scholarly journals Interior Structure of the Sun

1990 ◽  
Vol 142 ◽  
pp. 23-34
Author(s):  
Jørgen Christensen-Dalsgaard
Keyword(s):  
Equation Of State ◽  
Convection Zone ◽  
Solar Interior ◽  
The Sun ◽  
Interior Structure ◽  
Solar Oscillations ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Standard Models

Observations of solar oscillations have provided us with detailed information about the solar interior. Here I consider three examples of results obtained in such helioseismic investigations: i) the effect of the equation of state on the comparison between observed and theoretical frequencies; ii) a determination of the depth of the solar convection zone; and iii) indications of deviations from standard models of the structure of the solar core.

scholarly journals Magnetoconvection Patterns in Rotating Convection Zones

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.

scholarly journals Simulating the Solar Dynamo

1993 ◽  
Vol 157 ◽  
pp. 111-121
Author(s):  
Axel Brandenburg
Keyword(s):  
Eddy Viscosity ◽  
Convection Zone ◽  
Transport Coefficients ◽  
Mean Field ◽  
Field Orientation ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Magnetic Diffusivity ◽  
The Magnetic Field

Mean-field and direct simulations of the hydrodynamics and hydromagnetics of the solar convection zone are discussed with the ultimate aim to understand the generation of differential rotation and magnetic fields. Various arguments constraining the values of the various turbulent diffusion coefficients are presented. It is suggested that the turbulent magnetic diffusivity is much smaller than the eddy viscosity which, in turn, is by up to a factor of ten smaller than the eddy conductivity. The magnetic field obtained from direct simulations is highly intermittent, and there is no clear systematic orientation of bipolar regions emerging from the convection zone. Various mechanisms that might cause such a field orientation are considered. Finally, the application of direct simulations to the determination of mean-field transport coefficients is emphasised.

The Effect of Rotation on Thermal Convection

1972 ◽  
Vol 2 (2) ◽  
pp. 92-93 ◽  
Author(s):  
J. O. Murphy ◽  
R. Van Der Borght
Keyword(s):  
Rayleigh Number ◽  
Heat Transport ◽  
Cell Size ◽  
Thermal Convection ◽  
Convection Zone ◽  
Total Heat ◽  
The Sun ◽  
Maximum Heat ◽  
Solar Convection Zone ◽  
Solar Convection

An investigation into the influence of rotation on thermal convection has some applicability in the study of the solar convection zone. Of particular interest is the effect of rotation on the total heat transport and the cell size for maximum heat transport at high Rayleigh number, which is estimated to be as high as 1020 for the Sun.

Helioseismology and the Solar Interior Dynamics

2000 ◽  
Vol 179 ◽  
pp. 323-329
Author(s):  
S. Vauclair
Keyword(s):  
Equation Of State ◽  
Convection Zone ◽  
Diffusion Processes ◽  
Solar Rotation ◽  
Solar Interior ◽  
The Other ◽  
The Sun ◽  
Helium 3 ◽  
Radiative Zone ◽  
Neutrino Fluxes

AbstractThe inversion of helioseismic modes leads to the sound velocity inside the Sun with a precision of about 0.1 per cent. Comparisons of solar models with the “seismic sun” represent powerful tools to test the physics: depth of the convection zone, equation of state, opacities, element diffusion processes and mixing inside the radiative zone. We now have evidence that microscopic diffusion (element segregation) does occur below the convection zone, leading to a mild helium depletion in the solar outer layers. Meanwhile this process must be slowed down by some macroscopic effect, presumably rotation-induced mixing. The same mixing is also responsible for the observed lithium depletion. On the other hand, the observations of beryllium and helium 3 impose specific constraints on the depth of this mildly mixed zone. Helioseismology also gives information on the internal solar rotation: while differential rotation exists in the convection zone, solid rotation prevails in the radiative zone, and the transition layer (the so-called “tachocline”) is very small. These effects are discussed, together with the astrophysical constraints on the solar neutrino fluxes.

scholarly journals Magnetic Helicity Propagation from Inside the Sun

2005 ◽  
Vol 13 ◽  
pp. 97-100
Author(s):  
Dana Longcope
Keyword(s):  
Active Region ◽  
Flux Tube ◽  
Convection Zone ◽  
Active Regions ◽  
Magnetic Helicity ◽  
The Sun ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Region Emergence

AbstractModels of twisted flux tube evolution provide a picture of how magnetic helicity is propagated through the solar convection zone into the corona. According to the models, helicity tends toward an approximately uniform length-density along a tube, rather than concentrating at wider portions. Coronal fields lengthen rapidly during active region emergence, requiring additional helicity to propagate from the submerged flux tube. Recent observations of emerging active regions show an evolution consistent with this prediction, and no evidence of helicity concentrating in wider sections.

