M. Sanz-Novo, V. M. Rivilla, I. Jiménez-Serra, J. Martín-Pintado, L. Colzi, S. Zeng, A. Megías, Á. López-Gallifa, A. Martínez-Henares, S. Massalkhi, B. Tercero, P. de Vicente, D. San Andrés, S. Martín, and M. A. Requena-Torres
reported on the
Interstellar Detection of O-protonated Carbonyl Sulfide, HOCS⁺
Astrophys. J. 965, Art. No. 149 (2024).
The cation was detected in the course of a molecular line survey of the Galactic Center molecular cloud G+0.693–0.027 employing the Yebes 40 m and IRAM 30 m radio telecopes. The transitions cover 34 to 161 GHz with J“ = 2, 3, 6 − 13 and K_a = 0. These K_a = 0 are all considerably blended with K_a = 0 lines of HNC³⁴S because their B + C values are nearly identical. The contribution of HNC³⁴S could be accounted for accurately through lines of HNCS, OCS, and OC³⁴S and turned out to be less than that of HOCS⁺. Several lines are slightly or more severely blended in addition, but this is in most cases also well accounted. The cation is about a factor of 400 less abundant than OCS, about a factor of 7 less abundant than the isoelectronic HNCS, about a factor of 31 less abundant than the isovalent HOCO⁺, but at least more than a factor of 2 more abundant than the lower energy isomer HCSO⁺, which was not detected.

V. Lattanzi, M. Sanz-Novo, V. M. Rivilla, M. Araki, H. A. Bunn, J. Martín-Pintado, I. Jiménez-Serra, and P. Caselli
published more recently on
Advancing Spectroscopic Understanding of HOCS⁺: Laboratory Investigations and Astronomical Implications
Astron. Astrophys. 689, Art. No. A260 (2024).
After detection of HOCS⁺ a-type transitions with K_a > 0, it was possible to identify K_a = 1 transitions in the line survey described above. Most of the transitions were heavily blended, but some were sufficiently clear.

Contributor(s): H. S. P. Müller; 04, 2024; 09, 2024