How Planets Move in the Inner Disc

The inner region of the dead zone in a protoplanetary disc is likely predominantly lacking in viscosity-inducing turbulence. In addition to a disc wind driving accretion through upper layers, models suggest the midplane can be threaded by a Hall-effect generated large-scale horizontal magnetic field. I will describe the novel torques acting on low-mass (sub-earth) planets and cores elucidated in McNally et al. 2017 and 2018 which apply in this region of the disc. Dynamical corotation torque effects lead to new flow-locked and runaway migration regimes for these planets. Migration behaviour can also bifurcate sharply as a function of the planet mass/disc surface density. I will also describe ongoing work on the behaviour of super-earth planets in this regime, which are able to significantly alter the disc surface density profile in the thin inner disc and generate Rossby-wave vortices.