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A new set of very high signal-to-noise (S/N > 100/1), medium-resolution(R~3000) optical spectra have been obtained for 302 of the candidate"weak-metal" stars selected by Bidelman & MacConnell. We use these data tocalibrate the recently developed generalization of the SEGUE Stellar ParameterPipeline, and obtain estimates of the atmospheric parameters (Teff, log g , and[Fe/H]) for these non-SDSS/SEGUE data; we also obtain estimates of [C/Fe]. Thenew abundance measurements are shown to be consistent with availablehigh-resolution spectroscopic determinations, and represent a substantialimprovement over the accuracies obtained from the previous photometricestimates reported in Paper I of this series. The apparent offset in thephotometric abundances of the giants in this sample noted by several authors isconfirmed by our new spectroscopy; no such effect is found for the dwarfs. Thepresence of a metal-weak thick-disk (MWTD) population is clearly supported bythese new abundance data. Some 25% of the stars with metallicities -1.8 <[Fe/H] <= -0.8 exhibit orbital eccentricities e < 0.4, yet are clearlyseparated from members of the inner-halo population with similar metallicitiesby their location in a Lindblad energy vs. angular momentum diagram. Acomparison is made with recent results for a similar-size sample of RAVE starsfrom Ruchti et al. We conclude, based on both of these samples, that the MWTDis real, and must be accounted for in discussions of the formation andevolution of the disk system of the Milky Way.

astrophysical journal/the astrophysical journal

Population Studies. XIII. A New Analysis of the Bidelman-MacConnell  "Weak-Metal" Stars - Confirmation of Metal-Poor Stars in the Thick Disk of  the Galaxy