Free access article

A&A 423, 235-239 (2004)
DOI: 10.1051/0004-6361:20040161

Research Note

Suggestions for an interstellar C H search

S. Chandra and S. A. Shinde

School of Physical Sciences, SRTM University, Nanded 431 606, India
    e-mail: sch@iucaa.ernet.in

(Received 21 May 2003 / Accepted 5 May 2004)

Abstract
Laboratory detection of four isomers of C ₅H ₂ molecule have been reported by Travers et al. (1997), McCarthy et al. (1997), and Gottlieb et al. (1998). They suggested for detection of the ring-chain isomer of C ₅H ₂ ( c-C ₅H ₂) in cosmic objects, as it is the most stable one in comparison to the others. Two transitions 3_{1 3} - 2_{1 2} and 3_{0 3} - 2_{0 2} at 19.147 GHz and 19.606 GHz, respectively, of c-C ₅H ₂ have been detected in TMC-1. We suggest that the c-C ₅H ₂ may be identified in cool cosmic objects through its transition 3_{1 3} - 4_{0 4} at 4.3 GHz in absorption against the cosmic microwave background. Since in absence of availability of the collisional rates, we have used scaled values for them, we have checked the sensitivity of the lines on the rates by enhancing the rate for the transitions with by a factor of 10. Though the transitions are not found sensitive, our results may be treated as qualitative in nature. This absorption line may play an important role for identification of c-C ₅H ₂ in cosmic objects.

Key words: ISM: molecules

SIMBAD Objects
Tables at the CDS

© ESO 2004

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