Chirality and Magnetic Configurations of Solar Filaments

Ouyang, Yu; Zhou, Yuhao; Chen, P. F.; Fang, Cheng

doi:10.3847/1538-4357/835/1/94

Cited by 91 publications

(15 citation statements)

References 66 publications

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“…Thus, the magnetic chirality is left-handed for AR 10930 and right-handed for AR 11158. (Note that this definition of chirality for vector magnetic field in solar ARs is consistent with the chirality definition in literature for solar chromospheric filaments, see e.g., Ouyang et al 2017. ) The chiral characteristics of ARs can be quantitatively indicated by the signs of force-free factor α of the coronal magnetic field.…”

Section: Chirality Of the Magnetic Fields In The Two Active Regionssupporting

confidence: 88%

“…Flare activity was also discovered on the solar-type stars other than the Sun (Schaefer et al 2000;Benz & Güdel 2010;Shibata & Magara 2011;Maehara et al 2012;Notsu et al 2013;Shibayama et al 2013;Balona 2015;Davenport 2016). Solar flares commonly come from solar active regions (ARs), and the magnetic configuration of flare-bearing ARs is one key aspect for understanding the initiation and evolution of solar flares (e.g., Chen et al 2012;Sun et al 2015;Jiang et al 2016Jiang et al , 2018Liu et al 2016;Cheng et al 2017;Guo et al 2017;Hao et al 2017;Inoue et al 2018) and other related eruptive phenomena in the solar atmosphere (e.g., Zhang et al 2012;Ouyang et al 2017;Wang et al 2017;Liu et al 2018). The non-potential property of the magnetic fields with electric current permeating inside is believed to be the critical aspect related to the activity level of ARs (e.g., Wang et al 1996;Leka & Barnes 2003;Schrijver 2016).…”

Section: Introductionmentioning

confidence: 99%

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Chirality and magnetic configuration associated with two-ribbon solar flares: AR 10930 versus AR 11158

Wang

Yan

et al. 2020

Advances in Space Research

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The magnetic configuration of flare-bearing active regions (ARs) is one key aspect for understanding the initiation of solar flares. In this paper, we perform a comparative analysis on the chiral characteristics and the magnetic configurations of two X-class two-ribbon flares happening in AR 10930 and AR 11158, whose photospheric magnetic fields were observed by the Hinode and SDO satellites, respectively. The corresponding coronal magnetic fields were calculated based on the nonlinear forcefree field model. It is found that both the flares were initiated in local areas with extremely strong electric current density. The chirality of the magnetic field (indicated by the sign of force-free factor α) along the main polarity inversion line (PIL) is opposite for the two ARs, that is, left-handed (α < 0) for AR 10930 and right-handed (α > 0) for AR 11158. The analysis shows that, for both flare events, prominent magnetic connectivity (indicated by both high α and strong current distributions) was formed above the main PIL before the flare and was totally broken after the flare eruption. Yet the two branches of broken magnetic connectivity, combined with the isolated electric current at the magnetic connectivity breaking site, compose the opposite magnetic configurations for the two ARs owing to their opposite chiral characteristics. That is, Z-shaped configuration for AR 10930 with negative α and left-handed chirality, and inverse Z-shaped configuration for AR 11158 with positive α and right-handed chirality. We speculate that two-ribbon flares can be generally classified to these two magnetic configurations by chirality (α sign) of ARs.

