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Observations in polarized emission reveal the existence of large-scale coherent magnetic fields in a wide range of spiral galaxies. Radio-polarization data show that these fields are strongly inclined towards the radial direction, with…

Astrophysics · Physics 2009-11-13 Oliver Gressel , Udo Ziegler , Detlef Elstner , Günther Rüdiger

Many astrophysical bodies harbor magnetic fields that are thought to be sustained by a dynamo process. However, it has been argued that the production of large-scale magnetic fields by mean-field dynamo action is strongly suppressed at…

Astrophysics of Galaxies · Physics 2013-01-22 Fabio Del Sordo , Gustavo Guerrero , Axel Brandenburg

Context: Convectively-driven flows play a crucial role in the dynamo processes that are responsible for producing magnetic activity in stars and planets. It is still not fully understood why many astrophysical magnetic fields have a…

Solar and Stellar Astrophysics · Physics 2018-05-09 P. J. Bushby , P. J. Käpylä , Y. Masada , A. Brandenburg , B. Favier , C. Guervilly , M. J. Käpylä

We investigate dynamo action in global compressible solar-like convective dynamos in the framework of mean-field theory. We simulate a solar-type star in a wedge-shaped spherical shell, where the interplay between convection and rotation…

Solar and Stellar Astrophysics · Physics 2018-01-17 Jörn Warnecke , Matthias Rheinhardt , S. Tuomisto , Petri J. Käpylä , Maarit J. Käpylä , Axel Brandenburg

Numerical simulations are an important tool in furthering our understanding of turbulent dynamo action, a process that occurs in a vast range of astrophysical bodies. It is important in all computational work that comparisons are made…

Solar and Stellar Astrophysics · Physics 2015-05-27 D. W. Hughes , M. R. E. Proctor , F. Cattaneo

An update is given on the current status of solar and stellar dynamos. At present, it is still unclear why stellar cycle frequencies increase with rotation frequency in such a way that their ratio increases with stellar activity. The…

Solar and Stellar Astrophysics · Physics 2015-06-15 Axel Brandenburg

An overview is presented of several diverse branches of work in the area of effectively 2D fluid equilibria which have in common that they are constrained by an infinite number of conservation laws. Broad concepts, and the enormous variety…

Fluid Dynamics · Physics 2022-12-27 Peter B. Weichman , J. B. Marston

Numerical modelling of convection driven dynamos in the Boussinesq approximation revealed fundamental characteristics of the dynamo-generated magnetic fields and the fluid flow. Because these results were obtained for an incompressible…

Solar and Stellar Astrophysics · Physics 2016-02-22 M. Schrinner , L. Petitdemange , R. Raynaud , E. Dormy

We live near a magnetic star whose cycles of activity are driven by dynamo action beneath the surface. In the solar convection zone, rotation couples with plasma motions to build highly organized magnetic fields that erupt at the surface…

Solar and Stellar Astrophysics · Physics 2015-05-20 Benjamin P Brown

In this paper, written as a general historical and technical introduction to the various review papers collected in the special issue ``Solar and Stellar Dynamo: A New Era'', we review the evolution and current state of dynamo theory and…

Solar and Stellar Astrophysics · Physics 2023-07-05 Paul Charbonneau , Dmitry Sokoloff

This paper provides a brief overview of dynamo scaling relationships for the degree of equipartition between magnetic and kinetic energies. Three basic approaches are adopted to explore these scaling relationships, with a first look at two…

Solar and Stellar Astrophysics · Physics 2017-01-11 Kyle Augustson , Stéphane Mathis , Allan Sacha Brun

We investigate the energy pathways between the velocity and the magnetic fields in a rotating plane layer dynamo driven by Rayleigh-B\'enard convection using direct numerical simulations. The kinetic and magnetic energies are divided into…

Fluid Dynamics · Physics 2022-12-20 Souvik Naskar , Anikesh Pal

A numerical study of dynamos in rotating convecting plane layers is presented which focuses on magnetic energies and dissipation rates, and the generation of mean fields (where the mean is taken over horizontal planes). The scaling of the…

Fluid Dynamics · Physics 2015-06-22 A. Tilgner

We present a numerical study of dynamo action in a conducting fluid encased in a metallic spherical shell. Motions in the fluid are driven by differential rotation of the outer metallic shell, which we refer to as "the wall". The two…

Fluid Dynamics · Physics 2014-01-08 Celine Guervilly , Toby S. Wood , Nicholas H. Brummell

The diffusive motion of charged particles in synthetic magnetic turbulence with different properties is investigated by using numerical simulations with unprecedented dynamical range, which allow us to ensure that both the inertial range…

High Energy Astrophysical Phenomena · Physics 2020-11-24 Andrej Dundovic , Oreste Pezzi , Pasquale Blasi , Carmelo Evoli , William H. Matthaeus

The magnetic fields of terrestrial planets are generated in their liquid cores through dynamo action driven by thermal and compositional convection. The coexistence of these two buoyancy sources gives rise to double-diffusive convection…

Earth and Planetary Astrophysics · Physics 2025-08-14 Wei Fan , Yufeng Lin

Dynamo action refers to energy exchange processes through which magnetic fields are generated at the expense of kinetic energy of the plasma flows. Dynamos can generate magnetic fields across scales larger or smaller than the flows…

Spectropolarimetric observations show that many low-mass stars possess large-scale poloidal magnetic fields with considerable dipole component, which in some cases exhibit temporal dynamics - cycles or reversals. Although it is widely…

Solar and Stellar Astrophysics · Physics 2025-07-02 Anna Guseva , Ludovic Petitdemange , Charly Pinçon

The dynamo effect is the most popular candidate to explain the non-primordial magnetic fields of astrophysical objects. Although many systematic studies of parameters have already been made to determine the different dynamical regimes…

Fluid Dynamics · Physics 2020-07-14 Mélissa D. Menu , Ludovic Petitdemange , Sébastien Galtier

The transport dynamo mechanism, which describes the magnetic field generation by diffusion flow is reviewed. In this mechanism, the cross-field transport caused by the random motion of fluid breaks the frozen-flux approximation, and the…

Fluid Dynamics · Physics 2021-10-07 Chang-Mo Ryu