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We investigate the action of the magnetorotational instability (MRI) in the context of iron-core collapse. Exponential growth of the field on the rotation time scale by the MRI will dominate the linear growth process of field line…

Astrophysics · Physics 2009-11-07 Shizuka Akiyama , J. Craig Wheeler , David L. Meier , Itamar Lichtenstadt

We carry out a series of local, vertically stratified shearing box simulations of protoplanetary disks that include ambipolar diffusion and a net vertical magnetic field. The ambipolar diffusion profiles we employ correspond to 30AU and…

Solar and Stellar Astrophysics · Physics 2015-06-16 Jacob B. Simon , Xue-Ning Bai , Philip J. Armitage , James M. Stone , Kris Beckwith

We investigate the stability of incompressible, exact, non-ideal magnetorotational (MRI) modes against parasitic instabilities. Both Kelvin-Helmholtz and tearing-mode parasitic instabilities may occur in the dissipative regimes accessible…

High Energy Astrophysical Phenomena · Physics 2011-02-11 Martin E. Pessah , Jeremy Goodman

The extent to which angular momentum transport in accretion discs is primarily local or non-local and what determines this is an important avenue of study for understanding accretion engines. Taking a step along this path, we analyze…

Solar and Stellar Astrophysics · Physics 2014-10-28 Farrukh Nauman , Eric G. Blackman

The local properties of turbulence driven by the magnetorotational instability (MRI) in rotating, shearing flows are studied in the framework of a shearing-box model. Based on numerical simulations, we propose that the MRI-driven turbulence…

Solar and Stellar Astrophysics · Physics 2015-12-14 Justin Walker , Geoffroy Lesur , Stanislav Boldyrev

Simulations of the magnetorotational instability (MRI) in 'unstratified' shearing boxes exhibit powerful coherent flows, whereby the fluid vertically splits into countermoving planar jets or `channels'. Channel flows correspond to certain…

High Energy Astrophysical Phenomena · Physics 2015-05-18 Henrik N. Latter , Sebastien Fromang , Oliver Gressel

In Keplerian accretion disks, turbulence and magnetic fields may be jointly excited through a subcritical dynamo process involving the magnetorotational instability (MRI). High-resolution simulations exhibit a tendency towards statistical…

High Energy Astrophysical Phenomena · Physics 2017-02-08 A. Riols , F. Rincon , C. Cossu , G. Lesur , G. I. Ogilvie , P-Y. Longaretti

Though usually treated in isolation, the magnetorotational and gravitational instabilities (MRI and GI) may coincide at certain radii and evolutionary stages of protoplanetary discs and active galactic nuclei. Their mutual interactions…

High Energy Astrophysical Phenomena · Physics 2017-12-27 A. Riols , H. Latter

Despite the importance of the magnetorotational instability (MRI) as a fundamental mechanism for angular momentum transport in magnetized accretion disks, it has yet to be demonstrated in the laboratory. A liquid sodium alpha-omega dynamo…

Astrophysics · Physics 2009-11-07 K. Noguchi , V. I. Pariev , S. A. Colgate , J. Nordhaus , H. F. Beckley

We conduct a linear analysis of axisymmetric magnetorotational instability (MRI) in a magnetized cylindrical Taylor-Couette (TC) flow for its standard version (SMRI) with a purely axial background magnetic field and two further types --…

Fluid Dynamics · Physics 2022-06-07 A. Mishra , G. Mamatsashvili , F. Stefani

We study the properties of MHD turbulence driven by the magnetorotational instability (MRI) in accretion disks. We adopt the local shearing box model and focus on the special case for which the initial magnetic flux threading the disk…

Astrophysics · Physics 2009-11-13 S. Fromang , J. Papaloizou

The magnetorotational instability (MRI) is thought to play a key role in the formation of stars and black holes by sustaining the turbulence in hydrodynamically stable Keplerian accretion discs. In previous experiments the MRI was observed…

The magnetorotational instability (MRI) is a crucial mechanism of angular momentum transport in a variety of astrophysical accretion disks. In systems accreting at well below the Eddington rate, such as the central black hole in the Milky…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Mario A. Riquelme , Eliot Quataert , Prateek Sharma , Anatoly Spitkovsky

We present the results of axisymmetric, time-dependent magnetohydrodynamic simulations of accretion flows around black holes. The calculations begin from a rotationally supported thick torus which contains a weak poloidal field. Accretion…

Astrophysics · Physics 2009-10-31 James M. Stone , James E. Pringle

We investigate the behavior of the magneto-rotational instability in the limit of extremely weak magnetic field, i.e., as the ratio of ion cyclotron frequency to orbital frequency (X) becomes small. Considered only in terms of cold…

Astrophysics · Physics 2010-11-11 Julian H. Krolik , Ellen G. Zweibel

In accretion disks with large-scale ordered magnetic fields, the magnetorotational instability (MRI) is marginally suppressed, so other processes may drive angular momentum transport leading to accretion. Accretion could then be driven by…

High Energy Astrophysical Phenomena · Physics 2018-05-16 Megan D. Marshall , Mark J. Avara , Jonathan C. McKinney

Quasi-Keplerian flow, a special regime of Taylor-Couette co-rotating flow, is of great astrophysical interest for studying angular momentum transport in accretion disks. The well-known magnetorotational instability (MRI) successfully…

Fluid Dynamics · Physics 2024-10-08 Dongdong Wan , Rikhi Bose , Mengqi Zhang , Xiaojue Zhu

We present a new mechanism for generation of large-scale magnetic field by thermal convection which does not involve the alpha-effect. We consider weakly nonlinear perturbations of space-periodic steady convective magnetic dynamos in a…

Fluid Dynamics · Physics 2015-12-01 Roman Chertovskih , Vladislav Zheligovsky

The magnetorotational instability (MRI) (Balbus and Hawley 1991, Hawley and Balbus 1991) transports angular momentum radially outwards in accretion discs through the distortion of the magnetic field lines that connect fluid elements. In…

Astrophysics · Physics 2009-11-10 Raquel Salmeron , Mark Wardle

The magnetorotational instability (MRI) in cylindrical Taylor-Couette flow with external helical magnetic field is simulated for infinite and finite aspect ratios. We solve the MHD equations in their small Prandtl number limit and confirm…

Astrophysics · Physics 2008-11-26 Jacek Szklarski , Günther Rüdiger