Zmuidzinas, J. and Blake, G. A. and Carlstrom, J. and Keene, J. and Miller, D. (1995) HCl Absorption Toward Sagittarius B2. Astrophysical Journal Letters, 447 (2). L125-L128. ISSN 0004-637X http://resolver.caltech.edu/CaltechAUTHORS:20120912-133126871
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We have detected the 626 GHz J = 1 → 0 transition of hydrogen chloride (H^(35)Cl) in absorption against the dust continuum emission of the molecular cloud Sagittarius B2. The observed line shape is consistent with the blending of the three hyperfine components of this transition by the velocity profile of Sgr B2 observed in other species. The apparent optical depth of the line is t ≈ 1, and the minimum HCl column density is 1.6 x 10^(14) cm^(-2) A detailed radiative transfer model was constructed which includes collisional and radiative excitation, absorption and emission by dust, and the radial variation of temperature and density. Good agreement between the model and the data is obtained for HCl/H_2 ~ 1.1 x 10^(-9). Comparison of this result to chemical models indicates that the depletion factor of gas-phase chlorine is between 50–180 in the molecular envelope surrounding the SgrB2(N) and (M) dust cores.
|Additional Information:||© 1995 American Astronomical Society. Received 1995 Mar 9; accepted 1995 April 27. We thank P. Schilke for providing the results of his chlorine chemistry calculations, D. Lis for his contributions to both the correlator and radiative transfer software, and P. Schilke, D. Lis, W. Langer, and T. G. Phillips for helpful discussions. We are especially grateful to the crew of the NASA Kuiper Airborne Observatory for their outstanding support of this new project. The SIS devices were fabricated by H. G. LeDuc at the Center for Space Microelectronics Technology, Jet Propulsion Laboratory, California Institute of Technology. This work was supported in part by grants from NASA (NAG2-744 and NAGW-107), NASA/JPL, and an NSF Presidential Young Investigator grant to J. Zmuidzinas.|
|Subject Keywords:||ISM: abundances; ISM: individual (Sagittarius B2); ISM: molecules|
|Official Citation:||HCl Absorption toward Sagittarius B2 J. Zmuidzinas et al. 1995 ApJ 447 L125|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Ruth Sustaita|
|Deposited On:||12 Sep 2012 20:54|
|Last Modified:||26 Dec 2012 16:09|
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