Extended Far-Infrared CO Emission in the Orion OMC-1 Core

Maria J. Sempere; Jose Cernicharo; Bertrand Lefloch; Eduardo Gonzalez-Alfonso; Sarah Leeks

doi:10.1086/312489

paper

Extended Far-Infrared CO Emission in the Orion OMC-1 Core

arXiv:astro-ph/9912448 · doi:10.1086/312489

Abstract

We report on sensitive far-infrared observations of $^{12}$ CO pure rotational transitions in the OMC-1 core of Orion. The lines were observed with the Long Wavelength Spectrometer (LWS) in the grating mode on board the Infrared Space Observatory (ISO), covering the 43-197 $μ$ m wavelength range. The transitions from $J_{u p} = 14$ up to $J_{u p} = 19$ have been identified across the whole OMC-1 core and lines up to $J_{u p} = 43$ have been detected towards the central region, KL/IRc2. In addition, we have taken high-quality spectra in the Fabry-Perot mode of some of the CO lines. In KL/IRc2 the lines are satisfactorily accounted for by a three-temperature model describing the plateau and ridge emission. The fluxes detected in the high- $J$ transitions ( $J_{u p} > 34$ ) reveal the presence of a very hot and dense gas component ( $T = 1500 - 2500$ K; $N (CO)$ =2\times 10^{17}\cmmd $), p r o bab l y or i g ina t in g f r o m so m eo f t h ee mb e dd e d so u r ces p r e v i o u s l y o b ser v e d in t h e$ \rm H_2 $n e a r - in f r a r e d l in es . A t a l l o t h er p os i t i o n s in t h e O M C - 1 cor e, w ees t ima t e k in e t i c t e m p er a t u r es$ \geq 80$ K and as high as 150 K at some positions around IRc2, from a simple Large-Velocity Gradient model.

10 pages, 3 figures

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Extended Co(7-6) Emission from Warm Gas in Orion

Extended Far-Infrared CO Emission in the Orion OMC-1 Core

Abstract

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