J. Cernicharo, R. Fuentetaja, M. Agúndez, R. I. Kaiser, C. Cabezas, N. Marcelino, B. Tercero, J. R. Pardo, and P. de Vicente
reported on the
Discovery of fulvenallene in TMC-1 with the QUIJOTE line survey
Astron. Astrophys. 663, Art. No. L9 (2022).
The molecular line survey was carried out with the Yebes 40 m radio telescope between 31.0 and 50.4 GHz. Ethenylidenecyclopentadiene, aka fulvenallene, was detected in several a-type transitions having 8 ≤ J ≤ 14 and K_a ≤ 3. A considerable fraction of the lines is not or only slightly blended. A value of T_rot = 9 ± 1 K was derived through a rotation diagram. The column densities (in units of 10¹⁰ cm⁻²) of the butenenitriles is about 5, 13, 10, 7, and 8 for the E-1-, Z-1-, 2-, syn-3-, and gauche-3-forms, respectively, compared to ~4 × 10¹³ cm⁻² for propene. The combined cyanopropenes are much less abundant in relation to its parent hydrocarbon compared to other detected cyanide derivatives. It is also noteworthy to point out that the abundances among the cyanopropenes do not at all reflect relative energies among these species.

Contributor(s): H. S. P. Müller; 08, 2022