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Related papers: The kink-type instability of toroidal stellar magn…

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We show that radiation dominated accretion discs are likely to suffer from a ``photon bubble'' instability similar to that described by Arons in the context of accretion onto neutron star polar caps. The instability requires a magnetic…

Astrophysics · Physics 2009-10-30 Charles F. Gammie

Differential rotation induced by the r-mode instability can generate very strong toroidal fields in the core of accreting, millisecond spinning neutron stars. We introduce explicitly the magnetic damping term in the evolution equations of…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Carmine Cuofano , Simone Dall'Osso , Alessandro Drago , Luigi Stella

Jets and pulsar-fed supernova remnants (plerions) tend to develop highly organized toroidal magnetic field. Such a field structure could explain the polarization properties of some jets, and contribute to their lateral confinement. A…

Astrophysics · Physics 2009-10-30 Mitchell C. Begelman

We investigate the stability to nonaxisymmetric perturbations of an accretion disc in which a poloidal magnetic field provides part of the radial support against gravity. Interchange instability due to radial gradients in the magnetic field…

Astrophysics · Physics 2015-06-24 H. C. Spruit , R. Stehle , J. C. B. Papaloizou

We have performed 3-D numerical magnetohydrodynamic (MHD) jet experiments to study the instabilities associated with strongly toroidal magnetic fields and determine if such magnetic configurations in jets are as unstable as similar…

Astrophysics · Physics 2007-05-23 F. Thomsen , A. Nordlund

Asteroseismology has reached a level of accuracy that may allow us to detect the effect of a deep magnetic field on oscillation modes. We thus aim to develop an asymptotic theory for short-wavelength waves in radiative zones of rotating…

Solar and Stellar Astrophysics · Physics 2018-10-15 Aurélien Valade , Vincent Prat , Stéphane Mathis , Kyle Augustson

Based on the characteristics of the magnetorotational instability (MRI) and the MRI-driven turbulence, we construct a steady model for a geometrically thin disk using "non-standard" $\alpha$-prescription. The efficiency of the angular…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Hiroyuki R. Takahashi , Youhei Masada

This paper considers gravitational perturbations in geometrically thin disks with rotation curves dominated by a central object, but with substantial contributions from magnetic pressure and tension. The treatment is general, but the…

Astrophysics of Galaxies · Physics 2015-05-20 Susana Lizano , Daniele Galli , Mike J. Cai , Fred C. Adams

We have succeeded in obtaining magnetized equilibrium states with differential rotation and differential toroidal magnetic fields. If an internal toroidal field of a proto-neutron star is wound up from the initial poloidal magnetic field by…

High Energy Astrophysical Phenomena · Physics 2015-08-28 Kotaro Fujisawa

It is shown that the magnetic current-driven (`kink-type') instability produces flow and field patterns with helicity and even with \alpha-effect but only if the magnetic background field possesses non-vanishing current helicity…

Solar and Stellar Astrophysics · Physics 2015-05-20 Guenther Ruediger , Marcus Gellert , Rainer Arlt

Nuclear rings at centers of barred galaxies exhibit strong star formation activities. They are thought to undergo gravitational instability when sufficiently massive. We approximate them as rigidly-rotating isothermal objects and…

Astrophysics of Galaxies · Physics 2016-09-28 Woong-Tae Kim , Sanghyuk Moon

Fluctuations in a stellar system's gravitational field cause the orbits of stars to evolve. The resulting evolution of the system can be computed with the orbit-averaged Fokker-Planck equation once the diffusion tensor is known. We present…

Astrophysics of Galaxies · Physics 2016-04-11 Jean-Baptiste Fouvry , James Binney , Christophe Pichon

In the standard thin disc formalism the dimensionless $\alpha$ parameter is usually assumed to be constant. However, there are good theoretical reasons for believing, as well as evidence from simulations, that $\alpha$ is dependent on…

High Energy Astrophysical Phenomena · Physics 2017-08-08 William J. Potter , Steven A. Balbus

We investigate the effects of the purely toroidal magnetic field on the equilibrium structures of the relativistic stars. The master equations for obtaining equilibrium solutions of relativistic rotating stars containing purely toroidal…

Astrophysics · Physics 2008-11-26 Kenta Kiuchi , Shijun Yoshida

Gravitational-wave diagnostics are developed for discriminating between varieties of mixed poloidal-toroidal magnetic fields in neutron stars, with particular emphasis on differentially rotating protoneutron stars. It is shown that tilted…

High Energy Astrophysical Phenomena · Physics 2015-06-17 Paul D. Lasky , Andrew Melatos

Magnetic fields in upper main-sequence stars, white dwarfs, and neutron stars are known to persist for timescales comparable to their lifetimes. From a theoretical perspective this is problematic, as it can be shown that simple magnetic…

Solar and Stellar Astrophysics · Physics 2015-06-12 Taner Akgün , Andreas Reisenegger , Alpha Mastrano , Pablo Marchant

Strong magnetic fields play an important role in powering the emission of neutron stars. Nevertheless a full understanding of the interior configuration of the field remains elusive. In this work, we present General Relativistic…

High Energy Astrophysical Phenomena · Physics 2022-02-16 Ankan Sur , William Cook , David Radice , Brynmor Haskell , Sebastiano Bernuzzi

The main observational results from radio continuum and polarization observations about the magnetic field strength and large-scale pattern for face-on and edge-on spiral galaxies are summarized and compared within our sample of galaxies of…

Astrophysics · Physics 2009-05-07 Marita Krause

Simulations and analytic arguments suggest that the turbulence driven by magnetorotational instability (MRI) in accretion discs can amplify the toroidal (azimuthal) component of the magnetic field to a point at which magnetic pressure…

Astrophysics · Physics 2008-11-26 M. C. Begelman , J. E. Pringle

We have determined the physical mechanism responsible for the plasma instabilities, which was first found by Ramani and Laval (1978), associated with anisotropic velocity distributions induced by the temperature gradient in which there are…

Astrophysics · Physics 2009-11-10 Nobuhiro Okabe , Makoto Hattori