Migrating super-Earths in low-viscosity discs: Unveiling the roles of feedback, vortices, and laminar accretion flows

Colin P. McNally, Richard P. Nelson, Sijme Jan Paardekooper, Pablo Benítez-Llambay

Research output: Contribution to journalArticlepeer-review

27 Scopus citations

Abstract

We present the highest resolution study to date of super-Earths migrating in inviscid and lowviscosity discs, motivated by the connection to laminar, wind-driven models of protoplanetary discs. Our models unveil the critical role of vortices in determining the migration behaviour for partial gap-opening planets. Vortices form in pressure maxima at gap edges, and prevent the disc-feedback stopping of migration for intermediate planets in low-viscosity and inviscid discs, contrary to the concept of the 'inertial limit' or 'disc feedback' halting predicted from analytical models. Vortices may also form in the corotation region, and can dramatically modify migration behaviour through direct gravitational interaction with the planet. These features become apparent at high resolution, and for all but the highest viscosities there exist significant difficulties in obtaining numerically converged results. The migration of partial gap-opening planets, however, clearly becomes chaotic for sufficiently low viscosities. At moderate viscosity, a smooth disc-feedback regime is found in which migration can slow substantially, and the migration time-scale observed corresponds to migration being driven by diffusive relaxation of the gap edges. At high viscosity classical Type I migration is recovered. For Jupiter-analogue planets in inviscid discs, a wide, deep gap is formed. Transient Type II migration occurs over radial length-scales corresponding to the gap width, beyond which migration can stall. Finally, we examine the particle trapping driven by structures left in inviscid discs by a migrating planet, and find that particle traps in the form of multiple rings and vortices can persist long after the planet has passed. In this case, the observation of particle traps by submillimetre interferometers such as ALMA cannot be used to infer the current presence of an adjacent planet.

Original languageEnglish
Pages (from-to)728-748
Number of pages21
JournalMonthly Notices of the Royal Astronomical Society
Volume484
Issue number1
DOIs
StatePublished - 21 Mar 2019
Externally publishedYes

Keywords

  • Dynamical evolution and stability - planet-disc interactions - protoplanetary discs
  • Planets and satellites

Fingerprint

Dive into the research topics of 'Migrating super-Earths in low-viscosity discs: Unveiling the roles of feedback, vortices, and laminar accretion flows'. Together they form a unique fingerprint.

Cite this