Small satellite could form centaur rings

The two unique thin rings around Centauri Chariklo could be shaped by an even smaller satellite. Chariklo is a centaur, which are small bodies similar to asteroids in size but comets in composition, which orbit the sun in the outer solar system, primarily between the orbits of Jupiter and Neptune.

“Rings around minor planets have only recently been discovered, and only a small number of such systems are currently known. Significant research has been carried out on the dazzling rings around giant planets; however, the mechanisms of formation and d “Evolution of rings around small objects is not well understood,” said Amanda Sickafoose, a senior scientist at the Planetary Science Institute, lead author of “Numerical Simulations of (10199) Chariklo’s Rings with a Resonant Perturber” which appears in The Journal of Planetary Science.

“We showed that one possibility for thin rings to exist around small bodies is that they are sculpted by a small satellite.”

The paper reports the first N-body simulations of a small-body ring system with a satellite. N-body simulations are performed using computer software to simulate the physical dynamics of a number (N) of components. The results of the N-body simulations provide insight into the dynamic evolution of the modeled system.

In this case, by modeling a few million ring particles in a Chariklo-type system, it was demonstrated that a single one-kilometer moon can maintain two rings with properties similar to those observed.

“We think ring particles are mostly made of water ice, like those on giant planets. We don’t know the exact characteristics, such as how ‘hard’ or ‘soft’ the ring particles are when they enter colliding or the particle-size distribution. Further simulations can help constrain these properties,” Sickafoose said.

“Planetary rings will spread or disperse naturally over time. Chariklo has two thin rings, a few kilometers wide. For the rings to remain this thin, there must be a mechanism to confine the material and prevent it from spreading. disperse.” Sickafoose said.

“We show this in the paper by simulating a Chariklo-like ring system that has no satellite, and we find that the width of the rings increases linearly with time. This is different from the situation where there is a satellite in resonance with the material of the rings, which acts to confine the rings within the observed several kilometer widths.

Chariklo, measuring about 250 kilometers, is the first centaur to have rings, and they are constrained.

“Our paper shows that Chariklo-type rings can be constrained by a small satellite, with a radius of about 3 kilometers and a distance of 10 kilometers.¹³ kilograms in mass. A satellite of this size is below our current limits of direct imaging, so indirect methods or a space mission would be necessary to discover it. »

“An alternative mechanism that has been proposed is that Chariklo has a gravitational anomaly on its surface and the rings are in resonance with the spin of the core; every three rotations of Chariklo, the rings rotate once. The physics that acts on the core ring particles are similar for a satellite or spin-orbit resonance with a gravitational anomaly,” Sickafoose said.

“It is interesting to note that, under most reasonable assumptions, the Chariklo rings are also located near or outside the Roche limit. The Roche limit is the approximate distance beyond which the rings “should not exist because matter should begin to accumulate to form the moons. At this distance, the gravitational disturbance from the parent planet is not enough to shear the particles, and they can form into larger clumps.” Sickafoose said.

“A satellite in this situation can disrupt the ring material and prevent it from accreting, similar to what is observed in Saturn’s F ring.”