IDENTIFYING CONTRIBUTIONS TO THE STELLAR HALO FROM ACCRETED, KICKED-OUT, AND IN SITU POPULATIONS

We present a medium-resolution spectroscopic survey of late-type giant stars at mid-Galactic latitudes of (30[degrees] < |b| < 60[degrees]), designed to probe the properties of this population to distances of ~9 kpc. The distribution of radial velocity (RV) as a function of I for these stars shows (1) the expected thick disk population and (2) local metal-rich halo stars moving at high speeds relative to the disk, which in some cases form distinct sequences in RV-I space. These results are consistent with scenarios where the stellar halo, at least as probed by M giants, arises from multiple formation mechanisms; however, when taken at face value, our results for metal-rich halo giants suggest a much higher proportion to be accreted than found by Carollo et al. and more like the fraction suggested in the analysis by Nissen & Schuster and Schuster et al.