An infrared excess is a measurement of an astronomical source, typically a star, that has a greater measured infrared flux than expected by assuming the star is a blackbody radiator. Infrared excesses are often the result of circumstellar dust and are common in young stellar objects and evolved stars on the asymptotic giant branch or older.
Evans, Aneurin (1993). The Dusty Universe. Ellis Horwood. pp. 155–165.