HYDROGEN CHLORIDE IN DIFFUSE INTERSTELLAR CLOUDS ALONG THE LINE OF SIGHT TO W31C (G10.6-0.4)

Journal Article · Wed Apr 10 04:00:00 EDT 2013 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/767/1/81· OSTI ID:22167396

Monje, R. R.; Lis, D. C.; Phillips, T. G. ^[1]; Roueff, E. ^[2]; Gerin, M.; De Luca, M. ^[3]; Neufeld, D. A. ^[4]

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1. California Institute of Technology, MC 301-17, 1200 E. California Blvd., Pasadena, CA 91125-4700 (United States)
2. Observatoire de Paris-Meudon, LUTH UMR 8102, 5 Pl. Jules Janssen, F-92195 Meudon Cedex (France)
3. LERMA, CNRS, Observatoire de Paris and ENS, F-75231 Paris Cedex (France)
4. Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218 (United States)

We report the detection of hydrogen chloride, HCl, in diffuse molecular clouds on the line of sight toward the star-forming region W31C (G10.6-0.4). The J = 1-0 lines of the two stable HCl isotopologues, H{sup 35}Cl and H{sup 37}Cl, are observed using the 1b receiver of the Heterodyne Instrument for the Far-Infrared (HIFI) on board the Herschel Space Observatory. The HCl line is detected in absorption, over a wide range of velocities associated with diffuse clouds along the line of sight to W31C. The analysis of the absorption strength yields a total HCl column density of a few 10{sup 13} cm{sup -2}, implying that HCl accounts for {approx}0.6% of the total gas-phase chlorine, which exceeds the theoretical model predictions by a factor of {approx}6. This result is comparable to those obtained from the chemically related species H{sub 2}Cl{sup +} and HCl{sup +}, for which large column densities have also been reported on the same line of sight. The source of discrepancy between models and observations is still unknown; however, the detection of these Cl-bearing molecules provides key constraints for the chlorine chemistry in the diffuse gas.

• OSTI ID: 22167396
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 1 Vol. 767; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ABSORPTION
CHEMISTRY
CHLORINE
CLOUDS
DENSITY
DETECTION
HYDROGEN CHLORIDES
INTERSTELLAR SPACE
LIMITING VALUES
MOLECULES
STARS