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 aim of this work is to study the aqueous alteration process which acted in that zone, dominated by low albedo C{type asteroids, and to compare the spectra of these hydrous objects with those of CM2 carbonaceous chondrite meteorites. In fact, the spectra of these meteorites reveal features probably due to aqueous altered materials on their surfaces. The study of the aqueous alteration process can give important information on the chemical and thermal evo- lution of the earliest Solar System. More that 65% of the investigated objects have re- vealed features suggesting the presence of hydrous mate- rials. The comparison of the spectra of the hydrated aster- oids obtained to date with those of several CM2 carbona- ceous chondrite meteorites seems to indicate that aqueous altered asteroids could be the parents of CM2 meteorites. The data have been obtained during several observa- tional runs at the Asiago Observatory with the 1.8 m tele- scope and at ESO{LaSilla with the 1.5 m telescope.