Hubble Space Telescope Observations of the Center of Globular Cluster M15

Abstract

Images of the dense center of globular cluster M15 (NGC 7078) have been obtained with the Hubble Space Telescope in the V and I filters. Accurate photometry is possible in the very densest part of the cluster center with rms errors of <0.3 magnitudes for stars down to the main sequence turnoff. Evidence for radial segregation between horizontal branch, red giant branch, and blue straggler stars is presented. We discuss the possibility of the existence of a central stellar density cusp which does not flatten into a small central core at radii less than 2 arcseconds. (SECTION: The Second Hubble Fellows Symposium)