===== On the Detection of Cyanopyrenes, C<sub>16</sub>H<sub>9</sub>CN, in the ISM =====

G. Wenzel, I. R. Cooke, P. B. Changala, E. A. Bergin, S. Zhang, A. M. Burkhardt, A. N. Byrne, S. B. Charnley, M. A. Cordiner, M. Duffy, Z. T. P. Fried, H. Gupta, M. S. Holdren, A. Lipnicky, R. A. Loomis, H. T. Shay, C. N. Shingledecker, M. A. Siebert, D. A. Stewart, R. H. J. Willis, C. Xue, A. J. Remijan, A. E. Wendlandt, M. C. McCarthy, and B. A. McGuire\\
reported on the\\
**[[https://doi.org/10.1126/science.adq6391|Detection of Interstellar 1-Cyanopyrene: A Four-ring Polycyclic Aromatic Hydrocarbon]]**\\
//Science// **386**, 810−813 (2024).\\
The molecule was identified in the course of the GOTHAM survey of TMC-1 casrried out with the 100 m GBT dish. Several oblate paired //a//-type rotational transitions with 31 ≤ //J// ≤ 37 and //K<sub>c</sub>// close to //J//. Each pair of lines is close to the noise limit, but stacking achieves a S/N of about 7. The derived column density is, for example, about twice that of each of 1- and 2-cyanonaphtalene and only slightly less than that of benzonitrile.\\
The CfA issued a **[[https://www.cfa.harvard.edu/news/astronomers-discover-new-building-blocks-complex-organic-matter|press release]]**.\\
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G. Wenzel, T. H. Speak, P. B. Changala, R. H. J. Willis, A. M. Burkhardt, S. Zhang, E. A. Bergin, A. N. Byrne, S. B. Charnley, Z. T. P. Fried, H. Gupta, E. Herbst, M. S. Holdren, A. Lipnicky, R. A. Loomis, C. N. Shingledecker, C. Xue, A. J. Remijan, A. E. Wendlandt, M. C. McCarthy, I. R. Cooke, and B. A. McGuire\\
announced the\\
**[[https://doi.org/10.1038/s41550-024-02410-9|Detections of Interstellar Aromatic Nitriles 2-Cyanopyrene and 4-Cyanopyrene in TMC-1]]**\\
//Nat. Atron.// **9**, 262−270 (2025).\\
The isomers of 1-cyanopyrene were detected in a manner very similar to this one. The derived column densities of 1-cyanopyrene : 2-cyanopyrene  : 4-cyanopyrene are compatible with the 4 : 2 : 4 ratios of the number of equivalent substitution positions in pyrene.\\
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Contributor(s): H. S. P. Müller; 11, 2024; 02, 2025

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