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To elucidate the cascade direction of the solar wind turbulence, we analyzed magnetic helicity density spectra from the Parker Solar Probe data across more than 500 heliocentric distances. For the first time, we confirmed a persistent…

Sunspots and active regions observed on the solar surface are widely believed to be manifestations of compact predominantly-toroidal magnetic field structures (``flux tubes") that emerge by magnetic buoyancy from the deeper interior of the…

Solar and Stellar Astrophysics · Physics 2024-06-21 Bhishek Manek , Nicholas Brummell

We analyze direct numerical simulations of large-scale dynamos in inhomogeneous nonhelically driven rotating turbulence with and without shear. The forcing is modulated so that the turbulent intensity peaks in the middle of the…

Plasma Physics · Physics 2025-05-02 Axel Brandenburg , Ethan T. Vishniac

We study a turbulent helical dynamo in a periodic domain by solving the ideal magnetohydrodynamic (MHD) equations with the FLASH code using the divergence-cleaning eight-wave method and compare our results with direct numerical simulations…

Solar and Stellar Astrophysics · Physics 2020-01-28 Axel Brandenburg , Evan Scannapieco

Radio continuum observations allow to reveal the magnetic field structure in the disk and halo of nearby spiral galaxies, their magnetic field strength and vertical scale heights. The spiral galaxies studied so far show a similar magnetic…

Astrophysics of Galaxies · Physics 2014-01-08 Marita Krause

Field line helicity measures the net linking of magnetic flux with a single magnetic field line. It offers a finer topological description than the usual global magnetic helicity integral, while still being invariant in an ideal evolution…

Solar and Stellar Astrophysics · Physics 2023-11-16 A. R. Yeates , M. A. Berger

We investigate the evolution of field line helicity for magnetic fields that connect two boundaries without null points, with emphasis on localized finite-B magnetic reconnection. Total (relative) magnetic helicity is already recognized as…

In this paper we investigate the dynamics of magnetic helicity in magnetohydrodynamic (MHD) turbulent flows focusing at scales larger than the forcing scale. Our results show a nonlocal inverse cascade of magnetic helicity, which occurs…

Fluid Dynamics · Physics 2017-05-23 Moritz Linkmann , Vassilios Dallas

We investigate the effect of magnetic helicity on the stability of buoyant magnetic cavities as found in the intergalactic medium. In these cavities, we insert helical magnetic fields and test whether or not helicity can increase their…

Astrophysics of Galaxies · Physics 2020-06-24 Simon Candelaresi , Fabio Del Sordo

The Sun's magnetic dynamo cycle features a distinct pattern: a propagating region of sunspot emergence appears around 30 degrees latitude and vanishes near the equator every 11 years. Moreover, longitudinal flows called "torsional…

A fraction of solar active regions are observed to have current helicity of a sign that contradicts the polarity law for magnetic helicity; this law corresponds to the well-known Hale polarity law for sunspots. A significant excess of…

Astrophysics · Physics 2009-11-11 D. Sokoloff , S. D. Bao , N. Kleeorin , K. Kuzanyan , D. Moss , I. Rogachevskii , D. Tomin , H. Zhang

Using one-dimensional models, we show that a helical magnetic field with an appropriate sign of helicity can compensate the Faraday depolarization resulting from the superposition of Faraday-rotated polarization planes from a spatially…

Cosmology and Nongalactic Astrophysics · Physics 2014-04-23 Axel Brandenburg , Rodion Stepanov

We determine the magnetic helicity, along with the magnetic energy, at high latitudes using data from the Ulysses mission. The data set spans the time period from 1993 to 1996. The basic assumption of the analysis is that the solar wind is…

Solar and Stellar Astrophysics · Physics 2015-03-17 Axel Brandenburg , Kandaswamy Subramanian , André Balogh , Melvyn L. Goldstein

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

We continue our attempt to connect observational data on current helicity in solar active regions with solar dynamo models. In addition to our previous results about temporal and latitudinal distributions of current helicity (Kleeorin et…

Astrophysics · Physics 2009-11-10 H. Zhang , D. Sokoloff , I. Rogachevskii , D. Moss , V. Lamburt , K. Kuzanyan , N. Kleeorin

Two non-local asymptotic invariants of magnetic fields for the ideal magnetohydrodynamics are introduced. The velocity of variation of the invariants for a non-ideal magnetohydrodynamics with a small magnetic dissipation is estimated. By…

Mathematical Physics · Physics 2011-10-06 Petr M. Akhmet'ev

Solar flares and coronal mass ejections are the largest energy release phenomena in the current solar system. They cause drastic enhancements of electromagnetic waves of various wavelengths and sometimes eject coronal material into the…

Solar and Stellar Astrophysics · Physics 2022-04-14 Shin Toriumi , Sung-Hong Park

This work is devoted to study the magnetic reconnection instability under solar spicule conditions. Numerical study of the resistive tearing instability in a current sheet is presented by considering the magnetohydrodynamic (MHD) framework.…

Solar and Stellar Astrophysics · Physics 2014-06-30 Z. Fazel , H. Ebadi

It is demonstrated that the two-point correlation function of the magnetic helicity in the case of zero mean magnetic field has anomalous scalings for both, compressible and incompressible turbulent helical fluid flow. The magnetic helicity…

Astrophysics · Physics 2009-11-07 I. Rogachevskii , N. Kleeorin

An extended inertial range dominated by the cross-helicity effects has been studied for forced (statistically steady) and for freely decaying magnetohydrodynamic MHD turbulence (with and without imposed/mean magnetic field) using the…

Fluid Dynamics · Physics 2019-10-24 A. Bershadskii