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| molecules:ism:phenalene [2025/09/17 14:56] – mueller | molecules:ism:phenalene [2026/08/03 12:20] (current) – mueller |
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| ===== On the Detection of Phenalene, C<sub>13</sub>H<sub>10</sub>, in the ISM ===== | ===== On the Detection of Phenalene, c-C13H10, in the ISM ===== |
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| 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\\ | C. Cabezas, M. Agúndez, C. Pérez, D. Villar-Castro, G. Molpeceres, D. Pérez, A. L. Steber, R. Fuentetaja, B. Tercero, N. Marcelino, A. Lesarri, P. de Vicente, and J. Cernicharo\\ |
| reported on the\\ | 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]]**\\ | **[[https://doi.org/10.1051/0004-6361/202556687|Discovery of Interstellar Phenalene (c-C13H10): A new Piece in the Chemical Puzzle of PAHs in Space]]**\\ |
| //Astron. Astrophys.// **690**, Art. No. L13 (2024).\\ | //Astron. Astrophys.// **701**, Art. No. L8 (2025).\\ |
| 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).\\ | Phenalene was identified through several //a//-type rotational transitions, often series easier to detect because of oblate pairing of the transitions having the same //K<sub>c</sub>// close to //J// and then blended with weaker //b//-type transitions having equivalent quantum numbres. Some isolated //b//-type transitions were also assigned in the astronomical spectrum. The identifications were based on the QUIJOTE molecular line survey carried out with the Yebes 40 m radio telescope between 31.0 and 50.4 GHz, but phenalene assignments were made only up to 39.8 GHz. A rotational temperature of 8 K was derived. The column density of phenalene appears to be slightly larger than that of the lighter indene, albeit with considerable uncertainty.\\ |
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| 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.\\ | G. Wenzel, T. H. Speak, C. Xue, E. A. Bergin, A. M. Burkhardt, M. A. Cordiner, M. Duffy, Z. T. P. Fried, A. Lipnicky, C. N. Shingledecker, R. H. J. Willis, A. J. Remijan, M. C. McCarthy, B. A. McGuire, and I. R. Cooke\\ |
| | reported on the\\ |
| The authors also search for the parent acenaphthylene molecule and cyanofluorene isomers, but found neither.\\ | **[[https://doi.org/10.3847/2041-8213/ae8757|Detection of the Polycyclic Aromatic Hydrocarbon Phenalene (C13H10) in the Very |
| | Low-luminosity Object MC27/L1521F]]**\\ |
| | //Astrophys. J. Lett.// **1006**, Art. No. L38 (2026).\\ |
| | The molecule was identified by line stacking of observations carried out with thw GBT 100 m dish. While the column density of phenalene is similar to the one in TMC-1 CP, but the phenalene/benzonitrile ratios differ. It is ~9 in TMC-1 CP, whereas it is ~40 in MC27/L1521F.\\ |
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| Contributor(s): H. S. P. Müller; 09, 2025 | Contributor(s): H. S. P. Müller; 09, 2025; 08, 2026. |
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