Time Variability in the Radio Brightness Distribution of Saturn

Microwave observations of Saturn's rings: anisotropy in directly transmitted and scattered saturnian thermal emission

“…We also observe a marginal excess in the A ring in the far side of the west ansa by comparison to the east ansa. This ansae asymmetry was also observed at |B| = 2.7 • (Dunn, 1999;DMF02) and |B| > 20 • (de Pater and Dickel, 1991;van der Tak et al, 1999), but not at |B| = 5.0 • . This may be indicative of a dependence on multiple scattering or wake spacing.…”

“…These VLA datasets represented the first high resolution, high quality data at microwave wavelengths. van der Tak et al (1999) present data taken in the 1990s at inclinations from 0.1 • to 24.1 • and at wavelengths between 2.0 cm to 90 cm. Again, no more than two wavelengths were measured for any individual epoch.…”

HST observations of azimuthal asymmetry in Saturn's rings

“…Wake structure may also be responsible for an apparent east-west asymmetry in Saturn's thermal radiation scattered by the rings (van der Tak et al, 1999;Dunn et al, 2002). Recently, Molnar et al (2004) have reported a similar VLA microwave asymmetry signature in the inner B ring as well.…”

Viscosity in a Dense Planetary Ring with Self-Gravitating Particles

“…the local N -body simulations may be supported by observations of asymmetrical features in Saturn's A-ring (e.g., Franklin et al 1987, Dones et al 1993, van der Tak et al 1999 and PPS observation of hyperfine structures (∼100-m scale structures) by Voyager (e.g., Esposito 1993). Thus, to estimate the viscosity in the main ring, we have to include the effects of the wakes.…”