Structural Parameters of Globular Clusters in the Fornax Cluster

Abstract

We present measurements of the structural parameters of 24 globular cluster candidates with 19 < I < 22, ~4' from NGC 1399, the central giant elliptical galaxy in the Fornax cluster (distance modulus ~31). The data were obtained with the Hubble Space Telescope's Wide Field Camera prior to refurbishment. We use a two-dimensional model-fitting technique to take into account the aberrated point-spread function. This is the first time sizes have been measured for globular clusters in a galaxy beyond the Local Group. The concentration parameters range from 1 < c < 2.7, and the core radii from 1 < r_c_ < 10 pc. This is the same as the range for globular clusters in our Galaxy. The deduced tidal radii are consistent with recent determinations of the mass of NGC 1399 based on photometric and kinematic profiles.