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 \arcmin ) and have velocity dispersion 2.4 _ { -1.4 } ^ { +2.4 } km s ^ { -1 } .
The other two likely members lie near each other but far from the center ( R \sim 13 \arcmin \sim 700 pc ) and inflate the global velocity dispersion to 3.7 _ { -1.4 } ^ { +2.3 } km s ^ { -1 } .
Assuming the five central members are bound , we obtain a dynamical mass of M = 3.3 _ { -2.5 } ^ { +9.1 } \times 10 ^ { 5 } M _ { \odot } ( M / L _ { V } = 75 _ { -58 } ^ { +230 } [ M / L _ { V } ] _ { \odot } ) .
From the stacked spectrum of the five central members we estimate a mean metallicity of [ Fe/H ] = -2.0 \pm 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 \sim 180 kpc ) is difficult to reconcile with MW tidal stripping unless the orbit is very radial .