Letter to the Editor

Herschel-SPIRE spectroscopy of the DR21 molecular cloud core^*

¹ Department of Physics & Astronomy, The Open University, UK e-mail: g.j.white@open.ac.uk
² Space Science Department, Rutherford Appleton Laboratory, Chilton, UK
³ Institut d'Astrophysique Spatiale, CNRS/Université Paris-Sud 11, 91405 Orsay, France
⁴ Institute for Space Imaging Science, University of Lethbridge, Lethbridge, Alberta, Canada
⁵ Laboratoire AIM, CEA/IRFU – CNRS/INSU – Université Paris Diderot, CEA-Saclay, 91191 Gif-sur-Yvette Cedex, France
⁶ Laboratoire d'Astrophysique de Marseille, UMR6110 CNRS, 38 rue F. Joliot-Curie, 13388 Marseille, France
⁷ Université de Toulouse; UPS; CESR; 9 avenue du colonel Roche, 31028 Toulouse Cedex 4, France
⁸ CNRS; UMR5187; 31028 Toulouse, France
⁹ Department of Physics and Astronomy, Cardiff University, Cardiff, UK
¹⁰ Canadian Institute for Theoretical Astrophysics, Toronto, Ontario, M5S 3H8, Canada
¹¹ CEA, Laboratoire AIM, Irfu/SAp, Orme des Merisiers, 91191 Gif-sur-Yvette, France
¹² University of California, Radio Astronomy Laboratory, Berkeley, 601 Campbell Hall, US Berkeley CA 94720-3411, USA
¹³ Institut de Radioastronomie Millimétrique (IRAM), 300 rue de la Piscine, 38406 Saint-Martin-d'Hères, France
¹⁴ Joint Astronomy Centre, University Park, Hilo, USA
¹⁵ Istituto di Fisica dello Spazio Interplanetario, INAF, Via del Fosso del Cavaliere 100, 00133 Roma, Italy
¹⁶ NASA-Goddard SFC, USA
¹⁷ Laboratoire des Signaux et Systèmes (CNRS Supélec Université Paris-Sud 11), Plateau de Moulon, 91192 Gif-sur-Yvette, France

Received: 31 March 2010
Accepted: 11 May 2010

Abstract

We present far-infrared spectra and maps of the DR21 molecular cloud core between 196 and 671 μm, using the Herschel-SPIRE spectrometer. Nineteen molecular lines originating from CO, ¹³CO, HCO⁺ and H₂O, plus lines of [N ii] and [CI] were recorded, including several transitions not previously detected. The CO lines are excited in warm gas with T_kin ~ 125 K and ~7 × 10⁴ cm^-3, CO column density N(CO) ~ 3.5 × 10¹⁸ cm^-2 and a filling factor of ~12%, and appear to trace gas associated with an outflow. The rotational temperature analysis incorporating observations from ground-based telescopes reveals an additional lower excitation CO compoment which has a temperature ~78 K and N(CO) ~ 4.5 × 10²¹ cm^-2.