THE ROLE PLAYED BY ROTATION AND RANDOM MOTIONS IN ELLIPTICAL GALAXIES

The observable kinematical quantities (rotation velocity and velocity dispersion) of elliptical galaxies are affected, among other things, by the integration of the light along the line of sight. We present a method to spatially deproject the rotation velocity curve and the velocity dispersion profile. The application to a sample of 54 ellipticals shows that, as is it widely recognized, the total kinetic energy originates mainly from the random motions, and that there is no correlation between rotation and velocity dispersion. If the correction with respect to the line-of-sight integration is taken into account, the correlation between the total absolute magnitude and the rotation parameter log(V/sigma)* turns out to be rather weak, while boxy and disky ellipticals appear to be separated both in the (T(V), T-sigma) plane and in the (M(B),log(V/sigma)*) plane, thus confirming the existence of different dynamical properties between these two classes of objects.