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C. Leyrat, C. Ferrari, S. Charnoz (University Paris 7 and Sap/DAPNIA/DSM/CEA Saclay), L. Spilker (JPL/Caltech)
The dynamical evolution of a dense ring system strongly depends on the outcome of the inter-particle collisions and on the mutual gravitational perturbation of particles. Both the ring local thickness due to the vertical random motions and the energy stored in spins of particles due to surface friction in collisions reflect the microphysics of the rings. Only limited knowledge exists on the spin and surface properties of rings particles which control the output of collisions. Measuring the temperature of a planetary ring provides an independent method to constrain the local ring dynamics as well as the thermal properties of the ring particle surface. A new thermal emission model of a monolayer ring populated with finite spherical spinning particles have been developed in order to use the crossing of the Saturn’s shadow and the day/night anisotropic emission of particles, to recover both the spin and the thermal inertia of particles from observations at different phase angles. We present the first results of the comparison of this model with observations at several phase angles of the thermal emission of Saturn’s C ring by the ground based CAMIRAS/CFHT data and the IRIS/VOYAGER data. The 4-year-long Cassini and CIRS instrument Tour will provide a large range of geometries of observations to measure precisely the heating and the cooling of Saturn’s rings. We are developing this model in order to have a useful tool for the study of thermal properties of particles surface.
This work has been supported by the “Programme National de Planetologie”.
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.