On the Detection of Ethynylium in Space
A. M. Jacob, K. M. Menten, S. Brünken, A. Belloche, F. Wyrowski, W. G. D. P. Silva, O. Asvany, S. Khan, S. Kabanovic, K. Steenbakkers, G. C. Groenenboom, B. Redlich, and S. Schlemmer
reported on the
First Detection of C2H+ in the Interstellar Medium
Astron. Astrophys. 714, Art. No. A137 (2026).
Ethynylium, with a 3Π electronic ground state, was detected with the APEX 12 m sub-mm telescope in its lowest Ω = 2 J = 3 − 2 transition near 211.5 GHz toward the Orion Bar. The four strong hyperfine transitions, ΔF = +1, two each in the f and e Λ-doublets, were detected with good signal-to-noise ratio (S/N). The S/N was too low to detect the two weaker ΔF = 0 transitions. Ethynylium is about a factor of 15000 less abundant that the neutral C2H and about a factor of ~40 less than l-C3H.
Contributor(s): H. S. P. Müller; 10, 2026