What astronomers thought were rings around the asteroid Chiron in 2011 are actually something very strange, according to new research. The true nature of the matter swirling around the icy world is still unknown, but it appears to be a constantly shifting disk of dust and gas.
The initial discovery of the Chiron object, which has a diameter of about 210 km, was a major advance in our understanding of the outer solar system. With its orbit varying from within Saturn to near Uranus, Chiron was the first in a class of similarly positioned objects known as centaurs.
The development of astronomy shows that hundreds of centaurs have been found since the discovery of Chiron in 1977. Among them, he writes, is one of the strangest objects in the solar system. IFLScience.
Chiron has not been visited by any spacecraft, nor any centaur, and is too distant to be clearly seen with ground-based telescopes. However, we learned something interesting about it after it passed (obscured) an unnamed star in 2011. It was then discovered that there was a ring system around Chiron. Or at least we thought it was. The more recent crossings suggest that we have misinterpreted the evidence.
The strangest asteroid so far?
Speaking in favor of the rings around Chiron was the fact that just before and after Chiron passed in front of the star, the object became dim and brightened again. The operation was done four times. Twice before the main event and twice after. This allowed astronomers to conclude that the icy world is surrounded by two rings, each of which is capable of partially blocking the light of distant stars.
This discovery was surprising because Chiron’s gravity is so small that we have no idea how it could have a ring system. However, in addition to the fact that all four gas planets in the solar system have rings, one was recently found around Chariclo, the largest centaur, so this was not entirely unexpected. Placing the ring next to Jupiter seems to be the fashion. Since then, other candidates say this happens more often.
Only another star’s coverage of 2018 provided proof that things weren’t so simple. Although it also showed a dip in brightness before and after its passage, the dip was only half that of 2011, and there were three dips, not two, before the occultation.
The location and amount of material discovered around Chiron differs enough from previous observations that it is not a stable ring system, but rather material around it that is currently evolving.
Study author Dr. Amanda Sikafoos from the Planetary Science Institute said in a statement.
Chiron also eclipsed another star on December 15, 2022. Although the star was brighter in this case, observations of the event were of lower resolution. What is seen indicates a broad, fragmented disk, the focus of which does not match what happened in 2011 or 2018.
Around Chiron there is matter that evolves on a relatively short time scale.
Overall, there appears to be less starlight-blocking material around Chiron in 2018 than in 2011, but by 2022 there was more. This may be the result of an explosion in February 2021, during which Chiron became noticeably brighter, perhaps because it ejected material that enhanced its disk.
Strange but not unique?
Like many other centaurs, Chiron shows signs of comet-like activity. Even the closest part of its orbit is too far from the Sun to get too hot, but some of the more volatile gases escape, but how this relates to the disk is currently unclear.
Whether there is something more complex about Chariclo and other objects with apparent ring systems is also a question that requires further research, as are the reasons for the changes observed between 2011 and 2018.
On the other hand, from the 2018 observations, they were able to rule out that the constellation has a large atmosphere, such as one that could have been created by large escaping gases.
Small objects like Chiron block only a small portion of the light that reaches Earth. In the case of the 2018 cover, most of it fell into the ocean. Fortunately, this event was seen through the South African Astronomical Observatory’s 1.9-metre telescope, as well as a smaller telescope at the same location.
Unfortunately, Chiron is often confused with Pluto’s moon Charon, but they have nothing to do with each other.
2018 Coverage Study A Planetary Science Journal It is published with open access in the journal
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