Letter to the Editor

Herschel spectral surveys of star-forming regions ^*,**

Overview of the 555–636 GHz range

¹ Laboratoire d'Astrophysique de Grenoble, UMR 5571-CNRS, Université Joseph Fourier, Grenoble, France e-mail: cecilia.ceccarelli@obs.ujf-grenoble.fr
² Université de Bordeaux, Laboratoire d'Astrophysique de Bordeaux, Floirac, France
³ CNRS/INSU, UMR 5804, Floirac Cedex, France
⁴ Infared Processing and Analysis Center, Caltech, Pasadena, USA
⁵ Centre d'Etude Spatiale des Rayonnements, Université Paul Sabatier, Toulouse, France
⁶ CNRS/INSU, UMR 5187, Toulouse, France
⁷ Astronomical Institute “Anton Pannekoek”, University of Amsterdam, Amsterdam, The Netherlands
⁸ Department of Astrophysics/IMAPP, Radboud University Nijmegen, Nijmegen, The Netherlands
⁹ California Institute of Technology, Pasadena, USA
¹⁰ Max-Planck-Institut für Radioastronomie, Bonn, Germany
¹¹ Physikalisches Institut, Universität zu Köln, Köln, Germany
¹² SRON Netherlands Institute for Space Research, Groningen, The Netherlands
¹³ Kapteyn Astronomical Institute, University of Groningen, The Netherlands
¹⁴ INAF - Istituto di Fisica dello Spazio Interplanetario, Roma, Italy
¹⁵ School of Physics and Astronomy, University of Leeds, Leeds, UK
¹⁶ Centro de Astrobiologìa, CSIC-INTA, Madrid, Spain
¹⁷ INAF Osservatorio Astrofisico di Arcetri, Florence Italy
¹⁸ IGN Observatorio Astronómico Nacional, Alcalá de Henares, Spain
¹⁹ Department of Astronomy, University of Michigan, Ann Arbor, USA
²⁰ Laboratoire d'Études du Rayonnement et de la Matière en Astrophysique, UMR 8112 CNRS/INSU, OP, ENS, UPMC, UCP, Paris, France
²¹ Jet Propulsion Laboratory, Caltech, Pasadena, CA 91109, USA
²² Max-Planck-Institut für Astronomie, Heidelberg, Germany
²³ Ohio State University, Columbus, OH, USA
²⁴ Harvard-Smithsonian Center for Astrophysics, Cambridge MA, USA
²⁵ Johns Hopkins University, Baltimore MD, USA
²⁶ INAF - Osservatorio Astronomico di Roma, Monte Porzio Catone, Italy
²⁷ Institut de RadioAstronomie Millimétrique, Grenoble, France
²⁸ Leiden Observatory, Leiden University, Leiden, The Netherlands
²⁹ Department of Physics and Astronomy, University College London, London, UK
³⁰ Chalmers University of Technology, Department of Astronomy, Stockholm University, Stockholm, Sweden
³¹ N. Copernicus Astronomical Center, Torun, Poland
³² Institute of Astronomy, ETH Zurich, 8093 Zurich, Switzerland
³³ Institut für 4D-Technologien, Switzerland

Received: 29 May 2010
Accepted: 7 July 2010

Abstract

High resolution line spectra of star-forming regions are mines of information: they provide unique clues to reconstruct the chemical, dynamical, and physical structure of the observed source. We present the first results from the Herschel key project “Chemical HErschel Surveys of Star forming regions”, CHESS. We report and discuss observations towards five CHESS targets, one outflow shock spot and four protostars with luminosities bewteen 20 and 2 × 10⁵ : L1157-B1, IRAS 16293-2422, OMC2-FIR4, AFGL 2591, and NGC 6334I. The observations were obtained with the heterodyne spectrometer HIFI on board Herschel, with a spectral resolution of 1 MHz. They cover the frequency range 555–636 GHz, a range largely unexplored before the launch of the Herschel satellite. A comparison of the five spectra highlights spectacular differences in the five sources, for example in the density of methanol lines, or the presence/absence of lines from S-bearing molecules or deuterated species. We discuss how these differences can be attributed to the different star-forming mass or evolutionary status.