Near-Infrared Spectroscopy of Molecular Filaments in the Reflection Nebula NGC 7023
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Date
1997-07-20
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Publisher
American Astronomical Society
Abstract
We present near-infrared spectroscopy of fluorescent molecular hydrogen (H_2) emission from molecular filaments in the reflection 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 fields, and excitation mechanisms. Our best-fit models for one filament suggest, but do not require, either a combination of different densities, suggesting clumps of 10^6 cm^-3 in a 10^4-10^5 cm^-3 filament, or a combination of fluorescent excitation and thermally excited gas, perhaps due to a shock from a bipolar outflow. We derive densities and UV fields for these molecular filaments that are in agreement with previous determinations.
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Keywords
infrared: ISM, ISM: lines and bands, ISM: individual (NGC 7023), ISM: molecules, ISM: structure, reflection nebulae
Citation
Paul Martini, K. Sellgren, and Joseph L. Hora, "Near-Infrared Spectroscopy of Molecular Filaments in the Reflection Nebula NGC 7023," The Astrophysical Journal 484, no. 1 (1997), doi:10.1086/304322