We present Fe , Si , and Ca abundances for 61 giants in Plaut ’ s Window ( l=–1 \arcdeg , b=–8.5 \arcdeg ) and Fe abundances for an additional 31 giants in a second , nearby field ( l=0 \arcdeg , b=–8 \arcdeg ) derived from high resolution ( R \approx 25,000 ) spectra obtained with the Blanco 4m telescope and Hydra multifiber spectrograph .
The median metallicity of red giant branch ( RGB ) stars in the Plaut field is \sim 0.4 dex lower than those in Baade ’ s Window , and confirms the presence of an iron abundance gradient along the bulge minor axis .
The full metallicity range of our ( biased ) RGB sample spans –1.5 < [ Fe/H ] < +0.3 , which is similar to that found in other bulge fields .
We also derive a photometric metallicity distribution function for RGB stars in the ( l=–1 \arcdeg , b=–8.5 \arcdeg ) field and find very good agreement with the spectroscopic metallicity distribution .
The radial velocity and dispersion data for the bulge RGB stars are in agreement with previous results of the BRAVA survey , and we find evidence for a decreasing velocity dispersion with increasing [ Fe/H ] .
The [ \alpha /Fe ] enhancement in Plaut field stars is nearly identical to that observed in Baade ’ s window , and suggests that an [ \alpha /Fe ] gradient does not exist between b=–4 \arcdeg and –8 \arcdeg .
Additionally , a subset of our sample ( 23 stars ) appear to be foreground red clump stars that are very metal–rich , exhibit small metallicity and radial velocity dispersions , and are enhanced in \alpha elements .
While these stars likely belong to the Galactic inner disk population , they exhibit [ \alpha /Fe ] ratios that are enhanced above the thin and thick disk .