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7 results on '"Brophy, Thomas G."'

2. Numerical simulation of satellite-ring interactions: resonances and satellite-ring torques

Author

Brophy, Thomas G., Esposito, Larry W., Stewart, Glen R., and Rosen, Paul A.

Subjects
Planetary rings -- Research, Satellites -- Research, Astronomy, Earth sciences
Abstract

Satellite-ring interactions in terms of resonances and satellite-ring torques were investigated using numerical simulation. The results showed that previous analytic solutions for torque which indicate a nonzero net value were the result of small second-order deviations of the surface density which do not take second-order defects into account. Velocity dispersion in the resonance zone did not decrease, indicating that energy conservation factors do not require a net torque value.

Published
1992

3. Density waves in Saturn's rings probed by radio and optical occultation: observation tests of theory

Author

Brophy, Thomas G. and Rosen, Paul A.

Subjects
United States. Jet Propulsion Laboratory. Project Voyager -- Observations, Density wave theory -- Testing, Planetary rings -- Research, Saturn (Planet) -- Ring system, Occultations -- Research, Astronomy, Earth sciences
Abstract

Parallel analysis of radio and polarimeter occultations of Saturn's Ring A density waves is attempted to form a standard model of wave structures, involving satellite mass, disk mass, and azimuthal phase shift as parameters. The results suggest that the polarimetric data better fits the theory than the radio observations, because the latter involves phase residuals. The latter may be due to the oblique incidence of the radio occultations. The findings indicate a young dynamical age for Saturn's rings based on standard theory torques.

Published
1992

4. A phase-space fluid simulation of a two-component narrow planetary ring - Particle size segregation, edge formation, and spreading rates

Author

Brophy, Thomas G, Stewart, Glen R, and Esposito, Larry W

Subjects
Lunar And Planetary Exploration
Abstract

The Krook kinetic equation for identical planetary ring particles is presently generalized for the case of two-component systems, and the equations are numerically solved on the basis of Brophy and Esposito's (1989) phase-space CFD method. Attention is given to the simulation results obtained for a two-component narrow ring, in which the large particles are eight times as massive as the small particles. This ring's unconstrained edge dynamics are resolved by the simulation, and are found to exhibit a sharpening that would not have been expected in single-component rings.

Published
1990
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6. Simulation of collisional transport processes and the stability of planetary rings

Author

Brophy, Thomas G and Esposito, Larry W

Subjects
Lunar And Planetary Exploration
Abstract

The utility of the phase-space fluid method for the study of planetary ring dynamics is presently demonstrated through the numerical solution of a model kinetic equation for a flattened Keplerian disk. Attention is given to ringlets composed of single-sized particles, as well as to ringlets composed of two different-sized particles; in the latter case, the ringlets evolve in such a way that the lighter particles are confined by the heavier ones. The results obtained indicate that some natural process may sharpen the optical depth profile of edges even without an external forcing mechanism, and that intermediate optical depths are dynamically preferred in some cases.

Published
1989
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