Formation of sharp eccentric rings in debris disks with gas but without planets

TL;DR

This paper demonstrates that dust-gas interactions in debris disks can naturally form sharp, eccentric rings without the presence of planets, challenging the common assumption that such structures imply planetary influence.

Contribution

It introduces linear and nonlinear models showing dust-gas interactions can produce ring structures typically attributed to planets, highlighting an alternative formation mechanism.

Findings

Dust-gas interactions cause clumping into narrow, eccentric rings.

A robust instability leads to ring formation similar to observed systems.

Planet presence is not necessary to explain certain debris disk structures.

Abstract

"Debris disks" around young stars (analogues of the Kuiper Belt in our Solar System) show a variety of non-trivial structures attributed to planetary perturbations and used to constrain the properties of the planets. However, these analyses have largely ignored the fact that some debris disks are found to contain small quantities of gas, a component that all such disks should contain at some level. Several debris disks have been measured with a dust-to-gas ratio around unity at which the effect of hydrodynamics on the structure of the disk cannot be ignored. Here we report linear and nonlinear modelling that shows that dust-gas interactions can produce some of the key patterns attributed to planets. We find a robust clumping instability that organizes the dust into narrow, eccentric rings, similar to the Fomalhaut debris disk. The conclusion that such disks might contain planets is not necessarily required to explain these systems.