Strong absorption by interstellar hydrogen fluoride: Herschel/HIFI observations of the sight-line to G10.6-0.4 (W31C)
Journal article, 2010
We report the detection of strong absorption by interstellar hydrogen fluoride along the sight-line to the submillimeter continuum source G10.6-0.4 (W31C). We have used Herschel's HIFI instrument, in dual beam switch mode, to observe the 1232.4763 GHz J=1-0 HF transition in the upper sideband of the Band 5a receiver. The resultant spectrum shows weak HF emission from G10.6-0.4 at LSR velocities in the range -10 to -3 km/s, accompanied by strong absorption by foreground material at LSR velocities in the range 15 to 50 km/s. The spectrum is similar to that of the 1113.3430 GHz 1(11)-0(00) transition of para-water, although at some frequencies the HF (hydrogen fluoride) optical depth clearly exceeds that of para-H2O. The optically-thick HF absorption that we have observed places a conservative lower limit of 1.6E+14 cm-2 on the HF column density along the sight-line to G10.6-0.4. Our lower limit on the HF abundance, 6E-9 relative to hydrogen nuclei, implies that hydrogen fluoride accounts for between ~ 30 and 100% of the fluorine nuclei in the gas phase along this sight-line. This observation corroborates theoretical predictions that - because the unique thermochemistry of fluorine permits the exothermic reaction of F atoms with molecular hydrogen - HF will be the dominant reservoir of interstellar fluorine under a wide range of conditions.
Author
D.A. Neufeld
Johns Hopkins University
P. Sonnentrucker
Johns Hopkins University
T.G. Phillips
California Institute of Technology (Caltech)
D. Lis
California Institute of Technology (Caltech)
M. de Luca
Ecole Normale Superieure (ENS)
J. R. Goicoechea
Centro de Astrobiologia (CAB)
John H Black
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
M. Gerin
Ecole Normale Superieure (ENS)
T. A. Bell
California Institute of Technology (Caltech)
F. Boulanger
Institut d'Astrophysique Spatiale
J. Cernicharo
Centro de Astrobiologia (CAB)
A. Coutens
University of Toulouse
E. Dartois
Institut d'Astrophysique Spatiale
M. Kazmierczak
Nicolaus Copernicus University
P. Encrenaz
Ecole Normale Superieure (ENS)
E. Falgarone
Ecole Normale Superieure (ENS)
Thomas Geballe
Gemini Observatory North
T. Giesen
University of Cologne
B. Godard
Ecole Normale Superieure (ENS)
P.F. Goldsmith
Jet Propulsion Laboratory, California Institute of Technology
C. Gry
Laboratoire d'Astrophysique de Marseille
H. Gupta
Jet Propulsion Laboratory, California Institute of Technology
P. Hennebelle
Ecole Normale Superieure (ENS)
E. Herbst
Ohio State University
P. Hily-Blant
Laboratoire d'Astrophysique de Grenoble
C. Joblin
University of Toulouse
R. Kolos
Polish Academy of Sciences
J. Krelowski
Nicolaus Copernicus University
J. Martin-Pintado
Centro de Astrobiologia (CAB)
K.M. Menten
Max Planck Society
Raquel Monje
California Institute of Technology (Caltech)
B. Mookerjea
Tata Institute of Fundamental Research
T. J. Pearson
Jet Propulsion Laboratory, California Institute of Technology
M. Perault
Ecole Normale Superieure (ENS)
Carina Persson
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
R. Plume
University of Calgary
M. Salez
Ecole Normale Superieure (ENS)
S. Schlemmer
University of Cologne
M. Schmidt
Polish Academy of Sciences
J. Stutzki
University of Cologne
D. Teyssier
European Space Astronomy Centre (ESAC)
C. Vastel
Tata Institute of Fundamental Research
S. Yu
Jet Propulsion Laboratory, California Institute of Technology
P. Cais
University of Bordeaux
E. Caux
University of Toulouse
René Liseau
Chalmers, Earth and Space Sciences, Radio Astronomy and Astrophysics
P. Morris
Jet Propulsion Laboratory, California Institute of Technology
P. Planesas
Atacama Large Millimeter-submillimeter Array (ALMA)
Astronomy and Astrophysics
0004-6361 (ISSN) 1432-0746 (eISSN)
Vol. 518 4 108- L108Subject Categories
Astronomy, Astrophysics and Cosmology
DOI
10.1051/0004-6361/201014523