Numerical simulations show that the temperature gradient in the gas disk around a young gas giant planet could play a critical role in the development of a satellite system dominated by a single large moon, similar to Titan in the Saturn system. Researchers found that dust in the circumplanetary disk can create a “safety zone” that keeps the moon from falling into the planet as the system evolves.
Source:
https://phys.org/news/2020-03-safety-zone-giant-moons-fatal.html