TIDAL EFFECTS INDUCED IN A SPHERICAL GALAXY BY THE PASSAGE OF A COMPANION.

Abstract

ABSTRACT A gravitational encounter between a spherical galaxy and a smaller companion is simulated by computing a large number of stellar orbits in the restricted three-body approximation. For the case considered, i.e., galaxies of 1011 9)'t and 5 >c 10109)o passing in parabolic orbits at a closest distance of 20 kpc, the larger galaxy loses about 8% of its mass, and its outer regions swell up by 50% in radius. These effects may be important in interpreting the measured luminosities and light distributions of elliptical galaxies in cosmological studies. Key words: galaxies - gravitational encounter - evolution of galaxies