ISO-SWS Observations of OMC-1: H_2 and Fine Structure Lines

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dc.creatorRosenthal, Dirk
dc.creatorBertoldi, Frank
dc.creatorDrapatz, Siegfried
dc.date2000-02-24
dc.date.accessioned2026-07-07T01:52:28Z
dc.date.available2026-07-07T01:52:28Z
dc.descriptionUsing the Short-Wavelength-Spectrometer on the Infrared Space Observatory (ISO), we obtained near- and mid-infrared spectra toward the brightest H_2 emission peak of the Orion OMC-1 outflow. A wealth of emission and absorption features were detected, dominated by 56 H_2 ro-vibrational and pure rotational lines reaching from H_2 0-0 S(1) to 0-0 S(25). The spectra also show a number of H I recombination lines, atomic and ionic fine structure lines, and molecular lines of CO and H_2O. Between 6 and 12 mu the emission is dominated by PAH features. The H_2 level column density distribution shows no signs of fluorescent excitation or a deviation from an ortho-to-para ratio of three. It shows an excitation temperature which increases from about 600 K for the lowest rotational and vibrational levels to about 3200 K at level energies E(v,J)/k > 14 000 K. No single steady state shock model can reproduce the observed H_2 excitation. The higher energy H_2 levels may be excited either thermally in non-dissociative J-shocks, through non-thermal collisions between fast ions and molecules with H_2 in C-shocks, or they are pumped by newly formed H_2 molecules. The highest rotational levels may be populated by yet another mechanism, such as the gas phase formation of H_2 through H^-.
dc.description22 pages, 12 figures, A&A accepted
dc.identifierhttps://arxiv.org/abs/astro-ph/0002456
dc.identifierhttp://arxiv.org/abs/astro-ph/0002456
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/633
dc.subjectAstrophysics
dc.titleISO-SWS Observations of OMC-1: H_2 and Fine Structure Lines
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