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Using an efficient magnetic complexity index in the active-region solar photosphere, we quantify the preflare strength of the photospheric magnetic polarity inversion lines in 23 eruptive active regions with flare/CME/ICME events tracked…

Astrophysics · Physics 2015-05-13 M. K. Georgoulis

Violent solar flares and coronal mass ejections (CMEs) are magnetic phenomena. However, how magnetic fields reconnecting in the flare differ from non-flaring magnetic fields remains unclear owing to the lack of studies of the flare magnetic…

Solar and Stellar Astrophysics · Physics 2022-02-23 Maria D. Kazachenko , Benjamin J. Lynch , Antonia Savcheva , Xudong Sun , Brian T. Welsch

The dynamics of magnetic fields in the Sun's active regions plays a key role in triggering solar eruptions. Studies have shown that changes in the photosphere's magnetic field can destabilize large-scale structure of the corona, leading to…

Solar and Stellar Astrophysics · Physics 2025-03-25 Partha Chowdhury , Belur Ravindra , Sanjiv Kumar Tiwari

Solar sub-surface fluid topology provides an indirect approach to examine the internal characteristics of active regions (ARs). Earlier studies have revealed the prevalence of strong flows in the interior of ARs having complex magnetic…

Solar and Stellar Astrophysics · Physics 2010-04-19 R. A. Maurya , A. Ambastha

A magnetic power spectral analysis is performed on 53 solar active regions, observed from August 2011 to July 2012. Magnetic field data obtained from the Helioseismic and Magnetic Imager, inverted as Active Region Patches, are used to study…

Solar and Stellar Astrophysics · Physics 2016-12-28 Revati S. Mandage , R. T. James McAteer

Context: Solar active regions (ARs) are key manifestations of the Sun's magnetic activity, displaying diverse spatial and temporal characteristics. Their formation and evolution play a crucial role in understanding the solar dynamo and…

Solar and Stellar Astrophysics · Physics 2025-08-06 M. Švanda , J. Jurčák , M. Schmassmann

Solar flares originate from magnetically active regions but not all solar active regions give rise to a flare. Therefore, the challenge of solar flare prediction benefits by an intelligent computational analysis of physics-based properties…

Solar and Stellar Astrophysics · Physics 2019-10-09 Cristina Campi , Federico Benvenuto , Anna Maria Massone , D Shaun Bloomfield , Manolis K Georgoulis , Michele Piana

Solar flares are explosions in the solar atmosphere that release intense bursts of short-wavelength radiation and are capable of producing severe space-weather consequences. Flares release free energy built up in coronal fields, which are…

Solar and Stellar Astrophysics · Physics 2020-08-05 Shamik Bhattacharjee , Rasha Alshehhi , Dattaraj B. Dhuri , Shravan M. Hanasoge

In this ISSI-supported series of studies on magnetic helicity in the Sun, we systematically implement different magnetic helicity calculation methods on high-quality solar magnetogram observations. We apply finite-volume, discrete flux tube…

Solar and Stellar Astrophysics · Physics 2021-11-24 J. K. Thalmann , M. K. Georgoulis , Y. Liu , E. Pariat , G. Valori , S. Anfinogentov , F. Chen , Y. Guo , K. Moraitis , S. Yang , A. Mastrano

We have performed a three-dimensional magnetohydrodynamic simulation to study the emergence of a twisted magnetic flux tube from -20,000 km of the solar convection zone to the corona through the photosphere and the chromosphere. The middle…

Solar and Stellar Astrophysics · Physics 2015-06-03 S. Toriumi , T. Yokoyama

Active regions (ARs) appear in the solar atmosphere as a consequence of the emergence of magnetic flux-ropes (FR). In this study, we use Bayesian methods to analyze line-of-sight magnetograms of emerging ARs. We employ a FR model consisting…

Solar and Stellar Astrophysics · Physics 2024-05-21 Mariano Poisson , Marcelo López Fuentes , Cristina H. Mandrini , Pascal Démoulin , Francisco Grings

Erupting magnetic flux ropes (MFRs) play a crucial role in producing solar flares. However, the formation of erupting MFRs in complex coronal magnetic configurations and their subsequent evolution in the flaring events are not fully…

Solar and Stellar Astrophysics · Physics 2023-08-30 Avijeet Prasad , Sanjay Kumar , Alphonse C. Sterling , Ronald L. Moore , Guillaume Aulanier , R. Bhattacharyya , Qiang Hu

Linking solar wind properties to the activities and characteristics of its source regions can enhance our understanding of its origin and generation mechanisms. Using the Mount Wilson magnetic classification (MWMC), we categorize all active…

Solar and Stellar Astrophysics · Physics 2025-10-13 Xinzheng Shi , Hui Fu , Zhenghua Huang , Limei Yan , Qi Liu , Lidong Xia

Most models of solar eruptions assume that coronal field lines are anchored in the dense photosphere and thus the photospheric magnetic fields would not have rapid, irreversible changes associated with eruptions resulted from the coronal…

Solar and Stellar Astrophysics · Physics 2015-05-19 Haimin Wang , Chang Liu

Multiple recent investigations of solar magnetic field measurements have raised claims that the scale-free (fractal) or multiscale (multifractal) parameters inferred from the studied magnetograms may help assess the eruptive potential of…

Solar and Stellar Astrophysics · Physics 2015-05-20 Manolis K. Georgoulis

Aims. Although the temporal evolution of active regions (ARs) is relatively well understood, the processes involved continue to be the subject of investigation. We study how the magnetic field of a series of ARs evolves with time to better…

During Solar Cycle 23, some active regions(ARs) produced extremely energetic flares and CMEs. These ARs are expected to be characteristically distinct as compared to dormant ARs and quiet regions (QRs). It would be interesting to identify…

Solar and Stellar Astrophysics · Physics 2016-01-27 R. A. Maurya , A. Ambastha

Measuring the magnetic helicity distribution in the solar corona can help in understanding the trigger of solar eruptive events because magnetic helicity is believed to play a key role in solar activity due to its conservation property. A…

Solar and Stellar Astrophysics · Physics 2013-07-11 K. Dalmasse , E. Pariat , G. Valori , P. Démoulin , L. M. Green

We report a detailed event analysis on the M6.6-class flare in the active region (AR) NOAA 11158 on 2011 February 13. AR 11158, which consisted of two major emerging bipoles, showed prominent activities including one X- and several M-class…

Solar and Stellar Astrophysics · Physics 2015-06-16 Shin Toriumi , Yusuke Iida , Yumi Bamba , Kanya Kusano , Shinsuke Imada , Satoshi Inoue

Solar flares and coronal mass ejections, the primary space weather disturbances affecting the entire heliosphere and near-Earth environment, mainly emanate from sunspot regions harbouring high degrees of magnetic twist. However, it is not…

Solar and Stellar Astrophysics · Physics 2023-06-01 Shin Toriumi , Hideyuki Hotta , Kanya Kusano