Discovery of HC3O+ in space: The chemistry of O-bearing species in TMC-1
  Using the Yebes 40m and IRAM 30m radio telescopes, we detected a series of
harmonically related lines with a rotational constant B0=4460.590 +/- 0.001 MHz
and a distortion constant D0=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, HC3O+. We have succeeded
in producing this species in the laboratory and observed its J = 2-1 and 3-2
rotational transitions. Hence, we report the discovery of HC3O+ in space based
on our observations, theoretical calculations, and laboratory experiments. We
derive an abundance ratio N(C3O)/N(HC3O+) = 7. The high abundance of the
protonated form of C3O 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.
