Hubble Space Telescope NICMOS imaging of the cores of M31 and M32

We present 1.1, 1.6, and 2.2 mum images of the cores of the Local Group gal axies M31 and M32 obtained with the Near Infrared Camera and Multi-Object S pectrometer of the Hubble Space Telescope (HST). These images are also comp ared with optical images of the galaxies obtained with the HST Wide Field P lanetary Camera 2 (WFPC2). In M31, the nucleus remains distinctly asymmetri c in all of the infrared bands, with no evidence of concentrated dust, alth ough the distinction between the two nuclei, P1 and P2, is not as strong as in the WFPC2 and earlier WF/PC-1 images. This result is nonetheless consis tent with the model of the nucleus as an eccentric stellar disk produced by the dynamical influence of a central supermassive black hole. Several indi vidual M giant stars are detected within similar to3" of the nuclei and may represent stars that have escaped from the disk and phase-mixed around the nuclear center of mass. In M32 we also do not find strong evidence of dust , and the brightness profiles within the central similar to1" of the infrar ed images can be fitted by a power law of the same form as that fitted to t he optical images. The infrared color profiles of the central few arcsecond s of M32 show no strong gradients and indicate a population dominated by K giant stars. This is consistent with recent ground-based spectroscopy and p hotometry of the core region, which similarly show no strong gradients in a ge or metallicity within its stellar population.