An international team led by the Andalusian Institute of Astrophysics (IAA-CSIC) has demonstrated for the first time that the two rings of this small Solar System body evolve on a decadal timescale.
This work is part of the ANR-funded “Roche” research project (ANR-23-CE49-0012), led by Nicolas Rambaux at the LTE, with Bruno Sicardy (co-author of the article) participating. The project aims to better understand the environment and interactions of small bodies in the Solar System.
Among the authors are also Josselin Desmars (LTE) and Damya Souami (LIRA), who are working on stellar occultations as part of the “Lucky Star” project, which brings together teams from France, Spain, and Brazil.
Until 2013, it was thought that ring systems were exclusive to the giant planets of the solar system, such as Jupiter, Saturn, Uranus, and Neptune. However, that year, a small body barely 250 kilometers in diameter, located nearly 17 times the distance between Earth and the Sun, joined this select group. This body is Chariklo.
On October 18, 2022, the Andalusian Institute of Astrophysics (IAA-CSIC) led an observation using the James Webb Space Telescope (JWST) to study Chariklo’s rings via a stellar occultation—a technique that measures the decrease in a star’s brightness when an object passes in front of it. The results show that Chariklo’s rings have undergone changes on timescales of just a few years, with the inner ring gaining material and the outer ring losing it.
A SCIENTIFIC AND TECHNOLOGICAL ADVANCEMENT
This study also represents a major technological breakthrough : the occultation by Chariklo was the first stellar occultation specifically predicted and planned to be observed with the James Webb Space Telescope.
“To achieve this, we needed to know with extraordinary precision the orbit of Chariklo, the position of the star—thanks to ESA’s Gaia mission—and the trajectory of the JWST itself around the L2 Lagrange point, a region of space located about 1.5 million kilometers from Earth. The JWST orbits this region along a trajectory that must be periodically corrected through maintenance maneuvers,” explains Yücel Kilic, a postdoctoral researcher at the IAA-CSIC and co-author of the study.
Chariklo’s rings are so narrow and the body is so distant that it is impossible to photograph them directly even with the largest telescopes available today. Stellar occultations allow us to study them indirectly by measuring the brief drops in a star’s brightness as each ring passes in front of it. This observation has thus yielded an unprecedented spatial resolution (on the order of a kilometer) of Chariklo’s rings.
The detected changes suggest that Chariklo’s rings are dynamically active. “Our results force us to rethink how they form, how they evolve, and what mechanisms ensure their stability. The ability to detect these changes opens a new avenue for understanding the evolution of these systems and, eventually, that of other ring systems in the Solar System,” emphasizes Santos-Sanz. The physical origin of the detected changes, however, remains an open question : they could reflect temporal evolution of the rings, differences related to the use of different observation filters, or a combination of these two effects.
Learn more :
REFERENCES
‘JWST stellar occultation reveals unexpected changes in Chariklo’s ring system’
https://doi.org/10.1126/sciadv.aeh4794
’Link to the IAA CSIC website’
https://www.iaa.csic.es/noticia/jwst-descubre-invisibles-anillos-chariklo-cambiando/
Press Release :
CONTACTS :
Bruno Sicardy bruno.sicardy@obspm.fr (LTE)
Josselin Desmars josselin.desmars@obspm.fr (LTE)
Damya Souami damya.souami@obspm.fr (LIRA)
