Through the space telescope CHEOPS and the work of a team including French researchers, new measurements prove the existence of a ring around Quaoar, small and distant dwarf planet of our solar system. A feat that raises many questions and challenges Roche’s limit!
See Quaoar has pushed the limits of cloaking technique!
You will see what you will Quaoar
The French mathematician and astronomer Edouard Roche, in 1850, defined a limit beyond which normally a ring of debris or collisional dust is supposed to accrete and form a satellite around a celestial body. A calculation which was for the moment verified with the rings of Saturn, but also those of smaller and more distant bodies, such as the asteroid Chariklo or the dwarf planet Haumea. Close to the central body, the debris forms a disc or a ring, and after a while, one or more moons form. This limit is also called the “Roche limit”, and since the publication in the journal Nature ,February 8, the work of a group of scientists, it is the subject of discussion. Thanks to a unique observation, we now know that the dwarf planet Quaoar, more than 6.5 billion kilometers from the Sun, hosts a fairly dense ring located well beyond its Roche limit, 4100 km from its surface.
Coordination of assignments
Quaoar is a dwarf planet about 550 km in diameter, which has a small moon, Weywot (80km in diameter). The initial objective of the study was to be able to observe them thanks to the technique of occultation, already used recently to “weigh” a white dwarf. As in this news, it was the catalog of the Gaia cartographer telescope that enabled the precise observation, by calculating the exact moment at which Quaoar would pass between Earth and a distant star. A rare encounter that allows you to learn a lot, at the center of the project called “Lucky Star” and directed by the French researcher Bruno Sicardy (CNRS, Paris Observatory), who coordinates observations by occultation on distant objects. The novelty here is the use of ESA’s CHEOPS space telescope, in Earth orbit and specialized in observing exoplanet transits: the observation window was particularly short and it is a real technical feat… which has paid !
Understanding the Ring
The scientific article looks at different possibilities to explain the presence of this distant ring. The role of the small moon Weywot is imaginable, like that of a possible other satellite which would not have been detected on this date. Another parameter is that of the resonance between the rotation of Quaoar, its moon and the ring, which seem to be synchronized. There is also the temperature factor, which could play a link: it is extremely cold in this remote region… In short, there is still a lot of knowledge to be refined on the conditions leading to rings around small bodies! It is not tomorrow, in fact, that we will be able to go and see the rings of Quaoar.
Source : Isa
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