Understanding the initial stages of planet-driven gap formation 

Amelia J. Cordwell (DAMTP) Cambridge Fluids Network - fluids-related seminars 27 May 2025 1:00pm Ryle seminar room + ONLINE - Details to be sent by email Gaps and rings are ubiquitous in observations of protoplanetary discs, and their existence may be attributed to (proto-)planets interacting with their natal environments. However, constraining protoplanet masses or ages - or even just confirming that protoplanets are the cause of these substructures - in any given observation requires a clear theoretical understanding of large numbers of different gap processes. While theoretical and semi-analytical works exist for the viscously dominated end stages of gap evolution, due to the near inviscid nature of protoplanetary discs, time-dependent theories that can account for the nature of the mutual evolution between planet and disc are required to correctly interpret observations. I will first present on how planets form gaps in the simplest possible case: that of a low mass planet in an two-dimensional inviscid isothermal disc and show new analytical theory that is able to predict the initial stages of gap evolution in this case. Using both Athena++ numerical simulations and analytical arguments, I will then discuss how this picture is modified in the cases of viscous, thermodynamically active, or three-dimensional discs. I will show that the treatment of disc thermodynamics has significant effects on the planet disc interaction whereas viscosity - at the levels expected in protoplanetary discs - does not have a significant impact at the early stages of gap formation.