Fast degradation of the circular flare ribbon on 2014 August 24

Zhang, Q. M.; Yang, Shuhong; Li, Tao; Hou, Yijun; Li, Y.

doi:10.1051/0004-6361/202038072

Cited by 14 publications

(7 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The three-dimensional (3D) magnetic configuration of CRFs is usually related to a fan-spine structure associated with a magnetic null point (Wang and Liu, 2012;Zhang et al, 2012;Sun et al, 2013;Hou et al, 2019;Lee et al, 2020;Liu et al, 2020;Yang et al, 2020;Zhang et al, 2021). CRFs are occasionally accompanied by coronal jets or cool surges Li et al, 2017;Xu et al, 2017;Dai et al, 2020;Zhang et al, 2020). The dynamic evolution of CRFs, including magnetic reconnection near the null point, particle acceleration and precipitation, chromospheric evaporation and condensation, are found to resemble those of two-ribbon flares .…”

Section: Introductionmentioning

confidence: 99%

Energy Partition in Four Confined Circular-Ribbon Flares

Cai,

Zhang,

Ning

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

In this study, we investigated the energy partition of four confined circular-ribbon flares (CRFs) near the solar disk center, which are observed simultaneously by SDO, GOES, and RHESSI. We calculated different energy components, including the radiative outputs in 1−8, 1−70, and 70−370 Å, total radiative loss, peak thermal energy derived from GOES and RHESSI, nonthermal energy in flare-accelerated electrons, and magnetic free energy before flares. It is found that the energy components increase systematically with the flare class, indicating that more energies are involved in larger flares. The magnetic free energies are larger than the nonthermal energies and radiative outputs of flares, which is consistent with the magnetic nature of flares. The ratio E nth Emag of the four flares, being 0.70−0.76, is considerably higher than that of eruptive flares. Hence, this ratio may serve as an important factor that discriminates confined and eruptive flares. The nonthermal energies are sufficient to provide the heating requirements including the peak thermal energy and radiative loss. Our findings impose constraint on theoretical models of confined CRFs and have potential implication for the space weather forecast.

show abstract

Section: Introductionmentioning

confidence: 99%

Energy Partition in Four Confined Circular-Ribbon Flares

Cai,

Zhang,

Ning

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

“…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

View full text Add to dashboard Cite

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

show abstract

“…5). The breakout jet model is verified observationally by the signatures of a rotating jet and fast degradation of the circular flare ribbon following the coherent brightenings of the ribbon associated with the jet (Zhang et al 2020). Breakout reconnection at the null point of a fan-spine structure is recently evidenced by the bidirectional outflows ejected from the reconnection site (Yang et al 2020).…”

Section: Introductionmentioning

confidence: 75%

Spectroscopic observations of a flare-related coronal jet

Zhang,

Huang,

Hou

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

Context. Coronal jets are ubiquitous in active regions (ARs) and coronal holes. Aims. In this paper, we study a coronal jet related to a C3.4 circular-ribbon flare in active region 12434 on 2015 October 16. Methods. The flare and jet were observed in ultraviolet (UV) and extreme ultraviolet (EUV) wavelengths by the Atmospheric Imaging Assembly (AIA) on board the Solar Dynamics Observatory (SDO). The line-of-sight (LOS) magnetograms of the photosphere were observed by the Helioseismic and Magnetic Imager (HMI) on board SDO. The whole event was covered by the Interface Region Imaging Spectrograph (IRIS) during its imaging and spectroscopic observations. Soft X-ray (SXR) fluxes of the flare were recorded by the GOES spacecraft. Hard X-ray (HXR) fluxes at 4−50 keV were obtained from observations of RHESSI and Fermi. Radio dynamic spectra of the flare were recorded by the ground-based stations belonging to the e-Callisto network. Results. Two minifilaments were located under a 3D fan-spine structure before flare. The flare was generated by the eruption of one filament. The kinetic evolution of the jet was divided into two phases: a slow rise phase at a speed of ∼131 km s −1 and a fast rise phase at a speed of ∼363 km s −1 in the plane-of-sky. The slow rise phase may correspond to the impulsive reconnection at the breakout current sheet. The fast rise phase may correspond to magnetic reconnection at the flare current sheet. The transition between the two phases occurred at ∼09:00:40 UT. The blueshifted Doppler velocities of the jet in the Si iv 1402.80 Å line range from -34 to -120 km s −1 . The accelerated high-energy electrons are composed of three groups. Those propagating upward along open field generate type III radio bursts, while those propagating downward produce HXR emissions and drive chromospheric condensation observed in the Si iv line. The electrons trapped in the rising filament generate a microwave burst lasting for ≤40 s. Bidirectional outflows at the base of jet are manifested by significant line broadenings of the Si iv line. The blueshifted Doppler velocities of outflows range from -13 to -101 km s −1 . The redshifted Doppler velocities of outflows range from ∼17 to ∼170 km s −1 . Conclusions. Our multiwavelength observations of the flare-related jet are in favor of the breakout jet model and are important for understanding the acceleration and transport of nonthermal electrons.

show abstract

Fast degradation of the circular flare ribbon on 2014 August 24

Cited by 14 publications

References 51 publications

Energy Partition in Four Confined Circular-Ribbon Flares

Energy Partition in Four Confined Circular-Ribbon Flares

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

Spectroscopic observations of a flare-related coronal jet

Contact Info

Product

Resources

About