Contributed Talk - Splinter Exoplanets

Friday, 17 September 2021, 14:45   (virtual Exo)

Vortices by planets live shortest in disks with moderate cooling

Thomas Rometsch, Alexandros Ziampras, Wilhelm Kley, and William Béthune
University of Tübingen

Several observations of protoplanetary disks display non-axisymmetric features, often interpreted as vortices. Numerical modeling has repeatedly shown that gap-opening planets are capable of producing large and long-lasting vortices at their outer gap edge, making massive planets popular candidates as the source of such features. We explore the lifetime of vortices generated by Jupiter-sized planets as a function of disk parameters focusing on the thermal relaxation timescale, also including disk self-gravity. We perform 2D numerical simulations using the hydrodynamics codes PLUTO and FARGO. Vortex properties are automatically extracted from thousands of simulation snapshots. We find that vortices that spawn at the outer gap edge can survive for about 100–2000 planetary orbits for typical disk parameters, where the shortest lifetimes occur for a moderate efficiency of dissipation and cooling. However, we also observe a different regime of long-lasting vortices with lifetimes of at least 15000 orbits for very low viscosity and very short thermal relaxation timescales. Disk self-gravity significantly shortens the lifetime of regular vortices, but still allows long-lived ones to survive. Our results suggest that planet-generated vortices should be observable at large distances from the star for typical thermal relaxation timescales and turbulence levels. This is more likely for short thermal relaxation timescales, for which vortices belong in the long-living regime.