ISO results on bright Main Belt asteroids: PHT-S observations

Observations of asteroids have been performed by the ISO satellite with PHT -S. The aim of these observations was to investigate the physical and compo sitional propel-ties of five blight Main Belt Asteroids (1 Ceres, 2 Pallas, 3 Juno, 4 Vesta, and 52 Europa) in the spectral range 5.8-11.6 mu m. The S tandard Thermal Model and a black-body fit have been applied to the obtaine d spectra to derive sub-solar and black-body temperatures. An advanced Ther mo-Physical Model has been applied to model the thermal continuum. In order to better interpret the observed spectral features, we compared the ISO da ta with meteorite and mineral spectra available in literature and with spec tra of a selected number of minerals obtained in laboratory. The spectral b ehaviour of all the observed asteroids from 8 to 11 mu m suggest the presen ce of silicates on the surfaces.