Multiple rings in protoplanetary discs: one planet to govern them all

Recent observations of protoplanetary disks, these planetary systems in formation, frequently reveal sequences of dark and bright rings. While these structures are often attributed to multiple planets, numerical simulations show that they can be generated by a single Saturn moving to its star by jumps. These results published in Monthly Notices of the Royal Astronomical Society (MNRAS) are the result of work carried out at the Institut de Recherche en Astrophysique et Planétologie (IRAP – CNRS/CNES/UT3 Paul Sabatier).

Abstract: A key challenge for protoplanetary disks and planet formation models is to be able to make a reliable connection between observed structures in the disks emission, likebright and dark rings or asymmetries, and the supposed existence of planets triggeringthese structures. The observation of N dark rings of emission is often interpreted asevidence for the presence of N planets which clear dust gaps around their orbit andform dust-trapping pressure maxima in the disk. The vast majority of the models thatstudied the impact of planets on the dynamics of dust and gas in a protoplanetary diskassumed planets on fixed orbits. Here we go a different route and examine how thelarge-scale inward migration of a single planet structures the dust content of a massivedisk. In many circumstances, the migration of a partial gap-opening planet with amass comparable to Saturn is found to run away intermittently. By means of 2D gasand dust hydrodynamical simulations, we show that intermittent runaway migrationcan form multiple dust rings and gaps across the disk. Each time migration slowsdown, a pressure maximum forms beyond the planet gap that traps the large dust.Post-processing of our simulations results with 3D dust radiative transfer calculationsconfirms that intermittent runaway migration can lead to the formation of multiplesets of bright and dark rings of continuum emission in the (sub)millimeter beyond theplanet location.