Spectroscopic comparison of aqueous altered asteroids with CM2 carbonaceous chondrite meteorites

In the last year we have started a spectroscopic investigation of asteroids located in the region of the main-belt between about 2.2 and 3.6 AU. The a im of this work is to study the aqueous alteration process which acted in t hat zone, dominated by low albedo C-type asteroids, and to compare the spec tra of these hydrous objects with those of CM2 carbonaceous chondrite meteo rites. In fact. the spectra of these meteorites reveal features probably du e to aqueous altered materials on their surfaces. The study of the aqueous alteration process can give important information on the chemical and thermal evolution of the earliest Solar System. More that 65% of the investigated objects have revealed features suggesting the presence of hydrous materials. The comparison of the spectra of the hy drated asteroids obtained to date with those of several CM2 carbonaceous ch ondrite meteorites seems to indicate that aqueous altered asteroids could b e the parents of CM2 meteorites. The data have been obtained during several observiational runs at the Asiag o Observatory with the 1.8 m tele scope and at ESO-LaSilla with the 1.5 m t elescope.