Magnetic structures in a dynamo simulation
نویسندگان
چکیده
'Theoretical Astrophysics Center, Blegdamsvej 17, DK-2100 Copenhagen 0, Denmark 4Copenhagen University Observatory, 0ster Voldgade 3, DK-1350 Copenhagen, Denmark 50bservatoire Midi-Pyrenkes, 14 av. E. Belin, F-31400 Toulousc, France 6CERFACS. 42, Avenue Coriolis, F-31057 Toulouse, France 'Dept. of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, USA *Observatory, PO Box 14, SF-00014 University of Helsinki, Finland 9Dept. of Geosciences and Astronomy, Univcrsity of Oulu, PO Box 333, 90571 Oulu, Finland
منابع مشابه
Doubly Helical Coronal Ejections from Dynamos and their Role in Sustaining the Solar Cycle
Two questions about the solar magnetic field might be answered together once their connection is identified. The first is important for large scale dynamo theory: what prevents the magnetic backreaction forces from shutting down the dynamo cycle? The second question is: what determines the handedness of twist and writhe in magnetized coronal ejecta? Magnetic helicity conservation is important f...
متن کاملMach number dependence of the onset of dynamo action
The effect of compressibility on the onset of nonhelical turbulent dynamo action is investigated using both direct simulations as well as simulations with shock-capturing viscosities, keeping however the regular magnetic diffusivity. It is found that the critical magnetic Reynolds number increases from about 35 in the subsonic regime to about 70 in the supersonic regime. Although the shock stru...
متن کاملLagrangian Coherent Structures in a Nonlinear Dynamo
Turbulence and chaos play a fundamental role in stellar convective zones through the transport of particles, energy and momentum, and in fast dynamos, through the stretching, twisting and folding of magnetic flux tubes. A particularly revealing way to describe turbulent motions is through the analysis of Lagrangian coherent structures (LCS), which are material lines or surfaces that act as tran...
متن کاملStudy of Solar Magnetic and Gravitational Energies Through the Virial Theorem
Virial theorem is important for understanding stellar structures. It produces an interesting connection between magnetic and gravitational energies. Using the general form of the virial theorem including the magnetic field (toroidal magnetic field), we may explain the solar dynamo model in relation to variations of the magnetic and gravitational energies. We emphasize the role of the gravitatio...
متن کاملPercolation and the Solar Dynamo
The origin of magnetic field sources in the Sun’s dynamo is central to this paper. The Babcock-Leighton dynamo was originally envisaged as a shallow dynamo. The source of the Sun’s magnetism is now generally thought to reside near the base of the convection zone and that these fields rise by buoyancy to initiate sunspots. We reconsider this aspect of the solar dynamo. We do this by considering ...
متن کاملIntense bipolar structures from stratified helical dynamos
We perform direct numerical simulations of the equations of magnetohydrodynamics with external random forcing and in the presence of gravity. The domain is divided into two parts: a lower layer where the forcing is helical and an upper layer where the helicity of the forcing is zero with a smooth transition in between. At early times, a large-scale helical dynamo develops in the bottom layer. A...
متن کامل