HUBBLE-SPACE-TELESCOPE OBSERVATIONS OF GLOBULAR-CLUSTERS IN M31 .2. STRUCTURAL PARAMETERS

We analyze post-refurbishment Hobble Space Telescope images of four gl obular clusters in M31. The ability to resolve stars to below the hori zontal branch permits us to use star counts to extend the surface brig htness profiles determined using aperture photometry to almost 5 order s of magnitude below the central surface density. Three of the resulti ng cluster profiles are reasonably well-fit using single-mass King mod els, with core and tidal radii typical of those seen in Galactic globu lar clusters. We confirm an earlier report of the discovery of a clust er which has apparently undergone core collapse. Three of the four clu sters show departures in their outskirts from King model behavior whic h, based on recent results for Galactic globulars, may indicate the pr esence of tidal tails. (C) 1996 American Astronomical Society.