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Herschel Observations of Extraordinary Sources: Analysis of the HIFI 1.2 THz Wide Spectral Survey toward Orion KL. I. Methods

Crockett, Nathan R. and Bergin, Edwin A. and Neill, Justin L. and Favre, Cécile and Schilke, Peter and Lis, Dariusz C. and Bell, Tom A. and Blake, Geoffrey and Cernicharo, José and Emprechtinger, Martin and Esplugues, Gisela B. and Gupta, Harshal and Kleshcheva, Maria and Lord, Steven and Marcelino, Nuria and McGuire, Brett A. and Pearson, John and Phillips, Thomas G. and Plume, Rene and van der Tak, Floris and Tercero, Belén and Yu, Shanshan (2014) Herschel Observations of Extraordinary Sources: Analysis of the HIFI 1.2 THz Wide Spectral Survey toward Orion KL. I. Methods. Astrophysical Journal, 787 (2). Art. No. 112. ISSN 0004-637X.

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We present a comprehensive analysis of a broadband spectral line survey of the Orion Kleinmann-Low nebula (Orion KL), one of the most chemically rich regions in the Galaxy, using the HIFI instrument on board the Herschel Space Observatory. This survey spans a frequency range from 480 to 1907 GHz at a resolution of 1.1 MHz. These observations thus encompass the largest spectral coverage ever obtained toward this high-mass star-forming region in the submillimeter with high spectral resolution and include frequencies >1 THz, where the Earth's atmosphere prevents observations from the ground. In all, we detect emission from 39 molecules (79 isotopologues). Combining this data set with ground-based millimeter spectroscopy obtained with the IRAM 30 m telescope, we model the molecular emission from the millimeter to the far-IR using the XCLASS program, which assumes local thermodynamic equilibrium (LTE). Several molecules are also modeled with the MADEX non-LTE code. Because of the wide frequency coverage, our models are constrained by transitions over an unprecedented range in excitation energy. A reduced χ^2 analysis indicates that models for most species reproduce the observed emission well. In particular, most complex organics are well fit by LTE implying gas densities are high (>10^6 cm^(–3)) and excitation temperatures and column densities are well constrained. Molecular abundances are computed using H_2 column densities also derived from the HIFI survey. The distribution of rotation temperatures, T_(rot), for molecules detected toward the hot core is significantly wider than the compact ridge, plateau, and extended ridge T_(rot) distributions, indicating the hot core has the most complex thermal structure.

Item Type:Article
Related URLs:
URLURL TypeDescription
Crockett, Nathan R.0000-0002-6586-7591
Bergin, Edwin A.0000-0003-4179-6394
Favre, Cécile0000-0002-5789-6931
Schilke, Peter0000-0003-2141-5689
Lis, Dariusz C.0000-0002-0500-4700
Blake, Geoffrey0000-0003-0787-1610
McGuire, Brett A.0000-0003-1254-4817
Additional Information:© 2014 American Astronomical Society. Received 2013 September 25; accepted 2014 March 24; published 2014 May 9. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. We thank the anonymous referee for giving comments that greatly improved the paper. 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; Netherlands: SRON, TUD; Poland: CAMK, CBK; Spain: Observatorio Astronόmico Nacional (IGN), Centro de Astrobiología (CSIC-INTA); Sweden: Chalmers University of Technology—MC2, RSS & GARD; Onsala Space Observatory; Swedish National Space Board, Stockholm University—Stockholm Observatory; Switzerland: ETHZurich, FHNW; and USA: Caltech, JPL, NHSC. HIPE is a joint development by the Herschel Science Ground Segment Consortium, consisting of ESA, the NASA Herschel Science Center, and the HIFI, PACS, and SPIRE consortia. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. Support for this work was provided by NASA through an award issued by JPL/Caltech.
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Subject Keywords: ISM: abundances; ISM: individual objects (Orion KL); ISM: molecules
Issue or Number:2
Record Number:CaltechAUTHORS:20140619-104035130
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Official Citation:Herschel Observations of Extraordinary Sources: Analysis of the HIFI 1.2 THz Wide Spectral Survey toward Orion KL. I. Methods Nathan R. Crockett et al. 2014 ApJ 787 112
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:46358
Deposited By: Ruth Sustaita
Deposited On:19 Jun 2014 18:10
Last Modified:09 Mar 2020 13:19

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