Fascinating Rings Discovered Around Dwarf Planet Quaoar
FASCINATING RINGS DISCOVERED AROUND DWARF PLANET QUAOAR
The solar system is a constant source of wonder. As telescopes and imaging technologies advance, astronomers are learning more about distant worlds we can barely see. One of them is the icy dwarf planet Quaoar, which is only 1/3 the diameter of Earth's Moon. It orbits our Sun about 4 billion miles from Earth in the Kuiper Belt, a belt of frozen cosmic debris that includes Pluto. However, unlike Pluto, Quaoar has been found to have rings (as well as Saturn). Moreover, as recently published in the journal Nature, the rings are surprisingly far from the celestial body.
Kwawar (pronounced KWA-wahr and named after the native creator god Tongwa) appears to be about half the size of Pluto. Scientists believe it's likely a dwarf planet, meaning that its own gravity is pulling the mass together, but not enough to clear out areas of inhabited space. Quaoar also has a moon. But even in the most powerful telescopes, Quaoar is only a tiny speck. But by observing the spot with the world's largest optical telescope, the Canary Islands' Gran Telescopio CANARIAS, and a special HiPERCAM camera, the researchers were able to observe "flashes" in the light recorded as Quaoar passed between the camera and the distant star.
At the same time, researchers noticed other dips in light before and after this "splash." This falloff reflects both sides of the Quaoar ring passing in front of the distant light source. This was a very unexpected discovery. First, only a limited number of solar system objects have rings: Jupiter, Uranus, Neptune, Saturn, Chariklo (a centaur), and Haumea (another Kuiper belt body). The rings are also very far from the dwarf planet's central body. The distance of 3 planetary radii is commonly considered the Roche limit, named after the 19th-century French astronomer Edouard Roche. At this distance, the ring-forming fragments are within the gravitational range of the planet enough to keep them separated as rings.
It has long been believed that, beyond this distance, the ring will become the moon within a few decades. The ring, which looks jagged to Quaoar, is about 2,500 miles from the central body. This is about 1400 miles over the Roche limit. "It really shouldn't be there," said Dr. Bruno Morgado, a professor at the Federal University of Rio de Janeiro in Brazil and lead author of the paper. "We need to revisit these limits and better understand how satellites form." Perhaps Quaoar's moon, Weywot, broke normal gravitational calculations. It's also possible that ice particles in these colder regions don't form moons as easily.
"If the data isn't that convincing, I'd argue it's not real," Dr. Morgado told The New York Times. Dr. Richard G. French, Professor Emeritus of Astrophysics at Wellesley College who was not involved in the study, said: "The fact that we found rings around three of them already means that rings around objects are actually very common." says "You might think that tiny rings around tiny objects in distant solar systems aren't widely used. But in fact, this particle accretion process is actually an early step in planet formation."
The secrets of Quaoar's rings may actually help decipher the secrets of the solar system's formation.