An Unorthodox X-Class Long-Duration Confined Flare

Li, Rui; Titov, V. S.; Gou, Tingyu; Wang, Yuming; Li, Kai; Wang, Haimin

doi:10.1088/0004-637x/790/1/8

Cited by 69 publications

(72 citation statements)

References 53 publications

(62 reference statements)

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“…Nevertheless, distinctive discrepancies between QSLs footprints and flare ribbons can also be found in NLFFF extrapolations. Indeed, this clearly appears in the atypical flare studied by Liu et al (2014), as can be seen in their Figs. 7d and e. We thus conjecture that such mismatches between QSLs footprints and flare ribbons are more generally inherent to the force-free model of choice.…”

Section: Qsls and Flare-ribbonsmentioning

confidence: 63%

Can we explain atypical solar flares?

Dalmasse

Chandra

Schmieder

et al. 2015

A&A

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Context. We used multiwavelength high-resolution data from ARIES, THEMIS, and SDO instruments to analyze a non-standard, C3.3 class flare produced within the active region NOAA 11589 on 2012 October 16. Magnetic flux emergence and cancellation were continuously detected within the active region, the latter leading to the formation of two filaments. Aims. Our aim is to identify the origins of the flare taking the complex dynamics of its close surroundings into account. Methods. We analyzed the magnetic topology of the active region using a linear force-free field extrapolation to derive its 3D magnetic configuration and the location of quasi-separatrix layers (QSLs), which are preferred sites for flaring activity. Because the active region's magnetic field was nonlinear force-free, we completed a parametric study using different linear force-free field extrapolations to demonstrate the robustness of the derived QSLs.Results. The topological analysis shows that the active region presented a complex magnetic configuration comprising several QSLs. The considered data set suggests that an emerging flux episode played a key role in triggering the flare. The emerging flux probably activated the complex system of QSLs, leading to multiple coronal magnetic reconnections within the QSLs. This scenario accounts for the observed signatures: the two extended flare ribbons developed at locations matched by the photospheric footprints of the QSLs and were accompanied with flare loops that formed above the two filaments, which played no important role in the flare dynamics.Conclusions. This is a typical example of a complex flare that can a priori show standard flare signatures that are nevertheless impossible to interpret with any standard model of eruptive or confined flare. We find that a topological analysis, however, permitted us to unveil the development of such complex sets of flare signatures.

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Section: Qsls and Flare-ribbonsmentioning

confidence: 63%

Can we explain atypical solar flares?

Dalmasse

Chandra

Schmieder

et al. 2015

A&A

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“…These properties also usually point to the standard flare model of an eruptive flare, with reconnection continuing to extract energy from the field and cause the formation of the arcade of flare loops. In this case, Liu et al (2014) suggested that new emergence of magnetic field in the region of the second arcade triggered the events.…”

Section: Flares Cmes and X-class Flares Without Cmesmentioning

confidence: 86%

The Characteristics of Solar X-Class Flares and CMEs: A Paradigm for Stellar Superflares and Eruptions?

et al. 2016

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This paper explores the characteristics of 42 solar X-class flares that were observed between February 2011 and November 2014, with data from the Solar Dynamics Observatory (SDO) and other sources. This flare list includes nine X-class flares that had no associated CMEs. In particular our aim was to determine whether a clear signature could be identified to differentiate powerful flares that have coronal mass ejections (CMEs) from those that do not. Part of the motivation for this study is the characterization of the solar paradigm for flare/CME occurrence as a possible guide to the stellar observations; hence we emphasize spectroscopic signatures. To do this we ask the following questions: Do all eruptive flares have long durations? Do CME-related flares stand out in terms of active-region size vs. flare duration? Do flare magnitudes correlate with sunspot areas, and, if so, are eruptive events distinguished? Is the occurrence of CMEs related to the fraction of the activeregion area involved? Do X-class flares with no eruptions have weaker non-thermal signatures? Is the temperature dependence of evaporation different in eruptive and non-eruptive flares? Is EUV dimming only seen in eruptive flares? We find only one feature consistently associated with CME-related flares specifically: coronal dimming in lines characteristic of the quiet-Sun corona, i.e. 1 -2 MK. We do not find a correlation between flare magnitude and sunspot areas. Although challenging, it will be of importance to model dimming for stellar cases and make suitable future plans for observations in the appropriate wavelength range in order to identify stellar CMEs consistently.

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“…In this picture, the photospheric traces of the HFT are 2J-shaped (Titov 2007;Aulanier et al 2010) and they match the 2J-shaped flare ribbons of classical two-ribbon flares (Chandra et al 2009;Schrijver et al 2011). The match between the shapes of QSLs and flare ribbons has been achieved recently by Liu et al (2014), Savcheva et al (2015), and Zhao et al (2016). These QSLs have been shown to move together with the flare ribbons in direction perpendicular to the polarity inversion line (PIL) (Savcheva et al 2016b;Janvier et al 2016).…”

Section: Introductionmentioning

confidence: 84%

QSL Squasher: A Fast Quasi-separatrix Layer Map Calculator

Tassev

Savcheva

2017

ApJ

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Quasi-Separatrix Layers (QSLs) are a useful proxy for the locations where current sheets can develop in the solar corona, and give valuable information about the connectivity in complicated magnetic field configurations. However, calculating QSL maps even for 2-dimensional slices through 3-dimensional models of coronal magnetic fields is a non-trivial task as it usually involves tracing out millions of magnetic field lines with immense precision. Thus, extending QSL calculations to three dimensions has rarely been done until now. In order to address this challenge, we present QSL Squasher -a public, open-source code, which is optimized for calculating QSL maps in both two and three dimensions on GPUs. The code achieves large processing speeds for three reasons, each of which results in an orderof-magnitude speed-up. 1) The code is parallelized using OpenCL. 2) The precision requirements for the QSL calculation are drastically reduced by using perturbation theory. 3) A new boundary detection criterion between quasi-connectivity domains is used, which quickly identifies possible QSL locations which need to be finely sampled by the code. That boundary detection criterion relies on finding the locations of abrupt field-line length changes, which we do by introducing a new Field-line Length Edge (FLEDGE) map. We find FLEDGE maps useful on their own as a quick-and-dirty substitute for QSL maps. QSL Squasher allows constructing high-resolution 3D FLEDGE maps in a matter of minutes, which is two orders of magnitude faster than calculating the corresponding 3D QSL maps. We include a sample of calculations done using QSL Squasher to demonstrate its capabilities as a QSL calculator, as well as to compare QSL and FLEDGE maps.

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An Unorthodox X-Class Long-Duration Confined Flare

Cited by 69 publications

References 53 publications

Can we explain atypical solar flares?

Can we explain atypical solar flares?

The Characteristics of Solar X-Class Flares and CMEs: A Paradigm for Stellar Superflares and Eruptions?

QSL Squasher: A Fast Quasi-separatrix Layer Map Calculator

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