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Astron. Astrophys. 317, L1-L4 (1997)

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Letter to the Editor

Detection of a new linear carbon chain radical: C 7 H

M. Guélin 1, J. Cernicharo 2, M.J. Travers 3, M.C. McCarthy 3, C.A. Gottlieb 3, P. Thaddeus 3, M. Ohishi 4, S. Saito 5 and S. Yamamoto 6

1 IRAM, 300 Rue de la piscine, F-38406 S [FORMULA] Martin d'Hères, France
2 Instituto de Estructura de la Materia-CSIC, Serrano 123, E-28006 Madrid, Spain
3 Division of Applied Sciences, Harvard University, Cambridge, MA 02138, USA
4 N. R. O., Minamimaki, Minamisaku, Nagano 384-13, Japan
5 Institute for Molecular Science, Myodaiji, Okazaki 444, Japan
6 Department of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan

Received 3 September 1996 / Accepted 19 September 1996


Following our discovery of C 8 H in IRC+10216 (Cernicharo & Guélin 1996), we report the detection in this circumstellar envelope of another linear carbon chain radical, C 7 H. The microwave spectrum of C 7 H has been recently observed in the laboratory (Travers et al. 1996a) and its rotational line frequencies are precisely known.

With this new detection, the family of acetylenic chain radicals (C [FORMULA] H) observed in space is complete up to n= 8 . The members with even numbers of carbon atoms are consistently more abundant than the odd number members; C 7 H is found to be a factor of 4 less abundant than C 8 H and a factor of 20 less abundant than C 5 H.

Key words: stars: molecular data — stars: AGB — circumstellar matter — ISM: molecules — radio lines: stars

Send offprint requests to: M. Guélin

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© European Southern Observatory (ESO) 1997