The potential impact of groove modes on Type II planetary migration

TL;DR

This paper investigates how density grooves in protoplanetary disks can trigger spiral instabilities, potentially affecting planet migration processes, through linear analysis and hydrodynamical simulations.

Contribution

It extends the concept of groove modes to protoplanetary disks and demonstrates their role in driving gravitational instabilities relevant to planet formation.

Findings

Grooves induce fast-growing spiral modes in disks.

Self-gravitating instabilities occur at lower disk masses.

Implications for modifying Type II planetary migration.

Abstract

In this letter, we briefly describe the evolution of a variety of self-gravitating protoplanetary disk models that contain annular grooves (e.g. gaps) in their surface density. These grooves are inspired by the density gaps that are presumed to open in response to the formation of a giant planet. Our work provides an extension of the previously studied groove modes that are known in the context of stellar disks. The emergence of spiral gravitational instabilities (GI) is predicted via a generalized eigenvalue code that performs a linear analysis, and confirmed with hydrodynamical simulations. We find the presence of a groove drives a fast-growing two-armed mode in moderately massive disks, and extends the importance of self-gravitating instabilities down to lower disk masses than for which they would otherwise occur. We discuss the potential importance of this instability in the context of planet formation, e.g. the modification of the torques driving Type II migration.