On the Dynamics of the Solar Convection Zone

AbstractWe derive expressions for the turbulent viscosity and turbulent conductivity applicable to convection zones of rotating stars. We assume that the dimensions of the convective cells are known and derive a simple distribution function for the turbulent convective velocities under the influence of rotation. From this distribution function (which includes, in particular, the stabilizing effect of rotation on convection) we calculate in the mixing-length approximation: i) the turbulent Reynolds stresstensor and ii) the expression for the heat flux in terms of the superadiabatic gradient. The contributions of the turbulent convective motions to the mean momentum and energy equation are treated consistently, and assumptions about the turbulent viscosity and heat transport are replaced by assumptions about the turbulent flow itself. The free parameters in our formalism are the relative cell sizes and their dependence on depth and latitude.

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Magnetoconvection Patterns in Rotating Convection Zones

International Astronomical Union Colloquium ◽

10.1017/s0252921100079379 ◽

1991 ◽

Vol 130 ◽

pp. 37-56

Author(s):

Paul H. Roberts

Keyword(s):

Convection Zone ◽

Solar Surface ◽

Giant Cells ◽

Conclusive Evidence ◽

The Other ◽

The Sun ◽

Solar Convection Zone ◽

Solar Convection ◽

Entire Thickness ◽

Convective Motions

AbstractIn addition to the well-known granulation and supergranulation of the solar convection zone (the “SCZ”), the presence of so-called “giant cells” has been postulated. These are supposed span the entire thickness of the SCZ and to stretch from pole to pole in a sequence of elongated cells like a “cartridge belt” or a bunch of “bananas” strung uniformly round the Sun. Conclusive evidence for the existence of such giant cells is still lacking, despite strenuous observational efforts to find them. After analyses of sunspot motion, Ribes and others believe that convective motions near the solar surface occurs in a pattern that is the antithesis of the cartridge belt: a system of “toroidal” or “doughnut” cells, girdling the Sun in a sequence that extends from one pole to the other. Galloway, Jones and Roberts have recently tried to meet the resulting theoretical challenge, with the mixed success reported in this paper.

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Die Lithiumhäufigkeit und die Struktur der äußeren Konvektionszone in sonnenähnlichen Sternen

Zeitschrift für Naturforschung A ◽

10.1515/zna-1966-0735 ◽

1966 ◽

Vol 21 (7) ◽

pp. 1107-1115

Author(s):

K.-H. Böhm

Keyword(s):

Isotope Ratio ◽

Main Sequence ◽

Convection Zone ◽

Mixing Process ◽

Lithium Abundance ◽

Solar Convection Zone ◽

Solar Convection ◽

The Mean ◽

Convective Overshoot ◽

Slow Timescale

The observations of the Lithium abundance and the isotope ratio Li6/Li7 in stars are briefly reviewed and some simple conclusions are drawn. It is emphasized that — in addition to the mechanism proposed by BODENHEIMER — a slow (timescale ≈ 109 years) mixing process in main sequence F and G stars is necessary to account for the observations.The present state of the theory of convective overshooting is reviewed in this context. Two new models of the outer solar convection zone are presented. The temperature at their lower boundaries are 2.04 x 106 °K and 2.27 x 106 °K, showing that only a rather small convective overshoot may be sufficient for mixing the matter in the convection zone with the layers, in which Li7 is burnt.Our models differ from earlier ones, because (when calculating the mean stratification) we take into account the condition that the mixing length can nowhere be larger than the distance from the nearest boundary of the convection zone. It is shown that this approach also leads to a slight change of the numerical factors in the formulae usually used.

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Helicity–vorticity turbulent pumping of magnetic fields in the solar dynamo

Proceedings of the International Astronomical Union ◽

10.1017/s1743921313002780 ◽

2012 ◽

Vol 8 (S294) ◽

pp. 367-368

Author(s):

V. V. Pipin

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Differential Rotation ◽

Large Scale ◽

Convection Zone ◽

Solar Dynamo ◽

Solar Convection Zone ◽

Solar Convection ◽

Large Scale Magnetic Field ◽

Convective Motions

AbstractThe interaction of helical convective motions and differential rotation in the solar convection zone results in turbulent drift of a large-scale magnetic field. We discuss the pumping mechanism and its impact on the solar dynamo.

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Non-Linear Diamagnetic Transport of the Large-Scale Magnetic Field in the Solar Convection Zone

Symposium - International Astronomical Union ◽

10.1017/s0074180900173851 ◽

1993 ◽

Vol 157 ◽

pp. 49-50

Author(s):

V.N. Krivodubskij

Keyword(s):

Magnetic Field ◽

Turbulence Intensity ◽

Large Scale ◽

Convection Zone ◽

Back Reaction ◽

Solar Convection Zone ◽

Solar Convection ◽

Large Scale Magnetic Field ◽

Magnetic Buoyancy ◽

The Mean

The mean magnetic field transport due to inhomogeneity of the turbulence intensity is considered taking the field back reaction on motion into account. In spite of the magnetic quenching, the downward diamagnetic pumping is still powerful enough to keep the fields of 3 to 4 kG strength near the SCZ base against the magnetic buoyancy.

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Can short time delays influence the variability of the solar cycle?

Proceedings of the International Astronomical Union ◽

10.1017/s1743921311017716 ◽

2010 ◽

Vol 6 (S271) ◽

pp. 288-296

Author(s):

Laurène Jouve ◽

Michael R. E. Proctor ◽

Geoffroy Lesur

Keyword(s):

Solar Cycle ◽

Convection Zone ◽

Mean Field ◽

Period Doubling ◽

Temporal Modulation ◽

Solar Convection Zone ◽

Flux Tubes ◽

Solar Convection ◽

Short Time ◽

Period Doubling Bifurcations

AbstractWe present the effects of introducing results of 3D MHD simulations of buoyant magnetic fields in the solar convection zone in 2D mean-field Babcock-Leighton models. In particular, we take into account the time delay introduced by the rise time of the toroidal structures from the base of the convection zone to the solar surface. We find that the delays produce large temporal modulation of the cycle amplitude even when strong and thus rapidly rising flux tubes are considered. The study of a reduced model reveals that aperiodic modulations of the solar cycle appear after a sequence of period doubling bifurcations typical of non-linear systems. We also discuss the memory of such systems and the conclusions which may be drawn concerning the actual solar cycle variability.

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Simulating Solar Global Magnetism in 3-D

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314004736 ◽

2012 ◽

Vol 10 (H16) ◽

pp. 101-103

Author(s):

A. S. Brun ◽

A. Strugarek

Keyword(s):

Magnetic Field ◽

Recent Progress ◽

Convection Zone ◽

Thermal Structure ◽

Solar Convection ◽

Self Consistent ◽

The Mean ◽

The Magnetic Field

AbstractWe briefly present recent progress using the ASH code to model in 3-D the solar convection, dynamo and its coupling to the deep radiative interior. We show how the presence of a self-consistent tachocline influences greatly the organization of the magnetic field and modifies the thermal structure of the convection zone leading to realistic profiles of the mean flows as deduced by helioseismology.

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