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Several solar-like stars exhibit cyclic magnetic activity similar to the Sun as found in photospheric and chromospheric emission. We want to understand the physical mechanism involved in rotational dependence of these activity cycle…

Solar and Stellar Astrophysics · Physics 2018-08-22 Jörn Warnecke

The presence of low viscosity layers in the mantle is supported by line of geological and geophysical observations. Recent high pressure and temperature investigations indicated that partial carbonate melt should exist at the bottom of the…

General Physics · Physics 2007-09-11 Jozsef Garai

We discuss recent advances made in modelling the complex magnetohydrodynamics of the Sun using our anelastic spherical harmonics (ASH) code. We have conducted extensive 3--D simulations of compressible convection in rotating spherical…

Astrophysics · Physics 2007-05-23 Allan Sacha Brun , Juri Toomre

Computational heliophysics has shed light on the fundamental physical processes inside the Sun, such as the differential rotation, meridional circulation, and dynamo-generation of magnetic fields. However, despite the substantial advances,…

Solar and Stellar Astrophysics · Physics 2023-01-25 A. G. Kosovichev , G. Guerrero , A. M. Stejko , V. V. Pipin , A. V. Getling

This paper describes a new design of superconducting dipole magnet prototype by the use of tilted solenoids. The magnet prototype, which consists of four layers of superimposed tilted solenoids with operating current of 3708 A, will produce…

Instrumentation and Detectors · Physics 2015-07-28 Yuquan Chen , Lizhen Ma , Wei Wu , Beimin Wu , Tongjun Yang , Yu Liang

The exploration of mean-field galactic dynamos affected by a galactic spiral pattern, begun in Chamandy et al. (2013, hereafter Paper I) with numerical simulations, is continued here with an asymptotic solution. The mean-field dynamo model…

Astrophysics of Galaxies · Physics 2015-06-12 Luke Chamandy , Kandaswamy Subramanian , Anvar Shukurov

We recently presented the first 3D numerical simulation of the solar interior for which tachocline confinement was achieved by a dynamo-generated magnetic field. In this followup study, we analyze the degree of confinement as the magnetic…

Solar and Stellar Astrophysics · Physics 2024-01-09 Loren I. Matilsky , Nicholas H. Brummell , Bradley W. Hindman , Juri Toomre

We examine the effects of the magnetic field created by the Tayler--Spruit dynamo in differentially rotating stars. Magnetic fields of the order of a few $10^4$ G are present through most of the stellar envelope, with the exception of the…

Astrophysics · Physics 2009-11-11 André Maeder , Georges Meynet

We explore a response of a non-linear non-axisymmetric mean-field solar dynamo model to shallow non-axisymmetric perturbations. After a relaxation period the amplitude of the non-axisymmetric field depends on the initial condition, helicity…

Solar and Stellar Astrophysics · Physics 2015-11-18 V. V. Pipin , A. G. Kosovichev

A thermodynamic model for the generation of magnetic fields in the planets is proposed, considering crossed effects between gravitational and electric forces. The magnetic field of the Earth is estimated and found to be in agreement with…

Astrophysics · Physics 2007-05-23 F. X. Alvarez

We report the first experimental observation of reversals of a dynamo field generated in a laboratory experiment based on a turbulent flow of liquid sodium. The magnetic field randomly switches between two symmetric solutions B and -B. We…

The theory of the solar/stellar activity cycles is presented, based on the mean-field concept in magnetohydrodynamics. A new approach to the formulation of the electromotive force and the theory of differential rotation and meridional…

Astrophysics · Physics 2017-02-22 Günther Rüdiger , Rainer Arlt

We study some possible astrophysical implications of a very weakly coupled ultralight dilaton-type scalar field. Such a field may develop an (approximately stable) network of domain walls. The domain wall thickness is assumed to be…

Astrophysics · Physics 2009-11-06 Gia Dvali , Gregory Gabadadze , M. Shifman

We review the state of the art of three dimensional numerical simulations of solar and stellar dynamos. We summarize fundamental constraints of numerical modelling and the techniques to alleviate these restrictions. Brief summary of the…

Solar and Stellar Astrophysics · Physics 2023-05-29 Petri J. Käpylä , Matthew K. Browning , Allan Sacha Brun , Gustavo Guerrero , Jörn Warnecke

In their early stages, protoplanetary discs are sufficiently massive to undergo gravitational instability (GI). This instability is thought to be involved in mass accretion, planet formation via gas fragmentation, the generation of spiral…

Earth and Planetary Astrophysics · Physics 2021-06-30 A. Riols , W. Xu , G. Lesur , M. W. Kunz , H. Latter

Magnetic fields in nearby, star-forming galaxies reveal both large-scale patterns and small-scale structures. A large-scale field reversal may exist in the Milky Way but no such reversals have been observed so far in external galaxies. The…

Astrophysics of Galaxies · Physics 2015-05-30 David Moss , Rodion Stepanov , Tigran Arshakian , Rainer Beck , Marita Krause , Dmitri Sokoloff

Normal mode oscillations in Saturn excite density and bending waves in the C Ring, providing a valuable window into the planet's interior. Saturn's fundamental modes (f modes) excite the majority of the observed waves, while…

Earth and Planetary Astrophysics · Physics 2021-12-20 Janosz W. Dewberry , Christopher R. Mankovich , Jim Fuller , Dong Lai , Wenrui Xu

A solar-type dynamo model in a spherical shell is developed with allowance for random dependence of the poloidal field generation mechanism on time and latitude. The model shows repeatable epochs of strongly decreased amplitude of magnetic…

Solar and Stellar Astrophysics · Physics 2015-06-17 S. V. Olemskoy , L. L. Kitchatinov

Recent direct numerical simulations (DNS) of large-scale turbulent dynamos in strongly stratified layers have resulted in surprisingly sharp bipolar structures at the surface. Here we present new DNS of helically and non-helically forced…

Solar and Stellar Astrophysics · Physics 2018-05-24 Sarah Jabbari , Axel Brandenburg , Nathan Kleeorin , Igor Rogachevskii

The evolution of an initially stellar dipole type magnetosphere interacting with an accretion disk is investigated using numerical ideal MHD simulations. The simulations follow several 1000 Keplerian periods of the inner disk. The initial…

Astrophysics · Physics 2008-11-26 Ch. Fendt