Angular momentum transport, layering, and zonal jet formation by the GSF instability: nonlinear simulations at a general latitude
| Autor: | Chris A. Jones, Adrian J. Barker, Steven M. Tobias |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Physics
Earth and Planetary Astrophysics (astro-ph.EP) Jet (fluid) Angular momentum Subgiant Equator Rotational symmetry Fluid Dynamics (physics.flu-dyn) FOS: Physical sciences Astronomy and Astrophysics Tachocline Physics - Fluid Dynamics Mechanics 01 natural sciences Instability 010305 fluids & plasmas Astrophysics - Solar and Stellar Astrophysics Space and Planetary Science 0103 physical sciences Solar rotation Astrophysics::Earth and Planetary Astrophysics 010303 astronomy & astrophysics Solar and Stellar Astrophysics (astro-ph.SR) Astrophysics - Earth and Planetary Astrophysics |
| Zdroj: | Monthly Notices of the Royal Astronomical Society |
| ISSN: | 0035-8711 |
| DOI: | 10.48550/arxiv.2005.04941 |
| Popis: | We continue our investigation into the nonlinear evolution of the Goldreich-Schubert-Fricke (GSF) instability in differentially rotating radiation zones. This instability may be a key player in transporting angular momentum in stars and giant planets, but its nonlinear evolution remains mostly unexplored. In a previous paper we considered the equatorial instability, whereas here we simulate the instability at a general latitude for the first time. We adopt a local Cartesian Boussinesq model in a modified shearing box for most of our simulations, but we also perform some simulations with stress-free, impenetrable, radial boundaries. We first revisit the linear instability and derive some new results, before studying its nonlinear evolution. The instability is found to behave very differently compared with its behaviour at the equator. In particular, here we observe the development of strong zonal jets ("layering" in the angular momentum), which can considerably enhance angular momentum transport, particularly in axisymmetric simulations. The jets are, in general, tilted with respect to the local gravity by an angle that corresponds initially with that of the linear modes, but which evolves with time and depends on the strength of the flow. The instability transports angular momentum much more efficiently (by several orders of magnitude) than it does at the equator, and we estimate that the GSF instability could contribute to the missing angular momentum transport required in both red giant and subgiant stars. It could also play a role in the long-term evolution of the solar tachocline and the atmospheric dynamics of hot Jupiters. Comment: Accepted for publication in MNRAS on 8th May 2020 |
| Databáze: | OpenAIRE |
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