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Section: Chirality Of the Magnetic Fields In The Two Active Regionssupporting

confidence: 88%

Section: Introductionmentioning

confidence: 99%

Chirality and magnetic configuration associated with two-ribbon solar flares: AR 10930 versus AR 11158

Wang

Yan

et al. 2020

Advances in Space Research

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“…In general, the magnetic structures of filaments have been explained as a flux-rope configuration or a sheared-arcade configuration, in which magnetic dips were believed to provide upward support against gravity (Guo et al, 2010;Chen, Harra, and Fang, 2014;Yang et al, 2016a;Ouyang et al, 2017). Although no solid observational evidences showed that one of them outdoes the other, the twisted flux rope had been widely adopted in numerous formation models of solar filament/prominence.…”

Section: Introductionmentioning

confidence: 99%

The Formation of a Small-Scale Filament After Flux Emergence on the Quiet Sun

Chen

Yang

et al. 2018

Sol Phys

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We present observations of the formation process of a small-scale filament on the quiet Sun during 5-6 February 2016 and investigate its formation cause. Initially, a small dipole emerged and its associated arch filament system was found to reconnect with overlying coronal fields accompanied by numerous EUV bright points. When bright points faded out, many elongated dark threads formed bridging the positive magnetic element of dipole and external negative network fields. Interestingly, an anti-clockwise photospheric rotational motion (PRM) set in within the positive endpoint region of newborn dark threads following the flux emergence and lasted for more than 10 hours. Under the drive of the PRM, these dispersive dark threads gradually aligned along the north-south direction and finally coalesced into an inverse S-shaped filament. Consistent with the dextral chirality of the filament, magnetic helicity calculations show that an amount of negative helicity was persistently injected from the rotational positive magnetic element and accumulated during the formation of the filament. These observations suggest that twisted emerging fields may lead to the formation of the filament via reconnection with pre-existing fields and release of its inner magnetic twist. The persistent PRM might trace a covert twist relaxation from below photosphere to the low corona.

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“…The long-term variations of solar magnetic structures driven by the magnetic field evolution have been monitored systematically, and there is a statistical imbalance in the occurrence of magnetic activity indicators on both hemispheres when averaged over a certain time scale ranging from a year to a solar cycle (Yan et al, 2008;Xie et al, 2012;Ouyang et al, 2017). This phenomenon is known as the north-south asymmetry of solar activity, and the existence of the hemispheric asymmetry in different solar activity indicators observed in the solar atmosphere is well known.…”

Section: Introductionmentioning

confidence: 99%

Statistical properties of solar Hα flare activity

Deng

Xiao-juan

et al. 2017

J. Space Weather Space Clim.

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-Magnetic field structures on the solar atmosphere are not symmetric distribution in the northern and southern hemispheres, which is an important aspect of quasi-cyclical evolution of magnetic activity indicators that are related to solar dynamo theories. Three standard analysis techniques are applied to analyze the hemispheric coupling (north-south asymmetry and phase asynchrony) of monthly averaged values of solar Ha flare activity over the past 49 years (from 1966 January to 2014 December). The prominent results are as follows: (1) from a global point of view, solar Ha flare activity on both hemispheres are strongly correlated with each other, but the northern hemisphere precedes the southern one with a phase shift of 7 months; (2) the long-range persistence indeed exists in solar Ha flare activity, but the dynamical complexities in the two hemispheres are not identical; (3) the prominent periodicities of Ha flare activity are 17 years full-disk activity cycle and 11 years Schwabe solar cycle, but the short-and mid-term periodicities cannot determined by monthly time series; (4) by comparing the non-parametric rescaling behavior on a point-by-point basis, the hemispheric asynchrony of solar Ha flare activity are estimated to be ranging from several months to tens of months with an average value of 8.7 months. The analysis results could promote our knowledge on the long-range persistence, the quasi-periodic variation, and the hemispheric asynchrony of solar Ha flare activity on both hemispheres, and possibly provide valuable information for the hemispheric interrelation of solar magnetic activity.

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Chirality and Magnetic Configurations of Solar Filaments

Cited by 91 publications

References 66 publications

Chirality and magnetic configuration associated with two-ribbon solar flares: AR 10930 versus AR 11158

Chirality and magnetic configuration associated with two-ribbon solar flares: AR 10930 versus AR 11158

The Formation of a Small-Scale Filament After Flux Emergence on the Quiet Sun

Statistical properties of solar Hα flare activity

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