LEO V: Spectroscopy of a distant and disturbed satellite

M. G. Walker, V. Belokurov, N. W. Evans, M. J. Irwin, M. Mateo, Edward W Olszewski, G. Gilmore

Research output: Contribution to journalArticle

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Abstract

We present a spectroscopic study of Leo V, a recently discovered satellite of the Milky Way (MW). From stellar spectra obtained with the MMT/Hectochelle spectrograph we identify seven likely members of Leo V. Five cluster near the Leo V center (R < 3′) and have a velocity dispersion of 2.4 +2.4 -1.4 km s-1. The other two likely members lie near each other but far from the center (R 13′ 700 pc) and inflate the global velocity dispersion to 3.7+2.3 -1.4 km s -1. Assuming the five central members are bound, we obtain a dynamical mass of M = 3.3+9.1 -2.5 × 105 M (M/LV = 75+230 -58[M/LV ]). From the stacked spectrum of the five central members we estimate a mean metallicity of [Fe/H]=-2.0 0.2 dex. Thus, with respect to dwarf spheroidals of similar luminosity, Leo V is slightly less massive and slightly more metal rich. Since we resolve the central velocity dispersion only marginally, we do not rule out the possibility that Leo V is a diffuse star cluster devoid of dark matter. The wide separation of its two outer members implies Leo V is losing mass; however, its large distance (D 180 kpc) is difficult to reconcile with MW tidal stripping unless the orbit is very radial.

Original languageEnglish (US)
JournalAstrophysical Journal
Volume694
Issue number2
DOIs
StatePublished - 2009

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low Earth orbits
spectroscopy
stellar spectra
star clusters
stripping
spectrographs
metallicity
dark matter
luminosity
orbits
metal
estimates
metals

Keywords

  • Dark matter
  • Galaxies: dwarf
  • Galaxies: kinematics and dynamics
  • Local Group

ASJC Scopus subject areas

  • Space and Planetary Science
  • Astronomy and Astrophysics

Cite this

Walker, M. G., Belokurov, V., Evans, N. W., Irwin, M. J., Mateo, M., Olszewski, E. W., & Gilmore, G. (2009). LEO V: Spectroscopy of a distant and disturbed satellite. Astrophysical Journal, 694(2). https://doi.org/10.1088/0004-637X/694/2/L144

LEO V : Spectroscopy of a distant and disturbed satellite. / Walker, M. G.; Belokurov, V.; Evans, N. W.; Irwin, M. J.; Mateo, M.; Olszewski, Edward W; Gilmore, G.

In: Astrophysical Journal, Vol. 694, No. 2, 2009.

Research output: Contribution to journalArticle

Walker, MG, Belokurov, V, Evans, NW, Irwin, MJ, Mateo, M, Olszewski, EW & Gilmore, G 2009, 'LEO V: Spectroscopy of a distant and disturbed satellite', Astrophysical Journal, vol. 694, no. 2. https://doi.org/10.1088/0004-637X/694/2/L144
Walker, M. G. ; Belokurov, V. ; Evans, N. W. ; Irwin, M. J. ; Mateo, M. ; Olszewski, Edward W ; Gilmore, G. / LEO V : Spectroscopy of a distant and disturbed satellite. In: Astrophysical Journal. 2009 ; Vol. 694, No. 2.
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