The dwarf planet Quaoa has a ring (not shown in this visualization) that should not exist.
Andamati/Shutterstock
The dwarf planet Quaoa, located on the other side of Neptune in our solar system, appears to have a ring of debris farther away than previously thought.
Say “I observed a ring that shouldn’t exist” Bruno Morgado at the Federal University of Rio de Janeiro, Brazil.
So far, all rings or orbiting moons observed by astronomers obeyed the limits related to their distance from the parent body put forward by the astronomer Edouard Roche in 1848. When an object is below the Roche limit, the gravitational pull of its parent object rips the orbiting object into clusters of small clumps, eventually forming rings like those seen around Saturn. Outside that limit, dust and debris should coalesce to form larger objects such as the Moon.
At 1110 kilometers in diameter and slightly less dense than our Moon, Qua-or should only be at a distance greater than 2.4 times its 555-kilometre radius, but Morgado and his colleagues place the ring at 7.2 times the radius of Qua-or. Measured in doubles. “We’re way past this limit,” he says Morgado.
To find Kuaoa’s whimsical ring, the team will use a telescope located on Earth and the European Space Agency’s CHEOPS Exoplanet Exploration Space Telescope between 2018 and 2021 to locate dwarf planets against a backdrop of various stars. observed. The researchers calculated the ring’s properties using changes in the star’s brightness.
They found that the rings appear to be mostly made of water ice, a bit like Saturn’s F ring. One of the ring’s unusual properties is its irregular shape. Some sections are 5 km wide, others over 100 km. Standing on the surface of Kua Oa, Morgado says, you should be able to see a wider portion of the ring.
It’s not clear why Quaor’s rings are so far beyond Roche’s limit, but the researchers believe that the low temperatures (the dwarf planet is a chilly planet of -220°C) can help the ring’s contents coalesce. I believe it may play a role in prevention.
It is also possible that interactions between particles in the ring, or interactions with Quaor’s satellite Waywot, sustain the ring. Morgado says more observations of quaor and more simulations of the system’s dynamics are needed before a definitive answer can be found.
Whatever the answer, you may need to change your Roche limits. This can affect other calculations in astrophysics.
“This concept has been used, for example, to analyze the formation of the Moon and the formation of other satellites in the solar system,” Morgado says. “So if we see something that pushes this limit, we need to rethink and better understand why we have this ring.”
Karl Murray At Queen Mary University of London, he hopes this won’t change the situation too much, as the Roche limit is only a rough guide, but understanding Quaoar’s anomalous rings can improve it, he says. say.
“Roche limits have their uses, but they don’t really have an exact radius,” says Murray. “It depends on the physical properties of the orbiting matter, and there are other properties that need to be taken into account, as shown here.”
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