Stellar iron abundances at the Galactic center

We present measurements of [Fe/H] for six M supergiant stars and three gian t stars within 2.5 pc of the Galactic center (GC) and one M supergiant star within 30 pc of the GC. The results are based on high-resolution (lambda/D elta lambda = 40,000) K-band spectra, taken with CSHELL at the NASA Infrare d Telescope Facility. We determine the iron abundance by detailed abundance analysis, performed with the spectral synthesis program MOOG. The mean [Fe /H] of the GC stars is determined to be near solar, [Fe/H] = +0.12+/-0.22. Our analysis is a differential analysis, as we have observed and applied th e same analysis technique to 11 cool, luminous stars in the solar neighborh ood with similar temperatures and luminosities as the GC stars. The mean [F e/H] of the solar neighborhood comparison stars, [Fe/H] = +0.03+/-0.16, is similar to that of the GC stars. The width of the GC [Fe/H] distribution is found to be narrower than the width of the [Fe/H] distribution of Baade's window in the bulge but consistent with the width of the [Fe/H] distributio n of giant and supergiant stars in the solar neighborhood.