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Observations with the Hinode spectro-polarimeter have revealed strong horizontal internetwork magnetic fields in the quiet solar photosphere. We aim at interpreting the observations by means of results from numerical simulations. Radiative…

Astrophysics · Physics 2009-11-13 M Schuessler , A. Voegler

(Abridged) Based on the rapidly increasing all-sky data of Faraday rotation measures and polarised synchrotron radiation, the Milky Way's magnetic field is now modelled with an unprecedented level of detail and complexity. We aim to…

Astrophysics of Galaxies · Physics 2015-06-17 Oliver Gressel , Detlef Elstner , Udo Ziegler

Arguments for and against the widely accepted picture of a solar dynamo being seated in the tachocline are reviewed and alternative ideas concerning dynamos operating in the bulk of the convection zone, or perhaps even in the near-surface…

Astrophysics · Physics 2007-05-23 Axel Brandenburg

Stellar dynamos are driven by complex couplings between rotation and turbulent convection, which drive global-scale flows and build and rebuild stellar magnetic fields. When stars like our sun are young, they rotate much more rapidly than…

This paper presents scale invariant/self-similar galactic magnetic dynamo models based on the classic equations, and compares them qualitatively to recently observed magnetic fields in edge-on spiral galaxies. We classify the axially…

Astrophysics of Galaxies · Physics 2021-11-03 R. H. Henriksen , Judith Irwin

We explore effects of random non-axisymmetric perturbations of kinetic helicity (the $\alpha$ effect) and diffusive decay of bipolar magnetic regions on generation and evolution of large-scale non-axisymmetric magnetic fields on the Sun.…

Solar and Stellar Astrophysics · Physics 2018-11-28 V. V. Pipin , A. G. Kosovichev

Controlled creation of localized magnetic textures beyond conventional $\pi$-skyrmions is an important problem in the field of magnetism. Here by means of spin dynamics simulations, Monte Carlo simulations and harmonic transition state…

Mesoscale and Nanoscale Physics · Physics 2022-08-22 Vladyslav M. Kuchkin , Pavel F. Bessarab , Nikolai S. Kiselev

Recent simulations of supernova-driven turbulence within the ISM support the existence of a large-scale dynamo. With a growth time of about two hundred million years, the dynamo is quite fast -- in contradiction to many assertions in the…

Cosmology and Nongalactic Astrophysics · Physics 2009-11-13 Detlef Elstner , Oliver Gressel , Günther Rüdiger

Spherical shell dynamo models based on rotating convection show that the flow within the tangent cylinder is dominated by an off-axis plume that extends from the inner core boundary to high latitudes and drifts westward. Earlier studies…

Fluid Dynamics · Physics 2017-08-02 Binod Sreenivasan , Venkatesh Gopinath

Radio observations show that magnetic fields are present in dwarf irregular galaxies (dIrr) and its strength is comparable to that found in spiral galaxies. Slow rotation, weak shear and shallow gravitational potential are the main features…

Astrophysics of Galaxies · Physics 2015-05-27 H. Siejkowski , M. Soida , K. Otmianowska-Mazur , M. Hanasz , D. J. Bomans

We present non-radiative, cosmological zoom-simulations of galaxy cluster formation with magnetic fields and (anisotropic) thermal conduction of one very massive galaxy cluster with a mass at redshift zero that corresponds to…

Cosmology and Nongalactic Astrophysics · Physics 2022-07-20 Ulrich P. Steinwandel , Ludwig M. Boess , Klaus Dolag , Harald Lesch

Stellar winds are an integral part of the underlying dynamo, the motor of stellar activity. The wind controls the star's angular momentum loss, which depends on the magnetic field geometry which varies significantly in time and latitude.…

Solar and Stellar Astrophysics · Physics 2021-03-16 P. Jakab , A. Brandenburg

Convectively driven dynamos with rotation generating magnetic fields on scales large compared with the scale of the turbulent eddies are being reviewed. It is argued that such fields can be understood as the result of an alpha effect.…

Solar and Stellar Astrophysics · Physics 2011-08-19 A. Brandenburg , P. J. Käpylä , M. J. Korpi

We present numerical magnetohydrodynamic (MHD) simulations of the effect of stellar dipole magnetic fields on line-driven wind outflows from hot, luminous stars. Unlike previous fixed-field analyses, the simulations here take full account…

Astrophysics · Physics 2011-05-05 Asif ud-Doula , Stanley P. Owocki

We seek to understand the transition from nearly axisymmetric configurations at solar rotation rates to nonaxisymmetric configurations for rapid rotation using 3D numerical simulations of turbulent convection and considering rotation rates…

It has recently been shown that a significant slowdown of many stars can be attributed to the emergence of a strong magnetic field within the radiative region, where heat is transferred through radiation in a stably stratified layer. Here,…

Fluid Dynamics · Physics 2023-11-30 Florentin Daniel , Ludovic Petitdemange , Christophe Gissinger

We characterize and analyze rotational torsional oscillations developing in a large-eddy magnetohydrodynamical simulation of solar convection (Ghizaru, Charbonneau, and Smolarkiewicz, Astrophys. J. Lett., 715, L133 (2010); Racine et al.,…

Solar and Stellar Astrophysics · Physics 2015-06-11 P. Beaudoin , P. Charbonneau , E. Racine , P. K. Smolarkiewicz

This work tackles a significant challenge in dynamo theory: the possibility of long-term amplification and maintenance of an axisymmetric magnetic field. We introduce a novel model that allows for non-trivial axially-symmetric steady-state…

Earth and Planetary Astrophysics · Physics 2025-07-08 Naoki Sato , Kumiko Hori

The form of the solar meridional circulation is a very important ingredient for mean field flux transport dynamo models. Yet a shroud of mystery still surrounds this large-scale flow, given that its measurement using current helioseismic…

Solar and Stellar Astrophysics · Physics 2015-02-17 Dario Passos , Paul Charbonneau , Mark Miesch

We report on the results of four convective dynamo simulations with an outer coronal layer. The magnetic field is self-consistently generated by the convective motions beneath the surface. Above the convection zone, we include a polytropic…

Solar and Stellar Astrophysics · Physics 2013-11-14 Jörn Warnecke , Petri J. Käpylä , Maarit. J. Mantere , Axel Brandenburg