Letter to the Editor

Detection of anhydrous hydrochloric acid, HCl, in IRC +10216 with the Herschel SPIRE and PACS spectrometers ^*

Detection of HCl in IRC +10216

¹ Departamento de Astrofísica, Centro de Astrobiología, CSIC-INTA, Ctra. de Torrejón a Ajalvir km 4, Torrejón de Ardoz, 28850 Madrid, Spain e-mail: jcernicharo@cab.inta-csic.es
² Instituut voor Sterrenkunde, Katholieke Universiteit Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium
³ Sterrenkundig Instituut Anton Pannekoek, University of Amsterdam, Science Park 904, 1098 Amsterdam, The Netherlands
⁴ Dept of Physics & Astronomy, University College London, Gower St, London WC1E 6BT, UK
⁵ LUTH, Observatoire de Paris-Meudon, 5 Place Jules Janssen, 92190 Meudon, France
⁶ Space Science and Technology Department, Rutherford Appleton Laboratory, Oxfordshire, OX11 0QX, UK
⁷ Department of Physics, University of Lethbridge, Lethbridge, Alberta, T1J 1B1, Canada
⁸ Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse, 85748, Germany
⁹ School of Physics and Astronomy, Cardiff University, 5 The Parade, Cardiff, Wales CF24 3AA, UK
¹⁰ Royal Observatory of Belgium, Ringlaan 3, 1180 Brussels, Belgium
¹¹ Blue Sky Spectroscopy, 9/740 4 Ave S, Lethbridge, Alberta T1J 0N9, Canada
¹² UK Astronomy Technology Centre, Royal Observatory Edinburgh, Blackford Hill, Edinburgh EH9 3HJ, UK
¹³ University of Vienna, Department of Astronomy, Türkenschanzstraße 17, 1180 Vienna, Austria
¹⁴ Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
¹⁵ Dept of Astronomy, Stockholm University, AlbaNova University Center, Roslagstullsbacken 21, 10691 Stockholm, Sweden

Received: 30 March 2010
Accepted: 5 May 2010

Abstract

We report on the detection of anhydrous hydrochloric acid (hydrogen chlorine, HCl) in the carbon-rich star IRC +10216 using the spectroscopic facilities onboard the Herschel satellite. Lines from J = 1–0 up to J = 7–6 have been detected. From the observed intensities, we conclude that HCl is produced in the innermost layers of the circumstellar envelope with an abundance relative to H₂ of 5 × 10^-8 and extends until the molecules reach its photodissociation zone. Upper limits to the column densities of AlH, MgH, CaH, CuH, KH, NaH, FeH, and other diatomic hydrides have also been obtained.