Abstract

We propose a mechanism by which dust rings in protoplanetary discs can form and be long-lasting, which combines the idea of trapping dust in a pressure maximum ring between two planets followed by the decoupling of these particles due to a decrease in the ring’s surface density over time. We perform 2D gas hydrodynamical simulations to investigate the disc structure in the presence of two giant planets placed sufficiently far apart such that they do not open a common gap. We find that with two 1 MJup planets that open deep gaps and two 0.2 MJup planets that open partial gaps, a ring of material forms in between the two planets with the surface mass density being higher than either side of the ring. The ring is a region of pressure maximum where we expect larger grains to collect as a gap is easier to form in the large dust than the gas or smaller grains. Over time the gas surface density in the ring decreases which might cause some large particles that were marginally coupled to the gas (but trapped in the ring due to the pressure maximum) to begin to decouple. Consequently, as the surface density of the gas ring decreases over time the dust ring (larger sized particles) are expected to remain in the ring structure longer than the gas ring. For a MMSN model, we expect that millimetre and centimetre-sized grains in the outer O(10) au in a disc would be the ones that are most likely to be trapped and decoupled by this mechanism.

Presentation

Poster