===== On the Detection of HeH+ in the Interstellar Medium =====

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\\
**[[https://doi.org/10.1038/s41586-019-1090-x|Astrophysical detection of the helium hydride ion HeH<sup>+</sup>]]**\\
//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 [[https://www.mpifr-bonn.mpg.de/pressreleases/2019/5|MPIfR press release]] (in English; [[https://www.mpifr-bonn.mpg.de/pressemeldungen/2019/5|German version]] also available).\\


D. A. Neufeld, M. Goto, T. R. Geballe, R. Güsten, K. M. Menten, and H. Wiesemeyer\\
reported on the\\
**[[https://doi.org/10.3847/1538-4357/ab7191|Detection of Vibrational Emissions from the Helium Hydride Ion (HeH<sup>+</sup>) 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.\\

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


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