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We study the influence of a dynamo magnetic field on the buoyant rise and emergence of twisted magnetic flux-ropes, and their influence on the global external magnetic field. We ran 3D MHD numerical simulations using the ASH code and…

Solar and Stellar Astrophysics · Physics 2015-06-15 R. F. Pinto , A. S. Brun

This paper considers a possibility of magnetic-field generation by local turbulent flows at the bottom of convective zone. The cycle of magnetic-field generation in this model can be represented in the form of sequency of processes. There…

Solar and Stellar Astrophysics · Physics 2013-10-18 Andrey G. Tlatov

Observations have shown a clear association of filament/prominence eruptions with the emergence of magnetic flux in or near filament channels. Magnetohydrodynamic (MHD) simulations have been employed to systematically study the conditions…

Solar and Stellar Astrophysics · Physics 2023-12-22 T. Török , M. G. Linton , J. E. Leake , Z. Mikić , R. Lionello , V. S. Titov , C. Downs

Motivated by the dynamics in the deep interiors of many stars, we study the interaction between overshooting convection and the large-scale poloidal fields residing in radiative zones. We have run a suite of 3D Boussinesq numerical…

Solar and Stellar Astrophysics · Physics 2021-02-24 Lydia Korre , Nicholas H. Brummell , Pascale Garaud , Celine Guervilly

Our Sun exhibits strong convective dynamo action which results in magnetic flux bundles emerging through the stellar surface as magnetic spots. Global-scale dynamo action is believed to generate large-scale magnetic structures in the deep…

Solar and Stellar Astrophysics · Physics 2014-03-05 Nicholas J. Nelson , Mark S. Miesch

On SOL2017-09-06 solar active region 12673 produced an X9.3 flare which is regarded as largest to occur in solar cycle 24. In this work we have preformed a magnetohydrodynamic (MHD) simulation in order to reveal the three-dimensional (3D)…

Solar and Stellar Astrophysics · Physics 2018-11-07 Satoshi Inoue , Daikou Shiota , Yumi Bamba , Sung-Hong Park

The generation of large-scale magnetic fields is studied in dilaton electromagnetism in inflationary cosmology, taking into account the dilaton's evolution throughout inflation and reheating until it is stabilized with possible entropy…

Astrophysics · Physics 2008-11-26 Kazuharu Bamba , J. Yokoyama

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

We study the effects of the magnetic field on the dynamics of non-rotating stellar cores by performing two-dimensional (2D), magnetohydrodynamics (MHD) simulations. To this end, we have updated our neutrino-radiation-hydrodynamics supernova…

High Energy Astrophysical Phenomena · Physics 2020-10-07 Jin Matsumoto , Tomoya Takiwaki , Kei Kotake , Yuta Asahina , Hiroyuki R. Takahashi

We present results from 3D visco-resistive magnetohydrodynamic (MHD) simulations of the emergence of a convection zone magnetic flux tube into a solar atmosphere containing a pre-existing dipole coronal field, which is orientated to…

Solar and Stellar Astrophysics · Physics 2015-06-17 James E. Leake , Mark G. Linton , Tibor Török

We analyze recent high resolution photospheric small-scale dynamo simulations that were computed with the MURaM radiative MHD code. We focus the analysis on newly forming downflow lanes in exploding granules since they show how weakly…

Solar and Stellar Astrophysics · Physics 2018-06-27 Matthias Rempel

We present simulations of magnetized astrophysical shocks taking into account the interplay between the thermal plasma of the shock and supra-thermal particles. Such interaction is depicted by combining a grid-based magneto-hydrodynamics…

High Energy Astrophysical Phenomena · Physics 2017-10-02 Allard Jan van Marle , Fabien Casse , Alexandre Marcowith

Motivated by the problem of the formation of active regions from a deep-seated solar magnetic field, we consider the nonlinear three-dimensional evolution of magnetic buoyancy instabilities resulting from a smoothly stratified horizontal…

Astrophysics · Physics 2009-11-13 Evy Kersale , David W. Hughes , Steven M. Tobias

The Universe at present is highly magnetized, with fields of the order of a few 10^-5 G and coherence lengths larger than 10 kpc in typical galaxies like the Milky Way. We propose that the magnetic field was amplified to this values already…

Astrophysics of Galaxies · Physics 2015-06-17 Jennifer Schober , Dominik R. G. Schleicher , Ralf S. Klessen

We show that if the turbulent magnetic diffusivity used in solar dynamos is assumed to be 'quenched' by increasing toroidal fields, much larger amplitude and more concentrated toroidal fields can be induced by differential rotation from an…

Astrophysics · Physics 2009-11-10 Peter A. Gilman , Matthias Rempel

Magnetic fields are ubiquitous in the Universe. Recently, cosmological simulations of galaxies have successfully begun to incorporate magnetic fields and their evolution in galaxies and their haloes. However, so far they have mostly focused…

We describe the initial implementation of magnetohydrodynamics (MHD) in our astrophysical simulation code \genasis. Then, we present MHD simulations exploring the capacity of the stationary accretion shock instability (SASI) to generate…

Solar and Stellar Astrophysics · Physics 2015-06-04 E Endeve , C Y Cardall , R D Budiardja , A Mezzacappa

While the rising flux tube paradigm is an elegant theory, its basic assumptions, thin flux tubes at the bottom of the convection zone with field strengths two orders of magnitude above equipartition, remain numerically unverified at best.…

Solar and Stellar Astrophysics · Physics 2012-08-17 K. Kemel , A. Brandenburg , N. Kleeorin , I. Rogachevskii

Recent studies have demonstrated that in fully developed turbulence, the effective magnetic pressure of a large-scale field (non-turbulent plus turbulent contributions) can become negative. In the presence of strongly stratified turbulence,…

Solar and Stellar Astrophysics · Physics 2013-10-07 Axel Brandenburg , Nathan Kleeorin , Igor Rogachevskii

The amplification of magnetic fields in a highly conducting fluid is studied numerically. During growth, the magnetic field is spatially intermittent: it does not uniformly fill the volume, but is concentrated in long thin folded…

Chaotic Dynamics · Physics 2009-11-10 A. A. Schekochihin , S. C. Cowley , J. L. Maron , J. C. McWilliams