Disc and Planet Evolution in Circumbinary Systems

PhDThe inner regions of discs around close binary systems are dominated by tidally truncated eccentric cavities. These are believed to play a key role in dictating where planets formed in these circumbinary discs halt their disc-driven migration. In this thesis we present work examining processes which could impact the evolution and structure of this region, and the planets which interact with it. First, we investigate the role of self-gravity and disc-mass on circumbinary discs and planets. The greatest impact of self-gravity was found in discs around highly eccentric binaries, and in discs with high masses. In these cases, self-gravity acts to compact the scale of the inner cavity region. For the highest disc masses, additional eccentric features arise in the outer disc. A range of scenarios examining planetary migration, accretion and disc dissipation find that if planets form and evolve in a high-mass environment, the disc structures formed by self-gravity can leave a fingerprint on the planetary architecture once the disc has dissipated. We also significantly modify the publicly available fargo-adsg hydrodynamical code, to include radiative effects such as disc irradiation by the binary stars, radiative transport and disc surface cooling. We present preliminary results of simulations of adiabatic circumbinary discs with these effects included, and consider also the migration of protoplanets within them. Fully radiative discs produce a smaller inner cavity than obtained in previous isothermal models – a promising result for the end point of planet migration in these discs. Whilst we have found significant alteration of the circumbinary enviroment by self-gravity and radiative effects, future simulations that capture the 3-D nature of these discs will be required to fully describe the observed architecture of the circumbinary systems.STFC PhD studentship, grant no. STFC ST/K50225X/1. EPSRC grant EP/K000128/1 BIS National E-Infrastructure capital grant ST/K000373/1 STFC DiRAC Operations grant ST/K0003259/1 National Science Foundation Grant No. NSF PHY-1125915