2001PASP..113.1122S

Spectra for stars located redward of the fiducial red giant branches (RGBs) of the Ursa Minor and Draco dwarf spheroidal galaxies have been obtained with the Hobby-Eberly telescope and the Marcario Low Resolution Spectrometer. From a comparison of our radial velocities with those reported in previous medium-resolution studies, we find an average difference of 10 km.s^–1 with a standard deviation of 11 km.s^–1. On the basis of these radial velocities, we confirm the membership of five stars in Ursa Minor and find two others to be nonmembers. One of the confirmed members is a known carbon star that lies redward of the RGB; three others are previously unidentified carbon stars. The fifth star is a red giant that was found previously by Shetrone and coworkers to have [Fe/H]=-1.68±0.11 dex. In Draco, we find eight nonmembers, confirm the membership of one known carbon star, and find two new members. One of these stars is a carbon star, while the other shows no evidence for C₂ bands or strong atomic bands, although the signal-to-noise ratio of the spectrum is low. Thus, we find no evidence for a population of stars more metal-rich than [Fe/H]≃-1.45 dex in either of these galaxies. Indeed, our spectroscopic survey suggests that every candidate suspected of having a metallicity in excess of this value based on its position in the color-magnitude diagram is, in actuality, a carbon star. Based on the census of 13 known carbon stars in these two galaxies, we estimate the carbon star specific frequency to be ε_dSph≃2.4x10^–5 L^–1_V,☉, 25-100 times higher than that of Galactic globular clusters.