Low-frequency internal waves in magnetized rotating stellar radiation zones

Mathis, S.; Brye, N. de

doi:10.1051/0004-6361/201015571

Cited by 46 publications

(36 citation statements)

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“…Following Dintrans & Rieutord (2000), Ballot et al (2010), and Rogers et al (2013), it could be possible to study the behavior of IGWs in rapidly rotating stars (Mathis & Neiner 2013) and the transport of angular momentum by gravito-inertial waves (Mathis et al 2008;Mathis 2009). Also of great interest could be the addition of a magnetic field in the simulations to characterize its impact on IGWs (Goode & Thompson 1992;Rogers & MacGregor 2010;Mathis & de Brye 2011. Indeed, the presence of a magnetic field will modify the dispersion relation.…”

Section: Resultsmentioning

confidence: 99%

Theoretical seismology in 3D: nonlinear simulations of internal gravity waves in solar-like stars

Alvan

Brun

Mathis

2014

A&A

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Context. Internal gravity waves (IGWs) are studied for their impact on the angular momentum transport in stellar radiation zones and the information they provide about the structure and dynamics of deep stellar interiors. We present the first 3D nonlinear numerical simulations of IGWs excitation and propagation in a solar-like star. Aims. The aim is to study the behavior of waves in a realistic 3D nonlinear time-dependent model of the Sun and to characterize their properties. Methods. We compare our results with theoretical and 1D predictions. It allows us to point out the complementarity between theory and simulation and to highlight the convenience, but also the limits, of the asymptotic and linear theories. Results. We show that a rich spectrum of IGWs is excited by the convection, representing about 0.4% of the total solar luminosity. We study the spatial and temporal properties of this spectrum, the effect of thermal damping, and nonlinear interactions between waves. We give quantitative results for the modes' frequencies, evolution with time and rotational splitting, and we discuss the amplitude of IGWs considering different regimes of parameters. Conclusions. This work points out the importance of high-performance simulation for its complementarity with observation and theory. It opens a large field of investigation concerning IGWs propagating nonlinearly in 3D spherical structures. The extension of this work to other types of stars, with different masses, structures, and rotation rates will lead to a deeper and more accurate comprehension of IGWs in stars.

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Section: Resultsmentioning

confidence: 99%

Theoretical seismology in 3D: nonlinear simulations of internal gravity waves in solar-like stars

Alvan

Brun

Mathis

2014

A&A

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“…Both rotation and magnetic fields modify their propagation and damping, as well as the related transport of angular momentum and mixing, particularly for IGWs that are excited with frequencies close to the inertial frequency (2Ω) and to the Alfvén frequency (see Pantillon et al 2007;Mathis et al 2008a;Mathis 2009) for the action of the Coriolis acceleration and Mathis & de Brye (2011, 2012 for the combined action of rotation and magnetic fields); for example, equatorial trappings occur for these low-frequency IGWs. However, as has been demonstrated by Mathis & de Brye (2012), the net bias between pro-and retrograde waves that leads to the efficient extraction of angular momentum in solar-type stars by IGWs is conserved even when both the Coriolis acceleration and the Lorentz force are taken into account.…”

Section: Discussionmentioning

confidence: 99%

Diagnoses to unravel secular hydrodynamical processes in rotating main sequence stars

