, Edward F. Schlafly, Colin T. Slater, William S. Burgett, Kenneth C. Chambers, Heather Flewelling, Klaus A. Hodapp, Nicholas Kaiser, Rolf Peter Kudritzki, Robert H. Lupton, Eugene A. Magnier, Nigel Metcalfe, Jeffrey S. MorganPaul A. Price, John L. Tonry, Richard J. Wainscoat, Christopher Waters

Research output: Contribution to journalArticlepeer-review

145 Scopus citations


We present the discovery of a faint Milky Way satellite, Laevens 2/Triangulum II, found in the Panoramic Survey Telescope And Rapid Response System 3π imaging data and confirmed with follow-up wide-field photometry from the Large Binocular Cameras. The stellar system, with an absolute magnitude of MV = -1.8 ± 0.5, a heliocentric distance of 30-2+2 kpc, and a half-mass - radius of 34-8+9 pc, shows remarkable similarity to faint, nearby, small satellites such as Willman 1, Segue 1, Segue 2, and Boötes II. The discovery of Laevens 2/Triangulum II further populates the region of parameter space for which the boundary between dwarf galaxies and globular clusters becomes tenuous. Follow-up spectroscopy will ultimately determine the nature of this new satellite, whose spatial location hints at a possible connection with the complex Triangulum - Andromeda stellar structures.

Original languageEnglish (US)
Article numberL18
JournalAstrophysical Journal Letters
Issue number2
StatePublished - Apr 1 2015

All Science Journal Classification (ASJC) codes

  • Astronomy and Astrophysics
  • Space and Planetary Science


  • Galaxies: dwarf
  • Galaxy: structure
  • Globular clusters: general
  • Local group


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