Autori: Vernazza, P.; Mothé-Diniz, T.; Barucci, M. A.; Birlan, M.; Carvano, J. M.; Strazzulla, G.; Fulchignoni, M.; Migliorini, A.

Editorial: Astronomy and Astrophysics, 436, p.1113-1121, 2005.

Rezumat:

We obtained high signal to noise spectra of the two targets of the Dawn mission, 4 Vesta and 1 Ceres from observations carried out in remote control between the Observatoire de Paris-Meudon and the NASA Infrared Telescope Facility on Mauna Kea. 4 Vesta was observed in the 0.7-2.5 mum spectral region at three different rotational phases in order to i) determine the mineral composition; ii) understand the spectral variations across the surface. Vesta was also observed in the 2.0-3.8 mum range. The 3 mum absorption feature was not detected, implying the absence of OH and/or H2O-bearing minerals on the asteroid surface at the latitude of our observations. The spectrum of 1 Ceres was obtained in the 2.0-4.1 mum range and the presence of the 3.06 mum absorption feature confirmed. Laboratory measurement of ion-irradiated organics and ices suggest that the 3.06 mum feature can be reproduced with a linear mixture of crystalyne ice and residues of ion-irradiated asphaltite.

Cuvinte cheie: minor planets, asteroids, techniques: spectroscopic, infrared: solar system