Mathis

Decressin

Eggenberger

et al. 2013

A&A

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Context. With the progress of observational constraints on stellar rotation and on the angular velocity profile in stars, it is necessary to understand how angular momentum is transported in stellar interiors during their whole evolution. In this context, more highly refined dynamical stellar evolution models have been built that take into account transport mechanisms. Aims. Internal gravity waves (IGWs) excited by convective regions constitute an efficient transport mechanism over long distances in stellar radiation zones. They are one of the mechanisms that are suspected of being responsible for the quasi-flat rotation profile of the solar radiative region up to 0.2 R . Therefore, we include them in our detailed analysis started in Paper I of the main physical processes responsible for the transport of angular momentum and chemical species in stellar radiation zones. Here, we focus on the complete interaction between differential rotation, meridional circulation, shear-induced turbulence, and IGWs during the main sequence. Methods. We improved the diagnosis tools designed in Paper I to unravel angular momentum transport and chemical mixing in rotating stars by taking into account IGWs. The star's secular hydrodynamics is treated using projection on axisymmetric spherical harmonics and appropriate horizontal averages that allow the problem to be reduced to one dimension while preserving the nondiffusive character of angular momentum transport by the meridional circulation and IGWs. Wave excitation by convective zones is computed at each time-step of the evolution track. We choose here to analyse the evolution of a 1.1 M , Z star in which IGWs are known to be efficient. Results. We quantify the relative importance of the physical mechanisms that sustain meridional currents and that drive the transport of angular momentum, heat, and chemicals when IGWs are taken into account. First, angular momentum extraction, Reynolds stresses caused by IGWs, and viscous stresses sustain a large-scale multi-cellular meridional circulation. This circulation in turn advects entropy, which generates temperature fluctuations and a new rotation profile because of thermal wind. Conclusions. We have refined our diagnosis of secular transport processes in stellar interiors. We confirm that meridional circulation is sustained by applied torques, internal stresses, and structural readjustments, rather than by thermal imbalance, and we detail the impact of IGWs. These large-scale flows then modify the thermal structure of stars, their internal rotation profile, and their chemical stratification. The tools we developed in Paper I and generalised for the present analysis will be used in the near future to study secular hydrodynamics of rotating stars taking into account IGWs in the whole Hertzsprung-Russell diagram.

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“…The properties of MAC waves have already been outlined elsewhere (e.g. Gubbins & Roberts 1987;Mathis & de Brye 2011;Sreenivasan & Narasimhan 2017). Note that they have global bounded counterparts, known as Magneto-Archimedean-Coriolis (MAC) modes.…”

Section: Short-wavelength Perturbationsmentioning

confidence: 99%

Fossil field decay due to nonlinear tides in massive binaries

Vidal

Cébron

ud‐Doula

et al. 2019

A&A

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Context. Surface magnetic fields have been detected in 5 to 10% of isolated massive stars, hosting outer radiative envelopes. They are often thought to have a fossil origin, resulting from the stellar formation phase. Yet, magnetic massive stars are scarcer in (close) short-period binaries, as reported by the BinaMIcS (Binarity and Magnetic Interaction in various classes of Stars) collaboration. Aims. Different physical conditions in the molecular clouds giving birth to isolated stars and binaries are commonly invoked. In addition, we propose that the observed lower magnetic incidence in close binaries may be due to nonlinear tides. Indeed, close binaries are probably prone to tidal instability, a fluid instability growing upon the equilibrium tidal flow via nonlinear effects. Yet, stratified effects have hitherto been largely overlooked. Methods. We theoretically and numerically investigate tidal instability in rapidly rotating, stably stratified fluids permeated by magnetic fields. We use the short-wavelength stability method to propose a comprehensive (local) theory of tidal instability at the linear onset, discussing damping effects. Then, we propose a mixing-length theory for the mixing generated by tidal instability in the nonlinear regime. We successfully assess our theoretical predictions against proofof-concept, direct numerical simulations. Finally, we compare our predictions with the observations of short-period, double-lined spectroscopic binary systems. Results. Using new analytical results, cross-validated by a direct integration of the stability equations, we show that tidal instability can be generated by nonlinear couplings of inertia-gravity waves with the equilibrium tidal flow in short-period massive binaries, even against the Joule diffusion. In the nonlinear regime, a fossil magnetic field can be dissipated by the turbulent magnetic diffusion induced by the saturated tidal flows. Conclusions. We predict that the turbulent Joule diffusion of fossil fields would occur in a few million years for several short-period massive binaries. Therefore, turbulent tidal flows could explain the observed dearth of some short-period magnetic binaries.

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Low-frequency internal waves in magnetized rotating stellar radiation zones

Cited by 46 publications

References 62 publications

Theoretical seismology in 3D: nonlinear simulations of internal gravity waves in solar-like stars

Theoretical seismology in 3D: nonlinear simulations of internal gravity waves in solar-like stars

Diagnoses to unravel secular hydrodynamical processes in rotating main sequence stars

Fossil field decay due to nonlinear tides in massive binaries

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