The new ring system is around a dwarf planet called Quaoar. It is about half the size of Pluto and orbits the Sun beyond Neptune.

Scientists have found a new set of rings around a dwarf planet at the edge of the Solar System. The ring system orbits far further away than is common for other ring systems, bringing into doubt existing ideas about the formation of ring systems.

Quaoar, a dwarf planet around the size of Pluto that circles the Sun beyond Neptune, is where this ring system is located.

An international team of astronomers used HiPERCAM, a highly sensitive high-speed camera created by researchers at the University of Sheffield, to make the discovery, which was reported in Nature. HiPERCAM is mounted on the largest optical telescope in the world, the 10.4 m Gran Telescopio Canarias (GTC) on the island of La Palma.

The rings are too tiny and dim for direct visual observation. Instead, they found it by watching an occultation, which occurred when Quaoar passed in front of the background star during its orbit around the Sun. The occurrence lasted for less than a minute, but it was surprisingly preceded and followed by two dips in light, which indicated that Quaoar was surrounded by a ring system.

Only two additional small planets, Chariklo and Haumea, have rings in the Solar System, in addition to the well-known rings that surround the big planets Saturn, Jupiter, Uranus, and Neptune. Tidal forces prevent the ring material from accreting and generating moons since all of the previously discovered ring systems orbit very near to the parent body. This allows the ring material to remain intact and continue to exist.

The ring system around Quaoar is noteworthy because it is twice as far out as what was previously believed to be the maximum radius permitted by the so-called “Roche limit,” which is the greatest distance at which ring systems are supposed to be able to exist. Saturn’s main rings, on the other hand, are within three planetary radii. Thus, this finding has reshaped ring formation hypotheses.

“It was unexpected to discover this new ring system in our Solar System, and it was doubly unexpected to find the rings so far out from Quaoar, challenging our previous notions of how such rings form,” remarks co-author Prof. Vik Dhillon. 

“The use of our high-speed camera – HiPERCAM – was key to this discovery as the event lasted less than one minute and the rings are too small and faint to see in a direct image.

“Everyone learns about Saturn’s magnificent rings when they’re a child, so hopefully this new finding will provide further insight into how they came to be.”

Source:10.1038/s41586-022-05629-6

Image Credit: Paris Observatory