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Herschel Observations of Interstellar Chloronium. II. Detections toward G29.96-0.02, W49N, W51, and W3(OH), and Determinations of the Ortho-to-Para and ^(35)Cl/^(37)Cl Isotopic Ratios

Neufeld, David A. and Black, John H. and Gerin, Maryvonne and Goicoechea, Javier R. and Goldsmith, Paul F. and Gry, Cecile and Gupta, Harshal and Herbst, Eric and Indriolo, Nick and Lis, Dariusz C. and Menten, Karl M. and Monje, Raquel and Mookerjea, Bhaswati and Persson, Carina and Schilke, Peter and Sonnentrucker, Paule and Wolfire, Mark (2015) Herschel Observations of Interstellar Chloronium. II. Detections toward G29.96-0.02, W49N, W51, and W3(OH), and Determinations of the Ortho-to-Para and ^(35)Cl/^(37)Cl Isotopic Ratios. Astrophysical Journal, 807 (1). Art. No. 54. ISSN 0004-637X. doi:10.1088/0004-637X/807/1/54.

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We report additional detections of the chloronium molecular ion, H_2C^l+, toward four bright submillimeter continuum sources: G29.96-0.02, W49N, W51, and W3(OH). With the use of the HIFI instrument on board the Herschel Space Observatory, we observed the 2_(12)-1_(01) transition of ortho-H_2^{35}Cl^+ at 781.627 GHz in absorption toward all four sources. Much of the detected absorption arises in diffuse foreground clouds that are unassociated with the background continuum sources and in which our best estimates of the N(H_2Cl^+)/N(H) ratio lie in the range (0.9–4.8) x 10^(-9). These chloronium abundances relative to atomic hydrogen can exceed the predictions of current astrochemical models by up to a factor of 5. Toward W49N, we have also detected the 2_(12)-1_(01) transition of ortho-H_2^{37}Cl^+ at 780.053 GHz and the 1_(11)-0_(00) transition of para-H_2^{35}Cl^+ at 485.418 GHz. These observations imply (H_2^{35}Cl^+)/(H_2^{37}Cl^+) column density ratios that are consistent with the solar system ^(35)Cl/^(37)Cl isotopic ratio of 3.1, and chloronium ortho-to-para ratios consistent with 3, the ratio of spin statistical weights.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Neufeld, David A.0000-0001-8341-1646
Goldsmith, Paul F.0000-0002-6622-8396
Indriolo, Nick0000-0001-8533-6440
Lis, Dariusz C.0000-0002-0500-4700
Menten, Karl M.0000-0001-6459-0669
Schilke, Peter0000-0003-2141-5689
Wolfire, Mark0000-0003-0030-9510
Additional Information:© 2015. The American Astronomical Society. Received 2015 February 27, accepted for publication 2015 April 28, Published 2015 June 30. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA. 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 United States. 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. Support for this work was provided by NASA through an award issued by JPL/Caltech. J.R.G. thanks MINECO for funding support under grants CSD2009-00038, AYA2009-07304 and AYA2012-32032.
Funding AgencyGrant Number
Ministerio de Economía y Competitividad (MINECO)CSD2009-00038
Ministerio de Economía y Competitividad (MINECO)AYA2009-07304
Ministerio de Economía y Competitividad (MINECO)AYA2012-32032
Subject Keywords:astrochemistry; ISM: abundances; ISM: clouds; ISM: molecules; molecular processes; submillimeter: ISM
Issue or Number:1
Record Number:CaltechAUTHORS:20150825-110852960
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Official Citation:David A. Neufeld et al. 2015 ApJ 807 54 doi:10.1088/0004-637X/807/1/54
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:59884
Deposited By: George Porter
Deposited On:25 Aug 2015 20:44
Last Modified:10 Nov 2021 22:26

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