M32 is the prototype for the relatively rare class of galaxies referred to as compact ellipticals .
It has been suggested that M32 may be a tidally disturbed r ^ { 1 / 4 } elliptical galaxy , or the remnant bulge of a disk-stripped early-type spiral galaxy .
This paper reveals that the surface brightness profile , the velocity dispersion measurements , and the estimated supermassive black hole mass in M32 are inconsistent with the galaxy having , and probably ever having had , an r ^ { 1 / 4 } light profile .
Instead , the radial surface brightness distribution of M32 resembles an almost perfect ( bulge + exponential disk ) profile , which is accompanied by a marked increase in the ellipticity profile and an associated change in the position angle profile where the ‘ disk ’ starts to dominate .
Compelling evidence that this bulge/disk interpretation is accurate comes from the best-fitting r ^ { 1 / n } bulge model which has a Sérsic index n = 1.5 , in agreement with the recently discovered relation between a bulge ’ s Sérsic index and the mass of its supermassive black hole .
An index n \geqslant 4 would also be inconsistent with the stellar velocity dispersion of M32 .
The bulge-to-disk size ratio r _ { e } / h equals 0.20 , and the logarithm of the bulge-to-disk luminosity ratio \log ( B / D ) equals 0.22 , typical of lenticular galaxies .
The effective radius of the bulge is 27 \arcsec ( \sim 100 pc ) , while the scale-length of the disk is less well determined : due to possible tidal-stripping of the outer profile beyond 220-250 \arcsec , the scale-length may be as large as 1.3 kpc .
M32 is a relatively face-on , nucleated , dwarf galaxy with a low surface brightness disk and a high surface brightness bulge .
This finding brings into question the very existence of the compact elliptical class of galaxies .