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

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

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 $30_{-2}^{+2}\;{\rm kpc}$, and a half-mass–radius of $34_{-8}^{+9}\;{\rm pc}$, 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
Article number18
Number of pages6
JournalAstrophysical Journal Letters
Volume802
Issue number2
DOIs
Publication statusPublished - May 2015

Keywords

  • galaxies: dwarf
  • Galaxy: structure
  • globular clusters: general
  • Local Group
  • EXPLORING HALO SUBSTRUCTURE
  • DIGITAL SKY SURVEY
  • DWARF GALAXIES
  • TRIANGULUM-ANDROMEDA
  • SPECTROSCOPIC SURVEY
  • GALACTIC SATELLITES
  • GLOBULAR-CLUSTER
  • STELLAR STREAM
  • CALIBRATION

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