A Zodiacal Dust Emission Model

Several experiments have been devoted to the study of the zodiacal dust cloud emission in the infrared (ZIP, IRAS, ARGO etc.), but the agreement between theory and experimental results is poor: only semi-empirical models fit in satisfactory way the data (Price et al., 1985, Salama et al., 1987) while the standard model (Roser and Staude 1978) predicts fluxes about 20 times smaller than observed (Murdock and Price, 1985). Here we describe a deterministic model which, starting from known optical properties of the grains and using the expected interplanetary dust density and size distributions, predicts the infrared zodiacal emission. In order to reduce the number of free parameters we assume the simplest hypothesis of spherical graphite and silicate grains. Comparison with all available data shows an agreement within a factor 3 in the range of wavelengths between 5 and 200 µm and, for solar elongations, between 2° and 180°.