Volume 521, October 2010
Herschel/HIFI: first science highlights
|Number of page(s)||6|
|Published online||01 October 2010|
Letter to the Editor
California Institute of Technology, Pasadena, USA e-mail: email@example.com
2 Physikalisches Institut, Universität zu Köln, Köln, Germany
3 Max-Planck-Institut für Radioastronomie, Bonn, Germany
4 SRON, Groningen, The Netherlands
5 Laboratoire d'Astrophysique de Grenoble, UMR 5571-CNRS, Université Joseph Fourier, Grenoble, France
6 Université de Bordeaux, Laboratoire d'Astrophysique de Bordeaux, France; CNRS/INSU, UMR 5804, Floirac, France
7 INAF - Istituto di Fisica dello Spazio Interplanetario, Roma, Italy
8 Department of Astronomy, University of Michigan, Ann Arbor, USA
9 Infared Processing and Analysis Center, Caltech, Pasadena, USA
10 CESR, Université Toulouse 3 and CNRS, Toulouse, France
11 Observatoire de Paris-Meudon, LERMA UMR CNRS 8112, Meudon, France
12 School of Physics and Astronomy, University of Leeds, Leeds UK
13 Centro de Astrobiologìa, CSIC-INTA, Madrid, Spain
14 INAF Osservatorio Astrofisico di Arcetri, Florence, Italy
15 Astronomical Institute “Anton Pannekoek”, University of Amsterdam, Amsterdam, The Netherlands
16 Department of Astrophysics/IMAPP, Radboud University Nijmegen, Nijmegen, The Netherlands
17 IGN Observatorio Astronómico Nacional, Alcalá de Henares, Spain
18 Jet Propulsion Laboratory, Caltech, Pasadena, CA 91109, USA
19 Max-Planck-Institut fur Astronomie, Heidelberg, Germany
20 Ohio State University, Columbus, OH, USA
21 Max-Planck-Institut fur Sonnenphysikforschung, Lindau, Germany
22 Center for Astrophysics, Cambridge MA, USA
23 Johns Hopkins University, Baltimore MD, USA
24 INAF - Osservatorio Astronomico di Roma, Monte Porzio Catone, Italy
25 Institut de RadioAstronomie Millimétrique, Grenoble, France
26 Leiden Observatory, Leiden University, Leiden, The Netherlands
27 Department of Physics and Astronomy, University College London, London, UK
Accepted: 23 July 2010
Aims. We present observations of twelve rotational transitions of H216O, H218O, and H217O toward the massive star-forming region NGC 6334 I, carried out with Herschel/HIFI as part of the guaranteed time key program Chemical HErschel Surveys of Star forming regions (CHESS). We analyze these observations to obtain insights into physical processes in this region.
Methods. We identify three main gas components (hot core, cold foreground, and outflow) in NGC 6334 I and derive the physical conditions in these components.
Results. The hot core, identified by the emission in highly excited lines, shows a high excitation temperature of ~200 K, whereas water in the foreground component is predominantly in the ortho- and para- ground states. The abundance of water varies between 4 × 10-5 (outflow) and 10-8 (cold foreground gas). This variation is most likely due to the freeze-out of water molecules onto dust grains. The H218O/H217O abundance ratio is 3.2, which is consistent with the 18O/17O ratio determined from CO isotopologues. The ortho/para ratio in water appears to be relatively low (1.6±1) in the cold, quiescent gas, but close to the equilibrium value of three in the warmer outflow material (2.5±0.8).
Key words: stars: formation / ISM: molecules
Herschel is an ESA space observatory with science instruments provided by European-led principal Investigator consortia and with important participation from NASA.
Figures 1, 2 and 3 and Tables 2–4 (pages 5 to 6) are only available in electronic form at http://www.aanda.org
© ESO, 2010
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