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Solar flares occur due to the sudden release of energy stored in active-region magnetic fields. To date, the pre-cursors to flaring are still not fully understood, although there is evidence that flaring is related to changes in the…

Solar and Stellar Astrophysics · Physics 2012-02-01 Sophie A. Murray , D. Shaun Bloomfield , Peter T. Gallagher

The structure and dynamics of the solar corona is dominated by the magnetic field. In most areas in the corona magnetic forces are so dominant that all non-magnetic forces like plasma pressure gradient and gravity can be neglected in the…

Solar and Stellar Astrophysics · Physics 2021-03-24 Thomas Wiegelmann , Takashi Sakurai

We present simulations modeling closed regions of the solar corona threaded by a strong magnetic field where localized photospheric vortical motions twist the coronal field lines. The linear and nonlinear dynamics are investigated in the…

Solar and Stellar Astrophysics · Physics 2013-06-20 A. F. Rappazzo , M. Velli , G. Einaudi

Photospheric magnetic field not only plays important roles in building up free energy and triggering solar eruptions, but also has been observed to change rapidly and permanently responding to the coronal magnetic field restructuring due to…

Solar and Stellar Astrophysics · Physics 2011-03-02 Shuo Wang , Chang Liu , Rui Liu , Na Deng , Yang Liu , Haimin Wang

The theoretical concept that braided magnetic field lines in the solar corona may dissipate a sufficient amount of energy to account for the brightening observed in the active-region corona, has been substantiated by high-resolution…

Solar and Stellar Astrophysics · Physics 2015-06-17 J. K. Thalmann , S. K. Tiwari , T. Wiegelmann

We aim to better characterize the conditions of the solar corona, especially with respect to the occurrence of confined and eruptive flares. In this work, we model the coronal evolution around 231 large flares observed during solar cycle…

Solar and Stellar Astrophysics · Physics 2025-01-29 Julia K. Thalmann , Manu Gupta , Astrid M. Veronig , Yang Liu

Sunspots are regions of decreased brightness on the visible surface of the Sun (photosphere) that are associated with strong magnetic fields. They have been found to be locations associated with solar flares, which occur when energy stored…

Solar and Stellar Astrophysics · Physics 2013-01-24 Sophie A. Murray

The coronal magnetic field is an important quantity because the magnetic field dominates the structure of the solar corona. Unfortunately direct measurements of coronal magnetic fields are usually not available. The photospheric magnetic…

Astrophysics · Physics 2009-06-25 T. Wiegelmann

We used multi-wavelength high-resolution data from ARIES, THEMIS, and SDO instruments, to analyze a non-standard, C3.3 class flare produced within the active region NOAA 11589 on 2012 October 16. Magnetic flux emergence and cancellation…

Solar and Stellar Astrophysics · Physics 2016-02-22 K. Dalmasse , R. Chandra , B. Schmieder , G. Aulanier

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 study the quasi-static evolution of coronal magnetic fields constructed from the Non Linear Force Free Field (NLFFF) approximation aiming to understand the relation between the magnetic field topology and ribbon emission during an X1.5…

Solar and Stellar Astrophysics · Physics 2015-06-22 P. Vemareddy , T. Wiegelmann

The abrupt and permanent changes of photospheric magnetic field in the localized regions of active regions during solar flares called magnetic imprints (MIs), have been observed for the past nearly three decades. The well known "coronal…

Solar and Stellar Astrophysics · Physics 2022-03-14 N. Vasantharaju , P. Vemareddy , B. Ravindra , V. H. Doddamani

The magnetic field plays a key role in producing solar flares, so that the investigation on the relationship between the magnetic field properties and flares is significant. In this paper, based on the magnetic field extrapolated from the…

Solar and Stellar Astrophysics · Physics 2019-05-07 S. Liu , D. Liu

Flares and eruptions from solar active regions are associated with atmospheric electrical currents accompanying distortions of the coronal field away from a lowest-energy potential state. In order to better understand the origin of these…

Solar and Stellar Astrophysics · Physics 2016-04-06 C. J. Schrijver

Knowledge regarding the coronal magnetic field is important for the understanding of many phenomena, like flares and coronal mass ejections. Because of the low plasma beta in the solar corona the coronal magnetic field is often assumed to…

Astrophysics · Physics 2008-11-26 Thomas Wiegelmann , Bernd Inhester , Takashi Sakurai

The evolution of nonpotential characteristics of magnetic fields in AR 5747 is presented using Mees Solar Observatory magnetograms taken on Oct. 20, 1989 to Oct. 22, 1989. The active region showed such violent flaring activities during the…

Astrophysics · Physics 2007-05-23 Y. -J. Moon , H. S. Yun , G. S. Choe , Y. D. Park , D. L. Mickey

Predicting the severity of the solar eruptive phenomena like flares and Coronal Mass Ejections (CMEs) remains a great challenge despite concerted efforts for several decades. The advent of high quality vector magnetograms obtained from…

Solar and Stellar Astrophysics · Physics 2015-05-19 Sanjiv Kumar Tiwari , P. Venkatakrishnan , Sanjay Gosain

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 present study provides statistical information on the coronal magnetic field and intensity properties of small-scale bright and faint loops in the quiet Sun. We aim to quantitatively investigate the morphological and topological…

Solar and Stellar Astrophysics · Physics 2024-10-16 Maria S. Madjarska , Thomas Wiegelmann , Pascal Démoulin , Klaus Galsgaard

A nonlinear force-free solution is constructed for the coronal magnetic field in NOAA solar active region AR 10953 based on a photospheric vector magnetogram derived from Hinode satellite observations on 30 April 2007, taking into account…

Solar and Stellar Astrophysics · Physics 2015-05-20 M. S. Wheatland , K. D. Leka