* Astronomy

Title: Supersonic Cloud Collision-II
Authors: S. Anathpindika

In this, second paper of the sequel of two papers, we present five SPH simulations of fast head-on cloud collisions and study the evolution of the ram pressure confined gas slab. Anathpindika (2008) (hereafter paper I) considered highly supersonic cloud collisions and examined the effect of bending and shearing instabilities on the shocked gas slab. The post-collision shock here, as in paper I, is also modelled by a simple barotropic equation of state (EOS). However, a much stiffer EOS is used to model the shock resulting from a low velocity cloud collision. We explore the parameter space by varying the pre-collision velocity and the impact parameter.
We observe that pressure confined gas slabs become Jeans unstable if the sound crossing time, t_{cr}, is much larger than the freefall time, t_{ff}, of putative clumps condensing out of them. Self gravitating clumps may spawn multiple/larger N-body star clusters. We also suggest that warmer gas slabs are unlikely to fragment and may end up as diffuse gas clouds.

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