  Colliding galaxies are excellent laboratories for studying galactic evolution
and global star formation. Computer simulations of galaxy collisions, in which
at least one galaxy has a significant gaseous component, show the production of
density enhancements and shock waves in the interstellar medium. These
high-density regions coincide with the locations of recent, large-scale star
formation in observations of some real colliding galaxies. Thus, combined
n-body/hydrodynamic computer simulations can be used to explore the history and
conditions of star forming regions in colliding galaxies. The galaxy system Arp
119 (CPG 29) contains a southern member, Arp 119S (Mrk 984), that has an
extremely disturbed appearance, and a northern member, Arp 119N, a gas-poor
elliptical. The morphology of both members can be fit well by a simulation in
which a gas-rich disk galaxy has been impacted by an equal mass elliptical that
had a trajectory approximately perpendicular to the plane of the disk and
passed through the disk slightly off-center. We compare multi-wavelength
observations of the Arp 119 system with a combined n-body/SPH simulation of
colliding galaxies. We find that the progression of recent, large-scale star
formation in this galaxy can be accounted for by a single, outwardly
propagating collision-induced density wave in the gas.
