Oral Presentation

The Properties of Collisional Ring Galaxies

Yu-Ting Wu (ASIAA) and Ing-Guey Jiang (National Tsing-Hua University)

Ring galaxies present very unusual shapes in that the main disk of individual spiral galaxies are dominated by a ring centered on a nucleus. Head-on collisions were first proposed by Lynds & Toomre (1976) as a mechanism for producing ring galaxies. Motivated by the existence of observational asymmetric ring galaxies, we investigated the effects of relative inclinations and impact parameters of the galaxy pair in collisional events on the morphology of ring galaxies using N-body simulations. This is the first study to quantify the association between the different parameters, including the initial inclination angle and the impact parameter on the shapes of ring galaxies. We conclude that the eccentricity of rings is proportional to the relative inclinations and the nucleus off-center displacement is proportional to the impact parameter, suggesting that some observed ring galaxies could be explained by our simulations.