Planet migration in massive circumbinary disks

Most stars exist in multi-star systems, with the majority of those being binaries. Protoplanetary disks are common among young stars and are known to affect the formation and evolution of planets. To date almost 370 planets have been confirmed in binary star systems and therefore the evolution of these planets is an important area of research. We investigate the migration of gas giant planets embedded in circumbinary disks using the three-dimensional smooth particle hydrodynamic code SEREN. Firstly, a planet embedded in the massive disk of a single star system is simulated using parameters from Stamatellos & Inutsuka (2018) before planets in massive circumbinary disks are simulated. The binary parameters are varied to see their effect on the migration of the gas giant planet. We find that a planet in a massive circumbinary disk consistently undergoes a period of rapid inward migration before undergoing a slow outward migration, i.e. a Type I migration followed by a non-standard Type II migration. We find that the initial binary mass ratio has little effect on the migration timescale of the planet. We also find that a larger initial binary separation leads to higher final semi-major axis for the planet. Finally, we find that increasing the initial binary eccentricity leads to a faster outward migration of the planet, in several cases reaching beyond the initial semi-major axis in a relatively short timescale. Therefore, we find that the initial binary eccentricity has the greatest effect on the orbital migration of the planet in a massive circumbinary disk.