Quoar. That’s the name of the dwarf planet, which is about half the size of Pluto and orbits the Sun as far as Neptune. And according to a new study, it has its own ring, similar to the one Saturn boasts.
It was discovered by astronomers from the University of Sheffield, who they described in the journal Nature. They used the sensitive HiPERCAM high-speed camera, which is located on the largest optical telescope in the world, the Gran Telescopio Canarias on the island of La Palma, to study the dwarf planet.
The rings of Quaoar are too small and faint to be seen directly in the image. Scientists discovered them only when they used the often used cloaking method. They observed what happened when the background star’s light was eclipsed by Quaoar in the foreground—an event that lasted less than a minute, but was unexpectedly preceded and followed by two dips in light. And this is very good evidence for the existence of a ring system around Quaoar.
Rings are rare
Ring systems are relatively rare in the Solar System. In addition to the well-known rings around the giant planets Saturn, Jupiter, Uranus and Neptune, only two other smaller planets – Chariklo and Haumea – have rings. All known ring systems exist only because they orbit close to their parent body. And thanks to this, they do not fall apart and fly into free space.
Quaoar is a notable exception. Its ring lies twice as far away as it should theoretically be – so according to available theories it should not exist at all. How is it possible? Astronomers admit that this is a mystery to them, but that it will probably be necessary to rethink basic assumptions about planets with rings.
Professor Vik Dhillon, who was involved in the discovery, said: “The discovery of this new ring system in our solar system was unexpected, and it was doubly unexpected to find the rings so far from Quaoar. It challenged our previous ideas about how such rings form.”
