Carbon Monoxide in the Type Ic SN 2000ew

Abstract

We present K-band (1.9 -- 2.5 micron) spectra of the Type Ic SN 2000ew observed with IRCS on the Subaru Telescope. These data show the first detection of carbon monoxide (CO) emission in a Type Ic supernova. The detection of CO in SN 2000ew provides further evidence that molecule formation may be a common occurrence in core-collapse supernova ejecta. The spectrum also contains narrow emission lines of [Fe II] and He I probably from dense clumps of hydrogen-poor circumstellar gas surrounding SN 2000ew. Our spectrum of SN 2000ew shows no trace of an unidentified feature seen near 2.26 micron, just blueward of the CO emission, in the spectrum of SN 1987A and we discuss proposed detections of this feature in other Type II supernovae.