Collisional excitation of H2 by grains in C-type shocks

Abstract

We have performed classical trajectory Monte Carlo calculations of the probabilities of rovibrational excitation and dissociation of molecular hydrogen in collisions with a surface, modelled as MgO. The results show that, in C-type shock waves, states of high excitation energy are populated predominantly in collisions with charged grains, rather than with much more abundant neutral species. The intensities of rovibrational transitions of H2 have been calculated for a series of models of C-type shocks, considered to be relevant to molecular outflow sources. We compare the column densities of excited states of H2 and the intensities of representative rovibrational transitions, calculated excluding and including collisions with grains.