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 {sup 35}Cl/{sup 37}Cl isotopic ratios

Journal Article · Wed Jul 01 00:00:00 EDT 2015 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/807/1/54· OSTI ID:22882970

Neufeld, David A. ^[1]; Black, John H.; Persson, Carina ^[2]; Gerin, Maryvonne; Lis, Dariusz ^[3]; Goicoechea, Javier R. ^[4]; Goldsmith, Paul F. ^[5]; Gry, Cecile ^[6]; Gupta, Harshal; Monje, Raquel ^[7]; Herbst, Eric ^[8]; Indriolo, Nick ^[9]; Menten, Karl M. ^[10]; Mookerjea, Bhaswati ^[11]; Schilke, Peter ^[12]; Sonnentrucker, Paule ^[13]; Wolfire, Mark G. ^[14]

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1. Department of Physics and Astronomy, Johns Hopkins University, 3400 N. Charles St., Baltimore, MD 21218 (United States)
2. Department of Earth and Space Sciences, Chalmers University of Technology, Onsala (Sweden)
3. LERMA, Observatoire de Paris, PSL Research University, CNRS, UMR 8112, F-75014, Paris (France)
4. Grupo de Astrofísica Molecular, Instituto de Ciencia de Materiales de Madrid (ICMM, CSIC), Sor Juana Ines de la Cruz 3, E-28049 Cantoblanco, Madrid (Spain)
5. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109-8099 (United States)
6. Aix Marseille Université, CNRS, LAM (Laboratoire d’Astrophysique de Marseille) UMR 7326, F-13388 Marseille (France)
7. California Institute of Technology, Pasadena, CA 91125 (United States)
8. Departments of Chemistry, Astronomy, and Physics, University of Virginia, Charlottesville, VA 22904 (United States)
9. Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States)
10. Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany)
11. Tata Institute of Fundamental Research, Homi Bhabha Road, Mumbai 400005 (India)
12. I. Physikalisches Institut der Universität zu Köln, Zülpicher Str. 77, 50937 Köln (Germany)
13. Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States)
14. Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)

We report additional detections of the chloronium molecular ion, H{sub 2}Cl{sup +}, 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{sub 12}−1{sub 01} transition of ortho-H{sub 2}{sup 35}Cl{sup +} 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{sub 2}Cl{sup +})/N(H) ratio lie in the range (0.9–4.8) × 10{sup −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{sub 12}−1{sub 01} transition of ortho-H{sub 2}{sup 37}Cl{sup +} at 780.053 GHz and the 1{sub 11}−0{sub 00} transition of para-H{sub 2}{sup 35}Cl{sup +} at 485.418 GHz. These observations imply H{sub 2}{sup 35}Cl{sup +}/H{sub 2}{sup 37}Cl{sup +} column density ratios that are consistent with the solar system {sup 35}Cl/{sup 37}Cl isotopic ratio of 3.1, and chloronium ortho-to-para ratios consistent with 3, the ratio of spin statistical weights.

• OSTI ID: 22882970
• Journal Information: Astrophysical Journal, Vol. 807, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
• Country of Publication: United Kingdom
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ABSORPTION
CHLORINE 35
CHLORINE 37
COSMIC GASES
ELEMENT ABUNDANCE
FORECASTING
HYDROGEN
ISOTOPE RATIO
MOLECULAR IONS
MOLECULES
SPACE