Spokes in Saturn's B Ring: dynamical and physical properties deduced from Voyager Saturn Ring images

Thesis/Dissertation · Thu Jan 01 00:00:00 EST 1987

OSTI ID:6967515

Eplee, R E

This project studied dynamical and physical properties of spokes as deduced from Voyage Saturn ring images. Analysis of the orbital motion of two dynamically-anomalous spokes, in particular, set limits on the charge-to-mass ratios of spoke particles at various times during their dynamical evolution. These two spokes have charge-to-mass of at least -60 +/- 3 C kg/sup -1/ while corotating with Saturn, and charge-to-mass ratios of no more than -22 +/- 2 C kg/sup -1/ while orbiting Saturn at Keplerian velocities. Additionally, charge decay on the grains of these spokes, caused by solar UV photoemission, allowed a lower limit of 0.10 +/- 0.03 ..mu..m to be placed on the range of radii for spoke particles. In a study of spoke photometry, a single-scattering analysis of the 0.470-..mu..m phase function for spokes has set a mean radius for the dominant scatterers (at this wavelength) of 0.22 +/- 0.02 /sup +/m. The transport of angular momentum within the rings due to the radial motion of spoke grains is shown to be the most-significant effect of spoke activity on the dynamical evolution of the B Ring, as was predicted by Goertz et al. (1986, Nature 320, 141-143). The radial mass-transport velocity due to highly-charged spokes is -1 x 10/sup -9/m s/sup -1/. The subsequent spreading time for the B Ring is 600 million years, which is significantly less than the 4.6 billion-year age of the solar system.

• Research Organization: Arizona Univ., Tucson (USA)
• OSTI ID: 6967515
• Resource Relation: Other Information: Thesis (Ph. D.)
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
PLANETARY ATMOSPHERES
CLOUDS
SATURN PLANET
AGE ESTIMATION
ANGULAR MOMENTUM TRANSFER
ICE
MASS TRANSFER
ORBITAL ANGULAR MOMENTUM
RADIAL VELOCITY
ANGULAR MOMENTUM
ATMOSPHERES
MOMENTUM TRANSFER
PLANETS
VELOCITY
640107* - Astrophysics & Cosmology- Planetary Phenomena