March 27, 2014

Astronomers Find Minor Planet Chariklo Is Surrounded By Rings

[ Watch the Video: Artist’s Impression of Ring System Around Chariklo ]

Lee Rannals for - Your Universe Online

Astronomers writing in the journal Nature say they have observed a minor planet which contains two rings of ice and pebbles for the first time.

Chariklo sits about 1.2 billion miles out in the solar system between Saturn and Uranus, and the minor planet, or asteroid, has been known about for many years. However, this is the first time astronomers discovered rings around the minor planet.

Astronomers used a new camera installed on the Danish telescope at the European Southern Observatory’s (ESO) La Silla Observatory in Chile to make the discovery.

"The camera was specially developed at the Niels Bohr Institute and has a stunningly high resolution, which we especially exploit to look for exoplanets. But when the area where we are looking for exoplanets isn't 'up' in the sky, we use our observation time for other projects and so we followed Chariklo, which just passed in front of a star," Uffe Gråe Jørgensen, an astronomer in Astrophysics and Planetary Science at the Niels Bohr Institute at the University of Copenhagen, said in a statement.

The team made the observation as Chariklo passed in front of a star last summer. The minor planet’s transit allowed astronomers the conditions needed to help view the two fine rings.

"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!" Felipe Braga-Ribas, who planned the observation campaign and is lead author on the new paper, said in a statement.

The team used the observations to reconstruct the shape and size of the object, as well as the shape, width, orientation and other properties of the rings. They found that the ring system consists of two sharply confined rings that are just 4-to 1.8-miles wide and separated by a 5.5-mile gap.

"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 Jørgensen. "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-kilometre (12.4-mile) wide ring system 1000 times closer than the Moon."

Astronomers believe that these rings formed from debris left over after a collision. They said that the rings also indicate that Chariklo likely has at least one small moon. This discovery helps scientists learn more about how the Moon may have been formed around the Earth.

“In the collision, material hurled out in all directions, forming a circular disc around the Earth, which gradually condensed and formed the Moon. Similarly, we believe that another celestial body crashed into Chariklo and a good deal of material was cast out and formed rings. If the two discs around Chariklo gathers and forms a moon, it will be approximately 2 km in diameter," explains Jørgensen.

Image 2 (below): Observations at many sites in South America, including ESO’s La Silla Observatory, have made the surprise discovery that the remote asteroid Chariklo is surrounded by two dense and narrow rings. This is the smallest object by far found to have rings and only the fifth body in the Solar System — after the much larger planets Jupiter, Saturn, Uranus and Neptune — to have this feature. The origin of these rings remains a mystery, but they may be the result of a collision that created a disc of debris. This artist’s impression shows a close-up of what the rings might look like. Credit: ESO/L. Calçada/M. Kornmesser/Nick Risinger (