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Magnetic fluctuations generated by a tangling of the mean magnetic field by velocity fluctuations are studied in a developed turbulent convection with large magnetic Reynolds numbers. We show that the energy of magnetic fluctuations depends…

Astrophysics · Physics 2008-11-26 I. Rogachevskii , N. Kleeorin

We present simulations of collapsing filaments studying the impact of turbulence and magnetic field morphologies on their evolution and star formation properties. We vary the mass per unit length of the filaments as well as the orientation…

Astrophysics of Galaxies · Physics 2015-08-06 D. Seifried , S. Walch

We investigate the asymptotic behaviour of a reduced {\alpha}{\Omega}-dynamo model of magnetic field generation in spiral galaxies where fluctuation in the {\alpha}-effect results in a system with state-dependent stochastic perturbations.…

Dynamical Systems · Mathematics 2016-06-15 Cónall Kelly

We present full 2 Pi global 3-D stratified MHD simulations of accretion disks. We interpret our results in the context of proto-planetary disks. We investigate the turbulence driven by the magneto-rotational instability (MRI) using the…

Earth and Planetary Astrophysics · Physics 2015-05-27 M. Flock , N. Dzyurkevich , H. Klahr , N. J. Turner , Th. Henning

Fluctuation dynamo action has been obtained for a flow previously used to model fluid turbulence, where the sensitivity of the magnetic field parameters to the kinetic energy spectrum can be explored. We apply quantitative morphology…

Astrophysics · Physics 2008-11-26 S. Louise Wilkin , Carlo F. Barenghi , Anvar Shukurov

Solar magnetic fields comprise an 11-year activity cycle, represented by the number of sunspots. The maintenance of such a solar magnetic field can be attributed to fluid motion in the convection zone, i.e. a dynamo. This study conducts the…

Solar and Stellar Astrophysics · Physics 2022-08-24 Ryota Shimada , Hideyuki Hotta , Takaaki Yokoyama

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

Using direct numerical simulations, we verify that "flow IV" of Roberts (1972) exhibits dynamo action dominated by horizontally averaged large-scale magnetic field. With the test-field method we compute the turbulent magnetic diffusivity…

Solar and Stellar Astrophysics · Physics 2013-08-09 Ebru Devlen , Axel Brandenburg , Dhrubaditya Mitra

We argue that magnetic flux-conservation in turbulent plasmas at high magnetic Reynolds numbers neither holds in the conventional sense nor is entirely broken, but instead is valid in a novel statistical sense associated to the "spontaneous…

Plasma Physics · Physics 2013-05-29 Gregory L. Eyink

The standing quasi modes in a cylindrical incompressible flux tube with magnetic twist that undergoes a radial density structuring is considered in ideal magnetohydrodynamics (MHD). The radial structuring is assumed to be a linearly varying…

Solar and Stellar Astrophysics · Physics 2011-05-06 K. Karami , K. Bahari

In previous galactic dynamo theories of the origin of the magnetic field in our galaxy, the subject of flux-freezing has been omitted. As a consequence, the equation of mass flow has generally also been omitted, particularly in the halo…

Astrophysics of Galaxies · Physics 2015-12-23 Russell M. Kulsrud

The velocity fluctuations in a spherical shell arising from sinusoidal perturbations of a Keplerian shear flow with a free amplitude parameter \epsilon are studied numerically by means of fully 3D nonlinear simulations. The investigations…

Astrophysics · Physics 2009-11-06 G. Rudiger , A. Drecker

A theoretical framework for low-frequency electromagnetic (drift-)kinetic turbulence in a collisionless, multi-species plasma is presented. The result generalises reduced magnetohydrodynamics (RMHD) and kinetic RMHD (Schekochihin et al.…

High Energy Astrophysical Phenomena · Physics 2015-07-22 M. W. Kunz , A. A. Schekochihin , C. H. K. Chen , I. G. Abel , S. C. Cowley

Analytical solution of first order torsion ${\alpha}$-effect in twisted magnetic flux tubes representing a flux tube dynamo in Riemannian space is presented. Toroidal and poloidal component of the magnetic field decays as $r^{-1}$, while…

Astrophysics · Physics 2007-12-27 Garcia de Andrade

We study magnetic field evolution in flows with fluctuating in time governing parameters in electrically conducting fluid. We use a standard mean-field approach to derive equations for large-scale magnetic field for the fluctuating ABC-flow…

Astrophysics · Physics 2009-11-13 N. Kleeorin , I. Rogachevskii , D. Sokoloff , D. Tomin

A solution of magnetic Hall equations for plasma filaments in the Coulomb gauge is obtained in the non-holonomic frame. Some physical features of the solution include, the non-conservation of the magnetic helicity and the decay of the…

Astrophysics · Physics 2007-10-26 L. C. Garcia de Andrade

The Rayleigh-Taylor instability of a magnetic fluid superimposed on a non-magnetic liquid of lower density may be suppressed with the help of a spatially homogeneous magnetic field rotating in the plane of the undisturbed interface.…

Fluid Dynamics · Physics 2009-11-13 D. Rannacher , A. Engel

Planetary and stellar dynamos likely result from turbulent motions in magnetofluids with kinematic viscosities that are small compared to their magnetic diffusivities. Laboratory experiments are in progress to produce similar dynamos in…

Astrophysics · Physics 2009-11-11 P. D. Mininni

Observations show that there are twisted magnetic flux tubes and plasma flow throughout the solar atmosphere. The main purpose of this work is to obtain the damping rate of sausage modes in the presence of magnetic twist and plasma flow. We…

Solar and Stellar Astrophysics · Physics 2023-04-12 Mohammad Sadeghi , Karam Bahari , Kayoomars Karami

Understanding the nature of compressible fluctuations in a broad range of turbulent plasmas, from the intracluster medium to the solar wind, has been an active field of research in the past decades. Theoretical frameworks for weakly…

Solar and Stellar Astrophysics · Physics 2025-02-14 Riddhi Bandyopadhyay , James R. Beattie , Amitava Bhattacharjee