  We report on the discovery of a double nucleus in M 83, based on measurements
of the line of sight velocity distribution of stars observed at near infrared
wavelengths with the VLT ISAAC spectrograph. We observe two peaks separated by
2.7" in the velocity dispersion profile of light from late-type stars measured
along a slit 0.6" wide, centered on the peak of K band emission and with P.A.
51.7 degrees. The first peak coincides with the peak of the K band light
distribution, widely assumed to be the galaxy nucleus. The second peak, of
almost equal strength, almost coincides with the center of symmetry of the
outer isophotes of the galaxy. The secondary peak location has little K band
emission, and appears to be significantly extincted, even at near infrared
wavelengths. It also lies along a mid-infrared bar, previously identified by
Gallais et al. (1991) and shows strong hydrogen recombination emission at 1.875
microns. If we interpret the observed stellar velocity dispersion as coming
from a virialized system, the two nuclei would each contain an enclosed mass of
13.2 x 10^6 M_sun within a radius of 5.4pc. These could either be massive star
clusters, or supermassive dark objects.

Astrophysics