Observational Tests of a Double Loop Model for Solar Flares

1998 ◽  
Vol 15 (3) ◽  
pp. 318-324 ◽  
Author(s):  
S. J. Hardy ◽  
D. B. Melrose ◽  
H. S. Hudson
Keyword(s):  
Magnetic Reconnection ◽  
Energy Release ◽  
Numerical Investigation ◽  
Solar Flares ◽  
Active Regions ◽  
Double Loop ◽  
Loop Model ◽  
Strong Relation

AbstractA model for the energetics of solar flares, developed by Melrose (1997), is based on magnetic reconnection between two current-carrying magnetic loops. A detailed numerical investigation of the model has been made to identify those configurations that lead to energy release in a flare. Our results predict a strong relation between the ratio of currents in the interacting loops for a favoured flare configuration, and provide further support for a proposed method of generating long loops connecting different active regions. Both of these predictions are amenable to observational verification.

scholarly journals Hard X-ray Spectrum of the Above-the-Looptop Source in Impulsive Solar Flares

2000 ◽  
Vol 195 ◽  
pp. 413-414
Author(s):  
S. Masuda
Keyword(s):  
Magnetic Reconnection ◽  
Energy Release ◽  
Solar Flares ◽  
Count Rate ◽  
High Quality ◽  
X Ray ◽  
Flare Energy

Extended AbstractThe Hard X-ray Telescope (HXT: Kosugi et al. 1991) onboard Yohkoh has observed that, in impulsive solar flares, a hard X-ray source is located above the apex of a soft X-ray flaring loop, in addition to double footpoint sources (Masuda et al. 1994, 1995). This observation suggests that flare energy-release, probably magnetic reconnection, takes place not in the soft X-ray loop but above the loop. It is important to derive the hard X-ray spectrum of the above-the-looptop source accurately in order to understand how electrons are energized there. The above-the-looptop source was most clearly observed during the 13 January 1992 flare. However, the count rate, especially in the H-band (53–93 keV), is too small to synthesize high-quality images and to derive an accurate spectrum.

scholarly journals Preflare Activity

1989 ◽  
Vol 104 (1) ◽  
pp. 135-152
Author(s):  
V. Gaizauskas
Keyword(s):  
Magnetic Fields ◽  
Magnetic Reconnection ◽  
Energy Release ◽  
Solar Flares ◽  
Activity Complex ◽  
Multi Wavelength ◽  
Multiple Structures ◽  
Global Coupling ◽  
Necessary And Sufficient ◽  
Rapid Conversion

AbstractMagnetic reconnection at current sheets or in current-bearing arches in the solar atmosphere is generally accepted as the mechanism responsible for the sudden energy release in solar flares. Attempts have so far been unsuccessful to isolate from the observations some unique preconditions which would be necessary and sufficient to ensure rapid conversion of energy by this process. Here we survey recent multi-wavelength observations which illustrate the variety of preflare activity. Multiple structures are now believed to participate in the energy release. Dynamic global coupling of the magnetic fields between a flaring site and the rest of an activity complex is seen from the data to be an important aspect of preflare activity.

scholarly journals Observational Evidence for Magnetic Reconnection in Solar Flares

1993 ◽  
Vol 141 ◽  
pp. 333-342 ◽  
Author(s):  
J.C. Henoux ◽  
P. Demoulin ◽  
C.H. Mandrini ◽  
M.G. Rovira
Keyword(s):  
Magnetic Reconnection ◽  
Solar Flares ◽  
Active Regions ◽  
Observational Evidence ◽  
Magnetic Topology ◽  
Chromospheric Flare

AbstractFrom studies of the magnetic topology of flaring active regions, the separator - a region were magnetic reconnection can take place - appears to be magnetically connected to places of intense chromospheric flare brightening. This suggests that magnetic reconnection occurs in the separator region in solar flares. Observational support for magnetic reconnection releasing the energy stored in field align currents systems is presented.

scholarly journals Solar Flares as an Ongoing Magnetic Reconnection Process

1993 ◽  
Vol 141 ◽  
pp. 239-248 ◽  
Author(s):  
Saku Tsuneta
Keyword(s):  
Magnetic Reconnection ◽  
Energy Release ◽  
Solar Flares ◽  
Spatial Dimension ◽  
Energy Scale ◽  
Convincing Evidence ◽  
Neutral Sheet ◽  
X Ray ◽  
Reconnection Process ◽  
Limb Flare

AbstractThe soft X-ray images taken by the Yohkoh Soft X-ray Telescope (SXT) provide a powerful new tool to solve the mechanism of solar flares. In particular, a limb flare that occurred on 1991, December 2 gives us convincing evidence that magnetic reconnection of a neutral sheet formed at the loop top participates in the flare energy release. The neutral sheet appears to be associated with a destabilized rising loop system (filament) sheared with respect to the flaring loop. Similar formations of X-ray arcades are seen in the quiet Sun associated with filament eruptions on much larger spatial dimension and with a much smaller energy scale.

Magnetic reconnection in solar flares

2010 ◽  
Vol 180 (9) ◽  
pp. 997 ◽  
Author(s):  
B.V. Somov
Keyword(s):  
Magnetic Reconnection ◽  
Solar Flares

Evidence for a Cutoff in the Frequency Distribution of Solar Flares from Small Active Regions

1997 ◽  
Vol 475 (1) ◽  
pp. 338-347 ◽  
Author(s):  
T. A. Kucera ◽  
B. R. Dennis ◽  
R. A. Schwartz ◽  
D. Shaw
Keyword(s):  
Frequency Distribution ◽  
Solar Flares ◽  
Active Regions

scholarly journals The effects of density inhomogeneities on the radio wave emission in electron beam plasmas

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Xin Yao ◽  
Patricio A. Muñoz ◽  
Jörg Büchner ◽  
Xiaowei Zhou ◽  
Siming Liu
Keyword(s):  
Magnetic Reconnection ◽  
Radio Wave ◽  
Solar Flares ◽  
Electron Beams ◽  
Distribution Functions ◽  
Plasma Emission ◽  
Langmuir Waves ◽  
Radio Emissions ◽  
Density Inhomogeneities ◽  
Effects Of Density

Type III radio bursts are radio emissions associated with solar flares. They are considered to be caused by electron beams travelling from the solar corona to the solar wind. Magnetic reconnection is a possible accelerator of electron beams in the course of solar flares since it causes unstable distribution functions and density inhomogeneities (cavities). The properties of radio emission by electron beams in an inhomogeneous environment are still poorly understood. We capture the nonlinear kinetic plasma processes of the generation of beam-related radio emissions in inhomogeneous plasmas by utilizing fully kinetic particle-in-cell code numerical simulations. Our model takes into account initial electron velocity distribution functions (EVDFs) as they are supposed to be created by magnetic reconnection. We focus our analysis on low-density regions with strong magnetic fields. The assumed EVDFs allow two distinct mechanisms of radio wave emissions: plasma emission due to wave–wave interactions and so-called electron cyclotron maser emission (ECME) due to direct wave–particle interactions. We investigate the effects of density inhomogeneities on the conversion of free energy from the electron beams into the energy of electrostatic and electromagnetic waves via plasma emission and ECME, as well as the frequency shift of electron resonances caused by perpendicular gradients in the beam EVDFs. Our most important finding is that the number of harmonics of Langmuir waves increases due to the presence of density inhomogeneities. The additional harmonics of Langmuir waves are generated by a coalescence of beam-generated Langmuir waves and their harmonics.

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