A SIMULATION OF AN HH JET IN A MOLECULAR ENVIRONMENT

The heads of some Herbig-Haro (HH) jets have recently been detected in emission lines of molecular species such as H-2 and CO. In this paper we present an axisymmetric numerical simulation of an atomic, nonadia batic jet moving into a molecular environment, from which predictions of intensity maps in atomic/ionic and molecular emission lines can be carried out. While the maps predicted from these models for emission l ines of atoms and ions have the expected bow-shaped structure, the map s for H-2 lines have a ''hole'' in the stagnation region of the bowsho ck, where the molecules are dissociated. The morphology predicted for the molecular emission intensity maps is in clear qualitative agreemen t with recent observational results. We also present predictions of po sition-velocity diagrams, which will be useful for comparisons with fu ture long-slit spectroscopic observations of HH objects.