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Solar active regions are driven dissipative dynamical systems. The turbulent convection zone forces new magnetic flux tubes to rise above the photosphere and shuffles the magnetic fields which are already above the photosphere. The driven…

Astrophysics · Physics 2009-09-29 Loukas Vlahos

The coronal magnetic field evolution of AR 11437 is simulated by applying the magnetofrictional relaxation technique of Mackay et al. (2011). A sequence of photospheric line-of-sight magnetograms produced by SDO/HMI are used to drive the…

Solar and Stellar Astrophysics · Physics 2018-01-10 Stephanie L. Yardley , Duncan H. Mackay , Lucie M. Green

Contraction-driven self-propulsion of a large class of living cells can be modeled by a Keller-Segel system with free boundaries. The ensuing "active" system, exhibiting both dissipation and anti-dissipation, features stationary and…

Analysis of PDEs · Mathematics 2024-11-20 Leonid Berlyand , C. Alex Safsten , Lev Truskinovsky

Magnetic field extrapolation from the solar photosphere to the corona plays an important role in solar physics research. In this work, we present a fully-implicit viscous-relaxation nonlinear force-free field (FIVR-NLFFF) extrapolation code…

Solar and Stellar Astrophysics · Physics 2025-09-18 Zhenhua Liu , Chaowei Jiang

Magnetic fields and flows in coronal structures, for example, in gradual phases in flares, can be described by 2D and 3D magnetohydrostatic (MHS) and steady magnetohydrodynamic (MHD) equilibria. Within a physically simplified, but exact…

Solar and Stellar Astrophysics · Physics 2014-09-17 D. H. Nickeler , M. Karlicky , T. Wiegelmann , M. Kraus

To study the three-dimensional (3D) magnetic field topology and its long-term evolution associated with the X3.4 flare of 2006 December 13, we investigate the coronal relative magnetic helicity in the flaring active region (AR) NOAA 10930…

Solar and Stellar Astrophysics · Physics 2015-05-19 Sung-Hong Park , Jongchul Chae , Ju Jing , Changyi Tan , Haimin Wang

The Minimum Current Corona (MCC) model provides a way to estimate stored coronal energy using the number of field lines connecting regions of positive and negative photospheric flux. This information is quantified by the net flux connecting…

Solar and Stellar Astrophysics · Physics 2015-06-04 L. A. Tarr , D. W. Longcope

Modeling the interface region between solar photosphere and corona is challenging, because the relative importance of magnetic and plasma forces change by several orders of magnitude. While the solar corona can be modeled by the force-free…

Solar and Stellar Astrophysics · Physics 2018-10-31 Xiaoshuai Zhu , Thomas Wiegelmann

We present a code for solving the nonlinear force-free equations in spherical polar geometry, with the motivation of modeling the magnetic field in the corona. The code is an implementation of the Grad-Rubin method. Our method is applicable…

Solar and Stellar Astrophysics · Physics 2016-10-28 S. A. Gilchrist , M. S. Wheatland

Force-freeness of a solar magnetic field is a key to reconstructing invisible coronal magnetic structure of an emerging flux region on the Sun where active phenomena such as flares and coronal mass ejections frequently occur. We have…

Solar and Stellar Astrophysics · Physics 2015-06-23 Jihye Kang , Tetsuya Magara

Recent studies indicate that a small number of rogue solar active regions (ARs) may have a significant impact on the end-of-cycle polar field and the long-term behavior of solar activity. The impact of individual ARs can be qualified based…

Solar and Stellar Astrophysics · Physics 2024-05-13 Ruihui Wang , Jie Jiang , Yukun Luo

In this study, the non-potential magnetic field parameters of active region NOAA 9077 are investigated; this AR experienced a super-strong X5.7 solar flare. Using advanced extrapolation techniques, the 3D magnetic field structure from…

Solar and Stellar Astrophysics · Physics 2025-06-18 Liu Suo , Shahid Idrees , Liu Dian , Zeng Shuguang

The photospheric magnetic field vector is continuously derived from measurements, while reconstruction of the three-dimensional (3D) coronal magnetic field requires modelling with photospheric measurements as a boundary condition. For…

Solar and Stellar Astrophysics · Physics 2022-03-23 I. Chifu , B. Inhester , T. Wiegelmann

Solar flares are powered by energy stored in the coronal magnetic field, a portion of which is released when the field reconfigures into a lower energy state. Investigation of sunspot magnetic field topology during flare activity is useful…

Solar and Stellar Astrophysics · Physics 2015-03-10 Sophie A. Murray , D. Shaun Bloomfield , Peter T. Gallagher

Reliable measurements of the solar magnetic field are still restricted to the photosphere, and our present knowledge of the three-dimensional coronal magnetic field is largely based on extrapolation from photospheric magnetogram using…

Solar and Stellar Astrophysics · Physics 2015-06-05 Chaowei Jiang , Xueshang Feng , Changqing Xiang

Magnetohydrodynamics of the solar corona is simulated numerically. The simulation is initialized with an extrapolated non-force-free magnetic field using the vector magnetogram of the active region (AR) NOAA 12192 obtained on the solar…

Solar and Stellar Astrophysics · Physics 2018-06-26 A. Prasad , R. Bhattacharyya , Qiang Hu , Sanjay Kumar , Sushree S. Nayak

Non-linear force-free fields are the most general case of force-free fields, but the hardest to model as well. There are numerous methods of computing such fields by extrapolating vector magnetograms from the photosphere, but very few…

Solar and Stellar Astrophysics · Physics 2021-06-29 A. Malanushenko , D. W. Longcope , D. E. McKenzie

In this work, we introduce a novel generative denoising diffusion model for synthesizing the Sun's three-dimensional coronal magnetic field, a complex and dynamic region characterized by evolving magnetic structures. Despite daily…

Solar and Stellar Astrophysics · Physics 2025-10-03 Daniel E. da Silva , Michael Kirk , Nat Mathews , Andrés Muñoz-Jaramillo

Although it is generally believed that the solar photosphere is not magnetically force-free owning to its high plasma $\beta$, the estimations of force-freeness using observed magnetograms have produced disputable results. Some studies…

Solar and Stellar Astrophysics · Physics 2023-09-28 Mei Zhang , Haocheng Zhang

The recent observations of Singh et al. (2012) have shown multiple plasma ejections and the intermittent nature of magnetic reconnection in the solar chromosphere, highlighting the need for fast reconnection to occur in highly collisional…

Solar and Stellar Astrophysics · Physics 2016-04-20 K. A. P. Singh , Andrew Hillier , H. Isobe , K. Shibata
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