The Evolved Red Stellar Content of M32

Abstract

Near-infrared images obtained with the CFHT AOB are used to investigate the stellar content of the Local Group elliptical galaxy M32. Observations of a field 2.3 arcmin from the galaxy center reveal a large population of AGB stars, and comparisons with models indicate that these objects have an age log(t_Gyr) < 9.3. It is concluded that intermediate age stars account for roughly 25% of the total K light and 10% +/- 5% of the mass in this field. The K LF of bright sources between 20 and 30 arcsec from the nucleus is well matched by the LF of the outer regions of the galaxy after accounting for differences in surface brightness and correcting for crowding. It is concluded that the relative size of the intermediate age component with respect to other populations does not change with radius over most of the galaxy. However, the integrated J-K color and 2.3 micron CO index change with radius within a few tenths of an arcsec of the galaxy center indicating that, contrary to what might be inferred from observations at visible wavelengths, the integrated photometric properties of the central regions of M32 differ from those of the surrounding galaxy.