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