The Distance to the Galactic Center Obtained by Infrared Photometry of RR Lyrae Variables
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We report K-band photometry of 58 RR Lyraes in the field of Baade's Window (l=1, b=-3.9). Using a metallicity- and reddening-insensitive relation between MK and log P for RR Lyraes in this field and in another at l=0, b=-12 studied by Fernley et al. [MNRAS, 226, 927 (1987)], we derive the distance to the galactic center. Using the distance scale of Carney et al. [ApJ, 386, 663 (1992)], we find R0=7.80.4 kpc. Adjusting that distance scale's zero point to yield an LMC distance modulus (m-M)0=18.5 mag results in R0=8.90.5 kpc. Including the systematic uncertainties from the two different distance scales results in R0=8.31.0 kpc. We discuss some implications for the star formation history in the bulge using the derived distances. 1995 American Astronomical Society.