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The development of ring and arc structure following the collision between of a spherical galaxy and a disk galaxy is studied with a combined N-body/smoothed particle hydrodynamics numerical code. It is found that offcenter collisions normal to the disk plane between equal mass galaxies produce greater gas density enhancements in the non-nuclear portion of the disk when compared to an equivalent axisymmetric collision. Strong gas interactions cause the stellar and gaseous components of the disk to decouple. If star formation is associated with the strongest gas shocks, the observed morphology of collisionally produced ring galaxies is strongly influenced by large-scale gas dynamical processes. Comparison of the models to a number of observed systems indicates that this may be the case.
