JWST detects unexpected shifts in rings of centaur Chariklo
New observations reveal that the ring system of a small icy body is more dynamic than previously thought.
The James Webb Space Telescope (JWST) has detected unexpected changes in the ring system of Chariklo, a small icy centaur. The findings suggest that rings around minor solar system bodies may be active, evolving structures rather than static relics.
Researchers led by Pablo Santos-Sanz of the Institute of Astrophysics of Andalusia (IAA-CSIC) in Spain found that the opacity of Chariklo's rings has shifted over the last decade. By comparing 2022 data with previous observations, the team determined that the inner ring, known as C1R, has become more opaque and denser. Conversely, the outer ring, C2R, produced a weaker signal and appeared less opaque. These results were published in the journal Science Advances.
Mapping the Invisible
Chariklo is a centaur approximately 250 kilometers wide that orbits the Sun between Uranus and Neptune. Because its rings are too narrow and distant to be captured in direct photographs, astronomers must use a technique called stellar occultation. This process involves measuring the precise dips in a distant star's light as Chariklo passes in front of it, allowing scientists to map the rings' structure based on how much light is blocked.
According to the study, the 2022 observation marked the first time a stellar occultation was deliberately predicted and successfully observed using the JWST. This high-precision timing provided the clarity needed to identify the changes in ring density compared to data collected ten years prior.
Redefining Ring Stability
For years, the scientific community believed that only giant planets possessed the gravitational influence necessary to maintain ring systems. The discovery of Chariklo's rings in 2013 challenged that assumption, but the new JWST data adds a further layer of complexity. The fact that these rings are changing in opacity suggests they are not necessarily stable.
This volatility indicates that material may be migrating between rings or that other physical processes are actively reshaping the system. Such dynamics could reshape current scientific theories regarding how ring systems form and evolve across the solar system, proving that even small bodies can host complex, changing environments.
Future Implications
As researchers analyze the cause of these shifts, the discovery raises fundamental questions about the longevity of minor planet rings. Pablo Santos-Sanz noted that the findings raise new questions about how rings around small bodies form, evolve, and remain stable.
Astronomers will now look to determine whether these changes are cyclical or indicative of a gradual decay. Further occultation events will be critical in confirming whether other centaurs possess similar dynamic rings or if Chariklo is a unique case in the outer solar system.