Investigation of White-light Emission in Circular-ribbon Flares

Song, Yongliang

doi:10.3847/1538-4357/aae5d1

Cited by 31 publications

(12 citation statements)

References 82 publications

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“…Analysis of the magnetic field topology in active regions may help us understand the production of WLFs (Song & Tian 2018;Song et al 2018b). From the photospheric magnetogram obtained with HMI at 15:12 UT, we reconstructed the three-dimensional (3D) magnetic field structure about 10 minutes before the flare.…”

Section: Resultsmentioning

confidence: 99%

A White-light Flare Powered by Magnetic Reconnection in the Lower Solar Atmosphere

Song

Zhu

Chen

et al. 2020

ApJL

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White-light flares (WLFs), first observed in 1859, refer to a type of solar flares showing an obvious enhancement of the visible continuum emission. This type of enhancement often occurs in most energetic flares, and is usually interpreted as a consequence of efficient heating in the lower solar atmosphere through non-thermal electrons propagating downward from the energy release site in the corona. However, this coronal-reconnection model has difficulty in explaining the recently discovered small WLFs. Here we report a C2.3 white-light flare, which are associated with several observational phenomena: fast decrease in opposite-polarity photospheric magnetic fluxes, disappearance of two adjacent pores, significant heating of the lower chromosphere, negligible increase of hard X-ray flux, and an associated U-shaped magnetic field configuration. All these suggest that this white-light flare is powered by magnetic reconnection in the lower part of the solar atmosphere rather than by reconnection higher up in the corona.

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Section: Resultsmentioning

confidence: 99%

A White-light Flare Powered by Magnetic Reconnection in the Lower Solar Atmosphere

Song

Zhu

Chen

et al. 2020

ApJL

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“…When magnetic reconnection takes place at the null point of a fan-spine, the accelerated particles move along the fan surface and hit the lower atmosphere, where a circular ribbon would be observable in the chromosphere (Masson et al 2009(Masson et al , 2017Reid et al 2012;Zhang et al 2016Zhang et al , 2020Zhong et al 2019;Lee et al 2020) and even in the photosphere (Hao et al 2017;Song & Tian 2018) if the flare is strong enough. When the spine is open to the interplanetary space, a jet and a consequent coronal mass ejection may be formed (Pariat et al 2009;Hong et al 2017).…”

Section: Introductionmentioning

confidence: 99%

Imaging and spectral study on the null point of a fan-spine structure during a solar flare

Yang,

Zhang,

et al. 2020

Preprint

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Using the multi-instrument observations, we make the first simultaneous imaging and spectral study on the null point of a fan-spine magnetic topology during a solar flare. When magnetic reconnection occurs at the null point, the fan-spine configuration brightens in the (extreme-)ultraviolet channels. In the Hα images, the fan-spine structure is partly filled and outlined by the bi-directional material flows ejected from the reconnection site. The extrapolated coronal magnetic field confirms the existence of the fan-spine topology. Before and after the flare peak, the total velocity of the outflows is estimated to be about 60 km s −1 . During the flare, the Si iv line profile at the reconnection region is enhanced both in the blue-wing and red-wing. At the flare peak time, the total velocity of the outflows is found to be 144 km s −1 . Superposed on the Si iv profile, there are several deep absorption lines with the blueshift of several tens of km s −1 . The reason is inferred to be that the bright reconnection region observed in Si iv channel is located under the cooler material appearing as dark features in the Hα line. The blueshifted absorption lines indicate the movement of the cooler material toward the observer. The depth of the absorption lines also depends on the amount of cooler material. These results imply that this kind of spectral

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“…For threedimensional magnetic reconnection within the thin quasi-separatrix layers (Demoulin et al 1996), flare ribbons propagate along the intersection of QSLs with the chromosphere (Aulanier et al 2007). Circular-ribbon flares (CRFs) are a special kind of flares that consist of a central short ribbon and a surrounding ribbon with a circular or quasi-circular shape (e.g., Masson et al 2009;Reid et al 2012;Jiang et al 2013;Joshi et al 2015;Kumar et al 2015;Yang et al 2015;Hao et al 2017;Hernandez-Perez et al 2017;Song & Tian 2018;Chen et al 2019;Li & Yang 2019;. Most of them are confined flares without CMEs.…”

Section: Introductionmentioning

confidence: 99%

Energy Partition in Two M-class Circular-ribbon Flares

Zhang

Cheng

Feng

et al. 2019

ApJ

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In this paper, we investigate the energy partition of two homologous M1.1 circularribbon flares (CRFs) in active region (AR) 12434. They were observed by SDO, GOES, and RHESSI on 2015 October 15 and 16, respectively. The peak thermal energy, nonthermal energy of flare-accelerated electrons, total radiative loss of hot plasma, and radiant energies in 1−8Å and 1−70Å of the flares are calculated. The two flares have similar energetics. The peak thermal energies are (1.94±0.13)×10 30 erg. The nonthermal energies in flare-accelerated electrons are (3.9±0.7)×10 30 erg. The radiative outputs of the flare loops in 1−70Å, which are ∼200 times greater than the outputs in 1−8Å, account for ∼62.5% of the peak thermal energies. The radiative losses of SXR-emitting plasma are one order of magnitude lower than the peak thermal energies. Therefore, the total heating requirements of flare loops including radiative loss are (2.1±0.1)×10 30 erg, which could sufficiently be supplied by nonthermal electrons.

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Investigation of White-light Emission in Circular-ribbon Flares

Cited by 31 publications

References 82 publications

A White-light Flare Powered by Magnetic Reconnection in the Lower Solar Atmosphere

A White-light Flare Powered by Magnetic Reconnection in the Lower Solar Atmosphere

Imaging and spectral study on the null point of a fan-spine structure during a solar flare

Energy Partition in Two M-class Circular-ribbon Flares

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