Discovered the first asteroid with rings

Scientists have made a stunning discovery in the solar system - an asteroid with its own set of rings that revolves around the sun between Saturn and Uranus. The asteroid is the first non-planetary object ever found, which has its own ring system.

Filegiver continues the series of space discoveries posts. This time we will talk about the asteroid Hariklo, which is surrounded by a pair of rings. According to a study published March 26 in the journal Nature, rings were likely formed after a collision of scattered debris around an asteroid. The presence of asteroid rings also suggests an asteroid satellite that has not yet been discovered, which stabilizes them.

“We did not look for rings and did not even think that small bodies, like Chariklo, could have them. Therefore, the discovery was a complete surprise to us! ”, Says study leader Felipe Braga-Ribas from the National Observatory in Brazil. An asteroid with a diameter of 250 km looks just tiny against the background of giant gaseous planets that have rings. “This discovery proves that the formation of rings around the cosmic body is in no way connected with its size,” says Braga-Ribas.

On June 3, 2013, Braga-Ribas led a team of astronomers observing the passage of Chariklo against a star, a process known as coating. When an asteroid flies against the background of a star, it blocks its light, which gives scientists the opportunity to study the asteroid in more detail. Astronomers were surprised to find that a few seconds before and after the main eclipse, the star's light was interrupted, which made it possible to believe that the asteroid was surrounded by something. By comparing data collected from seven different telescopes, the team was able to determine the shape, size, and orientation of the rings. The system consists of a dense inner ring 7 km wide and an outer ring 3 km wide. “From the surface of the asteroid, they look simply amazing, the bright rings at a distance from the surface are 1000 times smaller than the Moon from the Earth,” says Braga-Ribas. Rings are similar to those around Saturn, very dense, bright and probably formed from stones and ice.
')


The speed of particles rotating around Chariklo is only a few tens of meters per second, which is relatively slow compared to tens of kilometers per second for the rings of Saturn. While Saturn is the most famous cosmic body with rings in the solar system, Jupiter, Neptune and Uranus also have them, they are just less visible. But all these gas giants are much larger than Hariklo.

Astronomers used seven telescopes, most of which were located in South America. Of these, only a telescope from La Silla ( European Southern Observatory (ESO) in Chile) was able to detect a small gap between the rings. “This is made possible by the use of Lucky Imager, a fast and sensitive camera that generates a series of images at 10 frames per second,” said Braga-Ribas. The eclipse of a star simultaneously with two rings of an asteroid lasted 0.6 seconds, which made it possible to examine them in detail. The exposure time of other telescopes was a longer time, so they managed to take pictures of the eclipse with only one ring. The video below shows how ring detection occurred.



Chariklo is one of the largest centaur asteroids. Centaurs - a group of asteroids located between the orbits of Jupiter and Neptune, transitional in properties between asteroids of the main belt and objects of the Kuiper belt, in some properties resemble comets. Perhaps it is precisely such a far distance from the Sun that will help reveal the reason for the presence of rings in comparison with asteroids, which are located near Mars and Jupiter, where the solar wind is stronger and probably carries small particles.



The relatively small size of Chariklo forms a fairly low level of gravity, which means that the asteroid was able to capture only small and slowly moving particles. The presence of a ring system answers questions about why the asteroid has become brighter since its last observations in 2008. Yet it remains a mystery how the rings remain stable. Over time, particles scatter from the rings in different directions, the only exception is the case when there is a satellite that stabilizes the rings. But the mass of the satellite for Hariklo should be like both rings together, and with such dimensions the satellite would easily have moved away from the asteroid due to the low gravity of the latter. Therefore, perhaps, the system of rings is young enough. But if there is still some satellite of the asteroid that keeps the rings in a stable state, then in the rings of Chariklo there can be particles that were formed at the time of the formation of the Solar System.

Additional useful materials:
1. Video about Hariklo with comments in English from Space.com
2. About asteroid Hariklo on Wikipedia .
3. Centaur asteroids .
4. An interesting virtual tour of the observatory in Chile.
5. A large 50-mb English presentation about the European Southern Observatory (ESO) and its latest technologies.
6. The recently discovered dwarf planet 2012 VP113 in the Oort cloud.
7. Infographics of a 36-year voyager probe travel 1.