Discovery of HC<sub>3</sub>O<sup>+</sup> in space: The chemistry of O-bearing species in TMC-1
J. Cernicharo, N. Marcelino, M. Agúndez, Y. Endo, C. Cabezas, C. Bermúdez, B. Tercero, P. de Vicente
Abstract
Using the Yebes 40m and IRAM 30m radio telescopes, we detected a series of harmonically related lines with a rotational constant B 0 = 4460.590 ± 0.001 MHz and a distortion constant D 0 = 0.511 ± 0.005 kHz towards the cold dense core TMC-1. High-level-of-theory ab initio calculations indicate that the best possible candidate is protonated tricarbon monoxide, HC 3 O + . We have succeeded in producing this species in the laboratory and observed its J u − J l = 2–1 and 3–2 rotational transitions. Hence, we report the discovery of HC 3 O + in space based on our observations, theoretical calculations, and laboratory experiments. We derive an abundance ratio N (C 3 O)/ N (HC 3 O + ) ∼ 7. The high abundance of the protonated form of C 3 O is due to the high proton affinity of the neutral species. The chemistry of O-bearing species is modelled, and predictions are compared to the derived abundances from our data for the most prominent O-bearing species in TMC-1.