Mapping the shape of circumbinary discs

Anna B. T. Penzlin, Jibin Joseph, Willy Kley

Stars do not form in isolation and 50% of all stars are part of a binary or multiple configuration. Therefore circumbinary discs are not just common during star formation but their interactive dynamics can further constrain our understanding of protoplanetary discs.
Binary created large asymmetric cavities threaded by streams between the binary and inner disc edge and spiral patterns in the inner disc as recently observed in discs like GG Tau or HD 142527. In this work, we use 2D hydrodynamics simulations to understand how the properties of binary and disc change and shape the interaction and resulting orbits and disc structure of the binary-disc system. To understand the binary evolution the distribution of the accreted mass is essential. We investigate the structural disc transition from a binary system to a planet-star system and connect it to the trend change in the mass accretion ratios onto the two components. The structure of the disc does not just depend on the binary object but also the viscosity and temperature of the disc. We simulate the viscosity dependent disc shape, and create a parameter space of simulations that allows to pin-point an observed protoplanetary, circumbinary disc to a specific viscosity. Thereby the structure of observed binary disc can inform our models of the protoplanetary environment.