Depth Dependence on the Various Scale Lengths in a Quasi-Vitense Model of the Solar Convection Zone

1971 ◽  
Vol 2 (1) ◽  
pp. 48-50 ◽  
Author(s):  
B. E. Waters
Keyword(s):  
Vertical Velocity ◽  
Temperature Fluctuation ◽  
Convection Zone ◽  
Wave Number ◽  
Mixing Length ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Depth Dependence

As has been previously stated (van der Borght) the lengths l1, l2, l3 and l4 are functions of and so a discussion of these lengths is in fact a discussion of the f’s. For a first approach to a determination of these f’s, a standard Vitense2 model of the convection zone—with mixing length l, is used. We assume that l = H. The variables we need are kz, which are the vertical wave number associated with the characteristic eddy, the average vertical velocity, and the average (non-dimensional) temperature fluctuation. These quantities are approximated, using the following relations

Testing Reynolds stress model in solar interior

2006 ◽  
Vol 2 (S239) ◽  
pp. 373-375
Author(s):  
J. Y. Yang ◽  
Y. Li
Keyword(s):  
Reynolds Stress ◽  
Convection Zone ◽  
Reynolds Stress Model ◽  
Solar Interior ◽  
Stress Model ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Mode Oscillation ◽  
Non Local ◽  
Oscillation Frequencies

AbstractThe Reynolds stress model (RSM) for turbulent convection motion is compared to the MLT in solar model. The free parameters involved in the RSM are also tested with the aid of helioseismology. It is found that, the structure of solar convection zone is differ from the MLT when using the RSM, especially for the Reynolds correlations and the temperature gradient. Both the local and non-local RSM can improve the calculated solar p-mode oscillation frequencies with the appropriate choice of the parameters' value.

A Model of the Solar Convection Zone

1972 ◽  
Vol 2 (2) ◽  
pp. 92-92 ◽  
Author(s):  
B. E. Waters ◽  
R. Van Der Borght
Keyword(s):  
Differential Equation ◽  
Convection Zone ◽  
Order Differential Equation ◽  
Wave Number ◽  
Length Scales ◽  
Model Calculations ◽  
Solar Convection Zone ◽  
Solar Convection ◽  
Second Order Differential Equation

In a previous paper it was shown how one could improve upon the Böhm-Vitense model of the solar convection zone by the inclusion of four different length scales and by the determination of these length scales with the use of the quasi-Vitense model as developed by Unno. In this way the vertical wave number kz, associated with a characteristic eddy, can be determined by the integration of a second order differential equation. The integrations have to be started at a suitable depth and all model calculations depend critically on the assumed structure of the top layer.

scholarly journals Rotation of the solar convection zone from helioseismology

2006 ◽  
Vol 2 (S239) ◽  
pp. 393-404 ◽  
Author(s):  
Jørgen Christensen-Dalsgaard
Keyword(s):  
Solar Cycle ◽  
Convection Zone ◽  
Periodic Variation ◽  
Solar Interior ◽  
Slow Rotation ◽  
Magnetic Cycle ◽  
Solar Convection Zone ◽  
Zonal Flows ◽  
Solar Convection ◽  
Solar Magnetic Cycle

AbstractHelioseismology has provided very detailed inferences about rotation of the solar interior. Within the convection zone the rotation rate roughly shares the latitudinal variation seen in the surface differential rotation. The transition to the nearly uniformly rotating radiative interior takes place in a narrow tachocline, which is likely important to the operation of the solar magnetic cycle. The convection-zone rotation displays zonal flows, regions of slightly more rapid and slow rotation, extending over much of the depth of the convection zone and converging towards the equator as the solar cycle progresses. In addition, there is some evidence for a quasi-periodic variation in rotation, with a period of around 1.3 yr, at the equator near the bottom of the convection zone.

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