2020MNRAS.493.5892W

A key challenge for protoplanetary discs and planet formation models is to be able to make a reliable connection between observed structures in the discs emission, like bright and dark rings or asymmetries, and the supposed existence of planets triggering these structures. The observation of N dark rings of emission is often interpreted as evidence for the presence of N planets which clear dust gaps around their orbit and form dust-trapping pressure maxima in the disc. The vast majority of the models that studied the impact of planets on the dynamics of dust and gas in a protoplanetary disc assumed planets on fixed orbits. Here, we go a different route and examine how the large-scale inward migration of a single planet structures the dust content of a massive disc. In many circumstances, the migration of a partial gap-opening planet with a mass comparable to Saturn is found to run away intermittently. By means of 2D gas and dust hydrodynamical simulations, we show that intermittent runaway migration can form multiple dust rings and gaps across the disc. Each time migration slows down, a pressure maximum forms beyond the planet gap that traps the large dust. Post-processing of our simulations results with 3D dust radiative transfer calculations confirms that intermittent runaway migration can lead to the formation of multiple sets of bright and dark rings of continuum emission in the (sub)millimeter beyond the planet location.