  Several mechanisms have been proposed to explain the formation process of
satellite systems, and relatively large moons are thought to be born in
circumplanetary disks. Making a single-moon system is known to be more
difficult than multiple-moon or moonless systems. We aim to find a way to form
a system with a single large moon, such as Titan around Saturn. We examine the
orbital migration of moons, which change their direction and speed depending on
the properties of circumplanetary disks. We modeled dissipating circumplanetary
disks with taking the effect of temperature structures into account and
calculated the orbital evolution of Titan-mass satellites in the final
evolution stage of various circumplanetary disks. We also performed N-body
simulations of systems that initially had multiple satellites to see whether
single-moon systems remained at the end. The radial slope of the
disk-temperature structure characterized by the dust opacity produces a patch
of orbits in which the Titan-mass moons cease inward migration and even migrate
outward in a certain range of the disk viscosity. The patch assists moons
initially located in the outer orbits to remain in the disk, while those in the
inner orbits fall onto the planet. We demonstrate for the first time that
systems can form that have only one large moon around giant planet. Our N-body
simulations suggest satellite formation was not efficient in the outer radii of
circumplanetary disks.
