===== On the Detection of Phenalene, C<sub>13</sub>H<sub>10</sub>, in the ISM =====

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\\
**[[https://doi.org/10.1051/0004-6361/202556687|Discovery of Interstellar Phenalene (//c//-C<sub>13</sub>H<sub>10</sub>): A new Piece in the Chemical Puzzle of PAHs in Space]]**\\
//Astron. Astrophys.// **701**, Art. No. L8 (2025).\\
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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Contributor(s): H. S. P. Müller; 09, 2025

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