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200 papers

It is shown that magnetic islands generated by pressure-gradient-driven turbulence are common across a wide range of conditions. The interaction among turbulence, magnetic island and other large scale structures (the zonal flow and the…

Plasma Physics · Physics 2025-07-01 Daniele Villa , Nicolas Dubuit , Olivier Agullo , Xavier Garbet

There is mounting evidence that the ejection of magnetic helicity from the solar surface is important for the solar dynamo. Observations suggest that in the northern hemisphere the magnetic helicity flux is negative. We propose that this…

Astrophysics · Physics 2009-11-07 A. Brandenburg , E. G. Blackman , G. R. Sarson

We study the nonlinear evolution of the magnetic buoyancy instability in rotating and non-rotating gas layers using numerical solutions of non-ideal, isothermal MHD equations. The unstable magnetic field is either imposed through the…

Astrophysics of Galaxies · Physics 2025-09-09 Yasin Qazi , Anvar Shukurov , Devika Tharakkal , Frederick A. Gent

We present the results of simulations of forced turbulence in a slab where the mean kinetic helicity has a maximum near the mid-plane, generating gradients of magnetic helicity of both large and small-scale fields. We also study systems…

Solar and Stellar Astrophysics · Physics 2010-11-30 A. Hubbard , A. Brandenburg

A three-dimensional numerical computation of magnetohydrodynamic dynamo behavior is described. The dynamo is mechanically forced with a driving term of the Taylor-Green type. The magnetic field development is followed from negligibly small…

Astrophysics · Physics 2007-05-23 P. D. Mininni , Y. Ponty , D. C. Montgomery , J. -F. Pinton , H. Politano , A. Pouquet

Kink instabilities are likely to occur in the current-carrying magnetized plasma jets. Recent observations of the blazar radiation and polarization signatures suggest that the blazar emission region may be considerably magnetized. While the…

High Energy Astrophysical Phenomena · Physics 2017-02-01 Haocheng Zhang , Hui Li , Fan Guo , Greg Taylor

Using a 3D non-linear mean-field solar dynamo model, we investigate the magnetic helicity flux and magnetic twist, and tilt parameters of bipolar magnetic regions (BMRs) emerging from the solar convection zone due to the magnetic buoyancy…

Solar and Stellar Astrophysics · Physics 2025-08-04 V. V. Pipin , Shangbin Yang , A. G. Kosovichev

We model the Parker instability in vertically stratified isothermal gas using non-ideal MHD three-dimensional simulations. Rotation, especially differential, more strongly and diversely affects the nonlinear state than the linear stage…

Astrophysics of Galaxies · Physics 2023-05-08 Devika Tharakkal , Anvar Shukurov , Frederick A. Gent , Graeme R. Sarson , Andrew Snodin

Understanding the in situ amplification of large scale magnetic fields in turbulent astrophysical rotators has been a core subject of dynamo theory. When turbulent velocities are helical, large scale dynamos that substantially amplify…

Fluid Dynamics · Physics 2012-06-22 Jonathan Pietarila Graham , Eric G. Blackman , Pablo D. Mininni , Annick Pouquet

A fraction of solar active regions are observed to have current helicity of a sign that contradicts the polarity law for magnetic helicity; this law corresponds to the well-known Hale polarity law for sunspots. A significant excess of…

Astrophysics · Physics 2009-11-11 D. Sokoloff , S. D. Bao , N. Kleeorin , K. Kuzanyan , D. Moss , I. Rogachevskii , D. Tomin , H. Zhang

In a magnetic fluid parametrically driven surface waves can be excited by an external oscillating magnetic field. A static magnetic field changes the restoring forces and damping coefficients of the various surface waves. This property…

patt-sol · Physics 2009-10-31 Thomas Mahr , Ingo Rehberg

Recent years have seen an increased interest in the question of whether the gravitational action of planets could have an influence on the solar dynamo. Without discussing the observational validity of the claimed correlations, we ask for a…

Solar and Stellar Astrophysics · Physics 2016-09-21 F. Stefani , A. Giesecke , N. Weber , T. Weier

The generation of large scale flows by the anisotropic kinetic alpha (AKA) effect is investigated in simulations with a suitable time-dependent space- and time-periodic anisotropic forcing lacking parity invariance. The forcing pattern…

Astrophysics · Physics 2007-05-23 A. Brandenburg , B. v. Rekowski

(1)The previous theoretical studies showed that in the presence of the small-scale dynamo the large-scale vorticity can produce the the divergent-type helicity flux breaking the equatorial reflection symmetry of the magnetic fluctuations in…

Solar and Stellar Astrophysics · Physics 2026-01-13 V. V. Pipin

We explore the alpha-effect and the small-scale current helicity, for the case of weakly compressible magnetically driven turbulence that is subjected to the differential rotation. No restriction is applied to the amplitude of angular…

Astrophysics · Physics 2007-05-23 V. V. Pipin

Magnetic fields in rotating and radiating astrophysical plasma can be produced due to a radiative interaction between plasma layers moving relative to each other. The efficiency of current drive, and with it the associated dynamo effect, is…

Plasma Physics · Physics 2017-09-22 Vadim R. Munirov , Nathaniel J. Fisch

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

The chiral magnetic effect emerges from a miroscopic level, and its interesting consequences have been discussed in the dynamics of the early universe, neutron stars and quark-gluon plasma. An instability is caused by anomalous electric…

High Energy Astrophysical Phenomena · Physics 2019-03-01 Yasufumi Kojima , Yuri Miura

Magnetic fields of planets, stars and galaxies are generated by self-excitation in moving electrically conducting fluids. Once produced, magnetic fields can play an active role in cosmic structure formation by destabilizing rotational flows…

Plasma Physics · Physics 2016-10-19 F. Stefani , M. Gellert , Ch. Kasprzyk , A. Paredes , G. Ruediger , M. Seilmayer

We show that the presence of a steady $\ao$ dynamo in astrophysical rotators likely leads to an outflow of relative magnetic helicity and thus magnetic energy available for particle acceleration in a corona. The connection between energy…

Astrophysics · Physics 2009-10-31 Eric G. Blackman , George B. Field