RIO – Researchers from Federal University of Rio de Janeiro (UFRJ) discovered, around a small astro of the Solar System, a ring that simply could not exist. At least not according to the prevailing laws of physics. Therefore, the study published in this Wednesday’s edition of the journal Nature challenges, for the first time, an internationally accepted 19th century theory.
Located in a region of space after Neptune, Quaoar was being observed by specialists from the Valongo Observatory in search of clues about the origins of the Solar System. To everyone’s surprise, they identified that the tiny star has a ring – which, in itself, is already considered rare. To date, rings have been discovered in only three small stars.
But even more extraordinary than the very presence of the ring is that it turned out to be “impossible” according to current astronomical concepts. According to the definition used today in astronomy, rings are non-solid structures that gather asteroids, dust and other particles around a larger star.
Until 2013, researchers only knew of rings circling giant planets, such as Saturn and Jupiter. Since then, however, astronomers have detected rings on the dwarf planet Haumea and on the centaur Chariklo, opening precedents for new studies on the subject. In the case of Quaoar, the biggest enigma is related to the dimensions of the ring.
As defined by the French astronomer Edouard Roche (1820-1883) in the mid-nineteenth century, for such particles to maintain the shape of a ring they need to be at a maximum distance of 1,750 kilometers from the star they surround. Beyond that limit, Roche established, the particles would start to clump together and eventually form a satellite. Known as the Roche Limit, this principle has never been challenged until today.
It so happens that Quaoar’s ring is located 4,100 kilometers from its central body, therefore far outside the Roche Limit.
formation of planets
“For the first time, we are seeing a ring beyond the Roche limit”, observed astronomer Bruno Morgado, from the Valongo Observatory, the main author of the study. “The first question we asked ourselves is whether we are witnessing the exact moment when the ring is becoming a natural satellite.”
This hypothesis, although incredible, is unlikely, according to Morgado himself.
“This process would take a few dozen years and, considering the entire long history of the Solar System, it is unlikely that we are in the right place at the right time to witness it,” he said. “But it is a possibility. If true, it will be very interesting to witness the formation of a moon.”
The Brazilian astronomer considers it more likely, however, that some other factor (not taken into account by Roche) makes the existence of the ring possible. The challenge now is to try to determine what that factor would be.
