After charaterization of its rotational spectrum by Fourier microwave spectroscopy,
magnesium hydride isocyanide, or hydridomagnesium isocyanide, HMgNC, was identified
in the circumstellar envelope of the late-type carbon-rich star CW Leonis,
also known as IRC +10216 by
C. Cabezas, J. Cernicharo, J. L. Alonso, M. Agúndez, S. Mata, M. Guélin, and I. Peña,
Laboratory and Astronomical Discovery of HydroMagnesium Isocyanide
Astrophys. J. 775, Art. No. 133 (2013).
Five rotational transitions, J" = 7 to 9 and 11 and 12 were observable in theory between 87 and 143 GHz in the course of a molecular line survey carried out with the IRAM 30 m radiotelecope on Pico Veleta, Spain. J" = 7 and 9 were seen with reasonable signal-to-noise ratio. J" = 8 was fully overlapped, and J" = 11 and 12 were overlapped in part, but could be included in the analysis. The rotational temperature of around 21 K is similar to that of MgNC and maybe slightly warmer than that of MgCN. Its column density is slightly smaller than that of MgCN, and much smaller, by a factor of about 20, than that of MgNC.