Chlorine in dense interstellar clouds : the abundance of HCl in OMC-1.
Abstract
The first detection of a chlorine-bearing molecular species in the interstellar medium via emission from the J = 1-0 transition of HCl at 625.9 GHz toward OMC-1 is reported. The relative strengths, widths, and velocities of the resolved hyperfine components are consistent with moderate optical depth emission originating from dense, quiescent molecular cloud material. The overall emission strength implies a fractional abundance of f(HCl/H2) of about (0.5-5.0) x 10 to the -8th, depending on the density of the emitting region. This is approximately an order of magnitude below previous theoretical estimates and a factor of 3-30 below the cosmic abundance of Cl. Recent laboratory work suggests that the lowered fractional abundance of HCl is caused by a combination of depletion onto grains with gas-phase loss processes such as the reaction of HCl with C(+).
- Publication:
-
The Astrophysical Journal
- Pub Date:
- August 1985
- DOI:
- 10.1086/163394
- Bibcode:
- 1985ApJ...295..501B
- Keywords:
-
- Astronomical Spectroscopy;
- Chlorine;
- Hydrochloric Acid;
- Interstellar Chemistry;
- Interstellar Gas;
- Molecular Clouds;
- Abundance;
- Emission Spectra;
- Optical Thickness;
- Astrophysics