Is Draco II one of the faintest dwarf galaxies? First study from Keck/DEIMOS spectroscopy

Nicolas F. Martin, Marla Geha, Rodrigo A. Ibata, Michelle L. M. Collins, Benjamin P. M. Laevens, Eric F. Bell, Hans-Walter Rix, Annette M. N. Ferguson, Kenneth C. Chambers, Richard J. Wainscoat, Christopher Waters

Research output: Contribution to journalArticlepeer-review

Abstract

We present the first spectroscopic analysis of the faint and compact stellar system Draco II (Dra II, MV = -2.9 ± 0.8, r_h=19^{+8}_{-6} pc), recently discovered in the Panoramic Survey Telescope and Rapid Response System 1 3π survey. The observations, conducted with DEIMOS on the Keck II telescope, establish some of its basic characteristics: the velocity data reveal a narrow peak with nine member stars at a systemic heliocentric velocity <v_rrangle =-347.6^{+1.7}_{-1.8} km s^{-1}, thereby confirming Dra II is a satellite of the Milky Way; we infer a velocity dispersion with σvr = 2.9 ± 2.1 km s-1 (
Original languageEnglish
JournalMonthly Notices of the Royal Astronomical Society: Letters
Volume458
Issue number1
DOIs
Publication statusPublished - 1 May 2016

Keywords

  • galaxies: individual: Draco II
  • galaxies: kinematics and dynamics
  • Local Group

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