Buoyancy torques prevent low-mass planets from stalling in low-turbulence radiative disks

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Main Authors: Ziampras, Alexandros, Nelson, Richard P., Paardekooper, Sijme-Jan
Format: Preprint
Published: 2024
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author Ziampras, Alexandros
Nelson, Richard P.
Paardekooper, Sijme-Jan
author_facet Ziampras, Alexandros
Nelson, Richard P.
Paardekooper, Sijme-Jan
contents Low-mass planets migrating inwards in laminar protoplanetary disks (PPDs) experience a dynamical corotation torque, which is expected to slow down migration to a stall. However, baroclinic effects can reduce or even reverse this effect, leading to rapid inward migration. In the radiatively inefficient inner disk, one such mechanism is the buoyancy response of the disk to an embedded planet. Recent work has suggested that radiative cooling can quench this response, but for parameters that are not necessarily representative of the inner regions of PPDs. We perform global three dimensional inviscid radiation hydrodynamics simulations of planet-disk interaction to investigate the effect of radiative cooling on the buoyancy-driven torque in a more realistic disk model. We find that the buoyancy response exerts a negative dynamical corotation torque -- albeit partially damped due to radiative cooling -- resulting in sustained, rapid inward migration. Models that adopt a local cooling prescription significantly overestimate the impact of the buoyancy response, highlighting the importance of a realistic treatment of radiation transport that includes radiative diffusion. Our results suggest that low-mass planets should migrate inwards faster than has been previously expected in radiative disks, with implications for the formation and orbital distribution of super-Earths and sub-Neptunes at intermediate distances from their host stars, unless additional physical processes that can slow down migration are considered.
format Preprint
id arxiv_https___arxiv_org_abs_2406_08555
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Buoyancy torques prevent low-mass planets from stalling in low-turbulence radiative disks
Ziampras, Alexandros
Nelson, Richard P.
Paardekooper, Sijme-Jan
Earth and Planetary Astrophysics
Low-mass planets migrating inwards in laminar protoplanetary disks (PPDs) experience a dynamical corotation torque, which is expected to slow down migration to a stall. However, baroclinic effects can reduce or even reverse this effect, leading to rapid inward migration. In the radiatively inefficient inner disk, one such mechanism is the buoyancy response of the disk to an embedded planet. Recent work has suggested that radiative cooling can quench this response, but for parameters that are not necessarily representative of the inner regions of PPDs. We perform global three dimensional inviscid radiation hydrodynamics simulations of planet-disk interaction to investigate the effect of radiative cooling on the buoyancy-driven torque in a more realistic disk model. We find that the buoyancy response exerts a negative dynamical corotation torque -- albeit partially damped due to radiative cooling -- resulting in sustained, rapid inward migration. Models that adopt a local cooling prescription significantly overestimate the impact of the buoyancy response, highlighting the importance of a realistic treatment of radiation transport that includes radiative diffusion. Our results suggest that low-mass planets should migrate inwards faster than has been previously expected in radiative disks, with implications for the formation and orbital distribution of super-Earths and sub-Neptunes at intermediate distances from their host stars, unless additional physical processes that can slow down migration are considered.
title Buoyancy torques prevent low-mass planets from stalling in low-turbulence radiative disks
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2406.08555