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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

Magnetoseismology, a technique of magnetic field diagnostics based on observations of magnetohydrodynamic (MHD) waves, has been widely used to estimate the field strengths of oscillating structures in the solar corona. However, previously…

Solar and Stellar Astrophysics · Physics 2020-11-05 Zihao Yang , Hui Tian , Steven Tomczyk , Richard Morton , Xianyong Bai , Tanmoy Samanta , Yajie Chen

We undertake a first attempt towards a consistent reconstruction of the coronal magnetic field and the coronal density structure. We consider a stationary solar corona which has to obey the equations of magnetohydrostatics. We solve these…

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

Solar flares and plasma eruptions are sudden releases of magnetic energy stored in the plasma atmosphere. To understand the physical mechanisms governing their occurrences, three-dimensional magnetic fields from the photosphere up to the…

Solar and Stellar Astrophysics · Physics 2021-03-24 Takafumi Kaneko , Sung-Hong Park , Kanya Kusano

This paper is dedicated to design a direct sampling method of inverse electromagnetic scattering problems, which uses multi-frequency sparse backscattering far field data for reconstructing the boundary of perfectly conducting obstacles. We…

Analysis of PDEs · Mathematics 2020-10-28 Tilo Arens , Xia Ji , Xiaodong Liu

With current observational methods it is not possible to directly measure the magnetic field in the solar corona with sufficient accuracy. Therefore, coronal magnetic field models have to rely on extrapolation methods using photospheric…

Solar and Stellar Astrophysics · Physics 2025-04-24 Lilli Nadol , Thomas Neukirch

Understanding and monitoring solar active regions is essential for operational space-weather forecasting and improved solar dynamo modeling. This requires comprehensive 360-degree observations of the Sun. While space-weather forecasting has…

Solar and Stellar Astrophysics · Physics 2026-03-04 Amr Hamada , Kiran Jain , Hanna Strecker , Charles Lindsey , David Orozco Suarez

The topology of the coronal magnetic field produces a strong impact on the properties of the solar corona and presumably on the origin of the slow solar wind. To advance our understanding of this impact, we revisit the concept of so-called…

Solar and Stellar Astrophysics · Physics 2020-03-04 R. Lionello , V. S. Titov , Z. Mikić , J. A. Linker

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

This paper is concerned with uniqueness, phase retrieval and shape reconstruction methods for solving inverse electromagnetic source scattering problems with multi-frequency sparse phased or phaseless far field data. With the phased data,…

Analysis of PDEs · Mathematics 2019-06-07 Xia Ji , Xiaodong Liu

Understanding many physical processes in the solar atmosphere requires determination of the magnetic field in each atmospheric layer. However, direct measurements of the magnetic field in the Sun's corona are difficult to obtain. Using…

Aims. We show how the build-up of magnetic gradients in the Sun's corona may be inferred directly from photospheric velocity data. This enables computation of magnetic connectivity measures such as the squashing factor without recourse to…

Solar and Stellar Astrophysics · Physics 2015-05-30 A. R. Yeates , G. Hornig , B. T. Welsch

We consider a model of an electric circuit, where differential algebraic equations for a circuit part are coupled to partial differential equations for an electromagnetic field part. An uncertainty quantification is performed by changing…

Numerical Analysis · Mathematics 2019-03-11 Roland Pulch , Sebastian Schöps

Solar variability investigations that include magnetic energy coupling are paramount to solving many key solar/stellar physics problems, particularly for understanding the temporal variability of magnetic energy redistribution and heating…

Solar and Stellar Astrophysics · Physics 2016-12-28 N. Brice Orange , David L. Chesny , Bruce Gendre , David C. Morris , Hakeem M. Oluseyi

We present a method to include stereoscopic information about the three dimensional structure of flux tubes into the reconstruction of the coronal magnetic field. Due to the low plasma beta in the corona we can assume a force free magnetic…

Astrophysics · Physics 2015-05-13 T. Wiegelmann , T. Neukirch

Faraday rotation of the polarization plane in magnetized thermal plasma provides one of the most efficient methods to deduce regular magnetic fields from radio astronomical observations. Since the Faraday rotation measure RM is proportional…

Astrophysics · Physics 2009-11-10 Rainer Beck , Anvar Shukurov , Dmitry Sokoloff , Richard Wielebinski

Solar magnetic fields play a key role in understanding the nature of the coronal phenomena. Global coronal magnetic fields are usually extrapolated from photospheric fields, for which farside data is taken when it was at the frontside,…

Solar and Stellar Astrophysics · Physics 2022-04-28 Hyun-Jin Jeong , Yong-Jae Moon , Eunsu Park , Harim Lee

AIMS: We develop an optimization principle for computing stationary MHD equilibria. METHODS: Our code for the self-consistent computation of the coronal magnetic fields and the coronal plasma uses non-force-free MHD equilibria. Previous…

Astrophysics · Physics 2008-11-26 Thomas Wiegelmann , Thomas Neukirch

We present a novel magnetohydrostatic numerical model that solves directly for the force-balanced magnetic field in the solar corona. This model is constructed with Radial Basis Function Finite Differences (RBF-FD), specifically 3D…

Solar and Stellar Astrophysics · Physics 2022-05-11 Nathaniel H. Mathews , Natasha Flyer , Sarah E. Gibson

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