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| Format: | Preprint |
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2026
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| Online Access: | https://arxiv.org/abs/2605.14243 |
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| _version_ | 1866913133292945408 |
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| author | Hyodo, Ryuki Torii, Naoya |
| author_facet | Hyodo, Ryuki Torii, Naoya |
| contents | Catastrophic collisions between proto-satellites have been proposed as a possible origin of Saturn's rings. This argument relies on the concept of the equivalent circular orbit. Here, we re-examine the post-impact dynamical evolution of collision debris using analytical arguments and $N$-body simulations with fragmentation. We focus on the long-term evolution of debris distributed in a broad V-shaped region in the $a$--$e$ plane, with two arms for particles sharing a common collision radius. Because particles on the two arms possess significantly different angular momenta, inter-arm collisions dominate the evolution and drive behavior fundamentally different from the simple circularization assumed in the equivalent circular orbit approach. As a result, the classical equivalent circular orbit concept cannot predict the long-term fate of collision debris. Both our analytical framework and $N$-body simulations show that, although some debris initially passes within the Roche limit on eccentric orbits, successive collisional evolution drives the particles approximately along the original V-shaped constraint curves toward the apex of the V-shape, i.e., the original collision radius. Instead of spreading inward to form a ring, the debris converges and reaccretes near the original collision location. We therefore conclude that catastrophic proto-satellite collisions do not produce massive Saturnian rings. Rather, the debris evolves toward reaccretion into a new generation of satellite-sized bodies near the impact radius. These results fundamentally revise the dynamical interpretation of collision-generated debris and establish a more general framework applicable beyond the Saturnian system, including other planetary ring systems and debris produced during planet formation. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_14243 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Dynamical Evolution of V-Shaped Collision Debris Hyodo, Ryuki Torii, Naoya Earth and Planetary Astrophysics Astrophysics of Galaxies Catastrophic collisions between proto-satellites have been proposed as a possible origin of Saturn's rings. This argument relies on the concept of the equivalent circular orbit. Here, we re-examine the post-impact dynamical evolution of collision debris using analytical arguments and $N$-body simulations with fragmentation. We focus on the long-term evolution of debris distributed in a broad V-shaped region in the $a$--$e$ plane, with two arms for particles sharing a common collision radius. Because particles on the two arms possess significantly different angular momenta, inter-arm collisions dominate the evolution and drive behavior fundamentally different from the simple circularization assumed in the equivalent circular orbit approach. As a result, the classical equivalent circular orbit concept cannot predict the long-term fate of collision debris. Both our analytical framework and $N$-body simulations show that, although some debris initially passes within the Roche limit on eccentric orbits, successive collisional evolution drives the particles approximately along the original V-shaped constraint curves toward the apex of the V-shape, i.e., the original collision radius. Instead of spreading inward to form a ring, the debris converges and reaccretes near the original collision location. We therefore conclude that catastrophic proto-satellite collisions do not produce massive Saturnian rings. Rather, the debris evolves toward reaccretion into a new generation of satellite-sized bodies near the impact radius. These results fundamentally revise the dynamical interpretation of collision-generated debris and establish a more general framework applicable beyond the Saturnian system, including other planetary ring systems and debris produced during planet formation. |
| title | Dynamical Evolution of V-Shaped Collision Debris |
| topic | Earth and Planetary Astrophysics Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2605.14243 |