Gone with the wind: the outward migration of eccentric giant planets in windy disks

Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France

^★ Corresponding author; gaylor.wafflard@univ-grenoble-alpes.fr

Received: 20 December 2024
Accepted: 6 March 2025

Abstract

Context. Recent studies indicate that circumstellar disks exhibit weak turbulence, with their dynamics and evolution being primarily influenced by magnetic winds. However, most numerical studies have focused on planet-disk interactions in turbulent disk models.

Aims. We aim to explore how wind-driven accretion affects the orbital and eccentricity evolution of a Jovian planet within a magnetized disk. Conversely, we seek to determine to what extent such a planet can modify the accretion behavior and the wind dynamics.

Methods. We performed high-resolution 3D global non-ideal magneto-hydrodynamic (MHD) simulations of a massive gap-carving planet interacting with a wind-launching disk, using the accelerated code IDEFIX. We considered the influence of the gap shape on planet migration by restarting a “fixed-planet” simulation at three different times, from which the planet evolved freely in the disk.

Results. For a strong initial magnetization and a sufficiently deep planet gap, we find that the planet becomes moderately eccentric and its migration is slow, unsteady, and mostly outward. This migration pattern is due to the gap’s radial asymmetry which enhances the inner Lindblad torque while reducing the outer Lindblad torque. We show that eccentricity can grow up to 6–8% and is likely driven by a finite-amplitude instability triggered by first-order external Lindblad resonances. These moderate eccentricity values periodically modulate the gap accretion rate and wind mass loss rate, possibly leading to the formation of discrete structures in CO outflows.

Conclusions. Slow outward migration and eccentricity growth appear to be common outcomes of planet-disk-wind interactions, which may contribute significantly to both the long orbital periods and the moderate eccentricities of warm jupiters. Additionally, eccentric massive protoplanets embedded in circumstellar disks could play a role in generating structured outflows.