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It is an indisputable fact that solar magnetic fields are force-free in the corona, where force free fields means that current and magnetic fields are parallel and there is no Lorentz force in the fields. While the force-free extent of…

Solar and Stellar Astrophysics · Physics 2015-06-05 S. Liu , J. T. Su , H. Q. Zhang , Y. Y. Deng , Y. Gao , X. Yang , X. J. Mao

We investigate how the azimuthal ambiguity in solar vector magnetogram data can be resolved by using the divergence-free property of magnetic fields. In a previous article, by Crouch, Barnes, and Leka (Solar Phys. 260, 271, 2009),…

Solar and Stellar Astrophysics · Physics 2012-10-12 Ashley D. Crouch

We investigate how the divergence-free property of magnetic fields can be exploited to resolve the azimuthal ambiguity present in solar vector magnetogram data, by using line-of-sight and horizontal heliographic derivative information as…

Solar and Stellar Astrophysics · Physics 2009-11-05 Ashley D. Crouch , Graham Barnes , K. D. Leka

Magnetic reconnections (MRs) for various magnetic field line (MFL) topologies are believed to be the initiators of various solar eruptive events like flares and coronal mass ejections (CMEs). Consequently, important is a thorough…

Solar and Stellar Astrophysics · Physics 2019-01-30 Sushree S. Nayak , R. Bhattacharyya , A. Prasad , Qiang Hu

The availability of vector magnetogram sequences with sufficient accuracy and cadence to estimate the time derivative of the magnetic field allows us to use Faraday's law to find an approximate solution for the electric field in the…

Solar and Stellar Astrophysics · Physics 2015-05-27 George H. Fisher , Brian T. Welsch , William P. Abbett

The magnetic field governs the corona; hence it is a crucial parameter to measure. Unfortunately, existing techniques for estimating its strength are limited by strong assumptions and limitations. These techniques include photospheric or…

Solar and Stellar Astrophysics · Physics 2022-10-26 Juan Martinez-Sykora , Viggo H. Hansteen , Bart De Pontieu , Enrico Landi

The Sun is a non-equilibrium dissipative system subjected to an energy flow which originates in its core. Convective overshooting motions create temperature and velocity structures which show a temporal and spatial evolution. As a result,…

Solar and Stellar Astrophysics · Physics 2015-06-11 F. Berrilli , S. Scardigli , S. Giordano

Context: This paper presents a method which can be used to calculate models of the global solar corona from observational data. Aims: We present an optimization method for computing nonlinear magnetohydrostatic equilibria in spherical…

Astrophysics · Physics 2009-06-25 T. Wiegelmann , T. Neukirch , P. Ruan , B. Inhester

Sequences of line-of-sight (LOS) magnetograms recorded by the Michelson-Doppler Imager are used to quantitatively characterize photospheric magnetic structure and evolution in three active regions that rotated across the Sun's disk during…

Solar and Stellar Astrophysics · Physics 2015-05-27 B. T. Welsch , S. Christe , J. M. McTiernan

We present a novel approach allowing an optically pumped magnetometer (OPM) to be operated within Earth's magnetic field as a vector magnetometer whose sensitive axis can be freely defined. This approach enables the measurement of any…

Instrumentation and Detectors · Physics 2024-08-20 Thomas Schönau , Theo Scholtes , Florian Wittkämper , Alexander Sekels , Stefan Hiebel , Gregor Oelsner , Ronny Stolz

In this work we describe a numerical optimization method for computing stationary MHD-equilibria. The newly developed code is based on a nonlinear force-free optimization principle. We apply our code to model the solar corona using synoptic…

Solar and Stellar Astrophysics · Physics 2020-11-11 Thomas Wiegelmann , Thomas Neukirch , Dieter H. Nickeler , Iulia Chifu

This paper introduces a new approach for simulating magnetic properties of nanocomposites comprising magnetic particles embedded in a non-magnetic matrix, taking into account the 3D structure of the system in which particles' positions…

Mesoscale and Nanoscale Physics · Physics 2014-10-22 R. F. Neumann , M. Bahiana , L. G. Paterno , M. A. G. Soler , J. P. Sinnecker , J. G. Wen , P. C. Morais

The temperature and density conditions in the magnetized photosphere and chromosphere of the Sun lead to a very small degree of atomic ionization. In addition, at particular height, the magnetic field may be strong enough to give rise to a…

Solar and Stellar Astrophysics · Physics 2015-04-08 Elena Khomenko

We propose a novel paradigm to vector magnetometry based on machine learning. Unlike conventional schemes where one measured signal explicitly connects to one parameter, here we encode the three-dimensional magnetic-field information in the…

Instrumentation and Detectors · Physics 2023-10-04 Xin Meng , Youwei Zhang , Xichang Zhang , Shenchao Jin , Tingran Wang , Liang Jiang , Liantuan Xiao , Suotang Jia , Yanhong Xiao

First, we describe a general procedure to produce high quality vector magnetograms using the Imaging Vector Magnetograph (IVM) at Mees Solar Observatory. At the spatial resolution 2"x2", the Stokes Q,U,V uncertainty reaches 0.001-0.0005 in…

Astrophysics · Physics 2011-02-11 Jing Li , A. A. van Ballegooijen , Don Mickey

The chromosphere is a complex solar atmosphere that hosts a variety of transients and transports significant free energy to heat the corona. However, due to the limited sensitivity of polarization measurement and the influence of spectral…

Solar and Stellar Astrophysics · Physics 2026-03-24 Jiasheng Wang , Wenxian Li , Xianyong Bai , Yingzi Sun , Yuanyong Deng , Jiaben Lin

Photospheric vector magnetograms from Helioseismic and Magnetic Imager on board the Solar Dynamic Observatory are utilized as the boundary conditions to extrapolate both non-linear force-free and potential magnetic fields in solar corona.…

Solar and Stellar Astrophysics · Physics 2015-06-19 J. T. Su , J. Jing , S. Wang , T. Wiegelmann , H. M. Wang

(abridged) Pulsar activity and its related radiation mechanism are usually explained by invoking some plasma processes occurring inside the magnetosphere. Despite many detailed local investigations, the global electrodynamics around those…

High Energy Astrophysical Phenomena · Physics 2015-06-05 J. Pétri

The emergence of magnetic flux, its transition to complex configurations, and the pre-eruptive state of active regions are probed using photospheric magnetograms. We aim to pinpoint different evolutionary stages in active regions, explore…

Solar and Stellar Astrophysics · Physics 2024-11-06 I. Kontogiannis , A. G. M. Pietrow , M. K. Druett , E. Dineva , M. Verma , C. Denker

We present a method of conducting data-driven simulations of solar active regions and flux emergence with the MURaM radiative magnetohydrodynamics (MHD) code. The horizontal electric field derived from the full velocity and magnetic…

Solar and Stellar Astrophysics · Physics 2023-06-14 Feng Chen , Mark C. M. Cheung , Matthias Rempel , Georgios Chintzoglou