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Planetary and stellar dynamos likely result from turbulent motions in magnetofluids with kinematic viscosities that are small compared to their magnetic diffusivities. Laboratory experiments are in progress to produce similar dynamos in…

Astrophysics · Physics 2009-11-11 P. D. Mininni

Understanding magnetic-field generation and amplification in turbulent plasma is essential to account for observations of magnetic fields in the universe. A theoretical framework attributing the origin and sustainment of these fields to the…

The mean-field dynamo model is employed to study the non-linear dynamo regimes in a fully convective star of mass 0.3$M_{\odot}$ rotating with period of 10 days. For the intermediate value of the parameter of the turbulent magnetic Prandl…

Solar and Stellar Astrophysics · Physics 2017-02-01 V. V. Pipin

The amplification of primordial magnetic fields via a small-scale turbulent dynamo during structure formation might be able to explain the observed magnetic fields in galaxy clusters. The magnetisation of more tenuous large-scale structures…

Cosmology and Nongalactic Astrophysics · Physics 2015-06-22 F. Vazza , M. Brüggen , C. Gheller , P. Wang

The mean-field theory of magnetized stellar convection gives rise to the two possibility of distinct instabilities: the large-scale dynamo instability, operating in the bulk of the convection zone, and a negative effective magnetic pressure…

Solar and Stellar Astrophysics · Physics 2014-11-03 Sarah Jabbari , Axel Brandenburg , Illa R. Losada , Nathan Kleeorin , Igor Rogachevskii

The mechanism of large-scale dynamos in rigidly rotating stratified convection is explored by direct numerical simulations (DNS) in Cartesian geometry. A mean-field dynamo model is also constructed using turbulent velocity profiles…

Solar and Stellar Astrophysics · Physics 2015-06-22 Youhei Masada , Takayoshi Sano

The magnetorotational instability (MRI) is a promising mechanism to amplify the magnetic field in fast rotating protoneutron stars. The diffusion of neutrinos trapped in the PNS induces a transport of momentum, which can be modelled as a…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Jerome Guilet , Ewald Mueller , Hans-Thomas Janka

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

We investigate the linear growth and vertical structure of the magnetorotational instability (MRI) in weakly ionised, stratified accretion discs. The magnetic field is initially vertical and dust grains are assumed to have settled towards…

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

The interaction between weak magnetic fields and rotation can lead to instabilities that transport angular momentum (AM) and chemical elements affecting the evolution of massive stars. We explore the effects of the magneto-rotational…

Solar and Stellar Astrophysics · Physics 2022-09-28 A. Griffiths , G. Meynet , P. Eggenberger , F. Moyano , M. A. Aloy

Magnetic fields are critical at many scales to galactic dynamics and structure, including multiphase pressure balance, dust processing, and star formation. Dynamo action determines their dynamical structure and strength. Simulations of…

Astrophysics of Galaxies · Physics 2026-02-17 Frederick A. Gent , Mordecai-Mark Mac Low , Maarit J. Korpi-Lagg , Touko Puro , Matthias Reinhardt

Magneto-rotational instability (MRI) is an important instability mechanism for rotating flows with magnetic fields. In particular, when the strength of the magnetic field tends to zero, the stability criterion for rotating flows is…

Analysis of PDEs · Mathematics 2024-10-28 Zhiwu Lin , Yucong Wang , Wenpei Wu

Angular momentum transport and particle acceleration during the magnetorotational instability (MRI) in a collisionless accretion disk are investigated using three-dimensional particle-in-cell (PIC) simulation. We show that the kinetic MRI…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Masahiro Hoshino

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

The Faraday rotation effect, quantified by the Rotation Measure (RM), is a powerful probe of the large-scale magnetization of the Universe - tracing magnetic fields not only on galaxy and galaxy cluster scales but also in the intergalactic…

Magnetic fields pervade the entire Universe and affect the formation and evolution of astrophysical systems from cosmological to planetary scales. The generation and dynamical amplification of extragalactic magnetic fields through cosmic…

Cosmology and Nongalactic Astrophysics · Physics 2016-04-27 F. Rincon , F. Califano , A. A. Schekochihin , F. Valentini

Dynamo action owing to helically forced turbulence and large-scale shear is studied using direct numerical simulations. The resulting magnetic field displays propagating wave-like behavior. This behavior can be modelled in terms of an…

Astrophysics · Physics 2011-02-11 P. J. Käpylä , A. Brandenburg

The magnetorotational instability (MRI) is the leading candidate for driving turbulence, angular momentum transport, and accretion in astrophysical disks. I consider the linear theory of the MRI in a thin, equatorial disk in the Kerr…

Astrophysics · Physics 2009-11-10 Charles F. Gammie

The ordered magnetic field observed via polarized synchrotron emission in nearby disc galaxies can be explained by a mean-field dynamo operating in the diffuse interstellar medium (ISM). Additionally, vertical-flux initial conditions are…

Astrophysics of Galaxies · Physics 2016-01-06 A. Bendre , O. Gressel , D. Elstner

We use global MHD galaxy simulations to investigate the effects of spiral arms on the evolution of magnetic fields and star formation within a self-regulated interstellar medium (ISM). The same galaxy is simulated twice: once with…

Astrophysics of Galaxies · Physics 2025-06-23 Hector Robinson , James Wadsley , J. A. Sellwood , Ralph E. Pudritz