At the edge of the solar system is a planet surrounded by “impossible” rings. It’s a dwarf planet called Quaoar, discovered in 2002, which has a ring system at an anomalous distance previously thought impossible. The discovery, published in the journal Nature, prompts us to reconsider current theories of how rings form around planets. The images were taken by several ground-based telescopes and by the European Space Agency (ESA) Cheops satellite, in which Italy is a major contributor through the National Institute of Astrophysics (INAF) and the Italian Space Agency (ASI). , next to the industry, with Leonardo. The data analysis is thanks to an international research group led by the Federal University of Rio de Janeiro, which also includes two Italians from INAF.
With a mass about two-thirds that of Pluto, Quaoar isn’t the only dwarf planet known to have rings: in fact, two others, Chariklo and Haumea, share similar properties. But what makes the Quaoar rings unique is their remoteness: they are located at a distance seven times the radius of the planetoid, twice what was previously thought to be the so-called “Roche limit”, the maximum limit beyond the planet , it was thought possible which ring systems are not viable. For comparison: the main rings around Saturn are within three planetary radii. “According to these data, the classical notion that dense rings survive only within the Roche limit of a planetary body needs to be completely revised,” comments INAF’s Giovanni Bruno, one of the authors of the study.
The rings of the dwarf planet Quaoar are too small and too faint to be observed directly. In fact, the researchers led by Bruno Morgado only identified them when the light from a background star was momentarily blocked by the sun-orbiting planetoid. The event lasted less than a minute, but was unexpectedly preceded and followed by two fainter occultations. accurately shows the presence of rings.
The Cheops satellite also participated in the observations that took place between 2018 and 2021, which notably followed the passage of the dwarf planet on June 11, 2020, thanks to the ingenious “eyes” designed and built by Leonardo in Italy. “The entire Cheops team was quite skeptical about the possibility of capturing this phenomenon – says Inaf’s Isabella Pagano, national manager for Cheops and co-author of the study – but after evaluating the feasibility, we decided to do it because of the Risking the time spent by the satellite to observe this event would have been short enough not to disrupt the mission’s primary schedules.” Cheops’ contribution ultimately proved crucial because it allowed the researchers to rule out the possibility that the light dips were caused by disturbances in the Earth’s atmosphere.