Abstract

Consisting of continuous matter in orbital motion around a massive body, astrophysical discs are one of the most ubiquitous of astronomical objects. They include the discs of dusty gas in which planets form around young stars, accretion discs of hot plasma around black holes on both stellar and galactic scales, and planetary rings of colliding debris such as Saturn’s. Astrophysical discs are therefore relevant to understanding both our own origins and some of the most extreme environments in the Universe. The last decade has seen intriguing images of discs from ALMA , VLT and the Event Horizon Telescope, as well as Cassini-Huygens.

In this talk I will explore some of the universal properties of astrophysical discs as well as some distinctive features of discs in various environments. I will explain how their evolution is regulated by the transport or removal of angular momentum and will highlight a surprising role for magnetic fields. I will discuss how the orbital geometry and the appearance of discs is affected by a binary companion, a planet orbiting within the disc, or by relativity.