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We present the first mid-infrared (MIR) detections of HNC and H13CN in theinterstellar medium, and numerous, resolved HCN rovibrational transitions. Ourobservations span 12.8 to 22.9 micron towards the hot core Orion IRc2, obtainedwith the Echelon-Cross-Echelle Spectrograph aboard the StratosphericObservatory for Infrared Astronomy (SOFIA). Exceptional, ~5 km/s, resolutiondistinguishes individual rovibrational transitions of the HNC and HCN P, Q, andR branches; and the H13CN R branch. This allows direct measurement of thespecies' excitation temperatures, column densities, and relative abundances.HNC and H13CN exhibit a local standard rest velocity of -7 km/s that may beassociated with an outflow from nearby radio source I and an excitationtemperature of about 100 K. We resolve two velocity components for HCN, theprimary component also being at -7 km/s with temperature 165 K. The hottestcomponent, which had never before been observed, is at 1 km/s with temperature309 K. This is the closest component to the hot core's centre measured to date.The derived 12C/13C=13 is below expectation for Orion's Galactocentricdistance, but the derived HCN/HNC=72 is expected for this extreme environment.Compared to previous sub-mm and mm observations, our SOFIA line survey of thisregion shows that the resolved MIR molecular transitions are probing a distinctphysical component and isolating the chemistry closest to the hot core.

The First Mid-Infrared Detection of HNC in the Interstellar Medium: Probing the Extreme Environment Towards the Orion Hot Core