Abstract
We present near-infrared spectroscopy of Nuorescent molecular hydrogen emission from molecu- (H 2 ) lar -laments in the reNection nebula NGC 7023. We derive the relative column densities of H 2 rotational-vibrational states from the measured line emission and compare these results with several model photodissociation regions covering a range of densities, incident UV -elds, and excitation mecha- nisms. Our best--t models for one -lament suggest, but do not require, either a combination of di†erent densities, suggesting clumps of 106 cm~3 in a1 0 4 E105 cm~3 -lament, or a combination of Nuorescent excitation and thermally excited gas, perhaps due to a shock from a bipolar outNow. We derive densities and UV -elds for these molecular -laments that are in agreement with previous determinations. Subject headings: infrared: ISM: lines and bands E ISM: individual (NGC 7023) E ISM: molecules E ISM: structure E reNection nebulae
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