Issue |
A&A
Volume 518, July-August 2010
Herschel: the first science highlights
|
|
---|---|---|
Article Number | L118 | |
Number of page(s) | 5 | |
Section | Letters | |
DOI | https://doi.org/10.1051/0004-6361/201014671 | |
Published online | 16 July 2010 |
Letter to the Editor
Strong CH+ J = 1–0 emission and absorption in DR21*
1
LERMA, CNRS, Observatoire de Paris & Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France e-mail: maryvonne.gerin@lra.ens.fr
2
I. Physikalisches Institut der Universität zu Köln, Zülpicher Straße 77, 50937 Köln, Germany
3
SRON Netherlands Institute for Space Research, PO Box 800, 9700 AV Groningen, The Netherlands
4
Institut d'Astrophysique Spatiale, CNRS and Université Paris-Sud, Bât. 121, 91405 Orsay Cedex, France
5
Jet Propulsion Laboratory, Caltech, 4800 Oak Grove Drive, Pasadena CA 91109-8099, USA
6
LERMA, CNRS & Observatoire de Paris, 61 Av. de l'Observatoire, Paris, France
7
CESR, CNRS and Université Paul Sabatier, 9 Avenue du Colonel Roche, 31062 Toulouse, France
8
Institute for Astronomy, ETH Zürich, 8093 Zürich, Switzerland
9
Observatorio Astronómico Nacional (OAN), Apdo. 112, 28803 Alcalá de Henares (Madrid), Spain
10
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
11
Astronomy Department, University of Maryland, College Park, MD 20742, USA
12
Instituto de Radio Astronomía Milimétrica (IRAM), Avenida Divina Pastora 7, Local 20, 18012 Granada, Spain
13
IPAC/Caltech, MS 100-22, Pasadena, CA 91125, USA
14
Department of Astronomy and Astrophysics, University of Toronto, 60 St. George Street, Toronto, ON M5S 3H8, Canada
15
Centro de Astrobiología, CSIC-INTA, 28850 Madrid, Spain
16
Department of Physics and Astronomy, John Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
17
California Institute of Technology, 320-47, Pasadena, CA 91125-4700, USA
18
Kapteyn Astronomical Institute, University of Groningen, PO box 800, 9700 AV Groningen, The Netherlands
19
European Space Astronomy Centre, Urb. Villafranca del Castillo, PO Box 50727, Madrid 28080, Spain
20
University of Massachusetts, Astronomy Dept., Amherst, MA 01003-9305 USA
21
Department of Physics and Astronomy, University of Waterloo, N2L 3G1, Canada
Received:
31
March
2010
Accepted:
15
May
2010
We report the first detection of the ground-state rotational transition of the methylidyne cation CH+ towards the massive star-forming region DR 21 with the HIFI instrument onboard the Herschel satellite. The line profile exhibits a broad emission line, in addition to two deep and broad absorption features associated with the DR 21 molecular ridge and foreground gas. These observations allow us to determine a 12CH+J = 1–0 line frequency of ν = 835 137 ± 3 MHz, in good agreement with a recent experimental determination. We estimate the CH+ column density to be a few 1013 cm-2 in the gas seen in emission, and >1014 cm-2 in the components responsible for the absorption, which is indicative of a high line of sight average abundance [CH+] /[H] > 1.2 × 10-8. We show that the CH+ column densities agree well with the predictions of state-of-the-art C-shock models in dense UV-illuminated gas for the emission line, and with those of turbulent dissipation models in diffuse gas for the absorption lines.
Key words: astrochemistry / ISM: molecules / ISM: kinematics and dynamics / turbulence
© ESO, 2010
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