Wide-Field CCD Photometry of the Globular Cluster M92

Abstract

New B, V photometry for stars in the Galactic globular cluster M92 are obtained, and the data are transformed to a standard system approximating that of Landolt (1973). The main sequence of M92 is found to be somewhat bluer than in previous studies, decreasing the size for the color shift of the isochrones toward the red that is required to match the observations to the theoretical models. The color-magnitude diagram of the cluster reveals some evidence of a break in the slope of the main sequence at the faintest levels studied. It is suggested that the significant excess of stars noted on the red fringe of the main sequence may consist of binary stars. It cannot be determined with certainty whether a final turnover in M92's luminosity function is detected before the faint limit of the data is reached.