Questions concerning the existence of sympathetic flares

Bumba, V.; Klvana, M.

doi:10.1007/bf00612976

Cited by 18 publications

(17 citation statements)

References 5 publications

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“…Therefore, we still need to further investigate coronal connections in sympathetic flares, although they may not be so visible. As alternative mechanisms of sympathetic flaring, we also have to consider subphotospheric connections suggested by Fritzova-Svestkova et al (1976) and large-scale convective motions proposed by Bumba & Klvana (1993).…”

Section: Resultsmentioning

confidence: 99%

“…However, it is a difficult task to decide whether a pair of flares is physically connected or not. And even the existence of sympathetic flares is still being debated (Pearce & Harrison 1990;Bumba & Klvana 1993;Biesecker & Thompson 2000). Thus, it has been quite common in previous studies to use the term '' sympathetic flares '' naively to denote any pair of flares with close temporal and/or spatial proximity, without information on actual physical relations.…”

Section: Introductionmentioning

confidence: 99%

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Statistical Evidence for Sympathetic Flares

Moon

Choe

Park

et al. 2002

ApJ

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Sympathetic flares are a pair of flares that occur almost simultaneously in different active regions, not by chance, but because of some physical connection. In this paper statistical evidence for the existence of sympathetic flares is presented. From GOES X-ray flare data, we have collected 48 pairs of near simultaneous flares whose positional information and Yohkoh soft X-ray telescope images are available. To select the active regions that probably have sympathetic flares, we have estimated the ratio R of actual flaring overlap time to random-coincidence overlap time for 38 active region pairs. We have then compared the waiting-time distributions for the two different groups of active region pairs (R > 1 and R < 1) with corresponding nonstationary Poisson distributions. As a result, we find a remarkable overabundance of short waiting times for the group with R > 1. This is the first time such strong statistical evidence has been found for the existence of sympathetic flares. To examine the role of interconnecting coronal loops, we have also conducted the same analysis for two subgroups of the R > 1 group: one with interconnecting X-ray loops and the other without. We do not find any statistical evidence that the subgroup with interconnecting coronal loops is more likely to produce sympathetic flares than the subgroup without. For the subgroup with loops, we find that sympathetic flares favor active region pairs with transequatorial loops.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Statistical Evidence for Sympathetic Flares

Moon

Choe

Park

et al. 2002

ApJ

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“…If there is another stable filament located just beside this erupting filament coincidentally, the interaction between these two filaments usually is inevitable and the direct collision would result in the eruption of the second filament (Bone et al 2009;Zheng et al 2017). However, different from the filament-filament interactions, the sympathetic filament eruptions occur without direct touching between the bodies of filaments or material of filaments (Bumba & Klvana 1993;Wang et al 2001;Lugaz et al 2017). The exact nature of sympathetic eruptions is still a controversial issue.…”

Section: Summary and Discussionmentioning

confidence: 99%

Sympathetic Eruptions of Two Filaments with an Identifiable Causal Link Observed by the Solar Dynamics Observatory

Song

Hou

Zhang

et al. 2020

ApJ

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Filament eruptions occurring at different places within a relatively short time internal, but with a certain physical causal connection are usually known as sympathetic eruption. Studies on sympathetic eruptions are not uncommon. However, in the existed reports, the causal links between sympathetic eruptions remain rather speculative. In this work, we present detailed observations of a sympathetic filament eruption event, where an identifiable causal link between two eruptive filaments is observed. On 2015 November 15, two filaments (F1 in the north and F2 in the south) were located at the southwestern quadrant of solar disk. The main axes of them were almost parallel to each other. Around 22:20 UT, F1 began to erupt, forming two flare ribbons. The southwestern ribbon apparently moved to southwest and intruded southeast part of F2. This continuous intrusion caused F2's eventual eruption. Accompanying the eruption of F2, flare ribbons and post-flare loops appeared in northwest region of F2. Meanwhile, neither flare ribbons nor post-flare loops could be observed in southeastern area of F2. In addition, the nonlinear force-free field (NLFFF) extrapolations show that the magnetic fields above F2 in the southeast region are much weaker than that in the northwest region. These results imply that the overlying magnetic fields of F2 were not uniform. So we propose that the southwest ribbon formed by eruptive F1 invaded F2 from its southeast region with relatively weaker overlying magnetic fields in comparison with its northwest region, disturbing F2 and leading F2 to erupt eventually.

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“…The horizontally aligned penumbral filaments suggest that they are aligned along the magnetic field lines, and emerge vertically out in the umbra and become inclined or horizontal in the penumbra. The first measurements of inclination of magnetic field were made by in the early 1920s at Mount Wilson Observatory, later Bumba (1960) and other authors determined the inclination of the field lines in sunspots, and found that lines of force emerge vertically from the umbra and become inclined or tilted at an angle of 25-30 • to the solar surface near the outer edge of penumbra.…”

Section: Inner and Outer Bright Ringsmentioning

confidence: 99%