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Project Progress

A. Delsanti at Institute for Astronomy (University of Hawaii, Manoa)

Minor bodies of the Outer Solar System (Kuiper Belt Objects, orbiting beyond Pluto, Comets, outer planets icy satellites) contain the most pristine material of the Solar System. Studying their surface composition provides relatively direct clues on the conditions of formation of our Solar System. The most fascinating feature is the ubiquitous presence of water ice and organic material. We are therefore trying to map the presence of water ice in the outer Solar System, by performing visible and infrared spectroscopy of the surface of these objects.

So far, we have detected water ice on one of the biggest Kuiper Objects, Orcus (De Bergh. Delsanti et al 2005). A new analysis performed with both the Keck 10m telescope and the Gemini 8m telescopes on top of Mauna Kea (Hawaii) during Spring 2005 will allow us to determine if the water ice is crystalline or amorphous, which has important implications for the outer Solar System thermal history. We might also identify some evidence for aqueous alteration processes displayed in the visible spectra. These studies encompass object Orcus, and several other outer Solar System minor bodies of interest. More spectroscopic observations with the Subaru 8m telescope (Hawaii) are scheduled in September 2005 to study the water content of outer planets icy satellites (e.g. Nereid, Oberon, Ariel, etc).

Chemical modeling of the different sets of data will allow us to provide insights on the surface composition of these objects, and put some constraints on the water and organic material supply to the inner Solar System. A parallel study of the composition of chondritic meteorites and the different aqueous alteration processes will allow us to eventually unveil links between meteorites and outer Solar System material.