Formation of multiple dust rings and gaps in protoplanetary discs by a single migrating planet II: radiative discs and observational signatures

Abstract

Dust structures in protoplanetary discs have been widely observed and their creation remains an active field of research. Several possible origins have already been explored, including magneto-hydrodynamics, shadows and planets-disc interactions. The goal of this paper is to investigate whether a single migrating planet in a low-viscosity disc, including radiative processes, is capable of generating observable dust structures. We aim to examine both the lifetime of such structures and potential asymmetries within them. We perform a set of high-resolution, two-dimensional hydrodynamic simulations of migrating planets using three different equations of state: isothermal, constant $\beta$-cooling and an adaptive $\beta$ model. Dust is included in all simulations and the resulting dust density profiles are then post-processed to create radiative transfer images. For all equations of state considered, the planet undergoes one or several migration jumps, each producing dust rings and gaps. The lifetime of these structures depends on the phase of slow migration preceding and occurring between jumps, but in all cases they remain visible for at least 400 kyr. We find that cooling has a deciding effect on the migration behaviour and the number of jumps, but no measurable influence on the lifetime of the dust structures. The structures exhibit relatively few asymmetries, and large-scale vortices persist for an average of only 90 kyr. Our models highlight the capacity of planets to open multiple gaps while migrating, and stress the importance of a realistic cooling model. Care should be taken when interpreting and comparing such models directly to observations.