ON THE FORMATION OF ELLIPTICAL RINGS IN DISK GALAXIES

Abstract

N-body simulations of galactic collisions are employed to investigate the formation of elliptical rings in disk galaxies. The relative inclination between disk and dwarf galaxies is studied with a fine step of 5°. It is confirmed that the eccentricity of elliptical rings is linearly proportional to the inclination angle. Deriving from the simulational results, an analytic formula that expresses the eccentricity as a function of time and inclination angle is obtained. This formula will be useful for the interpretation of observations of ring systems, and therefore reveals the merging histories of galaxies.