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The surprising thinness of the solar tachocline is still not understood with certainty today. Among the numerous possible scenarios suggested to explain its radial confinement, one hypothesis is based on Maxwell stresses that are exerted by…

Solar and Stellar Astrophysics · Physics 2017-04-26 R. Barnabé , A. Strugarek , P. Charbonneau , A. S. Brun , J. -P. Zahn

The competition between turbulent convection and global rotation in planetary and stellar interiors governs the transport of heat and tracers, as well as magnetic-field generation. These objects operate in dynamical regimes ranging from…

An overview is given about recent developments and results of comprehensive simulations of magneto-convective processes in the near-surface layers and photosphere of the Sun. Simulations now cover a wide range of phenomena, from whole…

Solar and Stellar Astrophysics · Physics 2015-06-12 Manfred Schüssler

The process referred to as "semi-convection" in astrophysics and "double-diffusive convection in the diffusive regime" in Earth and planetary sciences, occurs in stellar and planetary interiors in regions which are stable according to the…

Solar and Stellar Astrophysics · Physics 2015-06-03 Giovanni M. Mirouh , Pascale Garaud , Stephan Stellmach , Adrienne L. Traxler , Toby S. Wood

Spherical solar dynamo simulations are performed. Self-consistent, fully compressible magnetohydrodynamic system with a stably stratified layer below the convective envelope is numerically solved with a newly developed simulation code based…

Solar and Stellar Astrophysics · Physics 2015-06-15 Youhei Masada , Kohei Yamada , Akira Kageyama

Mean-field dynamo theory has important applications in solar physics and galactic magnetism. We discuss some of the many turbulence effects relevant to the generation of large-scale magnetic fields in the solar convection zone. The…

Solar and Stellar Astrophysics · Physics 2023-11-23 Axel Brandenburg , Detlef Elstner , Youhei Masada , Valery Pipin

The solar photosphere provides us with a laboratory for understanding turbulence in a layer where the fundamental processes of transport vary rapidly and a strongly superadiabatic region lies very closely to a subadiabatic layer. Our tools…

The Sun, aside from its eleven year sunspot cycle is additionally subject to long term variation in its activity. In this work we analyse a solar-like convective dynamo simulation, containing approximately 60 magnetic cycles, exhibiting…

Solar and Stellar Astrophysics · Physics 2017-10-11 Frederick A. Gent , Maarit J. Käpylä , Jörn Warnecke

Although it is widely accepted that photospheric motions provide the energy source and that the magnetic field must play a key role in the process, the detailed mechanisms responsible for heating the Sun's corona and accelerating the solar…

Solar and Stellar Astrophysics · Physics 2016-01-12 Roberto Lionello , Marco Velli , Cooper Downs , Jon A. Linker , Zoran Mikić

The diffusion of astrophysical magnetic fields in conducting fluids in the presence of turbulence depends on whether magnetic fields can change their topology or reconnect in highly conducting media. Recent progress in understanding fast…

Astrophysics of Galaxies · Physics 2010-03-16 A. Lazarian , R. Santos-Lima , E. Gouveia Dal Pino

We review the surface flux transport model for the evolution of magnetic flux patterns on the Sun's surface. Our underlying motivation is to understand the model's prediction of the polar field (or axial dipole) strength at the end of the…

Solar and Stellar Astrophysics · Physics 2023-05-31 Anthony R. Yeates , Mark C. M. Cheung , Jie Jiang , Kristof Petrovay , Yi-Ming Wang

The operation of the solar global dynamo appears to involve many dynamical elements. Self-consistent MHD simulations which realistically incorporate all of these processes are not yet computationally feasible, though some elements can now…

Astrophysics · Physics 2008-11-26 Allan Sacha Brun , Mark S. Miesch , Juri Toomre

We present new solar models in which we use the latest low abundances and we further include the effects of rotation, magnetic fields and extra-mixing processes. We assume that the extra-element mixing can be treated as a diffusion process,…

Solar and Stellar Astrophysics · Physics 2015-05-27 Shaolan Bi , Tanda Li , Linghuai Li , Wuming Yang

The diffusion of astrophysical magnetic fields in conducting fluids in the presence of turbulence depends on whether magnetic fields can change their topology via reconnection in highly conducting media. Recent progress in understanding…

Astrophysics of Galaxies · Physics 2012-12-17 R. Santos-Lima , A. Lazarian , E. M. de Gouveia Dal Pino , J. Cho

The Sun is a non-equilibrium dissipative system subjected to an energy flow which originates in its core. Convective overshooting motions create temperature and velocity structures which show a temporal and spatial evolution. As a result,…

Solar and Stellar Astrophysics · Physics 2015-06-11 F. Berrilli , S. Scardigli , S. Giordano

Models for the transport of high energy charged particles through strong magnetic turbulence play a key role in space and astrophysical studies, such as describing the propagation of solar energetic particles and high energy cosmic rays.…

We consider the diffusion-advection problem in two simple cellular flow models (often invoked as examples for subdiffusive tracer's motion) and concentrate on the intermediate time range, in which the tracer's motion indeed may show…

Fluid Dynamics · Physics 2016-09-28 Patrick Pöschke , Igor M. Sokolov , Alexander A. Nepomnyashchy , Michael A. Zaks

The rotational influence on the eddy-diffusivity tensor D_ij for anisotropic turbulence fields is considered in order to explain the lithium decay law during the spin-down process of solar-type stars. Rotation proves to be highly effective…

Astrophysics · Physics 2009-11-06 G. Rudiger , V. V. Pipin

The large-scale magnetic pattern of the quiet sun is dominated by the magnetic network. This network, created by photospheric magnetic fields swept into convective downflows, delineates the boundaries of large scale cells of overturning…

Solar and Stellar Astrophysics · Physics 2014-09-05 Francesco Berrilli , Stefano Scardigli , Dario Del Moro

We review recent insights into the dynamics of the solar convection zone obtained from global numerical simulations, focusing on two recent developments in particular. The first is quasi-cyclic magnetic activity in a long-duration dynamo…

Solar and Stellar Astrophysics · Physics 2015-05-20 Mark S. Miesch , Benjamin P. Brown , Matthew K. Browning , Allan Sacha Brun , Juri Toomre