next up previous contents
Next: New Preprints Up: Scientific results Previous: A survey of CN

Detection of a new linear carbon chain radical: C tex2html_wrap_inline856 H

M. Guélin tex2html_wrap_inline738 , J. Cernicharo tex2html_wrap_inline776 , M.J. Travers tex2html_wrap_inline778 , M.C. McCarthy tex2html_wrap_inline778 , C.A. Gottlieb tex2html_wrap_inline778 , P. Thaddeus tex2html_wrap_inline778 , M. Ohishi tex2html_wrap_inline840 , S. Saito tex2html_wrap_inline842 , S. Yamamoto tex2html_wrap_inline844
tex2html_wrap_inline738 IRAM, 300 Rue de la piscine, F-38406 S tex2html_wrap_inline834 Martin d'Hères, France
tex2html_wrap_inline776 Observatorio Astronomico Nacional, apartado 1143, E-28800 Alcalá de Henares, Spain
tex2html_wrap_inline778 Division of Applied Sciences, Harvard University, Cambridge, MA 02138, USA
tex2html_wrap_inline840 N. R. O., Minamimaki, Minamisaku, Nagano 384-13, Japan
tex2html_wrap_inline842 Institute for Molecular Science, Myodaiji, Okazaki 444, Japan
tex2html_wrap_inline844 Dept. of Physics, The University of Tokyo, Bunkyo-ku, Tokyo 113, Japan
Abstract: Following our discovery of C tex2html_wrap_inline858 H in IRC+10216 (Cernicharo & Guélin 1996), we report the detection in this circumstellar envelope of another linear carbon chain radical, C tex2html_wrap_inline856 H. The microwave spectrum of C tex2html_wrap_inline856 H has been recently observed in the laboratory and its rotational line frequencies are precisely known.

With this new detection, the family of acetylenic chain radicals (C tex2html_wrap_inline852 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 tex2html_wrap_inline856 H is found to be a factor of 4 less abundant than C tex2html_wrap_inline858 H and a factor of 20 less abundant than C tex2html_wrap_inline860 H.

Figure 1: Four 30-m telescope spectra covering 4 rotational transitions of C tex2html_wrap_inline856 H (the tex2html_wrap_inline712 doublet components are indicated by vertical arrows). Two 8 MHz-wide intervals contaminated by strong lines from the upper sideband have been deleted. Unidentified lines are denoted `U'. Note the N= 7-6 doublet of vibrationally excited MgNC and the possible identification of H tex2html_wrap_inline930 C tex2html_wrap_inline716 at 83264 MHz, on the right side of the C tex2html_wrap_inline856 H line.