Show pageOld revisionsBacklinksBack to top This page is read only. You can view the source, but not change it. Ask your administrator if you think this is wrong. ===== On the Detection of Cyanooctatetrayne, HC9N, in Space ===== N. W. Broten, T. Oka, L. W. Avery, J. M. MacLeod, and H. W. Kroto,\\ **[[https://ui.adsabs.harvard.edu/abs/1978ApJ...223L.105B|The Detection of HC<sub>9</sub>N in Interstellar Space]]**\\ //Astrophys. J.// **223**, L105–L107 (1978)\\ reported the first detection of this cyanopolyyne in two transitions (//J// = 18 – 17 and 25 – 24 near 10.5 and 14.5 GHz, respectively) in Heile's Cloud 2 employing the 46 m radio telecope of the Algonquin Radio Observatory before the molecules was detected in the laboratory. The spectroscopic parameters were estimated from the smaller cyanopolyynes. Heile's Cloud 2 is better known as TMC-1.\\ \\ More recently, the molecule was also detected in six transitions in the circumstellar shell of the famous carbon star CW Leo:\\ M. B. Bell, L. W. Avery, J. M. MacLeod, and H. E. Matthews,\\ **[[https://ui.adsabs.harvard.edu/abs/1992ApJ...400..551B|The Excitation Temperature of HC<sub>9</sub>N in the Circumstellar Envelope of IRC +10216]]**\\ //Astrophys. J.// **400**, 551–555 (1992).\\ \\ Truong-Bach, D. Graham, and Nguyen-Q-Rieu,\\ **[[https://ui.adsabs.harvard.edu/abs/1993A%26A...277..133T|HC<sub>9</sub>N from the Envelopes of IRC +10216 and CRL 2688]]**\\ //Astron. Astrophys.// **277**, 133–138 (1993);\\ detected one additional higher-//J// transition toward the former source and the same transition in a protoplanetary nebula.\\ \\ J. R. Pardo, C. Bermúdez, C. Cabezas, M. Agúndez, J. D. Gallego, J. P. Fonfría, L. Velilla-Prieto, G. Quintana-Lacaci, B. Tercero, M. Guélin, and J. Cernicharo\\ reported on the\\ **[[https://doi.org/10.1051/0004-6361/202038571|Detection of Vibrationally Excited HC<sub>7</sub>N and HC<sub>9</sub>N in IRC +10216]]**\\ //Astron. Astrophys.// **640**, Art. No. L13 (2020).\\ The authors carried out an unbiased molecular line survey with the Yebes 40 m dish between 31 and 50 GHz toward the circumstellar envelope of the famous C-rich AGB star CW Leonis. Numerous transitions of HC<sub>9</sub>N in its lowest excited state //v//<sub>19</sub> = 1 were detected despite the low rotational temperature. The lines could be assigned unambiguously although no laboratory data were available for this excited state. The derived HC<sub>5</sub>N to HC<sub>7</sub>N ratio is extremely low, roughly 2.4. The derived HC<sub>7</sub>N to HC<sub>9</sub>N ratio is still very low, roughly 7.7.\\ \\ J. R. Pardo, J. Cernicharo, J. P. Fonfría, C. Cabezas, M. Agúndez, B. Tercero, N. Marcelino, P. de Vicente, L. Velilla-Prieto and M. Guélin\\ announced some time later the\\ **[[https://doi.org/10.1051/0004-6361/202659372|Discovery of HC<sub>9</sub>N //v//<sub>19</sub> Overtones in IRC +10216]]**\\ //Astron. Astrophys.// **709**, Art. No. L13 (2026).\\ Deeper integration than in the previous entry permitted overtone states of HC<sub>9</sub>N to detect up to //v//<sub>19</sub> = 8.\\ \\ ---- Contributor(s): H. S. P. Müller; 02, 2006; 06, 2009; 08, 2020; 07, 2026. ---- molecules/ism/hc9n.txt Last modified: 2026/07/29 14:58by mueller