WARM MOLECULAR CLOUDS

Warm molecular gas is important in a large range of astronomical contexts. We discuss here determinations of the temperature and mass of warm material in protostellar disks and cores, photon dominated regions, and molecular material shocked by protostellar outflows. We then compare these results to heating and cooling models. The models of dense cores and photon dominated regions are not adequate to explain the large amounts of warm material observed. This conclusion raises the possibility that there may be other heating mechanisms at work in these regions which theorists have not yet included in their models.