Observations of infrared emission from a fast-moving knot in Cassiopeia A

Broadband (10 microns) and spectroscopic (8.99, 10.52 and 12.81 microns) scans were made of the metal-rich knots in Cas A using instrumentation at the NASA IR Telescope Facility. The observations were performed to distinguish between thermal continuum emission and other features of the metal-rich knots. A faint, forbidden Si IV line was detected, and upper limits were set on the forbidden Ar III and forbidden Ne II emissions, which are now expected to be completely due to lines that may be accessible to the 12 microns sensor on the IRAS. The implications of the measurements for the interpretation of broadband data on metal-rich remnants are discussed. 44 references