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We study the link between an expanding coronal shock and the energetic particles measured near Earth during the Ground Level Enhancement (GLE) of 17 May 2012. We developed a new technique based on multipoint imaging to triangulate the 3-D…

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

Duo to the large magnetic Reynolds number, the magnetic helicity originating from the solar interior can be carried away through the photosphere into the corona. However, the relationship between the accumulated magnetic helicity flux…

Solar and Stellar Astrophysics · Physics 2022-04-27 Quan Wang , Shangbin Yang , Mei Zhang , Xiao Yang

Estimates of the photospheric magnetic, electric and plasma velocity fields are essential for studying the dynamics of the solar atmosphere, for example through the derivative quantities of Poynting and relative helicity flux and by using…

Solar and Stellar Astrophysics · Physics 2017-12-18 E. Lumme , J. Pomoell , E. K. J. Kilpua

Three-dimensional field distributions from realistic beamline elements can be obtained only by measurement or by numerical solution of a boundary-value problem. In numerical charged-particle map generation, fields along a reference…

Divergence-free (div-free) and curl-free vector fields are pervasive in many areas of science and engineering, from fluid dynamics to electromagnetism. A common problem that arises in applications is that of constructing smooth approximants…

Numerical Analysis · Mathematics 2021-02-18 Kathryn P. Drake , Edward J. Fuselier , Grady B. Wright

We test a nonlinear force-free field (NLFFF) optimization code in spherical geometry using an analytical solution from Low and Lou. Several tests are run, ranging from idealized cases where exact vector field data are provided on all…

Solar and Stellar Astrophysics · Physics 2015-06-11 Y. Guo , M. D. Ding , Y. Liu , X. D. Sun , M. L. DeRosa , T. Wiegelmann

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 solar coronal magnetic field is a pivotal element in the study of eruptive phenomena, and understanding its dynamic evolution has long been a focal point in solar physics. Numerical models, driven directly by observation data, serve as…

Solar and Stellar Astrophysics · Physics 2024-10-15 Zhi-Peng Liu , Chao-Wei Jiang , Xin-Kai Bian , Qing-Jun Liu , Peng Zou , Xue-Shang Feng

We investigate the recently quantified misalignment of $\alpha_{mis} \approx 20^\circ-40^\circ$ between the 3-D geometry of stereoscopically triangulated coronal loops observed with STEREO/EUVI (in four active regions) and theoretical…

Solar and Stellar Astrophysics · Physics 2015-05-18 Markus J. Aschwanden , Anne W. Sandman

This work examines the relation between the fractal properties of the photospheric magnetic patterns and those of the coronal magnetic fields in solar active regions.Our results show no correlation between the fractal dimensions of the…

Solar and Stellar Astrophysics · Physics 2015-05-14 M. Dimitropoulou , M. Georgoulis , H. Isliker , L. Vlahos , A. Anastasiadis , D. Strintzi , X. Moussas

We studied the physical parameters of the penumbra in a large and fully-developed sunspot, one of the largest over the last two solar cycles, by using full-Stokes measurements taken at the photospheric Fe I 617.3 nm and chromospheric Ca II…

Solar and Stellar Astrophysics · Physics 2019-03-20 Mariarita Murabito , I. Ermolli , F. Giorgi , M. Stangalini , S. L. Guglielmino , S. Jafarzadeh , H. Socas-Navarro , P. Romano , F. Zuccarello

Full-disk measurements of the solar magnetic field by the Helioseismic and Magnetic Imager (HMI) are often used for magnetic field extrapolations, but its limited spatial and spectral resolution can lead to significant errors. We compare…

Solar and Stellar Astrophysics · Physics 2024-11-27 C. Beck , A. Prasad , Q. Hu , M. S. Yalim , S. Gosain , D. P. Choudhary

We recently proposed a method to calculate the relative magnetic helicity in a finite volume for a given magnetic field which however required the flux to be balanced separately on all the sides of the considered volume. In order to allow…

Solar and Stellar Astrophysics · Physics 2018-05-30 Shangbin Yang , Joerg Buechner , Jan Skala , Hongqi Zhang

A new form of time-harmonic Maxwells equations is developed and proposed for numerical modeling. It is written for the magnetic field strength, electric displacement, vector potential and the scalar potential. There are several attractive…

Computational Physics · Physics 2023-06-14 Vladimir E. Moiseenko , Olov Agren

The braiding of the solar coronal magnetic field via photospheric motions - with subsequent relaxation and magnetic reconnection -- is one of the most widely debated ideas of solar physics. We readdress the theory in the light of…

Astrophysics · Physics 2011-02-11 A. L. Wilmot-Smith , G. Hornig , D. I. Pontin

Estimating the magnetic field strength in the solar corona is crucial for understanding different physical processes happening over diverse spatio-temporal scales. However, the high temperatures and low density of the solar corona make this…

Solar and Stellar Astrophysics · Physics 2024-03-07 Upasna Baweja , Vaibhav Pant , Iñigo Arregui

The internal dynamics of the Sun generate magnetic and plasma structures in the photosphere and overlying atmosphere across a wide range of spatial scales. Identifying the critical spatial scale is essential for interpreting physical…

Solar and Stellar Astrophysics · Physics 2026-04-14 Ananya Hore , Prantika Bhowmik

Deciphering and understanding the small-scale magnetic activity of the quiet solar photosphere should help to solve many of the key problems of solar and stellar physics, such as the magnetic coupling to the outer atmosphere and the coronal…

Astrophysics · Physics 2007-05-23 J. Trujillo Bueno , N. Shchukina , A. Asensio Ramos

The hemispheric pattern of solar filaments is considered using newly-developed simulations of the real photospheric and 3D coronal magnetic fields over a 6-month period, on a global scale. The magnetic field direction in the simulation is…

Astrophysics · Physics 2015-05-13 A. R. Yeates , D. H. Mackay , A. A. van Ballegooijen