HERSCHEL OBSERVATIONS OF INTERS℡LAR CHLORONIUM. II. DETECTIONS TOWARD G29.96-0.02, W49N, W51, AND W3(OH), AND DETERMINATIONS OF THE ORTHO-TO-PARA AND (CI)-C-35/(CI)-C-37 ISOTOPIC

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

1 HSU - Humboldt State University
2 LERMA - Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique
3 LAM - Laboratoire d'Astrophysique de Marseille
4 JPL - Jet Propulsion Laboratory
5 OHIO STATE UNIVERSITY - Department of Physics
6 Departments of Astronomy and Chemistry
7 Millimeter and Submillimeter Astronomy
8 CSO - CalTech-CSO
9 TIFR - Tata Institute for Fundamental Research
10 OSO - Onsala Space Observatory
11 I. Physikalisches Institut [Köln]
12 Department of Physics and Astronomy [Baltimore]

We report additional detections of the chloronium molecular ion, H2Cl+, 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-(H2Cl+)-Cl-35 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(H2Cl+)/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-(H2Cl+)-Cl-37 at 780.053 GHz and the 1(11)-1(00) transition of para-(H2Cl+)-Cl-35 at 485.418 GHz. These observations imply (H2Cl+)-Cl-35/ (H2Cl+)-Cl-37 column density ratios that are consistent with the solar system Cl-35/Cl-37 isotopic ratio of 3.1, and chloronium ortho-to-para ratios consistent with 3, the ratio of spin statistical weights.

Domaines: Astrophysique [astro-ph]

David A. Neufeld, John H. Black, Maryvonne Gerin, Javier R. Goicoechea, Paul F. Goldsmith, et al.. HERSCHEL OBSERVATIONS OF INTERS℡LAR CHLORONIUM. II. DETECTIONS TOWARD G29.96-0.02, W49N, W51, AND W3(OH), AND DETERMINATIONS OF THE ORTHO-TO-PARA AND (CI)-C-35/(CI)-C-37 ISOTOPIC. The Astrophysical Journal, 2015, 807 (1), ⟨10.1088/0004-637X/807/1/54⟩. ⟨hal-01439985⟩