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A Direct Measurement of the Total Gas Column Density in Orion KL

Plume, R. and Bergin, E. A. and Phillips, T. G. and Lis, D. C. and Wang, S. and Crockett, N. R. and Caux, E. and Comito, C. and Goldsmith, P. F. and Schilke, P. (2012) A Direct Measurement of the Total Gas Column Density in Orion KL. Astrophysical Journal, 744 (1). p. 28. ISSN 0004-637X. doi:10.1088/0004-637X/744/1/28.

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The large number of high-J lines of C^(18)O available via the Herschel Space Observatory provide an unprecedented ability to model the total CO column density in hot cores. Using the emission from all the observed lines (up to J = 15-14), we sum the column densities in each individual level to obtain the total column after correcting for the population in the unobserved states. With additional knowledge of source size, V_(LSR), and line width, and both local thermodynamic equilibrium (LTE) and non-LTE modeling, we have determined the total C^(18)O column densities in the Extended Ridge, Outflow/Plateau, Compact Ridge, and Hot Core components of Orion KL to be 1.4 × 10^(16) cm^(–2), 3.5 × 10^(16) cm^(–2), 2.2 × 10^(16) cm^(–2), and 6.2 × 10^(16) cm^(–2), respectively. We also find that the C^(18)O/C^(17)O abundance ratio varies from 1.7 in the Outflow/Plateau, 2.3 in the Extended Ridge, 3.0 in the Hot Core, and to 4.1 in the Compact Ridge. This is in agreement with models in which regions with higher ultraviolet radiation fields selectively dissociate C^(17)O, although care must be taken when interpreting these numbers due to the size of the uncertainties in the C^(18)O/C^(17)O abundance ratio.

Item Type:Article
Related URLs:
URLURL TypeDescription
Bergin, E. A.0000-0003-4179-6394
Lis, D. C.0000-0002-0500-4700
Wang, S.0000-0002-6937-9034
Crockett, N. R.0000-0002-6586-7591
Goldsmith, P. F.0000-0002-6622-8396
Schilke, P.0000-0003-2141-5689
Additional Information:© 2011 American Astronomical Society. Received 2011 May 5; accepted 2011 September 11; published 2011 December 9. HIFI has been designed and built by a consortium of institutes and university departments from across Europe, Canada, and the United States under the leadership of SRON Netherlands Institute for Space Research, Groningen, The Netherlands, and with major contributions from Germany, France, and the US. Consortium members are Canada: CSA, U. Waterloo; France: CESR, LAB, LERMA, IRAM; Germany: KOSMA, MPIfR, MPS; Ireland, NUI Maynooth; Italy: ASI, IFSI-INAF, Osservatorio Astrofisico di Arcetri-INAF; The Netherlands: SRON, TUD; Poland: CAMK, CBK; Spain: Observatorio Astronmico Nacional (IGN), Centro de Astrobiologa (CSIC-INTA); Sweden: Chalmers University of Technology—MC2, RSS & GARD; Onsala Space Observatory; Swedish National Space Board, Stockholm University—Stockholm Observatory; Switzerland: ETH Zurich, FHNW; USA: Caltech, JPL, NHSC. Support for this work was provided, in part, by a National Sciences and Engineering Research Council of Canada (NSERC) grant to R. Plume, by the National Science Foundation grant AST-0838261 to the Caltech Submillimeter Observatory, and by NASA through an award issued by JPL/Caltech. Facility: Herschel, CSO.
Funding AgencyGrant Number
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
Subject Keywords:ISM: abundances; ISM: individual objects (Orion KL); ISM: molecules
Issue or Number:1
Record Number:CaltechAUTHORS:20120124-111203118
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Official Citation:A Direct Measurement of the Total Gas Column Density in Orion KL R. Plume et al. 2012 ApJ 744 28
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:28937
Deposited By: Jason Perez
Deposited On:24 Jan 2012 22:29
Last Modified:09 Nov 2021 17:02

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