Kinematics of the Interacting Elliptical Galaxy Pair NGC 4782/4783
The peculiar morphology of the elliptical galaxy pair NGC 4782/4783 reflects a stage of strong tidal interaction. Both galaxy centers are displaced with respect to the centers of the outer isophotes. Long-slit spectroscopy reveals disturbed kinematical properties. The velocity dispersion increases radially from the centers of both galaxies towards the centers of the outer isophotes to maximum values larger than 400 kms -1. It is supposed that dynamical friction strongly decelerates both galaxies on their orbits. In the central parts the crossing-time of the stars is much less than the encounter timescale. Therefore, the reaction of the cores is similar to the behaviour of a solid body while the sticky envelopes are subject to differential tidal forces.