Gas-Dynamic Shock Heating of Post-Flare Loops Due to Retraction Following Localized, Impulsive Reconnection

Longcope, D. W.; Guidoni, S. E.; Linton, M. G.

doi:10.1088/0004-637x/690/1/l18

Cited by 59 publications

(92 citation statements)

References 15 publications

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“…In particular, we adopted the model of Longcope et al (2009) and Guidoni & Longcope (2010), in which the retracting flux tube is confined within a planar current sheet, which is equivalent to taking the reconnection opening angle f D  0 in Figure 3. Since the dynamics of the retracting flux is dominated by the magnetic tension of the initially bent flux tube, the most important factor is the bend angle Δθ of the initial condition.…”

Section: Discussionmentioning

confidence: 99%

“…Longer loops evolve more slowly, shorter loops more quickly. Higher field strength, B 0 , or shear angle, q D , produces more intense retraction shocks with higher temperature (Longcope et al 2009). This may be the route to producing loop-top HXR sources more substantial than that seen in our modest flare.…”

Section: Discussionmentioning

confidence: 99%

“…This energy, a product of specific heat, c , V and temperature, T, changes in response to energy added to and removed from the fluid element Soward (1982), as reported by Forbes et al (1989) and Vršnak & Skender (2005). Diamonds show the 1D Riemann problem solution of Lin & Lee (1994), and the solid curves show the TFT from Longcope et al (2009). The top panel shows the ratio of post-shock density to ambient, pre-reconnection value, r r ; area; we derive this form below.…”

Section: The Energy Equationmentioning

confidence: 95%

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How Gas-Dynamic Flare Models Powered by Petschek Reconnection Differ From Those With Ad Hoc Energy Sources

Longcope

Klimchuk

2015

ApJ

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Aspects of solar flare dynamics, such as chromospheric evaporation and flare lightcurves, have long been studied using one-dimensional models of plasma dynamics inside a static flare loop, subjected to some energy input. While extremely successful at explaining the observed characteristics of flares, all such models so far have specified energy input ad hoc, rather than deriving it self-consistently. There is broad consensus that flares are powered by magnetic energy released through reconnection. Recent work has generalized Petschek's basic reconnection scenario, topological change followed by field line retraction and shock heating, to permit its inclusion ina onedimensional flare loop model. Here we compare the gas dynamics driven by retraction and shocking to those from more conventional static loop models energized by ad hoc source terms. We find significant differences during the first minute, when retraction leads to larger kinetic energies and produces higher densities at the loop top, while ad hoc heating tends to rarify the loop top. The loop-top density concentration is related to the slow magnetosonic shock, characteristic of Petschek's model, but persists beyond the retraction phase occurring in the outflow jet. This offers an explanation for observed loop-top sources of X-ray and EUV emission, with advantages over that provided by ad hoc heating scenarios. The cooling phases of the two models are, however, notably similar to one another, suggesting that observations at that stage will yield little information on the nature of energy input.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: The Energy Equationmentioning

confidence: 95%

See 1 more Smart Citation

How Gas-Dynamic Flare Models Powered by Petschek Reconnection Differ From Those With Ad Hoc Energy Sources

Longcope

Klimchuk

2015

ApJ

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“…It is further confirmed by Fletcher et al (2004) that the flare UV ribbons are made of small kernels outlining the feet of flare loops. These loops are formed by the so-called patchy reconnection (Longcope et al 2009) and heated at different times during the flare, and evolve independently of each other. The observed unresolved coronal radiation flux at any given time is the sum of radiation by these loops at different evolution stages with different temperatures and densities.…”

Section: Introductionmentioning

confidence: 99%

Heating of Flare Loops With Observationally Constrained Heating Functions

Qiu

Liu

Longcope

2012

ApJ

104

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We analyze high-cadence high-resolution observations of a C3.2 flare obtained by AIA/SDO on 2010 August 1. The flare is a long-duration event with soft X-ray and EUV radiation lasting for over 4 hr. Analysis suggests that magnetic reconnection and formation of new loops continue for more than 2 hr. Furthermore, the UV 1600 Å observations show that each of the individual pixels at the feet of flare loops is brightened instantaneously with a timescale of a few minutes, and decays over a much longer timescale of more than 30 minutes. We use these spatially resolved UV light curves during the rise phase to construct empirical heating functions for individual flare loops, and model heating of coronal plasmas in these loops. The total coronal radiation of these flare loops are compared with soft X-ray and EUV radiation fluxes measured by GOES and AIA. This study presents a method to observationally infer heating functions in numerous flare loops that are formed and heated sequentially by reconnection throughout the flare, and provides a very useful constraint to coronal heating models.

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“…Previous authors have modeled the dynamics of the retracting flux tube (Guidoni & Longcope 2010;Longcope et al 2009;Linton & Longcope 2006), but have not yet considered its effects on the surrounding, unreconnected flux. Cargill et al (1996) modeled the interaction of a magnetic cloud and the surrounding magnetic field, but their work focused on the high-β regime (β = 8πp/B 2 1).…”

Section: Introductionmentioning

confidence: 99%

Peristaltic Pumping Near Post-Coronal Mass Ejection Supra-Arcade Current Sheets

Scott¹,

Longcope²,

McKenzie³

2013

ApJ

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Temperature and density measurements near supra-arcade current sheets suggest that plasma on unreconnected field lines may experience some degree of "pre-heating" and "pre-densification" prior to reconnection. Models of patchy reconnection allow for heating and acceleration of plasma along reconnected field lines but do not offer a mechanism for transport of thermal energy across field lines. Here, we present a model in which a reconnected flux tube retracts, deforming the surrounding layer of unreconnected field. The deformation creates constrictions that act as peristaltic pumps, driving plasma flow along affected field lines. Under certain circumstances, these flows lead to shocks that can extend far out into the unreconnected field, altering the plasma properties in the affected region. These findings have direct implications for observations in the solar corona, particularly in regard to such phenomena as high temperatures near current sheets in eruptive solar flares and wakes seen in the form of descending regions of density depletion or supra-arcade downflows.

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Gas-Dynamic Shock Heating of Post-Flare Loops Due to Retraction Following Localized, Impulsive Reconnection

Cited by 59 publications

References 15 publications

How Gas-Dynamic Flare Models Powered by Petschek Reconnection Differ From Those With Ad Hoc Energy Sources

How Gas-Dynamic Flare Models Powered by Petschek Reconnection Differ From Those With Ad Hoc Energy Sources

Heating of Flare Loops With Observationally Constrained Heating Functions

Peristaltic Pumping Near Post-Coronal Mass Ejection Supra-Arcade Current Sheets

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