UFRJ researchers have discovered a ring around a small body in the solar system, something unknown until 10 years ago
Researchers from the Valongo Observatory, UFRJ (Federal University of Rio de Janeiro), have discovered a ring around a small body in the solar system, defined as a trans-Neptunian object, and very similar to the planet Pluto and, like this, a candidate for being a dwarf planet.
“May be considered a younger and smaller cousin of Pluto” explains Professor Bruno Morgado, from the Valongo Observatory, who led the research, published in the international journal Nature.
Asked what this discovery represents for science, Morgado explains that until 10 years ago, this type of structure was only known around giant planets. The location of the ring is the differential factor and it is observed for the 1st time – the ring is outside the limit established by scientific theory. “We have Saturn’s rings, which are beautiful; it has the rings of Uranus, Neptune, Jupiter” he says.
The professor says that in 2013, a Brazilian discovered the 1st ring system around a small body in the solar system, which was the asteroid Chariklo. In 2017 the 2nd example was discovered, around the dwarf planet Haumea, and now this 3rd example has been discovered, which is around the object called Quaoar.
Roche limit
Bruno Morgado however says that the ring around Quaoar is different and unexpected, as it is very far from the Quaoar object itself. “ This distance makes its existence a very big surprise, because there is something that is a limit known as the Roche Limit “, he stated.
The Roche limit is a theory developed in 1850 by French astronomer Édouard Roche that defines the distance of 1,750 km (kilometres) for a disk of particles to maintain the shape of a ring. Beyond this line, it was believed that the disk would begin to merge and eventually form a natural satellite, a moon.
This theory is also applied in exoplanets and in different research. In the case of Quaoar, which is only 555 km long, the ring is located 4,100 km from its central body.
“Imagine you have a natural satellite there, a moon. If that moon approaches its planet that it’s orbiting around and crosses that boundary of Roche, the gravitational forces are so strong that they’ll cause that moon to burst into million pieces. This will form a ring explain.
But if you have a reverse path, of a ring that starts moving away from the main body and crosses that Roche boundary, what should happen is that ring will start to come together and become a natural satellite again, a moon. “It’s one of the ways we see and believe how many solar system objects formed, our moon and other moons of giant planets”.
The professor, however, noted that the Quaoar ring lies well beyond this Roche limit. “Then it shouldn’t exist. She should have become a moon a long time ago. This is the great surprise and the great novelty of the book. Researchers still don’t have the answer as to why this ring is there.”.
He says the research provides evidence that something violates Roche’s limit as it was known. Studies will continue so that researchers can better understand what is going on.
“Because, on the one hand, it is very likely that this moon formation process is more complex than previously thought and that other physical phenomena have to be taken into account. Quaoar may be revealing this to us : what are the physical phenomena that we used to consider, related to the Roche limit known today, and what would be the most correct values, i.e. what physical concept is missing to consider that he had not been before”, it says.
Observation
The work carried out by Professor Bruno Morgado, from the Valongo Observatory, an academic unit attached to the Center for Mathematics and Natural Sciences of the UFRJ, addresses the observational part. “Our job was to show the existence of this ring and to bring the parameters of this ring to the scientific community, such as its location, its width, this most important observation point, what we observed and saw, but not directly”.
The survey brought together scientists from international institutions and amateur astronomers from around the world. “We have collaborators all over the world”. Morgado clarified that these objects are very small and very distant, which makes it impossible to observe them directly, even using the best telescopes in the world, such as the artificial satellite James Webb. “He is not able to see these small bodies in detail”.
To be able to determine these physical parameters, indirect methods are necessary. The technique used for this is called stellar occultation. It’s like an eclipse, where the moon passes in front of the sun and casts a shadow on the Earth.
“If you are in the right place at the right time, you will see the sun disappear for a few moments and then reappear. In physics, the process is relatively the same. We have the stars in the sky and a small body which at some point will pass in front of a star. We continue to measure this star and see it flash, disappear for a short period of time and then reappear. These events will take place in different places around the world,” explain.
The study led by Morgado had observers spread across the Canary Islands, the island of La Palma, Australia, Namibia and also with the Cheops space telescope, which focuses on exoplanets outside the solar system.
When and where this event will occur is predicted, observers are contacted in the regions and people are invited to observe in collaboration with scientists. Each event will take place in a certain place on the planet, the UFRJ professor said.
The search will continue not only by observing Quaoar, but by using the technique on other celestial objects to try to find other rings throughout the solar system. Bruno Morgado also said an answer will not be reached later this year. “It’s a long-term project” it says.
“Perhaps there are others that need to be discovered. It will be interesting to understand all of these systems and to realize that the rings, ultimately, end up appearing in different forms and types and that all of this will contribute to how the solar system formed and became what it is today..