Far-Ultraviolet and Visible Imaging of the Nucleus of M32

Abstract

We have imaged the nucleus of M32 at 1600 Angstroms (FUV) and 5500 Angstroms (V) using the Wide-Field/Planetary Camera 2 (WFPC2) aboard HST. We detected the nucleus at 1600 Angstroms using the redleak-free Woods filter on WFPC2. The FUV light profile can be fit with a Gaussian of FWHM 0.46" (4.6 pixels), but cannot be resolved into individual stars; no UV-bright nuclear structure was detected. The (FUV-V) color of the nucleus is 4.9 +/- 0.3, consistent with earlier observations. We are unable to confirm any radial variation in (FUV-V) within 0.8" of the nucleus; beyond that radius the FUV surface brightness drops below our detection threshhold. We also performed surface photometry in V and found our results to be in excellent agreement with deconvolved, WFPC1 results. M32's light profile continues to rise in a nuclear cusp even within 0.1" of its center. No intermediate-age stellar population is required by evolutionary population synthesis models to reproduce the (FUV-V) color of the nucleus, although these data and current models are insufficient to resolve this issue.