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In dilute astrophysical plasmas, thermal conduction is primarily along magnetic field lines, and therefore highly anisotropic. As a result, the usual convective stability criterion is modified from a condition on entropy to a condition on…

Astrophysics · Physics 2008-11-26 Ian J. Parrish , James M. Stone

We present the first demonstration of the negative effective magnetic pressure instability in direct numerical simulations of stably stratified, externally forced, isothermal hydromagnetic turbulence in the regime of large plasma beta. By…

Solar and Stellar Astrophysics · Physics 2011-10-05 Axel Brandenburg , Koen Kemel , Nathan Kleeorin , Dhrubaditya Mitra , Igor Rogachevskii

Stability properties of magnetic-field configurations containing the toroidal and axial field are considered. The stability is treated by making use of linear analysis. It is shown that the conditions required for the onset of instability…

Astrophysics · Physics 2009-11-13 Alfio Bonanno , Vadim Urpin

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

The linear stability of MHD Taylor-Couette flow of infinite vertical extension is considered for various magnetic Prandtl numbers Pm. The calculations are performed for a wide gap container with \hat\eta=0.5 with an axial uniform magnetic…

Astrophysics · Physics 2016-08-16 D. A. Shalybkov , G. Rüdiger , M. Schultz

Compositional convection is thought to be an important energy source for magnetic field generation within planetary interiors. The Prandtl number, $Pr$, characterizing compositional convection is significantly larger than unity, suggesting…

Geophysics · Physics 2017-04-05 Michael A. Calkins , Keith Julien , Steven M. Tobias

The magneto-rotational instability (MRI) is the most likely mechanism for transportation of angular momentum and dissipation of energy within hot, ionized accretion discs. This instability is produced through the interactions of a…

High Energy Astrophysical Phenomena · Physics 2021-12-08 Oscar M. Pimentel , P. Chris Fragile , F. D. Lora-Clavijo , Bridget Ierace , Deepika Bollimpalli

We measure the turbulent resistivity in the nonlinear regime of the MRI, and evaluate the turbulent magnetic Prandtl number. We perform a set of numerical simulations with the Eulerian finite volume codes Athena and Ramses in the framework…

Solar and Stellar Astrophysics · Physics 2015-05-13 Sebastien Fromang , James M. Stone

The nonaxisymmetric Tayler instability of toroidal magnetic fields due to axial electric currents is studied for conducting incompressible fluids between two coaxial cylinders without endplates. The inner cylinder is considered as so thin…

Solar and Stellar Astrophysics · Physics 2015-05-20 G. Ruediger , M. Schultz , M. Gellert

The linear marginal instability of an MHD Taylor-Couette flow of infinite vertical extension is considered. For hydrodynamically unstable flows the minimum Reynolds number exists even without a magnetic field, but there are also solutions…

Astrophysics · Physics 2016-08-16 G. Rüdiger

The linear stability of global non-axisymmetric modes in differentially rotating, magnetized, non-ideal plasma is crucial for understanding turbulence and transport phenomena. We investigate the competition between the local…

High Energy Astrophysical Phenomena · Physics 2025-11-18 Alexander Haywood , Fatima Ebrahimi

We studied Faraday rotation measure (RM) in turbulent media with the rms Mach number of unity, using isothermal, magnetohydrodynamic turbulence simulations. Four cases with different values of initial plasma beta were considered. Our main…

Astrophysics of Galaxies · Physics 2014-11-20 Qingwen Wu , Jongsoo Kim , Dongsu Ryu , Jungyeon Cho , Paul Alexander

Accretion disks are likely threaded by external vertical magnetic flux, which enhances the level of turbulence via the magnetorotational instability (MRI). Using shearing-box simulations, we find that such external magnetic flux also…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Xue-Ning Bai , James M. Stone

The magnetorotational instability (MRI) is an important process in sufficiently ionized accretion disks, as it can create turbulence that acts as an effective viscosity, mediating angular momentum transport. Due to its local nature, it is…

Earth and Planetary Astrophysics · Physics 2023-09-28 Oliver Zier , Volker Springel

Local shearing box simulations of stratified magneto rotational turbulence invariably exhibit cyclic field patterns which propagate away from the disc midplane. A common explanation for this is magnetic buoyancy. The recent analysis by Shi…

Earth and Planetary Astrophysics · Physics 2015-05-18 Oliver Gressel

The magneto-rotational instability (MRI) - which is due to an interplay between a sheared background and the magnetic field - is commonly considered a key ingredient for developing and sustaining turbulence in the outer envelope of binary…

High Energy Astrophysical Phenomena · Physics 2023-11-27 T. Celora , I. Hawke , N. Andersson , G. L. Comer

By following the Kazantsev theory and taking into account both microscopic and turbulent diffusion of magnetic fields, we develop a unified treatment of the kinematic and nonlinear stages of turbulent dynamo, and study the dynamo process…

Astrophysics of Galaxies · Physics 2016-12-28 Siyao Xu , A. Lazarian

Deviations from axial symmetry are necessary to maintain self-sustained MRI-turbulence. We define the parameters region where nonaxisymmetric MRI is excited and study dependence of the unstable modes structure and growth rates on the…

Solar and Stellar Astrophysics · Physics 2016-12-07 L. L. Kitchatinov , G. Ruediger

The amplification of astrophysical magnetic fields takes place via dynamo instability in turbulent environments. The presence of vorticity is crucial for the dynamo to happen. However, the role of vorticity is not yet fully understood. This…

Astrophysics of Galaxies · Physics 2024-12-11 Albert Elias-López , Fabio del Sordo , Daniele Viganò

Global three dimensional magnetohydrodynamic (MHD) simulations of turbulent accretion disks are presented which start from fully equilibrium initial conditions in which the magnetic forces are accounted for and the induction equation is…

High Energy Astrophysical Phenomena · Physics 2015-06-12 E. R. Parkin , G. V. Bicknell