University of Zurich Researchers Witness Potential Moon Birth Around Distant Exoplanet
ZURICH, SWITZERLAND – September 29, 2025 - Astronomers at the University of Zurich have observed a substantial disk of carbon-rich material surrounding the young exoplanet CT Cha B, located 625 light-years from Earth, offering a rare glimpse into the potential formation of moons. The finding, published today in The Astrophysical Journal Letters, suggests a mechanism for moon creation distinct from those previously understood, possibly reshaping theories of planetary system evolution.
The finding centers on CT Cha B, a planet still embedded within the remnants of it’s star’s protoplanetary disk. Researchers, led by Gabriele cugno and Sierra Grant, detected an unexpectedly large and dense disk encircling the exoplanet – a disk rich in carbon. This carbon abundance, coupled with the disk’s mass, indicates it could provide the raw materials for one or more moons to coalesce around CT Cha B. Traditionally, moons are thought to form from debris left over from planetary formation or through capture. This observation proposes an alternative: moons forming after a planet has already formed,directly from a circumplanetary disk.
“This is the first time we’ve seen a disk so massive around a planetary-mass companion,” explains Cugno (gabriele.cugno@uzh.ch). “The amount of material is significant enough to potentially build substantial moons.” The research team utilized data from the NASA/ESA/CSA James Webb Space Telescope to analyze the composition and structure of the disk.
The implications extend beyond understanding moon formation. The carbon-rich nature of the disk is also intriguing, as it differs from the composition of disks typically observed around young stars. This suggests that the planet may have migrated through the protoplanetary disk, sweeping up carbon-rich material along the way. Further research will focus on determining the disk’s long-term stability and whether moon formation is actively underway.
More information about the discovery is available at: https://www.news.uzh.ch/de/articles/media/2025/mond-entstehung.html
DOI: https://doi.org/10.3847/2041-8213/ae0290
Copyright: NASA,ESA,CSA,STScI,University of Zurich/NCCR PlanetS,Carnegie Institution for Science,STScI,STScI
