Evrim Yazgin
Cosmos science journalist
NASA’s James Webb Space telescope has found water ice in the ring of a distant object in our solar system, but it’s not Saturn with its remarkable rings, or Neptune, Uranus or even Jupiter which has rings which are too faint to be seen by most telescopes.
The fifth ringed object in our solar system is the asteroid Chariklo which was discovered in 1997, but it wasn’t until 2013 that scientists using ground-based telescopes found that Chariklo is the first asteroid to have a ring system.
Chariklo is a small, icy body about 3.2 million kms beyond the orbit of Saturn. At around 300 kilometres in diameter, the asteroid is the largest known object in the Centaur population – a group asteroids (estimated between 44,000 and more than 10 million objects).
The asteroid has two thin rings which orbit at a distance of about 400 kilometres from Chariklo’s centre.
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An analysis suggests the rings are probably composed of small particles of water ice mixed with a darker material – probably the remnant of an icy body which collided with Chariklo in the past.
“Spectra from ground-based telescopes had hinted at this ice, but the exquisite quality of the James Webb telescope spectrum revealed the clear signature of crystalline ice for the first time” says project lead Dr Noemí Pinilla-Alonso from the Florida Space Institute at the University of Central Florida.
“Because high-energy particles transform ice from crystalline into amorphous states, detection of crystalline ice indicates that the Chariklo system experiences continuous micro-collisions that either expose pristine material or trigger crystallization processes,” adds Dr Dean Hines from Baltimore’s Space Telescope Science Institute, principal investigator of the Chariklo spectral analysis program.