J. Cernicharo, C. Cabezas, M. Agúndez, Y. Endo, B. Tercero, N. Marcelino and P. de Vicente
reported on the
QUIJOTE discovery of the cation radicals HC5N+ and HC7N+
Astron. Astrophys. 686, Art. No. L15 (2024).
HC₅N⁺ and HC₇N⁺ were identified through 7 and 8 unblended or slightly blended transitions, respectively with 23/2 ≤ J ≤ 37/2 in the first case and 53/2 ≤ J ≤ 69/2 in the latter. The identifications were made 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 31.0 and 50.3 GHz. T_rot = 8.5 ± 0.5 K was derived for HC₅N⁺, while T_rot = 7.8 ± 0.1 K was derived for HC₇N⁺. The abundance ratios present a consistent and interesting picture. The HC₅N⁺ / HC₇N⁺ ratio is ~4.2; the HC₅N⁺ / HC₅N, HC₅N⁺ / C₅N⁻, and HC₅N⁺ / C₅N⁻ ratios are about 670, 4.8, and 1.2, respectively, while the HC₇N⁺ / HC₇N, HC₇N⁺ / C₇N⁻ ratios are about 1000 and 2.2, respectively.

Contributor(s): H. S. P. Müller; 06, 2024