Chariklo's Double Rings

Chariklo is the largest centaur, minor celestial bodies whose orbits are between those of Jupiter and Neptune. In 2014, two rings were discovered by stellar occultation, the phenomenon where light from a distant star is blocked by a foreground object. Chariklo’s rings are thought to consist of icy or rocky particles similar to Saturn’s rings. Previous simulations of Saturn’s ring have either focused on only local structures or have used an unrealistic size for the particles.
In this simulation, for the first time an entire ring structure was calculated using realistic partical sizes. Chariklo’s rings revealed by the numerical simulation is like waves in a river.

Chariklo and surrounding double rings. Chariklo’s average radius is about 125 km and the average radius of the rings is about 400 km.
Close-up view of the two rings. From the occultation observations, it was suggested that the outer ring is sparse but the inner one is dense. Considering previous research, meter-sized particles were assumed in this simulation.
In the outer ring, particle distribution is not completely uniform. There are clumps of particles due to self-gravity.
In the dense inner ring, complicated elongated structures like a wave are visible. These structures are called "self-gravity wakes." It is thought that similar structures also exist in Saturn’s rings.
From this simulation, it was concluded that self-gravity wakes should exist in the inner ring. However, from the theoretical point of view, the self-gravity wakes reduce the lifetime of the rings significantly. This suggests that the ring particles may be smaller than previously thought or that an undiscovered shepherd satellite may exist.

Details of Numerical Simulation

PurposeTo reveal the structure and origin of Chariklo’s rings.
Calculation MethodN-body simulation of self-gravitating collisional system
Number of Particles345,000,000 (largest model)
ComputerCray XC30 "ATERUI"
Time ScaleA few hours ~ days
Spatial ScaleA few hundred meters ~ kilometers
ReserchersShugo Michikoshi (Kyoto Women’s University), Eiichiro Kokubo (NAOJ)
ReferencesMichikoshi, S. Kokubo, E., 2017, ApJ, 837, 13L

Details of Visualization

This movie was visualized and rendered using the “Unity” game engine.
Particles constituting Chariklo's double ring are displayed as white spheres. And the shape and color of Chariklo's 3DCG model are based on actual observations. However, since Chariklo has not been observed in detail yet, the details are an imaginary representation. Because this video was made as an all-round stereoscopic image, you can view it with a head mounted display (HMD).

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  • Simulation: Shugo Michikoshi, Eiichiro Kokubo
  • Visualization: Hirotaka Nakayama
  • Four-Dimensional Digital Universe Project, NAOJ

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