Letter to the Editor

Detection of HD in emission towards Sagittarius B2 ^*

¹ Astrophysics, University of Oxford, Keble Road, Oxford, OX1 3RH, UK
² Rutherford Appleton Laboratory, Chilton, Didcot, Oxfordshire, OX11 0QX, UK
³ Laboratoire d'Astrophysique de Marseille, CNRS & Université de Provence, BP 8, 13376 Marseille Cedex 12, France
⁴ Observatoire de Bordeaux, BP 89, 33270 Floirac, France
⁵ Laboratoire d'Astrophysique, Observatoire de Grenoble, BP 53, 38041 Grenoble Cedex 09, France
⁶ CESR CNRS-UPS, BP 4346, 31028 Toulouse Cedex 04, France

Corresponding author: E. Polehampton, etp@astro.ox.ac.uk

Received: 4 February 2002
Accepted: 23 April 2002

Abstract

The giant molecular cloud Sagittarius B2, located near the Galactic Centre, has been observed in the far-infrared by the ISO Long Wavelength Spectrometer. Wavelengths in the range 47–196 μm were covered with the high resolution Fabry-Pérot spectrometer, giving a spectral resolution of 30–40 km s^-1. The and rotational transitions of HD fall within this range at 112 μm and 56 μm. A probable detection was made of the ground state line in emission but the line was not detected above the noise. This allowed us to calculate an upper limit on the temperature in the emitting region of approximately 80 K and a value for the deuterium abundance in the Sgr B2 envelope of .