Guo, Z, Ogilvie, GI and Barker, AJ orcid.org/0000-0003-4397-7332 (2023) Tidally excited gravity waves in the cores of solar-type stars: resonances and critical-layer formation. Monthly Notices of the Royal Astronomical Society, 521 (1). pp. 1353-1373. ISSN 0035-8711
Abstract
We simulate the propagation and dissipation of tidally induced non-linear gravity waves in the cores of solar-type stars. We perform hydrodynamical simulations of a previously developed Boussinesq model using a spectral-element code to study the stellar core as a wave cavity that is periodically forced at the outer boundary with a given azimuthal wavenumber and an adjustable frequency. For low-amplitude forcing, the system exhibits resonances with standing g modes at particular frequencies, corresponding to a situation in which the tidal torque is highly frequency-dependent. For high-amplitude forcing, the excited waves break promptly near the centre and spin up the core so that subsequent waves are absorbed in an expanding critical layer (CL), as found in previous work, leading to a tidal torque with a smooth frequency-dependence. For intermediate-amplitude forcing, we find that linear damping of the waves gradually spins up the core such that the resonance condition can be altered drastically. The system can evolve towards or away from g-mode resonances, depending on the difference between the forcing frequency and the closest eigenfrequency. Eventually, a CL forms and absorbs the incoming waves, leading to a situation similar to the high-amplitude case in which the waves break promptly. We study the dependence of this process on the forcing amplitude and frequency, as well as on the diffusion coefficients. We emphasize that the small Prandtl number in the centre of solar-like stars facilitates the development of a differentially rotating core owing to the non-linear feedback of waves. Our simulations and analysis reveal that this important mechanism may drastically change the phase of gravity waves and thus the classical picture of resonance locking in solar-type stars needs to be revised.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023 The Author(s) Published by Oxford University Press on behalf of Royal Astronomical Society. This is an author produced version of an article published in Monthly Notices of the Royal Astronomical Society. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | hydrodynamics, waves, planet–star interactions, binaries: close, stars: interiors, stars: rotation |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Engineering & Physical Sciences (Leeds) > School of Mathematics (Leeds) > Applied Mathematics (Leeds) |
Funding Information: | Funder Grant number STFC (Science and Technology Facilities Council) ST/S000275/1 STFC (Science and Technology Facilities Council) ST/W000873/1 |
Depositing User: | Symplectic Publications |
Date Deposited: | 24 Feb 2023 14:49 |
Last Modified: | 13 May 2023 02:01 |
Status: | Published |
Publisher: | Oxford University Press |
Identification Number: | 10.1093/mnras/stad569 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:196561 |