Letter to the Editor
Institute of Astronomy, ETH Zurich, 8093 Zurich, Switzerland e-mail: email@example.com
2 Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
3 Max Planck Institut für extraterrestrische Physik, Giessenbachstrasse 1, 85748 Garching, Germany
4 Institute of 4D Technologies, University of Applied Sciences NW, 5210 Windisch, Switzerland
5 Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
6 Department of Physics and Astronomy, Denison University, Granville, OH, 43023, USA
7 SRON Netherlands Institute for Space Research, PO Box 800, 9700 AV, Groningen, The Netherlands
8 Kapteyn Astronomical Institute, University of Groningen, PO Box 800, 9700 AV, Groningen, The Netherlands
9 Laboratory for Electromagnetic Fields and Microwave Electronics, ETH Zurich, 8092 Zurich, Switzerland
10 Observatorio Astronómico Nacional (IGN), Calle Alfonso XII 3, 28014 Madrid, Spain
11 Université de Bordeaux, Laboratoire d'Astrophysique de Bordeaux, France; CNRS/INSU, UMR 5804, Floirac, France
12 INAF - Istituto di Fisica dello Spazio Interplanetario, Area di Ricerca di Tor Vergata, via Fosso del Cavaliere 100, 00133 Roma, Italy
13 Department of Astronomy, The University of Michigan, 500 Church Street, Ann Arbor, MI 48109-1042, USA
14 Department of Radio and Space Science, Chalmers University of Technology, Onsala Space Observatory, 439 92 Onsala, Sweden
15 California Institute of Technology, Division of Geological and Planetary Sciences, MS 150-21, Pasadena, CA 91125, USA
16 School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
17 INAF - Osservatorio Astrofisico di Arcetri, Largo E. Fermi 5, 50125 Firenze, Italy
18 Centro de Astrobiología. Departamento de Astrofísica. CSIC-INTA. Carretera de Ajalvir, Km 4, Torrejón de Ardoz, 28850 Madrid, Spain.
19 Astronomical Institute Anton Pannekoek, University of Amsterdam, Kruislaan 403, 1098 SJ Amsterdam, The Netherlands
20 Department of Astrophysics/IMAPP, Radboud University Nijmegen, PO Box 9010, 6500 GL Nijmegen, The Netherlands
21 LERMA and UMR 8112 du CNRS, Observatoire de Paris, 61 Av. de l'Observatoire, 75014 Paris, France
22 University of Waterloo, Department of Physics and Astronomy, Waterloo, Ontario, Canada
23 Observatorio Astronómico Nacional, Apartado 112, 28803 Alcalá de Henares, Spain
24 INAF - Osservatorio Astronomico di Roma, 00040 Monte Porzio catone, Italy
25 National Research Council Canada, Herzberg Institute of Astrophysics, 5071 West Saanich Road, Victoria, BC V9E 2E7, Canada
26 Department of Physics and Astronomy, University of Victoria, Victoria, BC V8P 1A1, Canada
27 Centre for Star and Planet Formation, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen K., Denmark
28 Department of Astronomy, Stockholm University, AlbaNova, 106 91 Stockholm, Sweden
29 California Institute of Technology, Cahill Center for Astronomy and Astrophysics, MS 301-17, Pasadena, CA 91125, USA
30 The University of Western Ontario, Department of Physics and Astronomy, London, Ontario, N6A 3K7, Canada
31 Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, MS 42, Cambridge, MA 02138, USA
32 Department of Physics and Astronomy, Johns Hopkins University, 3400 North Charles Street, Baltimore, MD 21218, USA
33 KOSMA, I. Physik. Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany
34 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
35 Department of Physics and Astronomy, University of Calgary, Calgary, T2N 1N4, AB, Canada
36 Instituto de Radioastronomía Milimétrica (IRAM), Avenida Divina Pastora 7, Núcleo Central, 18012 Granada, Spain
Accepted: 14 July 2010
Context. Hydrides of the most abundant heavier elements are fundamental molecules in cosmic chemistry. Some of them trace gas irradiated by UV or X-rays.
Aims. We explore the abundances of major hydrides in W3 IRS5, a prototypical region of high-mass star formation.
Methods. W3 IRS5 was observed by HIFI on the Herschel Space Observatory with deep integration (2500 s) in 8 spectral regions.
Results. The target lines including CH, NH, H3O+, and the new molecules SH+, H2O+, and OH+ are detected. The H2O+ and OH+ J = 1–0 lines are found mostly in absorption, but also appear to exhibit weak emission (P-Cyg-like). Emission requires high density, thus originates most likely near the protostar. This is corroborated by the absence of line shifts relative to the young stellar object (YSO). In addition, H2O+ and OH+ also contain strong absorption components at a velocity shifted relative to W3 IRS5, which are attributed to foreground clouds.
Conclusions. The molecular column densities derived from observations correlate well with the predictions of a model that assumes the main emission region is in outflow walls, heated and irradiated by protostellar UV radiation.
Key words: astrochemistry / line: identification / stars: formation / stars: massive / photon-dominated region / submillimeter: ISM
Herschel is an ESA space observatory with science instruments provided by a European-led Principal Investigator consortia and with important participation from NASA.
Appendix (page 5) is only available in electronic form at http://www.aanda.org
© ESO, 2010