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).
Ethynylcyclopropenylidene, c-C₃HCCH, was identified through 12 unblended or slightly blended mostly b-type transitions with 1 ≤ J ≤ 10 and K_a ≤ 1 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 value of T_rot = 8 ± 3 K was derived through a rotation diagram, but the model is more compatible with 10 K. The column density of butenyne is about a factor of 4.5 higher than that of the isoelectronic allenyl cyanide. It is, in addition, similar to that of butenyne, a factor of 5 lower than that of the methyldiacetylene isomer (aka butadienyne), and a factor of 10 lower than that of methylacetylene (aka propyne).

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