The effect of an ordered azimuthal magnetic field on a migrating planet in a non-turbulent disc

TL;DR

This paper studies how an azimuthal magnetic field in a protoplanetary disc influences planetary migration, showing that stronger magnetic fields can slow or reverse inward migration of planets.

Contribution

It demonstrates that an ordered azimuthal magnetic field can significantly alter planetary migration by inducing magnetic resonances that slow or halt inward movement.

Findings

Stronger magnetic fields increase positive torque on planets.

Magnetic resonances can stop inward migration.

Outward migration occurs with sufficiently strong magnetic fields.

Abstract

In this work, we consider the physics of the interaction between a planet and a magnetized gaseous protoplanetary disc. We investigate the migration of a planet in a disc that is threaded with an azimuthal magnetic field. We find that, for a larger magnetic field amplitude, there is an increasingly large positive torque on the planet from the disc, resulting in slowed and even outward migration. Our results indicate that magnetic resonances due to a purely azimuthal, ordered magnetic field can slow or stop the inward migration of Jupiter-mass, Saturn-mass, and $5 M_{\oplus}$ planets.