OVERLYING EXTREME-ULTRAVIOLET ARCADES PREVENTING ERUPTION OF A FILAMENT OBSERVED BY AIA/<i>SDO</i>

Chen, Huadong; Ma, Suli; Zhang, Jun

doi:10.1088/0004-637x/778/1/70

Cited by 36 publications

(32 citation statements)

References 29 publications

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“…As revealed in previous observations, the overlying loops play an important role in resulting in failed filament eruptions (e.g., Ji et al 2003;Chen et al 2013). In this study, many pre-existing large loops above the confined flares are clearly observed in AIA EUV lines, e.g., 171 Å, and 131 Å (see Figures 3 and 4).…”

Section: Conclusion and Discussionsupporting

confidence: 79%

“…Based on the potential field source-surface model, the calculations showed that stronger overlying magnetic arcades can prevent energy release, thus resulting in confined flares (Wang & Zhang 2007;Guo et al 2010;Cheng et al 2011;Shen et al 2011). Direct observations of the overlying arcades above the failed filament eruptions have been provided by many authors (e.g., Ji et al 2003;Zheng et al 2012;Chen et al 2013).…”

Section: Introductionmentioning

confidence: 99%

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Fine Structures and Overlying Loops of Confined Solar Flares

Yang

Zhang

Xiang

2014

ApJ

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Using the Hα observations from the New Vacuum Solar Telescope at the Fuxian Solar Observatory, we focus on the fine structures of three confined flares and the issue why all the three flares are confined instead of eruptive. All the three confined flares take place successively at the same location and have similar morphologies, so can be termed homologous confined flares. In the simultaneous images obtained by the Solar Dynamics Observatory, many large-scale coronal loops above the confined flares are clearly observed in multi-wavelengths. At the pre-flare stage, two dipoles emerge near the negative sunspot, and the dipolar patches are connected by small loops appearing as arch-shaped Hα fibrils. There exists a reconnection between the small loops, and thus the Hα fibrils change their configuration. The reconnection also occurs between a set of emerging Hα fibrils and a set of pre-existing large loops, which are rooted in the negative sunspot, a nearby positive patch, and some remote positive faculae, forming a typical three-legged structure. During the flare processes, the overlying loops, some of which are tracked by activated dark materials, do not break out. These direct observations may illustrate the physical mechanism of confined flares, i.e., magnetic reconnection between the emerging loops and the pre-existing loops triggers flares and the overlying loops prevent the flares from being eruptive.

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Section: Conclusion and Discussionsupporting

confidence: 79%

Section: Introductionmentioning

confidence: 99%

Fine Structures and Overlying Loops of Confined Solar Flares

Yang

Zhang

Xiang

2014

ApJ

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“…Chen et al (2013) and Liu et al (2014) identify this event as a confined flare and failed filament eruption using stereoscopic data. Chen et al (2013) shows that between 20:20UT and 20:25UT a very small heated filament, which is bright in 304 Å, becomes unstable and moves roughly to the north-east at projected speeds of up to 400 km s −1 . If it had a small velocity component in the line of sight this could account for some of the flows we measure, though they continue for longer.…”

Section: Resultsmentioning

confidence: 99%

Doppler speeds of the hydrogen Lyman lines in solar flares from EVE

Brown

Fletcher

Labrosse

2016

A&A

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Aims. The hydrogen Lyman lines provide important diagnostic information about the dynamics of the chromosphere, but there have been few systematic studies of their variability during flares. We investigate Doppler shifts in these lines in several flares, and use these to calculate plasma speeds. Methods. We use spectral data from the Multiple EUV Grating Spectrograph B (MEGS-B) detector of the Extreme-Ultraviolet Variability Experiment (EVE) instrument on the Solar Dynamics Observatory. MEGS-B obtains full-disk spectra of the Sun at a resolution of 0.1 nm in the range 37-105 nm, which we analyse using three independent methods. The first method performs Gaussian fits to the lines, and compares the quiet-Sun centroids with the flaring ones to obtain the Doppler shifts. The second method uses crosscorrelation to detect wavelength shifts between the quiet-Sun and flaring line profiles. The final method calculates the "center-of-mass" of the line profile, and compares the quiet-Sun and flaring centroids to obtain the shift. Results. In a study of 6 flares we find strong signatures of both upflow and downflow in the Lyman lines, with speeds measured in Sun-as-a-Star data of around 10 km s −1 , and speeds in the flare excess signal of around 30 km s −1 . Conclusions. All events showing upflows in Lyman lines are associated with some kind of eruption or coronal flow in imaging data, which may be responsible for the net blueshifts. Events showing downflows in the Lyman lines may be associated with loop contraction or faint downflows, but it is likely that chromospheric condensation flows are also contributing.

