Changes in ellipticals due to collisions with spirals and their consequences

A study of collisions between spiral and elliptical galaxies (approximated as composite spherical masses) is made to assess the changes undergone by the elliptical. Results indicate that unless the spiral is extremely massive compared to the elliptical, the elliptical is almost unaffected, while the spiral is strongly affected. For the frequent type of collision between equally massive spiral and elliptical galaxies, the elliptical is negligibly affected, while disruptive effects set in the spiral. However, the stellar pattern of the elliptical is changed and the stars are found to crowd in faint shells after the collision. The consequences of these results are explored in the context of the morphology-density relationship and the elliptical companions of ring galaxies. ©2001 Plenum Publishing Corporation.