Large-Scale Internal Magnetic Field of the Sun

Dudorov, A. E.; Krivodubskij, V. N.; Ruzmaikin, A.; Ruzmaǐkina, T. V.

doi:10.1017/s0074180900044399

Cited by 3 publications

(2 citation statements)

References 7 publications

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“…The estimations for sample of main sequence stars show that the strength of dynamo supported fossil magnetic field inside the young stars may have the values ≈ (0.1 − 10) • 10 6 Gs. Such a strength of toroidal magnetic field is quite enough for the formation of magnetic ropes and their rising to the surface for Alfven time (Dudorov, Krivodubskii, Ruzmaikina & Ruzmaikin, 1989).…”

Section: Dynamo In Young Starsmentioning

confidence: 99%

Theory of fossil magnetic field

Dudorov

Khaibrakhmanov

2015

Advances in Space Research

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Section: Dynamo In Young Starsmentioning

confidence: 99%

Theory of fossil magnetic field

Dudorov

Khaibrakhmanov

2015

Advances in Space Research

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“…We can estimate the strength of a dynamo magnetic field on the basis of the equality of electromagnetic and Coriolis forces (see Dudorov et. al.…”

Section: 2 Scalingmentioning

confidence: 99%

Dynamo and Fossil Magnetic Field in Young Stars

Dudorov

1993

Symp. - Int. Astron. Union

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The theory of fossil magnetic fields shows that new born stars may have internal magnetic fields of more than 1 million gauss. Convection inside young solar type stars will tangle any strong fossil magnetic field. The small scale magnetic field rises to the surface and determines the young stars activity attenuating with their age. When a fossil field is diminished a turbulent dynamo may begin to work in the condition of nonlinear stabilization. The scaling relations for the turbulent αω dynamo show that the strength of the generated “fossil” magnetic field inside the main sequence stars is stabilized on the level one tenth — 10 millions gauss, depending on the mass of the stars.

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Study of magnetism cyclicity of the Sun in the framework of the macroscopic magnetohydrodynamics theory

Krivodubskij

2019

BTSNUA

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Since the mid-70s of the last century, a new direction in theoretical studies of the evolution of the global magnetism of the Sun in the framework of macroscopic MHD has been launched at the Astronomical Observatory of the Taras Shevchenko National University of Kyiv. The paper presents the results of a study of the processes of generation and restructuring of a large-scale (global) magnetic field based on the αΩ-dynamo model, taking into account new turbulent effects discovered in the theory of macroscopic MHD and data of helioseismological experiments on the internal rotation of the Sun. It was established that a sharp radial gradient of turbulent velocity in the lower half of the solar convective zone (SCZ) leads to a change in the sign of the azimuthal component of the helicity parameter α, resulting in the formation of a relatively thin layer of negative α-effect near the bottom of the SCZ. It was found that the layer of negative α-effect, together with the sign of the radial gradient of the angular velocity, detected in helioseismological experiments, makes it possible to explain the direction of migration of dynamo-waves on the solar surface. The magnetic saturation of the α-effect (alpha-quenching) in the deep layers of the SCZ was calculated. An explanation of the protracted duration of the 23rd solar cycle of about 13 years is proposed. For this, we used the observed data on a significant increase of the annual module of the magnetic fields of sunspots in the 23rd cycle. The calculated north-south asymmetry of the structure of the global magnetic field provides an opportunity to explain the phenomenon of the seeming magnetic “monopole”, which is observed during reversal of polar magnetism. It was found that the values of turbulent electrical conductivity and turbulent magnetic permeability of the solar plasma are significantly less than the corresponding gas-kinetic parameters. Therefore, the turbulent dissipation of solar magnetic fields is enhanced by 4–9 orders of magnitude compared with classical ohmic dissipation. Macroscopic turbulent diamagnetism of solar plasma was investigated. It has been found that in the lower part of the SCZ, turbulent diamagnetism acts against magnetic buoyancy, thus fulfilling the role of “negative magnetic buoyancy”. As a result of the balance of the effects of magnetic buoyancy and turbulent diamagnetism, a layer of blocked magnetic field of magnitude ≈ 3000 G is formed in the depths of the SCZ. The turbulent advection of a magnetic field in an inhomogeneous plasma density of the SCZ was studied. It was found that in the lower half of the SCZ of the equatorial domain, turbulent advection is directed upwards. As a result of the combined action of magnetic buoyancy and turbulent advection, deep strong toroidal fields are carried to the surface of the Sun in the latitudinal “royal zone” of sunspots. The role of horizontal turbulent diamagnetism in ensuring the long-term stability of sunspots was noted. To explain the observed phenomenon of double maxima of the solar spot cycle, a scenario was developed containing the generation of a magnetic field in the tachocline at the bottom of the SCZ and subsequent removal of this magnetic field from the depth layers to the surface in the latitudinal “royal zone”. The role of the radial omega-effect in the radiant zone in explaining the observed asymmetry in the amplitude of two neighbouring 11-years sunspot cycles was noted.

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Large-Scale Internal Magnetic Field of the Sun

Cited by 3 publications

References 7 publications

Theory of fossil magnetic field

Theory of fossil magnetic field

Dynamo and Fossil Magnetic Field in Young Stars

Study of magnetism cyclicity of the Sun in the framework of the macroscopic magnetohydrodynamics theory

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