The helium hydride ion, HeH+, has been detected in space for the first time with the use of the GREAT spectrometer on SOFIA. Through observations of its fundamental rotational transition at 2.010 THz (149.1 micron), HeH+ was detected toward the young planetary nebula NGC 7027. This detection brings a three-decades-long search to a successful conclusion. In this tele-talk, the history of the study of HeH+ will be reviewed, starting with its discovery in the laboratory almost a century ago, its recognition in the late-1970s as a potentially-detectable astrophysical molecule, and its role as the first molecule predicted by models for the Early Universe. The details of the recent SOFIA observations will be presented, and the implications of the measured line intensities will be considered in the context of astrochemical models. The possibilities for follow-up toward other sources and through observations of other spectral lines will be discussed briefly.
Reference: "Astrophysical detection of the helium hydride ion (HeH+)," Güsten, Wiesemeyer, Neufeld, Menten, Graf, Jacobs, Klein, Ricken, Risacher & Stutzki 2019, Nature, 568, 357 (arXiv:1904.09581)