R. Güsten, H. Wiesemeyer, D. Neufeld, K. M. Menten, U. U. Graf, K. Jacobs, B. Klein, O. Ricken, C. Risacher, and J. Stutzki
reported on the
Astrophysical detection of the helium hydride ion HeH⁺
Nature 568, 357 (2019).
The J = 1 − 0 transition at 2.0102 THz was detected in emission toward the NGC 7027 photo-dissociation region (PDR) with the upGREAT instrument using the SOFIA airplane. The column density is quite close to model calculations; interestingly, about a factor of four was detected compared to the expectations.
See also the MPIfR press release (in English; German version also available).

D. A. Neufeld, M. Goto, T. R. Geballe, R. Güsten, K. M. Menten, and H. Wiesemeyer
reported on the
Detection of Vibrational Emissions from the Helium Hydride Ion (HeH⁺) in the Planetary Nebula NGC 7027
Astrophys. J. 894, Art. No. 37 (2020).
The v = 1 − 0, P(1) and P(2) transitions were detected near 3.5 and 3.6 μm, respectively, using the iSHELL spectrograph at the Infrared Telescope Facility on Mauna Kea. Their best source model reproduced the P(1) flux very well, but underproduced the fluxes of the P(2) and rotational transitions.

Contributor(s): H. S. P. Müller; 04, 2019; 05, 2020