Description
We present Keck/DEIMOS spectroscopy and Canada-France-Hawaii Telescope/MegaCam photometry for the Milky Way globular cluster Palomar 13. We triple the number of spectroscopically confirmed members, including many repeat velocity measurements. Palomar 13 is the only known globular cluster with possible evidence for dark matter, based on a Keck/High Resolution Echelle Spectrometer 21 star velocity dispersion of {sigma}=2.2+/-0.4km/s. We reproduce this measurement, but demonstrate that it is inflated by unresolved binary stars. For our sample of 61 stars, the velocity dispersion is {sigma}=0.7^+0.6^_-0.5_km/s. Combining our DEIMOS data with literature values, our final velocity dispersion is {sigma}=0.4^+0.4^_-0.3_km/s. We determine a spectroscopic metallicity of [Fe/H]=-1.6+/-0.1 dex, placing a 1{sigma} upper limit of {sigma}_[Fe/H]_~0.2dex on any internal metallicity spread. We determine Palomar 13's total luminosity to be M_V_=-2.8+/-0.4, making it among the least luminous known globular clusters.
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