Planet migration in evolving protoplanetary discs

Sammanfattning: The rate of migration and accretion onto protoplanets is greatly influenced by the structure of the surrounding protoplanetary disc. This structure changes with time as the disc evolves on a million year timescale, implying that the process of planet formation might look very different depending on when it was initiated. Further on, the evolution of the disc structure is affected on smaller timescales by the presence of the planet, the most obvious effect being the planetary induced gap. In this project I will determine how much planet formation affects disc evolution. To do so I perform 1D simulations of an evolving viscous disc that is perturbed by an embedded planet that migrates and accretes gas. I will consider different models for migration and gas accretion, and compare the results to observations of protoplanetary discs with the ALMA telescopes. From the results I can confirm what was previously known, namely that 1D simulations yield deeper and narrower planetary gaps than their higher dimensional counterparts. The removal of gas from the disc due to gas accretion onto the planet significantly alters the final mass and semimajor axis of the planet. From my simulations I also find that the classical Type-I and Type-II migration scenario results in that most planets migrate to the inner edge of the protoplanetary disc. This can be avoided using a new migration model where the planets never enter into the Type-II regime, but continue to migrate under the actions of disc torques that are decreased by the opening of the planetary gap. In this scenario planets that start to accrete gas close to the star will migrate a short distance and then continue to accrete gas practically in-situ, while planets that start to accrete gas further out in the disc will migrate a longer distance before the migration halts.