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).
Cyclopentadiene, c-C₅H₆, was identified through five unblended or slightly blended b-type lines with 2 ≤ J ≤ 5 and K_a ≤ 3 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. One line corresponds to the unresolved K_c = J = 5 − 4 asymmetry doublet. A value of T_rot = 10 K was assumed. The column density of c-C₅H₆ is about the same as the C₄H₄ isomers butenyne and ethynylallene. It is about a factor of 7 lower than that of C₃H₃ and about factors of 15 and 63 higher than the 1- and 2-cyano derivatives of c-C₅H₆.

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