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Herschel Observations of Extra-ordinary Sources: Analysis of the HIFI 1.2 THz Wide Spectral Survey toward Orion KL II. Chemical Implications

Crockett, N. R. and Bergin, E. A. and Neill, J. L. and Favre, C. and Blake, G. A. and Herbst, E. and Anderson, D. E. and Hassel, G. E. (2015) Herschel Observations of Extra-ordinary Sources: Analysis of the HIFI 1.2 THz Wide Spectral Survey toward Orion KL II. Chemical Implications. Astrophysical Journal, 806 (2). Art. No. 239. ISSN 0004-637X.

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We present chemical implications arising from spectral models fit to the Herschel/HIFI spectral survey toward the Orion Kleinmann-Low nebula (Orion KL). We focus our discussion on the eight complex organics detected within the HIFI survey utilizing a novel technique to identify those molecules emitting in the hottest gas. In particular, we find the complex nitrogen bearing species CH_3CN, C_2H_3CN, C_2H_5CN, and NH_2CHO systematically trace hotter gas than the oxygen bearing organics CH_3OH, C_2H_5OH, CH_3OCH_3, and CH_3OCHO, which do not contain nitrogen. If these complex species form predominantly on grain surfaces, this may indicate N-bearing organics are more difficult to remove from grain surfaces than O-bearing species. Another possibility is that hot (T_(kin) ~ 300 K) gas phase chemistry naturally produces higher complex cyanide abundances while suppressing the formation of O-bearing complex organics. We compare our derived rotation temperatures and molecular abundances to chemical models, which include gas-phase and grain surface pathways. Abundances for a majority of the detected complex organics can be reproduced over timescales ≳10^5 years, with several species being underpredicted by less than 3σ. Derived rotation temperatures for most organics, furthermore, agree reasonably well with the predicted temperatures at peak abundance. We also find that sulfur bearing molecules that also contain oxygen (i.e., SO, SO_2, and OCS) tend to probe the hottest gas toward Orion KL, indicating the formation pathways for these species are most efficient at high temperatures.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Crockett, N. R.0000-0002-6586-7591
Bergin, E. A.0000-0003-4179-6394
Favre, C.0000-0002-5789-6931
Blake, G. A.0000-0003-0787-1610
Anderson, D. E.0000-0002-8310-0554
Alternate Title:Herschel Observations of Extraordinary Sources: Analysi sof the HIFI 1.2 THz Wide Spectral Survey toward Orion KL II. Chemical Implications
Additional Information:© 2015 American Astronomical Society. Received 2014 November 23; accepted 2015 May 18; published 2015 June 22. We gratefully acknowledge the anonymous referee for comments which improved this manuscript. 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 Astronómico 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: ETH Zurich, FHNW; 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. Support for this work was provided by NASA through an award issued by JPL/Caltech. E.H. acknowledges funding from the NASA/Jet Propulsion Laboratory to aid US participation in the Herschel/HIFI project.
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Subject Keywords:astrochemistry; ISM: abundances; ISM: individual objects (Orion KL); ISM: molecules
Issue or Number:2
Record Number:CaltechAUTHORS:20150805-073849341
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Official Citation:Herschel Observations of Extraordinary Sources: Analysis of the HIFI 1.2 THz Wide Spectral Survey toward Orion KL II. Chemical Implications N. R. Crockett et al. 2015 ApJ 806 239
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59195
Deposited By: Ruth Sustaita
Deposited On:05 Aug 2015 21:54
Last Modified:09 Mar 2020 13:18

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