Using a telescope located at the Roque de los Muchachos observatory on the island of Palma (Canary Islands), scientists have discovered that the dwarf planet Quaoar has a ring. But its location contradicts existing theories, writes The Guardian.
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Quaoar is a trans-Neptunian object that was discovered 20 years ago outside the orbit of Neptune in the Kuiper belt, at the outer edges of the solar system. This dwarf planet with a diameter of 1100 km is slightly smaller than Pluto. The average distance to Quaoar is approximately 42 astronomical units, that is, this dwarf planet is 42 times farther than the Earth from the Sun.
Scientists using a powerful telescope in the Canary Islands were able to discover that Quaoar has a ring. But it is located much farther from the small planet than theories predict.
According to Vic Dillon of the University of Sheffield, in order for the ring around the planet to exist and not disappear, there is a theoretically predicted maximum distance of its location from the planet. This distance is called the Roche limit, and within it the planet, by its influence on the environment, prevents the process of merging the fragments that make up the rings into the satellite. Beyond this limit, according to theories, rings cannot exist.
But a new observation of the dwarf planet Quaoar shows the theories don’t work here. The ring is at a distance from the object that exceeds 7 Quaoar radii. This is 2 times further than the Roche limit. According to theories, the debris in this ring, which consists of ice and stone, should have formed a satellite, that is, it cannot be located here. But scientists have shown with their discovery that existing theories about how planetary rings are formed will need to be revised.
How the ring around Quaoar remains stable is not yet clear. Scientists suggest that it is possible that the fragments in the ring colliding with each other do not merge together, but repel. But more detailed observations are needed to confirm this assumption.
The discovery of a ring around a dwarf planet that could survive at such a far distance came as a real surprise to scientists, Dillon said.