Astronomers today revealed that an asteroid in the outer solar system has been confirmed to have its own Saturn-like ring system. The new findings have been published today in the journal Nature.
The asteroid, named Chariklo, is a minor planet that orbits the sun between Saturn and Uranus. The object is also classified as a "centaur," one of the many small objects that orbit between Jupiter and Neptune, many of which were recently discovered to be comets. Chariklo is the largest of these Centaurs.
The discovery marks just the fifth object in our solar system to have a confirmed ring system. Saturn, Jupiter, Neptune, and Uranus are the only other objects known to have rings. Astronomers had previously searched for rings around minor planets and asteroids, but found none.
"We weren’t looking for a ring and didn’t think small bodies like Chariklo had them at all, so the discovery - and the amazing amount of detail we saw in the system - came as a complete surprise," said Felipe Braga-Ribas, lead author on the paper and an astronomer at the Observatório Nacional in Rio de Janeiro.
Chariklo's rings system was observed by telescopes in South American while passing in front of a distant star on June 3, 2013. Astronomers were able to observe that the asteroid has two distinct, thin rings that are from three to seven kilometers wide and separate by only nine kilometers.
In addition to the rings discovery, astronomers were able to measure the size and shape of Chariklo itself. The asteroid is 250 kilometers in diameter.
The paper's authors were not able to determine why Chariklo's rings exist, but they did speculate that the rings could be made up of debris left over after a collision that affected the asteroid. The astronomers went on to speculate that the gap between the rings may hold one or many small moons and that the rings may eventually form a moon.
"For me, it was quite amazing to realize that we were able not only to detect a ring system, but also pinpoint that it consists of two clearly distinct rings," said Uffe Gråe Jørgensen, a member of the research team an an astronomer at the Niels Bohr Institute. "I try to imagine how it would be to stand on the surface of this icy object - small enough that a fast sports car could reach escape velocity and drive off into space - and stare up at a 20-kilometer wide ring system 1000 times closer than the Moon."
Image via ESO/L. Calçada/M. Kornmesser/Nick Risinger