Drag-driven instability of a dust layer in a magnetized protoplanetary disc

TL;DR

This paper investigates how magnetic fields influence drag-driven instabilities in dust layers of protoplanetary discs, revealing that even weak magnetic fields can significantly amplify instability growth.

Contribution

It introduces a dispersion relation for axisymmetric disturbances in a magnetized dust-gas layer, highlighting the amplifying effect of magnetic fields on instability.

Findings

Magnetic fields significantly amplify dust layer instability.

Weak magnetic fields can enhance instability regardless of dust-gas coupling.

Magnetic effects are substantial even when the Toomre parameter is fixed.

Abstract

We study drag-driven instability in a protoplanetary disc consisting of a layer of single-sized dust particles which are coupled to the magnetized gas aerodynamically and the particle-to-gas feedback is included. We find a dispersion relation for axisymmetric linear disturbances and growth rate of the unstable modes are calculated numerically. While the secular gravitational instability in the absence of particle-to-gas feedback predicts the dust layer is unstable, magnetic fields significantly amplifies the instability if the Toomre parameter for the gas component is fixed. We also show that even a weak magnetic field is able to amplify the instability more or less irrespective of the dust-gas coupling.