Formation of planets in the 47 UMa system is followed in an evolving protoplanetary disk composed of gas and solids .
The evolution of the disk is calculated from an early stage , when all solids , assumed to be high-temperature silicates , are in the dust form , to the stage when most solids are locked in planetesimals .
The simulation of planetary evolution starts with a solid embryo of \sim 1 Earth mass , and proceeds according to the core accretion – gas capture model .
Orbital parameters are kept constant , and it is assumed that the environment of each planet is not perturbed by the second planet .
It is found that conditions suitable for both planets to form within several Myr are easily created , and maintained throughout the formation time , in disks with \alpha \approx 0.01 .
In such disks , a planet of 2.6 Jupiter masses ( the minimum for the inner planet of the 47 UMa system ) may be formed at 2.1 AU from the star in \sim 3 Myr , while a planet of 0.89 Jupiter masses ( the minimum for the outer planet ) may be formed at 3.95 AU from the star in about the same time .
The formation of planets is possible as a result of a significant enhancement of the surface density of solids between 1.0 and 4.0 AU , which results from the evolution of a disk with an initially uniform gas-to-dust ratio of 167 and an initial radius of 40 AU .