Magnetic Energy Release during the 2002 September 9 Solar Flare

Lee, Jeongwoo; Gary, Dale E.; Choe, G. S.

doi:10.1086/505416

Cited by 23 publications

(29 citation statements)

References 29 publications

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“…u ∼ e namely, HXR sources should move fast during the flare maximum phase and slowly at other times. An episodic variation of ribbon motion with the HXR light curves found by Lee et al (2006) does support this idea. However, there are also counterexamples: Krucker et al (2003) found a correlation of HXR light curves with parallel, rather than perpendicular, motions of HXR sources with respect to the PIL.…”

Section: Introductionmentioning

confidence: 75%

Parallel Motions of Coronal Hard X-Ray Source and Hα Ribbons

Lee

Gary

2008

ApJ

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During solar flares Ha ribbons form and often move away from the local magnetic polarity inversion line (PIL). While the motion perpendicular to the PIL has been taken as evidence for coronal magnetic reconnection in the so-called CSHKP standard model, the other velocity component parallel to the PIL is much less adopted as a property of the magnetic reconnection process. In this Letter we report an event in which the motion parallel to the PIL is found in both Ha ribbons and a thermal hard X-ray source. Such commonality would indicate a link between the coronal magnetic reconnection and footpoint emissions as in the standard solar flare model. However, its direction implies a reconnection region that is increasing in length, a feature missing from the standard two-dimensional model. We present a modified framework in which the variation along the third dimension is allowed, in order to assess the effect of such a proper motion on estimation of the magnetic reconnection rate. Data used are hard X-ray maps from the Reuven Ramaty

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Section: Introductionmentioning

confidence: 75%

Parallel Motions of Coronal Hard X-Ray Source and Hα Ribbons

Lee

Gary

2008

ApJ

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“…Forbes & Priest (1982) proposed a method for estimating the reconnection rate based on the separation rate of the Hα footpoints. Implementation of the method yields speeds from tens to as high as 200 km s −1 ( Jing et al 2005;Lee, Gary & Choe 2006). A sense of how dynamical these processes are can be obtained from movies such as those made from TRACE data, available at http://trace.lmsal.com/POD/TRACEpod.html.…”

Section: Reconnection Observedmentioning

confidence: 99%

Magnetic Reconnection in Astrophysical and Laboratory Plasmas

Zweibel

Yamada

2009

Annu. Rev. Astron. Astrophys.

530

438

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Magnetic reconnection is a topological rearrangement of magnetic field that converts magnetic energy to plasma energy. Astrophysical flares, from the Earth's magnetosphere to γ-ray bursts and sawtooth crashes in laboratory plasmas, may all be powered by reconnection. Reconnection is essential for dynamos and the large-scale restructuring known as magnetic self-organization. We review reconnection theory and evidence for it. We emphasize recent developments in two-fluid physics, and the experiments, observations, and simulations that verify two-fluid effects. We discuss novel environments such as line-tied, relativistic, and partially ionized plasmas, focusing on mechanisms that make reconnection fast, as observed. Because there is evidence that fast reconnection in astrophysics requires small-scale structure, we briefly introduce how such structure might develop. Several areas merit attention for astrophysical applications: development of a kinetic model of reconnection to enable spectroscopic predictions, better understanding of the interplay between local and global scales, the role of collisionless reconnection in large systems, and the effects of flows, including turbulence.

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“…The first is through measurements made by directly observing inflows at the coronal reconnection site, and estimating the inflow Mach number (M ≡ V in /V A ) with a certain assumption or estimate of coronal magnetic field and plasma density at the reconnection site (Yokoyama et al, 2001;Lin et al, 2005). The second approach derives reconnection rate in terms of reconnecting electric field (in a 2D approximation, but see Lee and Gary, 2008, concerning modifications to 3D) or reconnection flux (in a general configuration) by observing flare evolution in the lower atmosphere (Poletto and Kopp, 1986;Fletcher and Hudson, 2001;Isobe et al, 2002;Isobe, Takasaki, and Shibata, 2005;Qiu et al 2002Qiu et al , 2004Fletcher, Pollock, and Potts, 2004;Qiu and Yurchyshyn, 2005;Saba, Gaeng, and Tarbell, 2006) from which the energy-release rate can be deduced by assuming a constant Mach number (M) = 0.01 -0.1 (Isobe et al, 2002;Isobe, Takasaki, and Shibata, 2005;Lee, Gary, and Choe, 2006;Temmer et al, 2007;Miklenic et al, 2007).…”

Section: Introductionmentioning

confidence: 99%

Evaluating Mean Magnetic Field in Flare Loops

2009

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We analyze multiple-wavelength observations of a two-ribbon flare exhibiting apparent expansion motion of the flare ribbons in the lower atmosphere and rising motion of X-ray emission at the top of newly-formed flare loops. We evaluate magnetic reconnection rate in terms of V r B r by measuring the ribbon-expansion velocity (V r ) and the chromospheric magnetic field (B r ) swept by the ribbons. We also measure the velocity (V t ) of the apparent rising motion of the loop-top X-ray source, and estimate the mean magnetic field (B t ) at the top of newly-formed flare loops using the relation V t B t ≈ V r B r , namely, conservation of reconnection flux along flare loops. For this flare, B t is found to be 120 and 60 G, respectively, during two emission peaks five minutes apart in the impulsive phase. An estimate of the magnetic field in flare loops is also achieved by analyzing the microwave and hard X-ray spectral observations, yielding B = 250 and 120 G at the two emission peaks, respectively. The measured B from the microwave spectrum is an appropriately-weighted value of magnetic field from the loop top to the loop leg. Therefore, the two methods to evaluate coronal magnetic field in flaring loops produce fully-consistent results in this event.

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Magnetic Energy Release during the 2002 September 9 Solar Flare

Cited by 23 publications

References 29 publications

Parallel Motions of Coronal Hard X-Ray Source and Hα Ribbons

Parallel Motions of Coronal Hard X-Ray Source and Hα Ribbons

Magnetic Reconnection in Astrophysical and Laboratory Plasmas

Evaluating Mean Magnetic Field in Flare Loops

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