“Hariklo”, affectionately called by one researcher “a little bit strange object”, is an asteroid rotating in a strange place. Instead of settling in the usual place (between Mars and Jupiter, or beyond Neptune), it is located between Saturn and Uranus. Moreover, Harilko has its own ring system. The discovery of 2014 perplexes researchers even more, because, as we know, the only rings are located near huge planets: Jupiter, Saturn, Uranus and Neptune.
After the discovery, planetary scientist Margaret Pen from the University of Toronto became interested in the formation of these rings. Recent studies that she conducted, give hints to address this issue. Using mathematics and observations of Chariklo, her team proposed a new way of how rings could be created for an asteroid and other space stones (centaurs) in its vicinity.
Their work suggests that, like Hariklo, from the Kuiper belt (beyond the orbit of Neptune) ice objects shifted in relation to its current orbit, and this sudden heating would cause the degassing of carbon monoxide or nitrogen. This process would raise dust from the surface, and eventually formed a ring. This theory competes with another idea previously brought from literature, which states that Harilko picked up a small moon while in the Kuiper belt, which eventually broke up into a ring when Harilko passed near Neptune. Pen said that the last script is very rare. Only some centaurs could get rings in this way.
Rings are rare in the solar system. Saturn has an impressive ring system, along with Jupiter, Uranus and Neptune.
“(Our) scenario predicts that all 100 km (62 miles) centaurs should have some sort of orbital dusty material. We are committed to the future observation of the centaur in order to learn to distinguish these paths of formation, ”Pan wrote in an email to Discovery News.
Uranus and its system of rings, which is most similar to Chariklo rings
Why limit 100 km? Ban says that degassing at small sites will not have enough mass to stop dusty material from flying away. She adds that the Kuiper belt objects were not expected to have rings, as they are too far from the Sun and thus too cold to experience this degassing. Even if the Kuiper belt object has moved close enough to the planet to share the orbital moon, the trajectory will inevitably turn an asteroid into a centaur.
Harilko's observations are limited by distance, but astronomers have discovered that he has two rings. They are wider on one side of Harilko than on the other. The second ring contains about a tenth of the mass of the first ring.
Team Pen assumes that the ring is not quite round (elliptical). Particles do not form into a circle due to individual gravitational interactions between particles. Researchers report that in order for this to happen, you will need to have enough material to create a kilometer-long (0.62 mi) ice ball. Typical particles should also be several meters in size. If we compare the rings of Harilko with other ringed bodies in the Solar System, then it is closest to Uranus, despite its miniature size.
“The geometry of Harilko rings, which are rather dense and narrow, most of all resembles rings of Uranus. Interestingly, some rings of Uranus also have a noticeable elliptical shape. And the study of the Uranus system inspired us to process the Harilko rings, ”writes Pen.
Pen plans to further consider how the rings became primarily eccentric. She believes that the round shape has changed a kind of perturbation. She is also interested (in general) if it is possible to predict ring eccentricity based on its mass and width.