Effects of Grazing Encounters on Spiral Galaxies

We made radio, optical and CO observations of three pairs of spiral galaxies involved in recent, grazing encounters and compared our data with numerical simulations. The tidal structures seen in the galaxy undergoing a prograde, in-plan encounter share a number of key features which are adequately explained by our simulations. It is shown that the objects IC 2163/ NGC 2207, NGC2535/36, and NGC 5394/95 represent distinct stages in the evolution of the type of interactions discussed here.