Volume 518, July-August 2010
Herschel: the first science highlights
|Number of page(s)||5|
|Published online||16 July 2010|
Letter to the Editor
SPIRE spectroscopy of the prototypical Orion Bar photodissociation region*
Institut d'Astrophysique Spatiale, UMR 8617, CNRS/Université Paris-Sud 11, 91405 Orsay, France e-mail: email@example.com
2 Laboratoire d'Astrophysique de Marseille (UMR 6110 CNRS & Université de Provence), 38 rue F. Joliot-Curie, 13388 Marseille Cedex 13, France
3 Institute for Space Imaging Science, University of Lethbridge, Lethbridge, Canada
4 The Rutherford Appleton Laboratory, Chilton, Didcot OX11 0QX, UK
5 CESR, Université de Toulouse, UPS, CESR, 9 Av. du colonel Roche, 31028 Toulouse Cedex 4, France
6 CNRS, UMR5187, 31028 Toulouse, France
7 Department of Physics and Astronomy, Cardiff University, Cardiff, UK
8 CEA, Laboratoire AIM, Irfu/SAp, Orme des Merisiers, 91191 Gif-sur-Yvette, France
9 Canadian Institute for Theoretical Astrophysics, Toronto, Ontario, M5S 3H8, Canada
10 CNRS/INSU, Laboratoire d'Astrophysique de Bordeaux, UMR 5804, BP 89, 33271 Floirac Cedex, France
11 University of California, Radio Astronomy Laboratory, Berkeley, 601 Campbell Hall, US Berkeley CA 94720-3411, USA
12 Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, 38406 Saint-Martin-d'Hères, France
13 Joint Astronomy Centre, University Park, Hilo, USA
14 Blue Sky Spectrosocpy Inc, Lethbridge, Canada
15 National Astronomical Observatories, PR China
16 Istituto di Fisica dello Spazio Interplanetario, INAF, via del Fosso del Cavaliere 100, 00133 Roma, Italy
17 NASA - Goddard SFC, USA
18 Department of Physics & Astronomy, The Open University, Milton Keynes MK7 6AA, UK
Accepted: 14 May 2010
Aims. We present observations of the Orion Bar photodissociation region (PDR) obtained with the SPIRE instrument on-board Herschel.
Methods. We obtained SPIRE Fourier-transform spectrometer (FTS) sparse sampled maps of the Orion bar.
Results. The FTS wavelength coverage and sensitivity allow us to detect a wealth of rotational lines of CO (and its isotopologues), fine structure lines of C and N+, and emission lines from radicals and molecules such as CH+, CH, H2O or H2S. For species detected from the ground, our estimates of the column densities agree with previously published values. The comparison between 12CO and 13CO maps shows particularly the effects of optical depth and excitation in the molecular cloud. The distribution of the 12CO and 13CO lines with upper energy levels indicates the presence of warm (~100–150 K) CO. This warm CO component is a significant fraction of the total molecular gas, confirming previous ground based studies.
Key words: infrared: ISM / ISM: lines and bands / ISM: molecules / evolution / submillimeter: ISM / ISM: general
© ESO, 2010
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