Molecular hydrogen in star-forming regions: Implementation of its microphysics in cloudy

Much of the baryonic matter in the universe is in the form of H-2, which includes most of the gas in Galactic and extragalactic interstellar clouds. Molecular hydrogen plays a significant role in establishing the thermal balance in many astrophysical environments and can be important as a spectral diagnostic of the gas. Modeling and interpretation of observations of such environments requires a quantitatively complete and accurate treatment of H-2. Using this microphysical model of H-2, we present illustrative calculations of prototypical astrophysical environments. This work forms the foundation for future investigations of these and other environments in which H-2 is an important constituent.