Abstract

In this talk, I will discuss the dynamics of misaligned accretion discs around multiple systems, and in particular the case of discs orbiting a binary system, in the presence of a third companion. Prototypes of these kind of discs are the protostellar disc surrounding GG Tau A and the one surrounding HD 98800 . In my talk, I will focus on two particular secular effects which may be at play in these systems. For the case of GG Tau A, I will discuss the evolution of the shape and eccentricity of the disc in light of recent constraints of the system’s orbital parameters. For the case of HD 98800 , I will discuss the likelyhood of polar alignment of the disc with the binary orbit. Finally I will draw some general conclusions based on the increasing statistics about misaligned protostellar discs around binaries.