A Centaur and Its Rings
Up until now, rings have only been known around the four giant planets: Jupiter, Saturn, Uranus, and Neptune. It was recently observed that another body in our solar system also has a ring system. Chariklo is a centaur; a scattered KBO in orbit between Saturn and Uranus. Through stellar occultation observations at seven sites in South America, the authors, who announced the discovery, detected flux interruptions that can be explained by the presence of a ring system.
The light curve of the occultation showed two rings, the inner referred to as 2013C1R and the outer as 2013C2R. Ring 2013C1R is larger than 2013C2R, and they are both believed to be composed of water ice. These rings would appear brighter than Uranus’s rings, but dimmer than the A ring of Saturn.
It is still unclear how the rings originated, but the authors propose a few possibilities. All suggest that the rings formed from a debris disk. The first possibility is that the outer layers of Chariklo were disrupted by an impact. Another possibility is that two former satellites collided, or a retrograde satellite may have been disrupted by tidal forces from Chariklo. The authors also suggest the small probability that Chariklo’s rings formed due to a close encounter with Uranus.
Image: The star’s brightness as Chariklo passed in front. Time flows from left to right. Visible are the shadows of the two outer rings, 2013C2R and 2013C1R, as Chariklo is approaching the star and again as it is leaving. The big dip in the middle is the shadow of Chariklo. From F. Braga-Ribas et al.