The Splash Survey: Internal Stellar Kinematics of the Nearby Compact Elliptical M32
Abstract
M32, a satellite of the Andromeda (M31) galaxy, is our nearest example of the rare and enigmatic compact elliptical galaxy type. It has long been known that the outer isophotes of M32 are distorted; this is presumed to be caused by its tidal interaction with M31. In this paper, new Keck/DEIMOS spectroscopic observations are presented of the integrated light (r < 100") and, for the first time, resolved stellar population (100" < r < 200") of M32 (where M32's I-band reff = 29" = 0.1 kpc). Our measurement of the rotation curve and velocity dispersion profile extend beyond M32's tidal distortion radius of r 150", in contrast to previous kinematical studies that went out to r 30". Studies of M32 are made challenging by the fact that the galaxy is projected against the bright/complicated inner region of M31. This, combined with the steeply falling brightness profile of M32, implies that resolved stellar population studies are caught between a rock and hard place: crowding/blending is severe in the inner parts while M31 contamination is severe in the outer parts. In the resolved stellar population portion of our study, we use spatial and kinematical information to statistically account for M31 contamination. Unlike NGC 205, another close neighbor of M31, M32's kinematics appear to be regular and symmetric and do not show obvious sharp gradients across the tidal distortion region. This lack of a strong gradient will serve as a constraint on tidal interaction models. This work is funded through the NSF and NASA.
- Publication:
-
American Astronomical Society Meeting Abstracts #217
- Pub Date:
- January 2011
- Bibcode:
- 2011AAS...21720704H