We present a new wide field image of the distant cluster AC114 ( z = 0.31 ) obtained with Wide Field and Planetary Camera II onboard the Hubble Space Telescope .
This image considerably extends our knowledge of the lensing properties of the cluster beyond that derived by Smail et al . ( 1995a ) from a single WF/PC-1 pointing .
In conjunction with published ground-based spectroscopy , we utilise several newly-discovered multiple images to construct an improved mass model for the central regions of the cluster .
Using this model , we apply the methodology introduced by Natarajan & Kneib ( 1997 ) to interpret local perturbations to the cluster shear field on small scales resulting from mass associated with individual cluster galaxies .
We use the lensing signal to place new constraints on the average mass-to-light ratio and spatial extents of the dark matter halos associated with morphologically-classified early-type cluster members .
We find that the total mass of a fiducial L ^ { \ast } cluster spheroidal galaxy is largely contained within \sim 15 kpc radius halo ( \sim 8–10 R _ { e } ) with a mass-to-light ratio { M / L _ { V } } \sim { 15 ^ { +10 } _ { -4 } } ( 90 % c.l . )
in solar units within this radius .
Comparisons with similar estimates for field galaxies suggests that the cluster galaxies in AC114 may possess less extensive and less massive halos .
Additionally , we find some indication that , at a fixed luminosity , S0 galaxies are less extended than ellipticals , suggesting a difference in the efficiency of tidal stripping of different galaxy types .
We discuss the consequences of our results in the context of models for the dynamical evolution of cluster galaxies and the observational prospects for extending such analyses .