Magnetic reconnection model for X-ray flare loop interaction

1995 ◽  
Vol 226 (1) ◽  
pp. 31-46 ◽  
Author(s):  
Zhen-Da Zhang ◽  
Xiao-Qing Li ◽  
R. N. Smartt
Keyword(s):  
Magnetic Reconnection ◽  
Flare Loop ◽  
X Ray ◽  
Reconnection Model

scholarly journals The Magnetic Corona: Magnetic Reconnection in Solar Flares

2004 ◽  
Vol 219 ◽  
pp. 91-102
Author(s):  
Harry P. Warren
Keyword(s):  
Spatial Resolution ◽  
Solar Flares ◽  
Light Curves ◽  
Small Scale ◽  
Flare Loop ◽  
X Ray ◽  
Stellar Flares ◽  
Emission Models ◽  
Reconnection Model ◽  
High Cadence

The ability of the Transition Region and Coronal Explorer (TRACE) to image the Sun at high spatial resolution and high cadence over a very broad range of temperatures makes it a unique instrument for observing solar flare plasma. TRACE observations have confirmed the reconnection model for solar flares, at least qualitatively. TRACE flare observations show impulsive footpoint brightenings that are followed by the formation of high-temperature loops in the corona. These loops then cool to lower temperatures, forming post-flare loop arcades. Comparisons between TRACE and lower spatial resolution Yohkoh Soft X-Ray Telescope (SXT) observations have revealed that solar flares are composed of a multitude of fine coronal loops. Detailed hydrodynamic modeling of flare light curves shows that this fine scale structuring is crucial to understanding the evolution of the observed emission. Models based on single, isothermal loops are not consistent with the TRACE observations. Models based on the sequential heating of small-scale loops, in contrast, are able to reproduce many of the salient features of the observed light curves. We will discuss the implication of these results for more energetic stellar flares as well as smaller-scale events that may be responsible for the heating of solar active region loops.

Magnetic reconnection model of X-ray plasmas in the Galactic center

2000 ◽  
Vol 25 (3-4) ◽  
pp. 505-508
Author(s):  
T. Yokoyama ◽  
S. Tanuma ◽  
T. Kudoh ◽  
K. Shibata
Keyword(s):  
Magnetic Reconnection ◽  
Galactic Center ◽  
X Ray ◽  
Reconnection Model

scholarly journals MHD Simulation of Chromospheric Evaporation in a Solar Flare Based on Magnetic Reconnection Model

1998 ◽  
Vol 188 ◽  
pp. 213-214
Author(s):  
T. Yokoyama ◽  
K. Shibata
Keyword(s):  
Heat Conduction ◽  
Solar Flare ◽  
Magnetic Reconnection ◽  
The Other ◽  
Simple Loop ◽  
X Ray ◽  
Long Duration ◽  
Chromospheric Evaporation ◽  
Anisotropic Heat Conduction ◽  
Reconnection Model

Two-dimensional magnetohydrodynamic simulation of a solar flare is performed using a newly developed MHD code including nonlinear anisotropic heat conduction effect (Fig. 1; Yokoyama & Shibata 1997a). The numerical simulation starts with a vertical current sheet which is line-tied at one end to a dense chromosphere. The flare energy is released by the magnetic reconnection mechanism stimulated initially by the resistivity perturbation in the corona. The released thermal energy is transported into the chromosphere by heat conduction and drives chromospheric evaporation. Owing to the heat conduction effect, the adiabatic slow-mode MHD shocks emanated from the neutral point are dissociated into conduction fronts and isothermal shocks (Yokoyama & Shibata 1997b). Temperature and derived soft X-ray distributions are similar to the cusp-like structure of long-duration-event (LDE) flares observed by the soft X-ray telescope aboard Yohkoh satellite. On the other hand density and radio maps show a simple loop configuration which is consistent with the observation with Nobeyama Radio Heliograph. Two interesting new features are found. One is a pair of high density humps on the evaporated plasma loops formed at the collision site between the reconnection jet and the evaporation flow. The other is the loop-top blob behind the fast-mode MHD shock.

Space and Time Distribution of Hard X-Ray Emission in a Loop at the Beginning of a Flare

1994 ◽  
Vol 144 ◽  
pp. 275-277
Author(s):  
M. Karlický ◽  
J. C. Hénoux
Keyword(s):  
Time Distribution ◽  
Electron Bombardment ◽  
Spatial Evolution ◽  
Superthermal Electrons ◽  
Flare Loop ◽  
X Ray ◽  
Superthermal Electron ◽  
Flare Loops ◽  
Chromospheric Evaporation ◽  
Temporal And Spatial

AbstractUsing a new ID hybrid model of the electron bombardment in flare loops, we study not only the evolution of densities, plasma velocities and temperatures in the loop, but also the temporal and spatial evolution of hard X-ray emission. In the present paper a continuous bombardment by electrons isotropically accelerated at the top of flare loop with a power-law injection distribution function is considered. The computations include the effects of the return-current that reduces significantly the depth of the chromospheric layer which is evaporated. The present modelling is made with superthermal electron parameters corresponding to the classical resistivity regime for an input energy flux of superthermal electrons of 109erg cm−2s−1. It was found that due to the electron bombardment the two chromospheric evaporation waves are generated at both feet of the loop and they propagate up to the top, where they collide and cause temporary density and hard X-ray enhancements.

X-ray plasma ejection and magnetic reconnection

2000 ◽  
Vol 26 (3) ◽  
pp. 461-464 ◽  
Author(s):  
Masamitsu Ohyama ◽  
Kazunari Shibata
Keyword(s):  
Magnetic Reconnection ◽  
X Ray

scholarly journals Theory of Flares and MHD Jets

1998 ◽  
Vol 188 ◽  
pp. 9-12 ◽  
Author(s):  
Kazunari Shibata
Keyword(s):  
Numerical Modeling ◽  
Magnetic Reconnection ◽  
Solar Flares ◽  
Model Application ◽  
Reconnection Model

Recent development on the theory and numerical modeling of solar flares and jets is reviewed with emphasis on the magnetic reconnection model. Application to protostellar flares and jets is also discussed.

scholarly journals Statistical Properties of Magnetic Separators in Model Active Regions

2000 ◽  
Vol 195 ◽  
pp. 443-444
Author(s):  
B. T. Welsch ◽  
D. W. Longcope
Keyword(s):  
Active Region ◽  
Solar Corona ◽  
Magnetic Reconnection ◽  
First Principles ◽  
Magnetic Charge ◽  
Active Regions ◽  
Heating Rates ◽  
X Ray ◽  
Field Lines ◽  
Charge Topology

“Transient brightenings” (or “microflares”) regularly deposit 1027 ergs of energy in the solar corona, and account for perhaps 20% of the active corona's power (Shimizu 1995). We assume these events correspond to episodes of magnetic reconnection along magnetic separators in the solar corona. Using the techniques of magnetic charge topology, we model active region fields as arising from normally distributed collections of “magnetic charges”, point-like sources/sinks of flux (or field lines). Here, we present statistically determined separator (X-ray loop) lengths, derived from first principles. We are in the process of statistical calculations of heating rates due to reconnection events along many separators.

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