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 35Cl/37Cl ISOTOPIC RATIOS
Journal article, 2015
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 212-101 transition of ortho-H235Cl+ 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)× 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 212-101 transition of ortho-H237Cl+ at 780.053 GHz and the 111-000 transition of para-H235Cl+ at 485.418 GHz. These observations imply H235Cl+/H237Cl+ column density ratios that are consistent with the solar system 35Cl/37Cl isotopic ratio of 3.1, and chloronium ortho-to-para ratios consistent with 3, the ratio of spin statistical weights.
Author
D.A. Neufeld
Johns Hopkins University
John H Black
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
M. Gerin
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
Pierre and Marie Curie University (UPMC)
J.R. Goicoechea
CSIC - Instituto de Ciencia de Materiales de Madrid (ICMM)
P.F. Goldsmith
Jet Propulsion Laboratory, California Institute of Technology
C. Gry
Laboratoire d'Astrophysique de Marseille
H. Gupta
California Institute of Technology (Caltech)
E. Herbst
University of Virginia
N. Indriolo
University of Michigan
D. Lis
California Institute of Technology (Caltech)
LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres
K.M. Menten
Max Planck Society
Raquel Monje
California Institute of Technology (Caltech)
B. Mookerjea
Tata Institute of Fundamental Research
Carina Persson
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
P. Schilke
University of Cologne
P. Sonnentrucker
Space Telescope Science Institute (STScI)
M.G. Wolfire
University of Maryland
Astrophysical Journal
0004-637X (ISSN) 1538-4357 (eISSN)
Vol. 807 1 54Subject Categories
Fusion, Plasma and Space Physics
DOI
10.1088/0004-637X/807/1/54