Metallicity of Red Giants in the Galactic Bulge from Near-Infrared Spectroscopy

We present K-band spectra of more than 110 M giants in Galactic bulge fieldsinterior to -4 degrees and as close as 0.2 degrees of the Galactic Center. Fromthe equivalent widths of three features in these spectra, EW(Na),EW(Ca), andEW(CO) we calculate [Fe/H] for the stars with a calibration derived fromglobular clusters Stephens et al (2000). The mean [Fe/H] for each field is ingood agreement with the results from Frogel et al. (1999) based on the slope ofthe giant branch method. We find no evidence for a metallicity gradient alongthe minor or major axes of the inner bulge (R < 0.6 kpc). A metallicitygradient along the minor axis, found earlier, arises when fields located atlarger galactic radius are included. However, these more distant fields arelocated outside of the infrared bulge defined by the COBE/DIRBE observations.We compute the [Fe/H] distribution for the inner bulge and find a mean value of-0.21 dex with a full width dispersion of 0.30 dex, close to the values foundfor Baade's Window (BW) by Sadler et al. (1996) and to a theoretical predictionfor a bulge formed by dissipative collapse Molla et al (2000).Comment: 32 pages, 10 figures, AJ submitte