Inelastic collisions in narrow planetary rings |
| |
| Institution: | 1. Department of Earth, Planetary and Space Sciences, UCLA, Los Angeles, CA 90095, USA;2. Cold Pine Observatory, 201, 4-22, Matsugaoka 1-cho me, Chigasaki, Kanagawa, Japan;3. Department of Earth, Environmental, and Planetary Sciences, Washington University, St. Louis, MO 63130, USA;1. Space and Planetary Science Center, Department of Earth Sciences, Khalifa University, Abu Dhabi, United Arab Emirates;2. Laboratory for Atmospheric and Space Physics, University of Colorado Boulder, Boulder, CO, USA;3. NASA Goddard Space Flight Center, Greenbelt, MD, USA;4. Space Science Institute, Boulder, CO, USA;5. Mohammed Bin Rashid Space Center, Dubai, United Arab Emirates;6. Department of Astronomy and Planetary Science, Northern Arizona University, Flagstaff, AZ, USA;7. School of Earth and Space Exploration, Arizona State University, Tempe, AZ, USA;1. Stazione Astronomica di Sozzago, Cascina Guascona, I-28060 Sozzago (Novara), Italy;2. INAF-Osservatorio Astronomico di Padova, Vicolo dell''Osservatorio 5, I-35122 Padova, Italy;3. Department of Physics and Astronomy, University of Padova, Via F. Marzolo 8, I-35131 Padova, Italy;4. INAF – Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate (LC), Italy;5. Observatoire Chante-Perdrix, Dauban, France;6. Observatoire M53 Mayenne Astronomie, Maisoncelles-Du-Maine, France;7. TÜBITAK National Observatory, Akdeniz University Campus, Antalya 07058, Türkiye;8. Department of Space Sciences and Technologies, Akdeniz University, Campus, Antalya 07058, Türkiye |
| |
| Abstract: | It is shown that a particle ring with energy dissipation has an extremum in its energy when all the particles are in the same circular orbit. This extremum is a relative maximum in radial directions, indicating possible radial expansion; but it is a relative minimum in the particle velocity components, indicating a tendency for the velocity distribution to collapse. An N-body model of ring evolution incorporating two-body dynamics, oblateness perturbations, inelastic collisions, and phase averaging is described. By local analysis of impact statistics, it is shown that the velocity distribution of the ring will collapse if the coefficient of restitution ∈ ≲ 0.7. The collapse of the velocity distribution stabilizes a ring of point particles against radial dispersion. Furthermore, for ∈ ≲ 0.25, the semimajor axis distribution tends to collapse toward its local mean value, leading to radial collapse. A survey of ring evolution is presented for different values of coefficient of restitution and initial velocity dispersion. As has been predicted uy Goldreich and Tremaine, rings with equilibrium velocity distributions are unstable and expand, while rings where the velocity distribution collapses are shown to undergo massive, pervasive fragmentation into a myriad of ringlets. It is proposed that such fragmented rings are stable in their own right, and that the observational test to discriminate between the two cases is simply the presence of a smooth, featureless surface or the presence of intricate radial structure in the ring. |
| |
| Keywords: | |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
