J. Cernicharo, M. Agúndez, C. Cabezas, B. Tercero, N. Marcelino, J. R. Pardo, and P. de Vicente
reported on
Pure hydrocarbon cycles in TMC-1: Discovery of ethynylcyclopropenylidene, cyclopentadiene, and indene
Astron. Astrophys. 649, Art. No. L15 (2021).
Indene, c-C₉H₈, was identified as the first pure polycyclic aromatic hydrocarbon through a large number of mostly a-type lines with 10 ≤ J ≤ 20 and K_a ≤ 6 in the course of a molecular line survey of the prototypical cold dark molecular cloud TMC-1 carried out with the Yebes 40 m radio telescope between 32.8 and 49.2 GHz. A substantial fraction of the lines was unblended or slightly blended. A value of T_rot = 10 K was assumed. The column density of indene is about the same as cyclopentadienene or the C₄H₄ isomers butenyne and ethynylallene. It is about a factor of 7 lower than that of C₃H₃.

Contributor(s): H. S. P. Müller; 05, 2021