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We analyze the magneto-rotational instability (MRI) effects on gravitational collapse and its influence on the instability critical scale. In particular, we study an axisymmetric nonstratified differentially rotating cloud, embedded in a…

宇宙学与河外天体物理 · 物理学 2018-10-10 Giovanni Montani , Giovanni Palermo , Nakia Carlevaro

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…

天体物理学 · 物理学 2009-05-06 M. Obergaulinger , P. Cerdà-Duràn , E. Müller , M. A. Aloy

We use a global magnetohydrodynamic simulation of a geometrically thin accretion disk to investigate the locality and detailed structure of turbulence driven by the magnetorotational instability (MRI). The model disk has an aspect ratio $H…

高能天体物理现象 · 物理学 2015-05-28 Kris Beckwith , Philip J. Armitage , Jacob B. Simon

The magnetorotational instability (MRI) is a fundamental process of accretion disk physics, but its saturation mechanism remains poorly understood despite considerable theoretical and computational effort. We present a multiple scales…

高能天体物理现象 · 物理学 2017-05-24 S. E. Clark , Jeffrey S. Oishi

Discs that contain dead zones are subject to the Gravo-Magneto (GM) instability that arises when the turbulence shifts from gravitational to magnetic. We have previously described this instability through a local analysis at some radius in…

太阳与恒星天体物理 · 物理学 2015-06-15 Rebecca G. Martin , Stephen H. Lubow

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…

高能天体物理现象 · 物理学 2021-12-08 Oscar M. Pimentel , P. Chris Fragile , F. D. Lora-Clavijo , Bridget Ierace , Deepika Bollimpalli

The magnetorotational instability (MRI) is thought to be a powerful source of turbulence in Keplerian accretion disks. Motivated by recent laboratory experiments, we study the MRI driven by an azimuthal magnetic field in an electrically…

太阳与恒星天体物理 · 物理学 2017-11-21 Anna Guseva , Ashley P. Willis , Rainer Hollerbach , Marc Avila

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…

太阳与恒星天体物理 · 物理学 2014-10-28 Farrukh Nauman , Eric G. Blackman

The magnetorotational instability (MRI) of differential rotation under the simultaneous presence of axial and azimuthal components of the (current-free) magnetic field is considered. For rotation with uniform specific angular momentum the…

天体物理学 · 物理学 2009-11-13 Guenther Ruediger , Manfred Schultz

We investigate the evolution of hydromagnetic perturbations in a small section of accretion disks. It is known that molecular viscosity is negligible in accretion disks. Hence, it has been argued that a mechanism, known as Magnetorotational…

高能天体物理现象 · 物理学 2015-08-12 Sujit Kumar Nath , Banibrata Mukhopadhyay

The azimuthal version of the magnetorotational instability (MRI) is a non-axisymmetric instability of a hydrodynamically stable differentially rotating flow under the influence of a purely or predominantly azimuthal magnetic field. It may…

Linear instability of two equilibrium configurations with either poloidal (I) or toroidal (II) dominant magnetic field components are studied in thin vertically-isothermal Keplerian discs. Solutions of the stability problem are found…

星系天体物理 · 物理学 2015-05-20 Yuri M. Shtemler , Michael Mond , Edward Liverts

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…

高能天体物理现象 · 物理学 2015-06-22 Xue-Ning Bai , James M. Stone

We investigate the stability of partially ionised, differentially rotating, diffusive disc threaded by both azimuthal and vertical magnetic field. The general stability criterion of such a disc in the presence of axisymmetric fluctuations…

太阳与恒星天体物理 · 物理学 2015-06-03 B. P. Pandey , Mark Wardle

The magnetorotational instability (MRI) of a weakly ionized, differentially rotating, magnetized plasma disk is investigated in the multi-fluid framework. The disk is threaded by a uniform vertical magnetic field and charge is carried by…

天体物理学 · 物理学 2009-11-11 B. P. Pandey , Mark Wardle

We consider the evolution of accretion discs that contain some turbulence within a disc dead zone, a region about the disc midplane of a disc that is not sufficiently ionised for the magneto-rotational instability (MRI) to drive turbulence.…

太阳与恒星天体物理 · 物理学 2015-06-17 Rebecca G. Martin , Stephen H. Lubow

We study local magnetohydrodynamical (MHD) instabilities of differential rotation in magnetised, stably-stratified regions of stars and planets using a Cartesian Boussinesq model. We consider arbitrary latitudes and general shears (with…

太阳与恒星天体物理 · 物理学 2024-10-10 Robert W. Dymott , Adrian J. Barker , Chris A. Jones , Steven M. Tobias

The turbulence driven by gravitational instabilities (GIs) can amplify magnetic fields in massive gaseous disks. This GI dynamo may appear in young circumstellar disks, whose weak ionization challenges other amplification routes, as well as…

太阳与恒星天体物理 · 物理学 2022-07-27 William Béthune , Henrik Latter

We analyze a suite of global magnetohydrodynamic (MHD) accretion disk simulations in order to determine whether scaling laws for turbulence driven by the magnetorotational instability, discovered via local shearing box studies, are globally…

高能天体物理现象 · 物理学 2015-05-18 Kareem A. Sorathia , Christopher S. Reynolds , Philip J. Armitage

It has been recently suggested that the magneto-rotational instability (MRI) is a limiting case of the magneto-elliptic instability (MEI). This limit is obtained for horizontal modes in the presence of rotation and an external vertical…

流体动力学 · 物理学 2015-06-04 Krzysztof A. Mizerski , Wladimir Lyra