Energy Partition in Four Confined Circular-Ribbon Flares

Cai, Z. M.; Zhang, Q. M.; Ning, Zhouyu; Su, Yingna; Ji, Haisheng

doi:10.1007/s11207-021-01805-5

Cited by 7 publications

(9 citation statements)

References 86 publications

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“…For the first time, we find that for the same peak X-ray flux confined flares have higher mean peak reconnection rates than eruptive flares (see Figure 5(C)). This together with the fact that HXR (or microwave) emissions are temporally correlated with the global (see Qiu & Cheng 2022 and references therein) and local reconnection rates (Temmer et al 2007;Naus et al 2022), implies that large, eruptive flares are less efficient in particle acceleration than confined flares, in agreement with direct particle measurements (see, e.g., Thalmann et al 2015;Cai et al 2021).…”

Section: Discussionmentioning

confidence: 64%

“…They also found that confined flares are efficient particle accelerators; however, the energies to which electrons are accelerated in confined flares are lower (and do not produce HXR above 300 keV, indicating the lack of efficient acceleration of electrons to high energies), in agreement with Thalmann et al (2015). Cai et al (2021) analyzed energy partition in four confined flares. They found that the ratio of nonthermal energies to magnetic energies is significantly larger for confined than for eruptive flares, ranging within E nth /E mag ≈ 0.7-0.76, in agreement with the case study by Thalmann et al (2015).…”

Section: Introductionmentioning

confidence: 77%

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A Database of Magnetic and Thermodynamic Properties of Confined and Eruptive Solar Flares

Kazachenko

2023

ApJ

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Solar flares sometimes lead to coronal mass ejections that directly affect Earth's environment. However, a large fraction of flares, including on solar-type stars, are confined flares. What are the differences in physical properties between confined and eruptive flares? For the first time, we quantify the thermodynamic and magnetic properties of hundreds of confined and eruptive flares of GOES class C5.0 and above, 480 flares in total. We first analyze large flares of GOES class M1.0 and above observed by the Solar Dynamics Observatory, 216 flares in total, including 103 eruptive and 113 confined flares, from 2010 until 2016 April; we then look at the entire data set of 480 flares above class C5.0. We compare GOES X-ray thermodynamic flare properties, including peak temperature and emission measure, and active-region (AR) and flare-ribbon magnetic field properties, including reconnected magnetic flux and peak reconnection rate. We find that for fixed peak X-ray flux, confined and eruptive flares have similar reconnection fluxes; however, for fixed peak X-ray flux confined flares have on average larger peak magnetic reconnection rates, are more compact, and occur in larger ARs than eruptive flares. These findings suggest that confined flares are caused by reconnection between more compact, stronger, lower-lying magnetic fields in larger ARs that reorganizes a smaller fraction of these regions’ fields. This reconnection proceeds at faster rates and ends earlier, potentially leading to more efficient flare particle acceleration in confined flares.

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Section: Discussionmentioning

confidence: 64%

Section: Introductionmentioning

confidence: 77%

A Database of Magnetic and Thermodynamic Properties of Confined and Eruptive Solar Flares

Kazachenko

2023

ApJ

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“…It is revealed that the energy partitions in two flares are similar, and the heating requirement consisting of the peak thermal energy and radiative loss could sufficiently be supplied by the nonthermal energy. Furthermore, Cai et al (2021) investigated four confined CFs in detail, finding that the values of energy components increase systematically with flare classes. The ratio of nonthermal energy to magnetic free energy may provide a key factor for discriminating confined flares from eruptive ones.…”

Section: Introductionmentioning

confidence: 99%

Statistical Analysis of Circular-ribbon Flares

Zhang

De-chao

et al. 2022

ApJS

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Circular-ribbon flares (CFs) are a special type of solar flares owing to their particular magnetic topology. In this paper, we conducted a comprehensive statistical analysis of 134 CFs from 2011 September to 2017 June, including 4 B-class, 82 C-class, 40 M-class, and 8 X-class flares. The flares were observed by the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory spacecraft. The physical properties of CFs are derived, including the location, area (A CF), equivalent radius (r CF) assuming a semispherical fan dome, lifetime (τ CF), and peak soft X-ray (SXR) flux in 1–8 Å. It is found that all CFs are located in active regions, with the latitudes between −30° and 30°. The distributions of areas and lifetimes could be fitted with a lognormal function. There is a positive correlation between the lifetime and area. The peak SXR flux in 1–8 Å is well in accord with a power-law distribution with an index of −1.42. For the 134 CFs, 57% of them are accompanied by remote brightenings or ribbons. A positive correlation exists between the total length (L RB) and average distance (D RB) of remote brightenings. About 47% and 51% of the 134 CFs are related to type III radio bursts and jets, respectively. The association rates are independent of flare energies. About 38% of CFs are related to minifilament eruptions, and the association rates increase with flare classes. Only 28% of CFs are related to coronal mass ejections (CMEs), meaning that a majority of them are confined rather than eruptive events. There is a positive correlation between the CME speed and peak SXR flux in 1–8 Å, and faster CMEs tend to be wider.

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“…In general, an eruptive flare is characterized by the appearance of two ribbons on both sides of the PIL that spread apart with time as observed in Hα images and at other wavelengths. They have large-scale hot postflare loops observed in SXR and are of long duration (e.g., tens of minutes to a few hours), whereas a confined flare occurs in a relatively compact region and lasts for a short period (e.g., less than an hour) (Kushwaha et al 2014;Cai et al 2021). Although infrequent, even some large X-class flares have been found to belong to the confined category (Green et al 2002;Wang & Zhang 2007).…”

Section: Introductionmentioning

confidence: 99%

Homologous Compact Major Blowout-eruption Solar Flares and their Production of Broad CMEs

Sahu

Joshi

Sterling

et al. 2022

ApJ

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We analyze the formation mechanism of three homologous broad coronal mass ejections (CMEs) resulting from a series of solar blowout-eruption flares with successively increasing intensities (M2.0, M2.6, and X1.0). The flares originated from NOAA Active Region 12017 during 2014 March 28–29 within an interval of ≈24 hr. Coronal magnetic field modeling based on nonlinear force-free field extrapolation helps to identify low-lying closed bipolar loops within the flaring region enclosing magnetic flux ropes. We obtain a double flux rope system under closed bipolar fields for all the events. The sequential eruption of the flux ropes led to homologous flares, each followed by a CME. Each of the three CMEs formed from the eruptions gradually attained a large angular width, after expanding from the compact eruption-source site. We find these eruptions and CMEs to be consistent with the “magnetic-arch-blowout” scenario: each compact-flare blowout eruption was seated in one foot of a far-reaching magnetic arch, exploded up the encasing leg of the arch, and blew out the arch to make a broad CME.

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Energy Partition in Four Confined Circular-Ribbon Flares

Cited by 7 publications

References 86 publications

A Database of Magnetic and Thermodynamic Properties of Confined and Eruptive Solar Flares

A Database of Magnetic and Thermodynamic Properties of Confined and Eruptive Solar Flares

Statistical Analysis of Circular-ribbon Flares

Homologous Compact Major Blowout-eruption Solar Flares and their Production of Broad CMEs

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