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G. Filacchione, F. Capaccioni (INAF-IASF), A. Coradini (INAF-IFSI), P. Cerroni (INAF-IASF), T. B. McCord (University of Hawaii, HIGP/SOEST), K. H. Baines (JPL), G. Bellucci (INAF-IFSI), R. H. Brown (LPL univeristy of Arizona, Tucson, Az), J. P. Bibring (IAS, Orsay), B. J. Buratti (JPL), R. N. Clark (USGS), M. Combes (Obs. Paris Meudon), D. P. Cruikshank (NASA Ames), P. Drossart (Obs. Paris Meudon), V. Formisano (INAF-IFSI), R. Jaumann (DLR), Y. Langevin (IAS, Orsay), D. L. Matson (JPL), V. Mennella (INAF Osservatorio astronomico Capodimonte, Napoli), R. M. Nelson (JPL), P. D. Nicholson (Cornell University), B. Sicardy (Obs. Paris Meudon), C. Sotin (Laboratoire de Planetologie, Universitè de Nantes), G. Hansen, K. Hibbits (University of Washington, Seattle WA)
The Visual and Infrared Mapping Spectrometer (VIMS) collected a large amount of hyperspectral data on the icy satellites in the period June 2004 - April 2005. This study is devoted to the comparative analysis of the full-disk spectral properties of nine saturnian satellites (Dione, Enceladus, Epimetheus, Hyperion, Iapetus, Mimas, Phoebe, Rhea and Tethys) The observations were characterized by large variations in the observing conditions (distances, illumination phase angles, leading-trailing side percentages), increasing the statistical significance of this analysis. In the VIMS-V spectral range (350-1050 nm) the icy satellites spectra are almost featureless, nonetheless they can be grouped on the basis of their spectral slopes (from the bluish Enceladus and Phoebe to the redder Iapetus, Hyperion and Epimetheus). In the 1000-1300 nm range, three different behaviors can be defined: the first includes satellites with blue slopes (Enceladus, Mimas, Rhea and Tethys) while the second includes satellites with red slopes (Iapetus, Hyperion and Phoebe). In between these two classes are Dione and Epimetheus, which have a flat spectrum in this range. The main absorption bands identified in the infrared are the 1520, 2020, 3000 nm H2O/OH ice bands (for all satellites), although the Iapetus dark terrains show mostly a deep 3000 nm band and the 1520 and 2020 nm bands are very faint. In this spectral range, the Iapetus spectrum is characterized by a fast red slope. The CO2 band at 4260 nm and the Fresnel ice peak around 3100 nm are evident only on Hyperion, Phoebe and Iapetus. The observations were performed with phase angles ranging from 12 degrees to 140 degrees. We shall report on the results of the study on the spectral dependence of the satellites' phase curves. This work is supported by an ASI contract.
The author(s) of this abstract have provided an email address for comments about the abstract: gianrico.filacchione@rm.iasf.cnr.it
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Bulletin of the American Astronomical Society, 37 #3
© 2004. The American Astronomical Soceity.