VLT Spectroscopy of Ultra-faint Dwarf Galaxies

We perform consistent reductions and measurements for three ultra-faint dwarf galaxies (UFDs): Bootes I, Leo IV, and Leo V. Using the public archival data from the GIRAFFE spectrograph on the Very Large Telescope (VLT), we locate new members and provide refined measurements of physical parameters for these dwarf galaxies. We identify nine new Leo IV members and four new Leo V members, and perform a comparative analysis of previously discovered members.

Additionally, we identify one new binary star in both Leo IV and Leo V. After removing binary stars, we recalculate the velocity dispersions of Bootes I and Leo IV to be 5.1_-0.8_^+0.7^ and 3.4_-0.9_^+1.3^km/s, respectively; we do not resolve the Leo V velocity dispersion. We identify a weak velocity gradient in Leo V that is ~4x smaller than the previously calculated gradient and that has a corresponding position angle that differs from the value in the literature by ~120{deg}.