The magnetic nature of solar flares

Priest, E. R.; Forbes, T. G.

doi:10.1007/s001590100013

Cited by 828 publications

(618 citation statements)

References 0 publications

Supporting

Mentioning

585

Contrasting

Unclassified

Order By: Relevance

“…Figure 2 incorporates the flare models summarized by Forbes and Acton (1996) and the CME model of Lin and Forbes (2000), and clearly illustrates the relationship among solar flares, eruptive prominences, and CMEs such that these three phenomena are different manifestations of a single physical process that involves a disruption of the coronal magnetic field (see also Martens and Kuin 1989;Priest and Forbes 2002). On the other hand, the scenario described by Fig.…”

Section: Have Convincingly Showed That Both the Reconnection Sites Comentioning

confidence: 96%

“…However, we also need to point out here that, according to the standard model of the tworibbon flare (see Forbes and Acton 1996;Priest and Forbes 2002; and references therein), the HXR source on the top of the post-flare loop is basically created by the collision of the energetic particles and the downward reconnection outflow from the CS with the closed magnetic field lines where flare loops are believed to lie on (see also the lower part of Fig. 2).…”

Section: Identifications Of the Current Sheet In The Solar Eruptive Ementioning

confidence: 99%

“…In the solar eruptive process, the closed magnetic field is severely stretched, and the neutral region generally appears in the form of a CS (e.g., see also Priest and Forbes 2002;Lin et al 2003;Forbes et al 2006). Magnetic reconnection through the CS helps the magnetized plasma ejected by the eruption propagate away smoothly and produces a flare near the solar surface.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Review on Current Sheets in CME Development: Theories and Observations

et al. 2015

View full text Add to dashboard Cite

We introduce how the catastrophe model for solar eruptions predicted the formation and development of the long current sheet (CS) and how the observations were used to recognize the CS at the place where the CS is presumably located. Then, we discuss the direct measurement of the CS region thickness by studying the brightness distribution of the CS region at different wavelengths. The thickness ranges from 10 4 km to about 10 5 km at heights between 0.27 and 1.16 R from the solar surface. But the traditional theory indicates that the CS is as thin as the proton Larmor radius, which is of order tens of meters in the corona. We look into the huge difference in the thickness between observations and theoretical expectations. The possible impacts that affect measurements and results are studied, and physical causes leading to a thick CS region in which reconnection can still occur at a reasonably fast rate are analyzed. Studies in both theories and observations suggest that the difference between the true value and the apparent value of the CS thickness is not significant as long as the CS could be recognised in observations. We review observations that show complex structures and flows inside the CS region and present recent numerical modelling results on some aspects of these structures. Both observations and numerical experiments indicate that the downward reconnection outflows are usually slower than the upward ones in the same eruptive event. Numerical simulations show that the complex structure inside CS and its temporal behavior as a result of turbulence and the Petschek-type slow-mode shock could probably account for the thick CS and fast reconnection. But whether the CS itself is that thick still remains unknown since, for the time being, we cannot measure the electric current directly in that region. We also review the most recent laboratory experiments of reconnection driven by energetic laser beams, and discuss some important topics for future works.

show abstract

Section: Have Convincingly Showed That Both the Reconnection Sites Comentioning

confidence: 96%

Section: Identifications Of the Current Sheet In The Solar Eruptive Ementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Review on Current Sheets in CME Development: Theories and Observations

et al. 2015

View full text Add to dashboard Cite

show abstract

“…Based on these observations, the general picture is agreed upon that flare plasmas, whether in the corona or in the loweratmosphere, are heated on relatively short timescales. As is commonly accepted, energy release in flares is governed by magnetic reconnection in the corona on Alfvénic timescales of the order of a few seconds (Priest & Forbes 2002). Although the debate exists regarding where exactly in the Sun's atmosphere particles or plasmas are energized primarily, what is the form of heating, and how energy is transferred between different layers of the atmosphere, the impulsive rise of flare emission in many wavelengths, including hard X-ray, microwave, optical, and UV bands, is considered to reflect short timescales of flare energy release and also heating (Fletcher et al 2011).…”

Section: Introductionmentioning

confidence: 99%

Long Duration Flare Emission: Impulsive Heating or Gradual Heating?

