Particle Concentration At Planet Induced Gap Edges and Vortices: I. Inviscid 3-D Hydro Disks

TL;DR

This study uses 2-D and 3-D inviscid hydrodynamic simulations to explore how embedded planets influence dust particle dynamics, revealing gap formation, vortex trapping, and potential planetesimal growth in protoplanetary disks.

Contribution

It provides the first systematic analysis of dust behavior around planet-induced gaps and vortices in inviscid 3-D disks, highlighting the effects of planet mass on dust trapping and gap structure.

Findings

Low-mass planets create shallow gaps affecting dust drift.

More massive planets induce vortex formation at gap edges.

Dust can be concentrated by over 100 times in vortices.

Abstract

We perform a systematic study of the dynamics of dust particles in protoplanetary disks with embedded planets using global 2-D and 3-D inviscid hydrodynamic simulations. Lagrangian particles have been implemented into magnetohydrodynamic code Athena with cylindrical coordinates. We find two distinct outcomes depending on the mass of the embedded planet. In the presence of a low mass planet ($8 M_{\oplus}$), two narrow gaps start to open in the gas on each side of the planet where the density waves shock. These shallow gaps can dramatically affect particle drift speed and cause significant, roughly axisymmetric dust depletion. On the other hand, a more massive planet ($>0.1 M_{J}$) carves out a deeper gap with sharp edges, which are unstable to the vortex formation. Particles with a wide range of sizes ($0.02<\Omega t_{s}<20$) are trapped and settle to the midplane in the vortex, with the strongest concentration for particles with $\Omega t_{s}\sim 1$. The dust concentration is highly elongated in the $\phi$ direction, and can be as wide as 4 disk scale heights in the radial direction. Dust surface density inside the vortex can be increased by more than a factor of 10$^2$ in a very non-axisymmetric fashion. For very big particles ($\Omega t_{s}\gg 1$) we find strong eccentricity excitation, in particular around the planet and in the vicinity of the mean motion resonances, facilitating gap opening there. Our results imply that in weakly turbulent protoplanetary disk regions (e.g. the "dead zone") dust particles with a very wide range of sizes can be trapped at gap edges and inside vortices induced by planets with $M_{p}<M_{J}$, potentially accelerating planetesimal and planet formation there, and giving rise to distinctive features that can be probed by ALMA and EVLA.