scholarly journals Double Coronal Hard and Soft X‐Ray Source Observed byRHESSI: Evidence for Magnetic Reconnection and Particle Acceleration in Solar Flares

2008 ◽  
Vol 676 (1) ◽  
pp. 704-716 ◽  
Author(s):  
Wei Liu ◽  
Vahé Petrosian ◽  
Brian R. Dennis ◽  
Yan Wei Jiang
Keyword(s):  
Particle Acceleration ◽  
Magnetic Reconnection ◽  
Solar Flares ◽  
X Ray

Observations of Energetic Electrons in Solar Flares

1990 ◽  
Vol 142 ◽  
pp. 438-438
Author(s):  
B. Lokanadham
Keyword(s):  
Particle Acceleration ◽  
Energy Release ◽  
Observational Data ◽  
Solar Flares ◽  
Energetic Electrons ◽  
X Ray

A study of the simultaneous observations of solar flares in optical, radio and X-ray bands is important in understanding the process of energy release and particle acceleration in the explosive phenomena of solar flares. In order to determine the characteristics of such energetic electrons in solar flares, a total number of 50 two-ribbon flares have been carefully selected during the period 1979-89 having simultaneous observational data in the optical, X-ray and radio bands.

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.

Large-scale particle acceleration during magnetic reconnection in solar flares

2020 ◽  
Author(s):  
Xiaocan Li ◽  
Fan Guo
Keyword(s):  
Particle Acceleration ◽  
Magnetic Reconnection ◽  
Power Law ◽  
Solar Flares ◽  
Large Scale ◽  
Magnetic Energy ◽  
High Energy ◽  
Macroscopic Model ◽  
Scale Particle ◽  
Reconnection Layer

<p>Magnetic reconnection is a primary driver of magnetic energy release and particle acceleration processes in space and astrophysical plasmas. Solar flares are a great example where observations have suggested that a large fraction of magnetic energy is converted into nonthermal particles and radiation. One of the major unsolved problems in reconnection studies is nonthermal particle acceleration. In the past decade or two, 2D kinetic simulations have been widely used and have identified several acceleration mechanisms in reconnection. Recent 3D simulations have shown that the reconnection layer naturally generates magnetic turbulence. Here we report our recent progresses in building a macroscopic model that includes these physics for explaining particle acceleration during solar flares. We show that, for sufficient large systems, high-energy particle acceleration processes can be well described as flow compression and shear. By means of 3D kinetic simulations, we found that the self-generated turbulence is essential for the formation of power-law electron energy spectrum in non-relativistic reconnection. Based on these results, we then proceed to solve an energetic particle transport equation in a compressible reconnection layer provided by high-Lundquist-number MHD simulations. Due to the compression effect, particles are accelerated to high energies and develop power-law energy distributions. The power-law index and maximum energy are both comparable to solar flare observations. This study clarifies the nature of particle acceleration in large-scale reconnection sites and initializes a framework for studying large-scale particle acceleration during solar flares.</p>

scholarly journals Radio and X-ray diagnostics of electrons accelerated in solar flares

2006 ◽  
Vol 2 (14) ◽  
pp. 88-88
Author(s):  
Miroslav Bárta ◽  
Marian Karlický
Keyword(s):  
Particle Acceleration ◽  
Solar Flare ◽  
Test Particle ◽  
Solar Flares ◽  
Global Scale ◽  
X Ray ◽  
Particle Simulations

AbstractStarting from 2.5D MHD modelling of solar flares on a global scale we calculate (using the PIC and test-particle simulations) the radio and X-ray emissions generated in solar flare reconnection. Our results – the radio and X-ray spectra and brightness distributions, and their dynamics – are directly comparable with observations providing thus a test of particle acceleration models as well as of the ‘standard’ global flare scenario.

scholarly journals The solar system: a laboratory for the study of the physics of particle acceleration

2006 ◽  
Vol 2 (14) ◽  
pp. 83-85
Author(s):  
Robert P. Lin
Keyword(s):  
Particle Acceleration ◽  
Solar System ◽  
Magnetic Reconnection ◽  
Coronal Mass Ejections ◽  
Solar Flares ◽  
Electron Acceleration ◽  
Physical Conditions ◽  
System A ◽  
Bow Shocks ◽  
Imaging And Spectroscopy

AbstractA remarkable variety of particle acceleration occurs in the solar system, from lightning-related acceleration of electrons to tens of MeV energy in less than a millisecond in planetary atmospheres; to acceleration of auroral and radiation belt particles in planetary magnetospheres; to acceleration at planetary bow shocks, co-rotating interplanetary region shocks, shocks driven by fast coronal mass ejections, and possibly at the heliospheric termination shock; to acceleration in magnetic reconnection regions in solar flares and at planetary magnetopause and magnetotail current sheets. These acceleration processes often occur in conjunction with transient energy releases, and some are very efficient. Unlike acceleration processes outside the solar system, the accelerated particles and the physical conditions in the acceleration region can be studied through direct in situ measurements, and/or through detailed imaging and spectroscopy. Here I review recent observations of tens of MeV electron acceleration in the Earth's atmosphere and in the Earth's radiation belts, electron and ion acceleration related to magnetic reconnection in solar flares, electron acceleration to ≥ 300 keV in magnetic reconnection regions in the Earth's deep magnetotail, and acceleration of solar energetic particles (SEPs) by shocks driven by fast coronal mass ejections (CMEs).

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