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Based on the drift-kinetic theory, we develop a model for particle acceleration and transport in solar flares. The model describes the evolution of the particle distribution function by means of a numerical simulation of the drift-kinetic…

Solar and Stellar Astrophysics · Physics 2015-05-18 T. Minoshima , S. Masuda , Y. Miyoshi

An essential ingredient in kinematic dynamo models is the velocity field within the solar convection zone. In particular, the differential rotation is now well constrained by helioseismic observations. Helioseismology also gives us…

Astrophysics · Physics 2009-06-30 Andrés Muñoz-Jaramillo , Dibyendu Nandy , Petrus C. H. Martens

Circulation-dominated solar dynamo models, which employ a helioseismic rotation profile and a fixed meridional flow, give a good approximation to the large scale solar magnetic phenomena, such as the 11-year cycle or the so called Hale's…

Astrophysics · Physics 2016-08-16 G. A. Guerrero , J. D. Muñoz , E M. de Gouveia Dal Pino

In Sun and sun-like stars, it is believed that the cycles of the large-scale magnetic field are produced due to the existence of differential rotation and helicity in the plasma flows in their convection zones (CZs). Hence, it is expected…

Solar and Stellar Astrophysics · Physics 2021-12-08 Vindya Vashishth , Bidya Binay Karak , Leonid Kitchatinov

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

Recent analyses of the helioseismic observations indicate that the previously observed surface torsional oscillations with periods of about 11 years extend significantly downwards into the solar convective zone. Furthermore, there are…

Astrophysics · Physics 2007-05-23 Eurico Covas , Reza Tavakol , David Moss

Magnetic buoyancy is believed to drive the transport of magnetic flux tubes from the convection zone to the surface of the Sun. The magnetic fields form twisted loop-like structures in the solar atmosphere. In this paper we use helical…

Solar and Stellar Astrophysics · Physics 2011-09-28 Jörn Warnecke , Axel Brandenburg

We present a realistic numerical model of sunspot and active region formation based on the emergence of flux bundles generated in a solar convective dynamo. To this end we use the magnetic and velocity fields in a horizontal layer near the…

Solar and Stellar Astrophysics · Physics 2017-09-20 Feng Chen , Matthias Rempel , Yuhong Fan

In this paper we address a discrepancy between the surface flux evolution in a 3D kinematic dynamo model and a 2D surface flux transport model that has been closely calibrated to the real Sun. We demonstrate that the difference is due to…

Solar and Stellar Astrophysics · Physics 2019-07-24 T. Whitbread , A. R. Yeates , A. Muñoz-Jaramillo

In contrast to the situation with the geodynamo, no breakthrough has been made in the solar dynamo problem for decades. Since the appearance of mean-field electrodynamics in the 1960's, the only really significant advance was in the field…

Astrophysics · Physics 2016-08-30 K. Petrovay

We present the exact solution for the full dynamics of a nonequilibrium spin chain and its dual reaction-diffusion model, for arbitrary initial conditions. The spin chain is driven out of equilibrium by coupling alternating spins to two…

Statistical Mechanics · Physics 2007-05-23 M. Mobilia , B. Schmittmann , R. K. P. Zia

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

Solar meridional circulation, which manifests as poleward flow near the surface, is a relatively weak flow. While meridional circulation has been measured through various local helioseismic techniques, there is a lack of consensus about the…

Solar and Stellar Astrophysics · Physics 2025-12-08 Samarth G. Kashyap , Shravan M. Hanasoge

The latitudinal distribution of starspots deviates from the solar pattern with increasing rotation rate. Numerical simulations of magnetic flux emergence and transport can help model the observed stellar activity patterns and the associated…

Solar and Stellar Astrophysics · Physics 2018-12-19 Emre Işık , Sami K. Solanki , Natalie A. Krivova , Alexander I. Shapiro

In this paper we discuss a dynamic flux-transport dynamo model that includes the feedback of the induced magnetic field on differential rotation and meridional flow. We consider two different approaches for the feedback: meanfield Lorentz…

Astrophysics · Physics 2009-11-11 Matthias Rempel

Using mean-field hydrodynamic models of the solar angular momentum balance we show that the non-monotonic latitudinal dependence of the radial angular momentum fluxes caused by Lambda-effect can affect the number of the meridional…

Solar and Stellar Astrophysics · Physics 2016-09-21 V. V. Pipin , A. G. Kosovichev

Meridional circulation is a crucial component of the Sun's internal dynamics, but its inference in the deep interior is complicated by a systematic center-to-limb effect in helioseismic measurement techniques. Previously, an empirical…

Solar and Stellar Astrophysics · Physics 2017-11-15 Ruizhu Chen , Junwei Zhao

Analysis of synoptic data from the Vector Stokes Magnetograph (VSM) of the Synoptic Optical Long-term Investigations of the Sun (SOLIS) and the NASA/NSO Spectromagnetograph (SPM) at the NSO/Kitt Peak Vacuum Telescope facility shows that the…

Solar and Stellar Astrophysics · Physics 2016-02-09 Alexander V. Mordvinov , Alexei A. Pevtsov , Luca Bertello , Gordon J. D. Petrie

Energetic particle fluxes in the outer magnetosphere present a significant challenge to modelling efforts as they can vary by orders of magnitude in response to solar wind driving conditions. In this article, we demonstrate the ability to…

We present results of convective turbulent dynamo simulations including a coronal layer in a spherical wedge. We find an equatorward migration of the radial and azimuthal fields similar to the behavior of sunspots during the solar cycle.…

Solar and Stellar Astrophysics · Physics 2013-08-13 Jörn Warnecke , Petri J. Käpylä , Maarit. J. Mantere , Axel Brandenburg