Abstract
ABSTRACT. Two-dimensional hydrodynamic simulations for the interaction of neutral hydrogen high-velocity clouds and a galactic disk are presented. The models consider and cylindrical clouds (with densities 0.1 <=flc < 100 cm , sizes 10 < Rc <- 100 pc, and velocities 50 km 1 <= Vc < 300 km 1) colliding with a disk represented by i) a constant density slab and, ii) a gaussian density distribution. When the infalling clouds are completely shocked in a time short compared with the crossing time of the disk, the leading shocks continue to penetrate into the disk, generating large scale and massive structures which have the appearance of curved arcs. When the cloud is shocked in a time scale longer than or comparable to the crossing time, a cylindrical hole with the dimensions of the impinging cloud is simply drilled across the entire disk. Cloud-galaxy collisions are compared with other energy sources and the resultant structures are suggested to resemble, in some cases, the large scale structures observed in HI. VJO : GALAXIES-DISK - INTERSTELLAR-CLOUDS-HIGH VELOCITY
