Long Term Evolution of Planet-Induced Vortices in Protoplanetary Disks

TL;DR

This study uses high-resolution hydrodynamic simulations to explore how disk viscosity, temperature, and planet mass influence the formation and longevity of vortices induced by planets in protoplanetary disks, with implications for observations.

Contribution

It provides the first long-term simulation analysis of planet-induced vortices, highlighting the critical role of low disk viscosity in vortex sustainability over thousands of orbits.

Findings

Low disk viscosity ($^{-5}$ to $10^{-4}$) is essential for vortex longevity.

Vortices are less likely to form or persist with smaller planet orbital radii or higher viscosities.

Vortex presence is influenced by planet mass, disk temperature, and viscosity, affecting observational prospects.

Abstract

Recent observations of large-scale asymmetric features in protoplanetary disks suggest that large-scale vortices exist in such disks. Massive planets are known to be able to produce deep gaps in protoplanetary disks. The gap edges could become hydrodynamically unstable to the Rossby wave/vortex instability and form large-scale vortices. In this study we examine the long term evolution of these vortices by carrying out high-resolution two dimensional hydrodynamic simulations that last more than $10^4$ orbits (measured at the planet's orbit). We find that the disk viscosity has a strong influence on both the emergence and lifetime of vortices. In the outer disk region where asymmetric features are observed, our simulation results suggest that the disk viscous $\alpha$ needs to be low $\sim 10^{-5 }$ - $10^{-4}$ to sustain vortices to thousands and up to $10^{4}$ orbits in certain cases. The chance of finding a vortex feature in a disk then decreases with smaller planet orbital radius. For $\alpha \sim 10^{-3}$ or larger, even planets with masses of 5 Jupiter-masses will have difficulty either producing or sustaining vortices. We have also studied the effects of different disk temperatures and planet masses. We discuss the implications of our findings on current and future protoplanetary disk observations.