Summary -me J=9-8 rotational transition of HC5N (24 GHz) and the J=2l-20 transition of HC7N (23.7 GHz) have been detected in the molecular envelope surrounding the carbon star IRC+l02l6. The HC5N emission appears to be extended in declination relative to our 40 arc sec angular resolution. Upper limits have been obtained for the J=9-8 transition of vibrationally excited HC5N and the J=4l-40 transition of HC9N. Comparison of the column densities estimated on the basis of our observations suggests that long chain cyanopolyyne compounds (HC+1N, n=O, 1, 2..) are more abundant than woutbe predicted on the basis of molecular equilibrium calculations for cool carbon star atmospheres. Possible explanations for this are discussed. Key words: Carbon star, Molecular lines, Cyanodiactylene, Cyanotriacetylene.
Astronomy and Astrophysics
- Pub Date:
- December 1978
- Carbon Stars:Molecules;
- Circumstellar Shells:Molecules;
- Interstellar Matter:Molecules