There are actually five bodies in our solar system that have rings around them. Saturn is the one everyone immediately thinks of. Jupiter, Uranus and Neptune also have them. The fifth one is Chariklo, one of a class of minor planets known as centaurs. Basically, they are rocky bodies that have the qualities of asteroids and comets.
A sixth body may be about to join the exclusive club. Chiron.
Scientists from MIT and other institutions believe Chiron has a possible ring system.
Four years ago, the group of scientists watched Chiron pass in front of a bright star, blocking its light. As the group analyzed this stellar occultation (when Chiron passes in front of the star) they noticed features that suggest Chiron may have debris orbiting it. Possilbly, a ring system.
“It’s interesting, because Chiron is a centaur — part of that middle section of the solar system, between Jupiter and Pluto, where we originally weren’t thinking things would be active, but it’s turning out things are quite active,” says Amanda Bosh, a lecturer in MIT’s Department of Earth, Atmospheric and Planetary Sciences.
Until the discovery of a ring system around Chariklo, centaurs were believed to be mostly dormant bodies.
Chiron has always been of interest for astronomers. It was discovered in 1977 and was the first to be categorized as a centaur. Now, scientists believe there are about 44,000 centaurs in our solar system. Most of them are concentrated between the orbits of Jupiter and Pluto.
James Elliot first noticed some type of debris around Chiron in 1993 and 1994. At the time, he was a professor of planetary astronomy and physics at MIT.
The new research showed something else was blocking star light. Analysis showed sharp features near the beginning and end of the stellar occultation. This indicates some kind of debris, or maybe a ring system around Chiron.
Jessica Ruprecht, a research at MIT’s Lincoln Laboratory, explains how the sun could be responsible for a potential ring system around Chiron.
“Another possibility involves the history of Chiron’s distance from the sun,” Ruprecht says. “Centaurs may have started further out in the solar system and, through gravitational interactions with giant planets, have had their orbits perturbed closer in to the sun. The frozen material that would have been stable out past Pluto is becoming less stable closer in, and can turn into gases that spray dust and material off the surface of a body. ”
This material could have come from another body or from Chiron itself and captured by the centaur’s gravity.
The group of scientists will need several more observations of Chiron to know for certain if it has a ring system. If it does, “it will show it’s more common than previously thought,” said Bosh.
Image credit: European Southern Observatory