Detection of hydrogen fluoride absorption in diffuse molecular clouds with Herschel/HIFI: an ubiquitous tracer of molecular gas
Artikel i vetenskaplig tidskrift, 2010

We discuss the detection of absorption by interstellar hydrogen fluoride (HF) along the sight line to the submillimeter continuum sources W49N and W51. We have used Herschel's HIFI instrument in dual beam switch mode to observe the 1232.4762 GHz J = 1-0 HF transition in the upper sideband of the band 5a receiver. We detected foreground absorption by HF toward both sources over a wide range of velocities. Optically thin absorption components were detected on both sight lines, allowing us to measure - as opposed to obtain a lower limit on - the column density of HF for the first time. As in previous observations of HF toward the source G10.6-0.4, the derived HF column density is typically comparable to that of water vapor, even though the elemental abundance of oxygen is greater than that of fluorine by four orders of magnitude. We used the rather uncertain N(CH) - N(H-2) relationship derived previously toward diffuse molecular clouds to infer the molecular hydrogen column density in the clouds exhibiting HF absorption. Within the uncertainties, we find that the abundance of HF with respect to H-2 is consistent with the theoretical prediction that HF is the main reservoir of gas-phase fluorine for these clouds. Thus, hydrogen fluoride has the potential to become an excellent tracer of molecular hydrogen, and provides a sensitive probe of clouds of small H-2 column density. Indeed, the observations of hydrogen fluoride reported here reveal the presence of a low column density diffuse molecular cloud along the W51 sight line, at an LSR velocity of similar to 24 km s(-1), that had not been identified in molecular absorption line studies prior to the launch of Herschel.

regions

ISM: molecules

line-of-sight

h2o

w51

astrochemistry

co

astronomy

abundance

w49n

submillimeter: ISM

molecular processes

Författare

P. Sonnentrucker

Johns Hopkins University

D. A. Neufeld

Johns Hopkins University

T. G. Phillips

CalTech

M. Gerin

LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres

D. C. Lis

CalTech

M. de Luca

LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres

J. R. Goicoechea

Centro de Astrobiologia (CAB)

John H Black

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

T. A. Bell

CalTech

F. Boulanger

Institut d'Astrophysique Spatiale

J. Cernicharo

Centro de Astrobiologia (CAB)

A. Coutens

Université de Toulouse

E. Dartois

Institut d'Astrophysique Spatiale

M. Kazmierczak

Uniwersytet Mikołaja Kopernika w Toruniu

P. Encrenaz

LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres

E. Falgarone

LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres

T. R. Geballe

Gemini Telescope

T. Giesen

Universität zu Köln

B. Godard

LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres

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

LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres

E. Herbst

Ohio State University

P. Hily-Blant

Laboratoire d'Astrophysique de Grenoble

C. Joblin

Université de Toulouse

R. Kolos

Polish Academy of Sciences

J. Krelowski

Uniwersytet Mikołaja Kopernika w Toruniu

J. Martin-Pintado

Centro de Astrobiologia (CAB)

K. M. Menten

Max Planck-institutet

Raquel Monje

CalTech

B. Mookerjea

Tata Institute of Fundamental Research

J. C. Pearson

Jet Propulsion Laboratory, California Institute of Technology

M. Perault

LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres

Carina Persson

Chalmers, Rymd- och geovetenskap, Radioastronomi och astrofysik

R. Plume

University of Calgary

M. Salez

LERMA - Laboratoire d'Etudes du Rayonnement et de la Matiere en Astrophysique et Atmospheres

S. Schlemmer

Universität zu Köln

M. Schmidt

Polish Academy of Sciences

J. Stutzki

Universität zu Köln

D. Teyssier

European Space Astronomy Centre (ESA)

C. Vastel

Université de Toulouse

S. Yu

Jet Propulsion Laboratory, California Institute of Technology

E. Caux

Université de Toulouse

R. Güsten

Max Planck-institutet

W. A. Hatch

Jet Propulsion Laboratory, California Institute of Technology

T. Klein

Max Planck-institutet

Imran Mehdi

Jet Propulsion Laboratory, California Institute of Technology

P. Morris

CalTech

J. S. Ward

Jet Propulsion Laboratory, California Institute of Technology

Astronomy and Astrophysics

0004-6361 (ISSN) 1432-0746 (eISSN)

Vol. 521 1 Article Number: L12- L12

Ämneskategorier

Astronomi, astrofysik och kosmologi

DOI

10.1051/0004-6361/201015082

Mer information

Senast uppdaterat

2018-11-05