Extreme pebble accretion in ringed protoplanetary discs

High-resolution imaging of protoplanetary discs has revealed their wealth of substructure and, perhaps most notably, the prevalence of rings of dust. Commonly interpreted as dust traps, these rings are predicted to have high dust-to-gas ratios and are therefore expected to promote planet formation processes. The dust grains that are most efficiently trapped in these rings — “pebbles” — are also understood to have an enhanced accretion rate onto planetary embryos; the formation of an embryo within a dust ring thus presents a compelling scenario for giant planet formation, especially given the large inferred dust masses in the brightest rings. I will present results from dust and gas hydrodynamics simulations of a planetary embryo undergoing pebble accretion within a dust ring, and show how in a sufficiently massive ring, the pebble accretion rate can generate an accretion luminosity capable of sourcing vorticity at the location of the planet. The formation of a vortex increases the accretion cross section, amplifying the accretion rate, leading to the formation of a massive planetary core. The subsequent trapping of dust within the vortex leads to an observable azimuthal asymmetry in the disc, similar to those observed with ALMA.