Asteroid Chariklo has two rings.
Asteroid Chariklo, which circles the Sun between the orbits of Uranus and Saturn, is encircled by two thin rings composed of ice particles. This makes it the fifth heavenly body in our solar system to have a ring system. The other bodies exhibiting this trait are Jupiter, Neptune, Saturn and Uranus state scientists from Germany’s MPS (Max Planck Institute for Solar System Research).
They are part of an international team that also recently reported this is the first rocky body to have such rings. They learned all this thanks to “a rare occultation on June 3, 2013 when the Asteroid Chariklo passed in front of a star hiding it for a few seconds. MPS scientist Colin Snodgrass, part of the research team headed by Felipe Braga-Ribas from the Observatório Nacional in Rio de Janeiro, Brazil recalls the moment: “Sometimes in astronomy you get lucky.”
He notes that they had been hoping to use the event to determine the size of asteroid Chariklo. He compared it to the moon’s concealing the sun a solar eclipse. This was the perfect time to establish asteroid Chariklo’s size.
Seven different observatories in South America observed the alignment through their telescopes. Surprisingly, the star disappeared more than once. There were also a few seconds before and after the occurrence that its brightness quickly lessened. Snodgrass reflects: “The analysis of all observational data revealed a surprising result. Chariklo must be surrounded by a ring.”
A Danish 1.34-m telescope at the European Southern Observatory (ESO) in La Silla, Chile was used to determine that the diameter of asteroid Chariklo is approximately 250 km. Chariklo is significantly smaller. Asteroid Chariklo is classified by size as being part of a category of heavenly bodies named Centaurs.
They also discovered “a ring system” made up of two separate rings. Snodgrass reports:”Both rings are very thin, almost filigree from an astronomical point of view.” Data analysis determined that there is a space of nine kilometers between the two rings. Snodgrass also discovered that the inner ring—the brighter of the two– is seven kilometers wide and the outer ring is three kilometers wide.
The new data also clarifies past puzzlements regarding asteroid Chariklo and the supposed presence of frozen water. Snodgrass elaborates: “(T)he ice is found in the ring system, rather than on the surface.” Asteroid Chariklo also sends out a fluctuating signal which Snodgrass explains:
“The situation is similar to looking at a sheet of paper from the side. If you hold it exactly horizontally at the level of your eyes, it is hard to see. Tilt it slightly and it becomes visible.”
The scientists remain clueless, however, in terms of the actual origin of asteroid Chariklo’s rings. They can only theorize that they are the remnants of a prior collision. They also remain unsure as to whether or not asteroid Chariklo is truly unique.
They refer to the asteroid belt located in between the orbits of Jupiter and Mars and note that the area includes perhaps over a million different asteroids as evidence that asteroid Chariklo is probably not one-of-a-kind. Snodgrass concludes: “Compared to the gas planets, these small bodies have only a minimal gravitational field binding the components of the rings. Maybe in years to come we will discover other centaurs like asteroid Chariklo.”
(Image courtesy of ESO)