Collisions of supersonic clouds

We present simulations of supersonic collisions between molecular clouds of mass 500M_ and radius 2.24 pc. The simulations are performed with the SEREN SPH code. The code treats the energy equation and the associated transport of heating and cooling radiation. The formation of protostars is captured by introducing sink particles. Low velocity collisions form a shock-compressed layer which fragments to form stars. For high-velocity collisions, vr el _ 5 kms−1 , the non-linear thin shell instability strongly disrupts the shock-compressed layer, and may inhibit the formation of stars.