R=100,000 Spectroscopy of Photodissociation Regions: H2 Rotational Lines in the Orion Bar

摘要

Ground state rotational lines of H2 are good temperature probes of moderatelyhot (200-1000 K) gas. The low A-values of these lines result in low criticaldensities while ensuring that the lines are optically thin. ISO observations ofH2 rotational lines in PDRs reveal large quantities of warm gas that aredifficult to explain via current models, but the spatial resolution of ISO doesnot resolve the temperature structure of the warm gas. We present and discusshigh spatial resolution observations of H2 rotational line emission from theOrion Bar.