Ring discovered around dwarf planet surprises astronomers

Feb. 8 (UPI) -- Astronomers have discovered a ring around a dwarf planet called Quaoar in the outer reaches of the solar system.

The ring was found at seven and a half times the radius of Quaoar, much farther away from a planet than is usual. The finding was made during an occultation event, when a planet passes directly in front of a star, allowing the space-based telescope Cheops to observe its silhouette.

"When we put everything together, we saw drops in brightness that were not caused by Quaoar, but that pointed to the presence of material in a circular orbit around it," Bruno Morgado, an astronomer at Universidade Federal do Rio de Janeiro, said. "The moment we saw that we said, 'OK, we are seeing a ring around Quaoar.'"

Normally, rings that exist beyond a certain point, called the Roche Limit, will coalesce into small moons, as the one around Quaoar should have done, according to the European Space Agency.

"As a result of our observations, the classical notion that dense rings survive only inside the Roche limit of a planetary body must be thoroughly revised," Giovanni Bruno, INAF's Astrophysical Observatory of Catania, Italy, said.

Early results suggest that the frigid temperatures at Quaoar may play a role in preventing the icy particles from sticking together but more investigations are needed, the ESA said.