Qiu

Longcope

2016

ApJ

View full text Add to dashboard Cite

Flare emissions in X-ray and EUV wavelengths have previously been modeled as the plasma response to impulsive heating from magnetic reconnection. Some flares exhibit gradually evolving X-ray and EUV light curves, which are believed to result from superposition of an extended sequence of impulsive heating events occurring in different adjacent loops or even unresolved threads within each loop. In this paper, we apply this approach to a long duration two-ribbon flare SOL2011-09-13T22 observed by the Atmosphere Imaging Assembly (AIA). We find that to reconcile with observed signatures of flare emission in multiple EUV wavelengths, each thread should be heated in two phases, an intense impulsive heating followed by a gradual, low-rate heating tail that is attenuated over 20-30 minutes. Each AIA resolved single loop may be composed of several such threads. The two-phase heating scenario is supported by modeling with both a zero-dimensional and a 1D hydrodynamic code. We discuss viable physical mechanisms for the two-phase heating in a post-reconnection thread.

show abstract

“…In the standard CSHKP flare model (Carmichael 1964;Sturrock 1966;Hirayama 1974;Kopp & Pneuman 1976), the flare ribbons are the consequence of accelerated particles flowing down along reconnected magnetic field lines, generating ribbon-shaped brightenings in the denser lower layers of the solar atmosphere (e.g., Priest & Forbes 2002). They separate with time as they are the result of sequentially reconnected loop arcades that are located at higher and higher atmospheric layers.…”

Section: Introductionmentioning

confidence: 99%

A MULTI-INSTRUMENT ANALYSIS OF a C4.1 FLARE OCCURRING IN a Δ SUNSPOT

Guglielmino¹,

Zuccarello²,

Romano

et al. 2016

ApJ

View full text Add to dashboard Cite

We present an analysis of multi-instrument space-and ground-based observations relevant to a C4.1 solar flare that occurred in the active region (AR) NOAA 11267 on 2011 August 6. Solar Dynamics Observatoryobservations indicate that at the flare's beginning, it was localized in the preceding sunspot of the AR, which exhibits a δ configuration. Along the polarity inversion line between its opposite polarities we find a large shear angle of about 80°. The helicity accumulation shows that the AR does not obey the general hemispheric helicity rule. At the flare peak, unique observations taken with the X-Ray Telescope aboard Hinode reveal that the bulk of the X-ray emission takes place in the δ-spot region, where the plasma heats up to 1.9 10 7 · » K. During the gradual phase, we observe the development of a Y-shaped structure in the corona and in the high chromosphere. An extruding structure forms, being directed from the emitting region above the δ spot toward the following sunspot. This structure cools down in a few tens of minutes while moving eastward along a direction opposite to the flare ribbon expansion. Finally, remote brightenings are found at the easternmost footpoint of this structure, appearing as a third flare ribbon in the chromosphere. After some minutes, RHESSI measurements show that the X-ray emission is localized in the region close to the crossing point of the coronal Y-shaped structure. Simultaneously, highresolution (0 15) observations performed at the Swedish 1 m Solar Telescope indicate a decreasing trend of the Ca II H intensity in the flare ribbons with some transient enhancements. All these findings suggest that this event is a manifestation of magnetic reconnection, likely induced by an asymmetric magnetic configuration in a highly sheared region.

show abstract

The magnetic nature of solar flares

Cited by 828 publications

References 0 publications

Review on Current Sheets in CME Development: Theories and Observations

Review on Current Sheets in CME Development: Theories and Observations

Long Duration Flare Emission: Impulsive Heating or Gradual Heating?

A MULTI-INSTRUMENT ANALYSIS OF a C4.1 FLARE OCCURRING IN a Δ SUNSPOT

Contact Info

Product

Resources

About