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The magnetorotational instability (MRI) has been proposed as the method of angular momentum transport that enables accretion in astrophysical discs. However, for weakly-ionized discs, such as protoplanetary discs, it remains unclear whether…

Instrumentation and Methods for Astrophysics · Physics 2023-09-15 Amy Secunda , Peter Donnel , Hantao Ji , Jeremy Goodman

Possible effects of magnetic fields in core collapse supernovae rely on an efficient amplification of the weak pre-collapse fields. It has been suggested that the magneto-rotational instability (MRI) leads to rapid field growth. Although…

Astrophysics · Physics 2009-05-06 M. Obergaulinger , P. Cerdà-Duràn , E. Müller , M. A. Aloy

Tidally distorted accretion disks in binary star systems are subject to a local hydrodynamic instability which excites $m=1$ internal waves. This instability is three dimensional and approximately incompressible. We study the global aspects…

Astrophysics · Physics 2009-10-28 Dongsu Ryu , Jeremy Goodman , Ethan T. Vishniac

Magnetorotational instability (MRI) in a convectively-stable layer around the neutrinosphere is simulated by a three-dimensional model of supernova core. To resolve MRI-unstable modes, a thin layer approximation considering only the radial…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Youhei Masada , Tomoya Takiwaki , Kei Kotake

Magnetohydrodynamic (MHD) instabilities can play an important role in the dynamics of the pulsar magnetosphere and can be responsible for the formation of various structures. We consider the instability caused by a gradient of the magnetic…

Solar and Stellar Astrophysics · Physics 2014-03-05 Vadim Urpin

Cool weakly ionized gaseous rotating disk form the basis for many models in astrophysics objects. Instabilities against perturbations in such disks play an important role in the theory of the formation of stars and planets. Traditionally,…

Astrophysics · Physics 2008-09-19 Edward Liverts , Michael Mond , Vadim Urpin

We reveal and investigate a new type of linear axisymmetric helical magnetorotational instability which is capable of destabilizing viscous and resistive rotational flows with radially increasing angular velocity, or positive shear. This…

Fluid Dynamics · Physics 2019-10-23 G. Mamatsashvili , F. Stefani , R. Hollerbach , G. Rüdiger

We show, by means of a perturbative weakly nonlinear analysis, that the axisymmetric magneto-rotational instability (MRI) in a magnetic Taylor-Couette (mTC) flow in a thin-gap gives rise, for very small magnetic Prandtl numbers (P_m), to a…

Astrophysics · Physics 2015-05-13 O. Regev

The linear stability of MHD Taylor-Couette flows in axially unbounded cylinders is considered, for magnetic Prandtl number unity. Magnetic fields varying from purely axial to purely azimuthal are imposed, with a general helical field…

Solar and Stellar Astrophysics · Physics 2015-05-14 G. Ruediger , M. Gellert , M. Schultz , R. Hollerbach

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

The magnetic Rayleigh-Taylor instability has been shown to play a key role in many astrophysical systems. The equation for the growth rate of this instability in the incompressible limit, and the most-unstable mode that can be derived from…

Solar and Stellar Astrophysics · Physics 2016-10-27 Andrew Hillier

Instabilities in magnetic fields wound up by differential rotation as reviewed in Spruit (1999) are discussed with some detail and new developments added. In stellar models which include magnetic torques, the differential rotation tends to…

Astrophysics · Physics 2007-05-23 H. C. Spruit

Electrostatic Gravitational or Rayleigh-Taylor (RT) instability in an inhomogeneous magnetized multi-ions plasma with some fraction of quantum mechanical electrons. The effect of Bohm potential, temperature degeneracy and magnetic field are…

Plasma Physics · Physics 2018-05-08 A. Mushtaq , Sajad Ali , Zahida Ehsan

The electromagnetic modes possibly unstable in strongly magnetized plasmas are identified. The regime where this instability might stand out compared to the incoherent electron-cyclotron radiation is explored. These modes are relevant to…

Plasma Physics · Physics 2012-11-06 S. Son , Sung Joon Moon

Equations describing plasma equilibria are derived from the total energy of the system. The MHD equilibrium is shown to hold even for systems where the magnetic field may locally vanish. Through conservation of helicity, confinement is…

Plasma Physics · Physics 2019-06-20 John Hedditch

We study the global bending modes of a thin annular disc subject to both an internally generated magnetic field and a magnetic field due to a dipole embedded in the central star with axis aligned with the disc rotation axis. When there is a…

Astrophysics · Physics 2007-05-23 Vasso Agapitou , John C. B. Papaloizou , Caroline Terquem

It was shown previously that the current-carrying state of a Field Effect Transistor with asymmetric source and drain boundary conditions may become unstable against spontaneous generation of plasma waves [1]. By extending the analysis to…

Mesoscale and Nanoscale Physics · Physics 2009-11-13 M. I. Dyakonov

We investigate the stability of test-particle equilibrium orbits in axisymmetric, but otherwise arbitrary, gravitational and electromagnetic fields. We extend previous studies of this problem to include a toroidal magnetic field. We find…

Solar and Stellar Astrophysics · Physics 2019-01-23 Gopakumar Mohandas , Tobias Heinemann , Martin E. Pessah

The equilibrium of an axisymmetric magnetically confined plasma with anisotropic resistivity and toroidal flow is investigated in the framework of magnetohydrodynamics (MHD). The stationary states are determined by an elliptic differential…

Plasma Physics · Physics 2015-06-26 G. Poulipoulis , G. N. Throumoulopoulos , H. Tasso

In this paper and a companion work, we report on the first global numerical simulations of self-gravitating magnetized tori, subject in particular to the influence of the magnetorotational instability (MRI). In this work, paper I, we…

Astrophysics · Physics 2009-11-10 Sebastien Fromang , Steven A. Balbus , Jean-Pierre De Villiers