NASA's Webb provides fresh insights into the ringed asteroid Chariklo
Scientists have been able to peer closer at a ringed asteroid named Chariklo by using the James Webb Space Telescope. The rings were initially spotted in 2013 while watching Chariklo pass in front of a distant star. Two other smaller objects also appeared to cross in front of the star momentarily, which turned out to be the rings of Chariklo.
Why does this story matter?
Larger planets such as Jupiter and Neptune are known to possess rings but what makes the 2013 discovery interesting is that it marks "the first rings ever detected around a small solar system object." The Webb telescope now provides a better, more precise, picture of the ringed asteroid, and demonstrates a new way of exploring objects in our solar system.
This is the "first stellar occultation" attempted with Webb
Astronomers by means of Webb's near-infrared camera observed Chariklo occult star Gaia DR3 6873519665992128512 in October 2022. This is the "first stellar occultation" attempted with the Webb telescope. Researchers looked for dips in the brightness of the Gaia star that would indicate an occultation. Upon careful analysis of the star's brightness, the rings around the Chariklo asteroid were detected, revealed NASA.
The asteroid is 51 times smaller than Earth
Chariklo measures 250 kilometers wide, about 51 times smaller than Earth, and its rings orbit at a distance of about 400 kilometers from the center. It is located more than 3.2 billion kilometers away, beyond Saturn's orbit. The asteroid's size and distance make it hard for Webb to directly image the rings, so occultations are the "only tool to characterize the rings by themselves."
What are the asteroid's rings made up of?
Chariklo rings are predicted to be made up of ice along with other dark material, possibly the debris from an ancient cosmic collision with the asteroid. "Spectra from ground-based telescopes had hinted at this ice, but the exquisite quality of the Webb spectrum revealed the clear signature of crystalline ice for the first time," said Noemí Pinilla-Alonso, who led Webb's spectroscopic observations of Chariklo.
Astronomers hope to gain insights into the asteroid's rings
"As we delve deeper into the data, we will explore whether we cleanly resolve the two rings. From the shapes of rings' occultation light curves, we also will explore the rings' thickness, the sizes, and colors of the ring particles, and more, said Pablo Santos-Sanz, a planetary scientist. We may also learn why this small body (Chariklo) even has rings at all.
