Analysis of near-IR spectra of 1 Ceres and 4 Vesta, targets of the Dawn mission

• Published in: Astronomy and astrophysics (Berlin) Vol. 436; no. 3; pp. 1113 - 1121
• Main Authors: Vernazza, P., Mothé-Diniz, T., Barucci, M. A., Birlan, M., Carvano, J. M., Strazzulla, G., Fulchignoni, M., Migliorini, A.
• Format: Journal Article
• Language: English
• Published: Les Ulis EDP Sciences 01.06.2005
• Subjects: asteroids; Astrophysics; Earth and Planetary Astrophysics; infrared: solar system; minor planets; Physics; Sciences of the Universe; techniques: spectroscopic; Noise spectrum; Planets; infrared: solar system; minor planets, asteroids; Asteroids; techniques: spectroscopic; Mineralogical composition; Ice; Infrared spectra; Solar system; Organic ion; minor planets; asteroids
• ISSN: 0004-6361; 1432-0746; 1432-0756
• DOI: 10.1051/0004-6361:20042506

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 $\mu{\rm m}$ 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 $\mu{\rm m}$ range. The 3 μm 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 μm range and the presence of the 3.06 μm absorption feature confirmed. Laboratory measurement of ion-irradiated organics and ices suggest that the 3.06 μm feature can be reproduced with a linear mixture of crystalyne ice and residues of ion-irradiated asphaltite.