IRTS observations of the mid-infrared spectrum of the zodiacal emission Original Research Article

We present the spectrum of the zodiacal emission from 3 to 12 μm obtained by the Infrared Telescope in Space (IRTS). The spectrum is fitted by models based on the IRAS data. The models consist of spatial distributions of the dust volumetric emissivity and temperature. The entire spectrum of 3–12 μm cannot be fitted by one gray body emissivity model. This suggests that either the dust emissivity is not constant for 3–12 μm or there are very hot dust grains. The present analysis suggests a dominant population of submicron size particles in the solar system.