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“…On this point we ought to be able to gain insight from the Sun: a case study of AR 12192, one of the largest active regions seen in decades, which produced several energetic flares in the October-November 2014 time frame without accompanying CMEs, can reveal the detailed processes for noneruptive energetic flares. Preliminary work on failed solar eruptive events by Chen et al (2013) and Sun et al (2015) does suggest that overlying arcades may prevent the eruption of a filament. In the end, only direct observations of CMEs in other stars (or more stringent constraints) can address whether and how the above topics are influenced by transient mass loss.…”

Section: Astrophysical Consequences Of High Mass Loss Ratesmentioning

confidence: 99%

Connecting Flares and Transient Mass-Loss Events in Magnetically Active Stars

Osten

Wolk

2015

ApJ

138

176

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We explore the ramification of associating the energetics of extreme magnetic reconnection events with transient mass loss in a stellar analogy with solar eruptive events. We establish energy partitions relative to the total bolometric radiated flare energy for different observed components of stellar flares, and show that there is rough agreement for these values with solar flares. We apply an equipartition between the bolometric radiated flare energy and kinetic energy in an accompanying mass ejection, seen in solar eruptive events and expected from reconnection. This allows an integrated flare rate in a particular waveband to be used to estimate the amount of associated transient mass loss. This approach is supported by a good correspondence between observational flare signatures on high flaring rate stars and the Sun, which suggests a common physical origin.If the frequent and extreme flares that young solar-like stars and low-mass stars experience are accompanied by transient mass loss in the form of coronal mass ejections, then the cumulative effect of this mass loss could be large. We find that for young solar-like stars and active M dwarfs, the total mass lost due to transient magnetic eruptions could have significant impacts on disk evolution, and thus planet formation, and also exoplanet habitability. Subject headings: stars: activity -stars: flare -stars: late-type -stars: mass-loss redshifted than blue-shifted emission components, and the hetergeneous nature of the events prevents a systematic exploration. Thus, in the absence of conclusive evidence of stellar CMEs, stellar astronomers must look to the Sun to gain insight into transient stellar mass loss on magnetically active stars. The commonality of stellar flare phenomenology with solar observations suggests that an extrapolation of solar flare/CME behavior to the more distant stars should be appropriate. The Sun has a low overall rate of mass loss (Ṁ ⊙ = 2 ×10 −14 M ⊙ yr −1 ), of which transient mass loss events comprise a minor component (typically <10%; Howard et al. 1985). However, if mass loss due to CMEs scales with flare occurrence, stars with a high flaring rate ought to also show an enhanced rate of mass lost due to transient events like CMEs. Recently, Aarnio et al. (2012) used an empirical scaling between solar flareX-ray energy and associated CME mass and extrapolated to pre-main sequence stars with measured X-ray flare energies to deduce mass loss rates of putative CMEs associated with the stellar flares. They inferred high levels of CME-related mass loss in these solar-type pre-main sequence stars of 10 −12 -10 −9 M ⊙ yr −1 . Drake et al. (2013) also used an empirical relationship between solar flare X-ray energy and associated CME mass to extrapolate to observed stellar coronal X-ray luminosities and investigate the radiative and kinetic energy requirements, assuming that the stellar coronal emissions are produced by flares whose occurrence has a power-law dependence on flare energy. They likewise find a large CME mass loss rate. Th...

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OVERLYING EXTREME-ULTRAVIOLET ARCADES PREVENTING ERUPTION OF A FILAMENT OBSERVED BY AIA/SDO

Cited by 36 publications

References 29 publications

Fine Structures and Overlying Loops of Confined Solar Flares

Fine Structures and Overlying Loops of Confined Solar Flares

Doppler speeds of the hydrogen Lyman lines in solar flares from EVE

Connecting Flares and Transient Mass-Loss Events in Magnetically Active Stars

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