Migration of low-mass planets in inviscid discs

Migration of low-mass planets in inviscid discs: the effect of radiation transport on the dynamical corotation torque

Ziampras, Alexandros (Queen Mary University of London)
Nelson, Richard P. (Queen Mary University of London)
Paardekooper, S. (TU Delft Planetary Exploration; Queen Mary University of London)

2024

Low-mass planets migrate in the type-I regime. In the inviscid limit, the contrast between the vortensity trapped inside the planet's corotating region and the background disc vortensity leads to a dynamical corotation torque, which is thought to slow down inward migration. We investigate the effect of radiative cooling on low-mass planet migration using inviscid 2D hydrodynamical simulations. We find that cooling induces a baroclinic forcing on material U-turning near the planet, resulting in vortensity growth in the corotating region, which in turn weakens the dynamical corotation torque and leads to 2-3 × faster inw ard migration. This mechanism is most efficient when cooling acts on a time-scale similar to the U-turn time of material inside the corotating region, but is none the less rele v ant for a substantial radial range in a typical disc ( R ~5-50 au). As the planet migrates inwards, the contrast between the vortensity inside and outside the corotating region increases and partially regulates the effect of baroclinic forcing. As a secondary ef fect, we sho w that radiati ve damping can further weaken the vortensity barrier created by the planet's spiral shocks, supporting inward migration. Finally, we highlight that a self-consistent treatment of radiative diffusion as opposed to local cooling is critical in order to avoid overestimating the vortensity growth and the resulting migration rate.

hydrodynamics
methods: numerical
planet-disc interactions

http://resolver.tudelft.nl/uuid:fd4dad4b-495b-496a-83c4-8abd136499e3

https://doi.org/10.1093/mnras/stae372

0035-8711

Monthly Notices of the Royal Astronomical Society, 528 (4), 6130-6140

Institutional Repository

journal article

© 2024 Alexandros Ziampras, Richard P. Nelson, S. Paardekooper