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
Discovery of Interstellar Phenalene (//c//-C₁₃H₁₀): A new Piece in the Chemical Puzzle of PAHs in Space
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-C₁₂H₇CN were detected while the 3- and 4-C₁₂H₇CN 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 a plethora of a-type rotational transitions, several series easier to detect because of oblate pairing of the transitions having the same K_c close to J. A rotational temprerature of 8 K was derived. The column density of phenalene appears to be slightly larger than that of the slightly smaller indene, albeit with considerable uncertainty.

Contributor(s): H. S. P. Müller; 09, 2025