Numerical simulations of interacting gas-rich barred galaxies

Using an N-body + SPH code, we have performed numerical simulations to investigate the dynamical effects of an interaction between an initially barred galaxy and a small spherical companion. In the models described here the small companion passes through the disc of the larger galaxy perpendicularly to its plane. The impact positions and times are varied with respect to the evolutionary phase of the bar and disc. The interactions produce expanding ring structures, offset bars, spokes and other asymmetries in the stars and gas. They also affect the strength and pattern speed of the bar.