===== On the Detection of Cyanoacenaphtalenes, C<sub>12</sub>H<sub>7</sub>CN, in the ISM =====

J. Cernicharo, C. Cabezas, R. Fuentetaja, M. Agúndez, B. Tercero, J. Janeiro, M. Juanes, R. I. Kaiser, Y. Endo, A. L. Steber, D. Pérez, C. Pérez, A. Lesarri, N. Marcelino, and P. de Vicente\\
reported on the\\
**[[https://doi.org/10.1051/0004-6361/202452196|Discovery of Two Cyano Derivatives of Acenaphthylene (C<sub>12</sub>H<sub>8</sub>) in TMC-1 with the QUIJOTE Line Survey]]**\\
//Astron. Astrophys.// **690**, Art. No. L13 (2024).\\
The molecular line survey was carried out with the Yebes 40 m radio telescope between 31.0 and 50.4 GHz. The two cyanoacenaphtalene isomers 1- and 5-C<sub>12</sub>H<sub>7</sub>CN were detected while the 3- and 4-C<sub>12</sub>H<sub>7</sub>CN isomers were not detected. While all of the isomers are asymmetric rotors of the prolate type, the detected isomers are more asymmetric (or closer to an oblate top asymmetric rotor).\\

The molecules were identified through a plethora of //a//-type rotational transitions, several series easier to detect because of oblate pairing of the transitions having the same //K<sub>c</sub>// close to //J//. The derived column densities were equal, and a rotational temprerature of 9 K was derived. The authours also detected many lines of 1- and 2-cyanonaphtalene, again with equal column densities. Interestingly, the column densities of these slightly smaller molecules were about a factor of 1.7 lower than those of each of the cyanoacenaphtalenes.\\

The authors also search for the parent acenaphthylene molecule and cyanofluorene isomers, but found neither.\\
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More recently,\\
J. Cernicharo, B. Tercero, N. Marcelino, J. A. López-Pérez, J. D. Gallego, F. Tercero, G. Esplugues, C. Cabezas, M. Agúndez, C. Limeres, A. L. Steber, D. Pérez, C. Pérez, A. Lesarri, and P. de Vicente\\
announced the\\
**[[https://doi.org/10.1051/0004-6361/202452196|Discovery of Two New Isomers of Cyanoacenaphthylene (C<sub>12</sub>H<sub>8</sub>) in the Taurus molecular cloud 1 with the QUIJOTE Line Survey]]**\\
//Astron. Astrophys.// **705**, Art. No. L7 (2026).\\
The identifications were made under conditions similar to the previous two isomers. The column densities of 3- and 4-cyanoacenaphthylene are about 3/4 and 1/2, respectively of those of each of the 1- and 5 cyanoacenaphthylene isomers.\\
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Contributor(s): H. S. P. Müller; 10, 2024; 01, 2026

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