Carbon monoxide in supernova 1995ad

Infrared spectroscopy of the type II supernova 1995ad 105 d after its discovery has been performed at the Anglo-Australian Telescope. The spectra exhibit strong emission longwards of 2.3 µm, consistent with emission from carbon monoxide from within the ejecta of the supernova. A local thermodynamic equilibrium (LTE) analysis of the spectrum gives 10−4 M⊙; of CO emitting at a temperature of 3000 K. The similarity of these observations to those of SN 1987A allow for the possibility that due to non-LTE and optical depth effects the mass of CO present in the ejecta of SN 1995ad may be as high as 5 × 10−2 M⊙.