07.20-P

Small Solar System Objects Spectroscopic Survey: First Results

D. Lazzaro, C.A. Angeli (Observatorio Nacional, Brazil), M. Florczak (Obs. Nacional/CEFET, Brazil), A. Betzler (Obs. Nacional/UFRJ, Brazil), M.A. Barucci (Obs. Meudon, France), M. Fulchignoni (Obs. Meudon, Univ. Paris 7, France)

We began a systematic study of primitive bodies, called tex2html_wrap_inline19 , Small Solar System Objects Spectroscopic Survey. Among the objects we are studying are: Near-Earth objects, asteroid families, asteroids near resonances, dark objects, Centaurs, objects representing a possible transition comet-asteroid, and asteroids with a very slow or complex rotation.

The chemical and mineralogical composition of an asteroid's surface is studied through the analysis of its reflectance spectra in different wavelenghts. Four observation missions were carried out at the European Southern Observatory (La Silla, Chile), when we obtained a mineral characterization of about 300 asteroids. The observations were realized with a 1.52 m telescope with a Boller & Chivens spectrograph and a 2048x2048 CCD. The spectra were obtained in wavelenghts from 3000 to 9200 Å and were reduced using the IRAF reduction package with usual techniques like flat-field, He-Ar lamps and solar analogs.

Concerning concentrations in the Main Belt due to resonances with Jupiter, we present the initial results of Cybeles, Hildas, Hungarias, NEAs and Phocaea. We observed also, along all its opposition, the Centaur object 2060 Chiron, that displays a small cometary activity represented by variations in its reflectance spectrum.

Concerning asteroid families, concentrations we believe are debris of an energetic collision causing the total breakup of the original bodies, we observed members of Adeona, Dora, Eos, Eunomia, Flora, Merxia and Themis. The Main Belt is represented in our sample by Flora, in the most inner region, Eunomia, Adeona, Dora and Merxia in the intermediary region, and Themis and Eos representing the most outer region of the belt.

*Based on observations made with the 1.52 m telescope at the European Southern Observatory (La Silla, Chile) under the agreement with the CNPq/Observatorio Nacional (Brazil).