Resonant orbits of grains and the formation of satellites

Grains, an abundant constituent of the former solar system, will have had a high probability of being driven into orbits resonant with major bodies already formed. This arises because of the presence of gas drag and Poynting-Robertson drag on small grains, providing the dissipation necessary to concentrate matter into special orbits. Since the mean density in resonant orbits can be built up by such a process without limit, these may become the favored orbits for gravitational contraction to gather material into major bodies. Satellite formation processes may therefore depend upon the buildup of resonant lanes of dust grains around the parent body. Saturn's rings are possibly one example of such lanes, though an unsuitable one for the final step of satellite formation on account of their being too close to Saturn.