14 DAY TRIAL // An international group of astronomers was recently able to determine the existence of two very narrow rings of debris around the remote asteroid Chariklo. Researchers say that this is the first object in the solar system, except Jupiter, Saturn, Uranus and Neptune, to feature such structures in orbit. The origin of the rings is poorly understood at this point, so more work is needed to assess their nature.
For the new observations campaign, astronomers have used telescopes at seven different locations across South America, including the Coquimbo region, in the Chilean Andes, at the outskirts of the Atacama Desert. This is the site where the European Southern Observatory's (ESO) La Silla Observatory operates from. A total of 9 telescopes are installed at the observatory.
For the recent study, researchers have used the 1.5-meter (5-foot) Danish National Telescope and the 0.6-meter (2-foot) TRAnsiting Planets and PlanetesImals Small Telescope (TRAPPIST). Two dense and narrow rings of debris were identified around Chariklo, and astronomers now believe that these formations may have emerged as a result of an ancient impact.
In a paper published in the March 26 online issue of the top scientific journal Nature, the research group argues that collisions which occurred millions of years ago are most likely responsible for producing a disk of debris that eventually developed into this minute ring system. This study is the first to reveal dust rings around a small-scale object in the solar system.
“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!” explains observation campaign planner, astronomer Felipe Braga-Ribas. He is based at the Observatório Nacional/MCTI in Rio de Janeiro, Brazil.
Scientists explain that (10199) Chariklo is a member of the Centaurs group of asteroids, which orbits the Sun between the orbits of Saturn and Uranus. Theoretical predictions suggested that the object would pass in front of the distant star UCAC4 248-108672 on June 3, 2013, so astronomers were ready to observe the event using multiple telescopes.
As the asteroid moved in front of the star, blocking out its light, astronomers observed that the occultation was accompanied by two other events. Shortly before and shortly after the space rock moved in front of the distant star, two additional dips in the latter's brightness were recorded, suggesting the presence of additional structures around the asteroid that were blocking incoming light.
After combining data from multiple telescopes, astronomers were able to determine that two distinct rings were orbiting the 250-kilometer (155-mile) asteroid. These structures were 7 and 3 kilometers (4.3 and 1.24 miles) in diameter, respectively, and were separated by a clearly defined gap covering around 9 kilometers (5.6 miles)
“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,” says research team member Uffe Gråe Jørgensen, who holds an appointment with the Niels Bohr Institute at the University of Copenhagen, in Denmark.
“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,” the investigator concludes.