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Increasing observations are becoming available about a relatively weak, but persistent, non-axisymmetric magnetic field co-existing with the dominant axisymmetric field on the Sun. It indicates that the non-axisymmetric magnetic field plays…

Astrophysics · Physics 2008-11-26 J. Jiang , J. X. Wang

A simple way to couple an interface dynamo model to a fast tachocline model is presented, under the assumption that the dynamo saturation is due to a quadratic process and that the effect of finite shear layer thickness on the dynamo wave…

Astrophysics · Physics 2008-06-05 K. Petrovay

Several solar-like stars exhibit cyclic magnetic activity similar to the Sun as found in photospheric and chromospheric emission. We want to understand the physical mechanism involved in rotational dependence of these activity cycle…

Solar and Stellar Astrophysics · Physics 2018-08-22 Jörn Warnecke

The calling card of solar magnetism is the sunspot cycle, during which sunspots regularly reverse their polarity sense every 11 years. However, a number of more complicated time-dependent behaviors have also been identified. In particular,…

Solar and Stellar Astrophysics · Physics 2020-04-06 Loren Matilsky , Juri Toomre

The paper presents a study of a solar dynamo model operating in the bulk of the convection zone with the toroidal magnetic field flux concentrated in the subsurface rotational shear layer. We explore how this type of dynamo may depend on…

Solar and Stellar Astrophysics · Physics 2015-05-28 V. V. Pipin , A. G. Kosovichev

This work builds on a recently developed self-consistent synchronization model of the solar dynamo which attempts to explain Rieger-type periods, the Schwabe/Hale cycle and the Suess-de Vries and Gleissberg cycles in terms of resonances of…

Solar and Stellar Astrophysics · Physics 2025-05-27 F. Stefani , G. M. Horstmann , G. Mamatsashvili , T. Weier

An $\alpha\Omega$ dynamo, combining shear and cyclonic convection in the tachocline, is believed to generate the solar cycle. However, this model cannot explain cycles in fast rotators (with minimal shear) or in fully convective stars (no…

Solar and Stellar Astrophysics · Physics 2023-06-14 Zackery A. Irving , Steven H. Saar , Bradford J. Wargelin , José-Dias do Nascimento

We propose a solar dynamo model distributed in the bulk of the convection zone with the toroidal magnetic field the flux concentrated in the near-surface layer. We show that if the boundary conditions at the top of the dynamo region allow…

Solar and Stellar Astrophysics · Physics 2015-05-20 V. V. Pipin , A. G. Kosovichev

We compare spectra of the zonal harmonics of the large-scale magnetic field of the Sun using observation results and solar dynamo models. The main solar activity cycle as recorded in these tracers is a much more complicated phenomenon than…

Solar and Stellar Astrophysics · Physics 2021-04-16 V. N. Obridko , V. V. Pipin , D. D. Sokoloff , A. S. Shibalova

We explore consequences for the solar dynamo of a newly-developed physical hypothesis describing a weak coupling of the orbital and rotational motions of extended bodies. The coupling is given by - c ((dL/dt) x omega sub alpha) x r, where…

Solar and Stellar Astrophysics · Physics 2017-06-07 James H. Shirley

Observations of the meridional circulation of the Sun, which plays a key role in the operation of the solar dynamo, indicate that its speed varies with the solar cycle, becoming faster during the solar minima and slower during the solar…

Solar and Stellar Astrophysics · Physics 2017-10-11 Gopal Hazra , Arnab Rai Choudhuri

It is well accepted that the solar cycle originates from a magnetohydrodynamics dynamo deep inside the Sun. Many dynamo models have long been proposed based on a lot of observational constraints. In this paper, using 342 NSO/Kitt Peak solar…

Astrophysics · Physics 2009-06-23 W. B. Song

Context: Large-scale magnetic fields resulting from hydromagnetic dynamo action may differ substantially in their time dependence. Cyclic field variations, characteristic for the solar magnetic field, are often explained by an important…

Solar and Stellar Astrophysics · Physics 2015-05-27 M. Schrinner , L. Petitdemange , E. Dormy

Parameters of magnetic activity on the solar type stars depend on the properties of the dynamo processes operating in stellar convection zones. We apply nonlinear mean-field axisymmetric $\alpha^2\Omega$ dynamo models to calculate of the…

Solar and Stellar Astrophysics · Physics 2015-05-08 V. V. Pipin

A magnetic flux tube may be considered both as a separate body and as a confined field. As a field, it is affected both by differential rotation ($\Omega$-effect) and cyclonic convection ($\alpha$-effect). As a body, the tube experiences…

Astrophysics · Physics 2009-11-13 L. H. Li , S. Sofia , G. Belvedere

Global and semi-global convective dynamo simulations of solar-like stars are known to show a transition from an anti-solar (fast poles, slow equator) to solar-like (fast equator, slow poles) differential rotation (DR) for increasing…

Solar and Stellar Astrophysics · Physics 2019-11-25 M. Viviani , M. J. Käpylä , J. Warnecke , P. J. Käpylä , M. Rheinhardt

The scale separation approximation, which is in the base of the solar mean field dynamo models, can be hardly justified both by observations and theoretical applications to astrophysical dynamos.{ The general expression for the mean…

Solar and Stellar Astrophysics · Physics 2023-05-17 V. V. Pipin

A model for the solar dynamo, consistent in global flow and numerical method employed with the differential rotation model, is developed. The magnetic turbulent diffusivity is expressed in terms of the entropy gradient, which is controlled…

Solar and Stellar Astrophysics · Physics 2017-06-28 L. L. Kitchatinov , A. A. Nepomnyashchikh

The Sun's magnetic dynamo cycle features a distinct pattern: a propagating region of sunspot emergence appears around 30 degrees latitude and vanishes near the equator every 11 years. Moreover, longitudinal flows called "torsional…

We describe the defining observations of the solar cycle that provide constraints for the dynamo processes operating within the Sun. Specifically, we report on the following topics: historical sunspot numbers and revisions; active region…

Solar and Stellar Astrophysics · Physics 2023-09-29 Aimee Norton , Rachel Howe , Lisa Upton , Ilya Usoskin