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Magnetic fields are important for accretion disc structure. Magnetic fields in a disc system may be transported with the accreted matter. They can be associated with either the central body and/or jet, and be fossil or dynamo excited in…

高能天体物理现象 · 物理学 2016-03-23 David Moss , Dmitri Sokoloff , Valery Suleimanov

Rotational shear layers at the boundary between radiative and convective zones, tachoclines, play a key role in the process of magnetic field generation in solar-like stars. We present two sets of global simulations of rotating turbulent…

太阳与恒星天体物理 · 物理学 2016-03-08 G. Guerrero , P. K. Smolarkiewicz , E. M. de Gouveia Dal Pino , A. G. Kosovichev , N. N. Mansour

We report the first successful simulation of spontaneous formation of surface magnetic structures from a large-scale dynamo by strongly-stratified thermal convection in Cartesian geometry. The large-scale dynamo observed in our…

太阳与恒星天体物理 · 物理学 2016-05-25 Youhei Masada , Takayoshi Sano

We consider dynamo action driven by three-dimensional rotating anelastic convection in a spherical shell. Motivated by the behaviour of the solar dynamo, we examine the interaction of hydromagnetic modes with different symmetries and…

太阳与恒星天体物理 · 物理学 2016-07-06 Raphaël Raynaud , Steven M. Tobias

Convectively driven dynamos with rotation generating magnetic fields on scales large compared with the scale of the turbulent eddies are being reviewed. It is argued that such fields can be understood as the result of an alpha effect.…

太阳与恒星天体物理 · 物理学 2011-08-19 A. Brandenburg , P. J. Käpylä , M. J. Korpi

The theory of large scale dynamos is reviewed with particular emphasis on the magnetic helicity constraint in the presence of closed and open boundaries. In the presence of closed or periodic boundaries, helical dynamos respond to the…

天体物理学 · 物理学 2009-11-07 A. Brandenburg , W. Dobler , K. Subramanian

Helioseismology provides important constraints for the solar dynamo problem. However, the basic properties and even the depth of the dynamo process, which operates also in other stars, are unknown. Most of the dynamo models suggest that the…

太阳与恒星天体物理 · 物理学 2014-02-11 Alexander G. Kosovichev , Valery V. Pipin , Junwei Zhao

The amplification of magnetic fields is crucial for understanding the observed magnetization of stars and galaxies. Turbulent dynamo is the primary mechanism responsible for that but the understanding of its action in a collapsing…

星系天体物理 · 物理学 2026-04-22 Muhammed Irshad P , Pallavi Bhat , Kandaswamy Subramanian , Anvar Shukurov

I review the large scale global magnetic field structure of our Galaxy, using all information available for disk fields, halo fields and magnetic fields near the Galactic center (GC). In the local disk of our Galaxy, RM and dispersion…

天体物理学 · 物理学 2015-06-11 Jinlin Han

Dynamos in astrophysical disks are usually explained in terms of the standard alpha-omega mean field dynamo model where the local helicity generates a radial field component from an azimuthal field. The subsequent shearing of the radial…

天体物理学 · 物理学 2015-06-24 Ethan T. Vishniac

We present the results of 3--D simulations of core convection within A-type stars of 2 solar masses, at a range of rotation rates. We consider the inner 30% by radius of such stars, thereby encompassing the convective core and some of the…

天体物理学 · 物理学 2008-11-26 Matthew Browning , Allan Sacha Brun , Juri Toomre

Initial results are presented from 3D MHD modelling of stellar-wind bubbles around O stars moving supersonically through the ISM. We describe algorithm updates that enable high-resolution 3D MHD simulations at reasonable computational cost.…

星系天体物理 · 物理学 2020-10-06 Jonathan Mackey , Samuel Green , Maria Moutzouri

We study the connections between the sun's convection zone and the evolution of the solar wind and corona. We let the magnetic fields generated by a 2.5D axisymmetric kinematic dynamo code (STELEM) evolve in a 2.5D axisymmetric coronal…

太阳与恒星天体物理 · 物理学 2015-05-28 Rui F. Pinto , Allan Sacha Brun , Laurène Jouve , Roland Grappin

Possibilities and difficulties of applying the theory of magnetic field generation by convection flows in rotating spherical fluid shells to the Giant Planets are outlined. Recent progress in the understanding of the distribution of…

地球与行星天体物理 · 物理学 2009-06-02 F. H. Busse , R. D. Simitev

We explore effects of random non-axisymmetric perturbations of kinetic helicity (the $\alpha$ effect) and diffusive decay of bipolar magnetic regions on generation and evolution of large-scale non-axisymmetric magnetic fields on the Sun.…

太阳与恒星天体物理 · 物理学 2018-11-28 V. V. Pipin , A. G. Kosovichev

Magnetic fields can be created in stably stratified (non-convective) layers in a differentially rotating star. A magnetic instability in the toroidal field (wound up by differential rotation) replaces the role of convection in closing the…

天体物理学 · 物理学 2009-11-07 H. C. Spruit

We describe a 3D finite-difference spherical anelastic MHD (FSAM) code for modeling the subsonic dynamic processes in the solar convective envelope. A comparison of this code with the widely used global spectral anlastic MHD code, ASH…

太阳与恒星天体物理 · 物理学 2013-05-29 Yuhong Fan , Nicholas Featherstone , Fang Fang

A fully three-dimensional computation of induction processes in a disk is performed to investigate the evolution of a large-scale magnetic field in gas-rich barred and spiral galaxies in the presence of field diffusion. As input parameters…

天体物理学 · 物理学 2007-05-23 S. von Linden , K. Otmianowska-Mazur , H. Lesch , G. Skupniewicz

The solar cycle is a complex phenomenon. To comprehensively understand it, we have to study various tracers. The most important component of this complex is the solar dynamo, which is understood as self-excitation of the solar magnetic…

太阳与恒星天体物理 · 物理学 2025-01-10 V. N. Obridko , A. S. Shibalova , D. D. Sokoloff

We report the finding of an azimuthal dynamo wave of a low-order (m=1) mode in direct numerical simulations (DNS) of turbulent convection in spherical shells. Such waves are predicted by mean field dynamo theory and have been obtained…

太阳与恒星天体物理 · 物理学 2013-12-19 Elizabeth Cole , Petri J. Käpylä , Maarit J. Mantere , Axel Brandenburg