Anisotropic turbulent transport in stably stratified rotating stellar radiation zones

Mathis, S.; Prat, V.; Amard, Louis; Charbonnel, C.; Palacios, Ana; Lagarde, N.; Eggenberger, P.

doi:10.1051/0004-6361/201629187

Cited by 50 publications

(90 citation statements)

References 85 publications

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“…Several studies have examined the turbulence in radiative zones (e.g. Zahn 1992; Mathis et al 2004;Garaud et al 2017;Gagnier & Garaud 2018;Mathis et al 2018). Yet, these models focus on shear-driven turbulence.…”

Section: Turbulent Mixing Due To Nonlinear Tidal Flowsmentioning

confidence: 99%

“…To estimate the local tidal mixing in stratified interiors, we develop a mixing-length theory, by analogy with mixing-length arguments commonly used for shear-driven turbulence in radiative interiors of stars (e.g. Zahn 1992; Mathis et al 2004Mathis et al , 2018.…”

Section: Mixing-length Theorymentioning

confidence: 99%

“…Le Reun et al (2018) investigated the small-scale turbulence sustained by tides in the regime R ≤ 1, in which vertical viscous shearing is significant. However, radiative interiors are in the opposite regime R 1 (Mathis et al 2018). Moreover, they neglected rotation, by setting Ω s = 0.…”

Section: Stratified Regimes (N 0 /ω S ≥ 1)mentioning

confidence: 99%

“…with α 2 ∼ 0.6 a (numerical) pre-factor constrainted from local turbulent simulations in rapidly rotating and strongly stratified turbulent regime (Reinaud et al 2003;Waite & Bartello 2006). This regime is expected to be valid for radiative interiors, notably to describe shear-driven turbulence (Mathis et al 2018). For strong stratification (N 0 /Ω s ≥ 10), we combine the two balances obtained by equating (i) the nonlinear term with the buoyancy force in momentum equation (3a) and (ii) the injection term (u · ∇) T 0 and the nonlinear term (u ·∇) Θ in energy equation (3b).…”

Section: Stratified Regimes (N 0 /ω S ≥ 1)mentioning

confidence: 99%

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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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Section: Turbulent Mixing Due To Nonlinear Tidal Flowsmentioning

confidence: 99%

Section: Mixing-length Theorymentioning

confidence: 99%

Section: Stratified Regimes (N 0 /ω S ≥ 1)mentioning

confidence: 99%

Section: Stratified Regimes (N 0 /ω S ≥ 1)mentioning

confidence: 99%

See 2 more Smart Citations

Fossil field decay due to nonlinear tides in massive binaries

Vidal

Cébron

ud‐Doula

et al. 2019

A&A

View full text Add to dashboard Cite

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“…Therefore, the values we derive for the central Rossby number are certainly underestimated. A consistent study of the dynamo in convective stellar cores would thus require models including very efficient transport of angular momentum in stellar interiors, with processes related, for example, to internal gravity waves , to fossil magnetic fields (Charbonneau & MacGregor 1993;Gough & McIntyre 1998;Eggenberger et al 2005;Strugarek et al 2011), or including new prescriptions for rotation-induced turbulence proposed by Mathis & et al (2017a) that lead to better agreement with asteroseismology (Mathis & et al 2017b;Amard et al 2017). This is out of the scope of the present paper.…”

Section: Appendix A: Turnover Timescale and Rossby Number In Stellar mentioning

confidence: 99%

The magnetic strip(s) in the advanced phases of stellar evolution

Charbonnel

Decressin

Lagarde

et al. 2017

A&A

Self Cite

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Context. Recent spectropolarimetric observations of otherwise ordinary (in terms e.g. of surface rotation and chemical properties) G, K, and M giants have revealed localized magnetic strips in the Hertzsprung-Russell diagram coincident with the regions where the first dredge-up and core helium burning occur. Aims. We seek to understand the origin of magnetic fields in such late-type giant stars, which is currently unexplained. In analogy with late-type dwarf stars, we focus primarily on parameters known to influence the generation of magnetic fields in the outer convective envelope. Methods. We compute the classical dynamo parameters along the evolutionary tracks of low-and intermediate-mass stars at various metallicities using stellar models that have been extensively tested by spectroscopic and asteroseismic observations. Specifically, these include convective turnover timescales and convective Rossby numbers, computed from the pre-main sequence (PMS) to the tip of the red giant branch (RGB) or the early asymptotic giant branch (AGB) phase. To investigate the effects of the very extended outer convective envelope, we compute these parameters both for the entire convective envelope and locally, that is, at different depths within the envelope. We also compute the turnover timescales and corresponding Rossby numbers for the convective cores of intermediate-mass stars on the main sequence. Results. Our models show that the Rossby number of the convective envelope becomes lower than unity in the well-delimited locations of the Hertzsprung-Russell diagram where magnetic fields have indeed been detected. Conclusions. We show that α − Ω dynamo processes might not be continuously operating, but that they are favored in the stellar convective envelope at two specific moments along the evolution tracks, that is, during the first dredge-up at the base of the RGB and during central helium burning in the helium-burning phase and early-AGB. This general behavior can explain the so-called magnetic strips recently discovered by dedicated spectropolarimetric surveys of evolved stars.

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Solar structure and evolution

Christensen‐Dalsgaard

2021

Living Rev Sol Phys

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The Sun provides a critical benchmark for the general study of stellar structure and evolution. Also, knowledge about the internal properties of the Sun is important for the understanding of solar atmospheric phenomena, including the solar magnetic cycle. Here I provide a brief overview of the theory of stellar structure and evolution, including the physical processes and parameters that are involved. This is followed by a discussion of solar evolution, extending from the birth to the latest stages. As a background for the interpretation of observations related to the solar interior I provide a rather extensive analysis of the sensitivity of solar models to the assumptions underlying their calculation. I then discuss the detailed information about the solar interior that has become available through helioseismic investigations and the detection of solar neutrinos, with further constraints provided by the observed abundances of the lightest elements. Revisions in the determination of the solar surface abundances have led to increased discrepancies, discussed in some detail, between the observational inferences and solar models. I finally briefly address the relation of the Sun to other similar stars and the prospects for asteroseismic investigations of stellar structure and evolution.

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Anisotropic turbulent transport in stably stratified rotating stellar radiation zones

Cited by 50 publications

References 85 publications

Fossil field decay due to nonlinear tides in massive binaries

Fossil field decay due to nonlinear tides in massive binaries

The magnetic strip(s) in the advanced phases of stellar evolution

Solar structure and evolution

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