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.