The opposition and tilt effects of Saturn's rings from HST observations

Heikki Salo (1) , Richard G. French (2)

1 Astronomy Division
2 Astronomy Department [Wellesley]

The two major factors contributing to the opposition brightening of Saturn's rings are i) the of particles due to coherent backscattering and/or shadow-hiding on their surfaces, and ii) the when the solar phase angle α→0. We utilize the extensive set of Hubble Space Telescope observations (Cuzzi et al. 2002, Icarus 158, 199-223) for different elevation angles and wavelengths λ to disentangle these contributions. We assume that the intrinsic contribution is independent of , so that any dependence of the phase curves is due to interparticle shadowing, which must also act similarly for all λ's. Our study complements that of Poulet et al. (2002, Icarus 158, 224), who used a subset of data for a single ∼10, and the French et al. (2007b, PASP 119, 623-642) study for the ∼23 data set that included exact opposition. We construct a grid of dynamical/photometric simulation models, with the method of Salo and Karjalainen (2003, Icarus 164, 428-460), and use these simulations to fit the elevation-dependent part of opposition brightening. Eliminating the modeled interparticle component yields the intrinsic contribution to the opposition effect: for the B and A rings it is almost entirely due to coherent backscattering; for the C ring, an intraparticle shadow hiding contribution may also be present.

Mots clés: Planetary Rings; Saturn; Hubble Space Telescope observations; Photometry; Radiative Transfer

Domaines: Planète et Univers [physics]

Heikki Salo, Richard G. French. The opposition and tilt effects of Saturn's rings from HST observations. Icarus, 2010, 210 (2), pp.785. ⟨10.1016/j.icarus.2010.07.002⟩. ⟨hal-00693815⟩