The Axis-Symmetric Ring Galaxies: AM 0053-353, AM 0147-350, AM 1133-245, AM 1413-243, AM 2302-322, ARP 318, and Head-On Penetrations

Axis-symmetric ring systems can be identified from the new catalog of collisional ring galaxies in Madore et al. (2009). These are O-type-like collisional ring galaxies. Head-on collisions by dwarf galaxies moving along the symmetric axis were performed through N-body simulations to address their origins. It was found that the simulations with smaller initial relative velocities between two galaxies, or the cases with heavier dwarf galaxies, could produce rings with higher density contrasts. There are more than one generation of rings in one collision and the lifetime of any generation of rings is about one dynamical time. It was concluded that head-on penetrations could explain these O-type-like ring galaxies identified from the new catalog in Madore et al. (2009), and the simulated rings resembling the observational O-type-like collisional rings are those at the early stage of one of the ring-generations.