Abstract
view Abstract Citations (56) References (25) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Detection of an Isotopic Short Submillimeter CO Line: Column Densities of Warm Gas in Molecular Clouds Graf, U. U. ; Genzel, R. ; Harris, A. I. ; Hills, R. E. ; Russell, A. P. G. ; Stutzki, J. Abstract The first astronomical detection of isotopic (C-13)O J = 6 - 5 emission at 661 GHz from the molecular clouds in Orion A and in NGC 2024 is reported. Strong lines indicate large column densities of warm, dense, molecular gas in these star formation regions. It is estimated that H2 column densities of gas with temperature of 100 K or more lie between 3 x 10 to the 22nd and 4 x 10 to the 23rd/sq cm. These column densities are difficult to explain by present theoretical heating models. In NGC 2024 and the Orion Bar, where lines are narrow, shock heating is very unlikely. The correlation of warm CO column density with UV intensity, also indicated by the nondetection of (C-13)O J = 6 - 5 emission toward the weak UV source NGC 2023, favors heating by UV radiation. However, present photodissociation region models fail to predict the large quantities of warm gas detected in NGC 2024 and in the Orion Bar. Publication: The Astrophysical Journal Pub Date: August 1990 DOI: 10.1086/185777 Bibcode: 1990ApJ...358L..49G Keywords: Carbon Monoxide; Interstellar Chemistry; Interstellar Gas; Millimeter Waves; Molecular Clouds; Carbon 13; Density (Mass/Volume); H Ii Regions; Line Spectra; Orion Nebula; Astrophysics; INTERSTELLAR: MATTER; INTERSTELLAR: MOLECULES; NEBULAE: INDIVIDUAL NAME: ORION A; NEBULAE: INDIVIDUAL NGC NUMBER: NGC 2024 full text sources ADS | data products SIMBAD (2)
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