HEATING OF INTERSTELLAR CLOUDS BY VIBRATIONALLY EXCITED MOLECULAR-HYDROGEN

We discuss the possibility that vibrationally excited H2 may be collisionally de-excited, so providing a heating mechanism for interstellar clouds which operates by coupling the stellar radiation to the gas. The majority of excitations in the Lyman and Werner bands of H2 return the molecules to the ground electronic state in a vibrationally excited level, the most favoured being ν ″ = 7. We compare the heating rate obtained in this way with other mechanisms which have been postulated, and present the results of calculations of temperature as a function of depth into clouds of different densities. It appears that this mechanism is a significant one, which should be taken into account in detailed models of dense clouds. © 1973 Royal Astronomical Society. Provided by the NASA Astrophysics Data System.