Abstract

In the gravitational instability (GI) theory of planet formation, planets form through the fragmentation of young, massive discs. After formation, these planets migrate, open gaps and accrete gas and dust. This leads to a diverse zoo of outcomes that the GI community are attempting to constrain.

In this talk I’ll provide an overview of the theory and summarise some of the main findings in recent years. I will then outline my research into how GI planets interact with dust in the disc. The accretion of dust has important implications for the metallic composition and rocky core formation inside GI fragments. We have found that feedback from core growth has the potential to unbind fragments completely, opening up a new formation channel for sub-Jupiter mass planets at tens of AU. This result may provide a crucial clue in explaining the gaps in young protoplanetary dust discs observed by ALMA . If such core feedback occurs frequently, it will dramatically alter the observational predictions of GI as a planet formation mechanism.