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Ray tracing particle arrays for the modelling of Saturn’s main rings

Presentation #407.01 in the session “Planetary Rings: Theory and Observations”.

Published onOct 03, 2021
Ray tracing particle arrays for the modelling of Saturn’s main rings

The thermal emission and temperatures of the main rings of Saturn depend on the energy the ring particles absorb, reflect and scatter and/or on their Bond albedo, emissivity, thermal inertia, rotation rate and porosity. However, the energy that each particle absorbs also depends on the amount of energy (e.g., solar energy) that reaches its surface and this latter on the local optical depth, that controls the mutual eclipsing between neighbouring particles and, in general, all shadowing effects on the rings. Not surprisingly, thermal models of the rings of Saturn based on the energy balance equation strongly depend on a function that described how the non-shadowed area of ring particles changes with solar elevation. Experimental and analytical shadowing functions have been proposed by Froidevaux (1981) and Altobelli et al. (2009), respectively. In this work, we propose shadowing functions based on the creation of 3D arrays of spherical particles, not based on dynamical N-body models, that simulate specific regions of the main rings of Saturn. Combining the former shadowing functions with the energy balance equation we are able to reproduce Cassini CIRS data temperature trends of selected regions of Saturn’s main rings reasonably well. In order to evaluate our method we compare the derived Bond albedo values with those obtained with the Cassini Imaging Science Subsystem (ISS) at wavelengths in the range [451, 650] nm.

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