منابع مشابه
Electron acceleration in solar flares: theory of spectral evolution
Context. Stochastic acceleration is thought to be a key mechanism in the energization of solar flare electrons. Aims. We study whether stochastic acceleration can reproduce the observed soft-hard-soft evolution of the spectral features of the hard X-ray emitted by suprathermal electrons. We pay special attention to the effects of particle trapping and escape. Methods. The Fokker-Planck equation...
متن کاملElectron Firehose instability and acceleration of electrons in solar flares
An electron distribution with a temperature anisotropy T‖/T⊥ > 1 can lead to the Electron Firehose instability (Here ‖ and ⊥ denote directions relative to the background magnetic field B0). Since possible particle acceleration mechanisms in solar flares exhibit a preference of energizing particles in parallel direction, such an anisotropy is expected during the impulsive phase of a flare. The p...
متن کاملACCELERATION AND ENRICHMENT OF 3He IN IMPULSIVE SOLAR FLARES BY ELECTRON FIREHOSE WAVES
A new mechanism for acceleration and enrichment of He during impulsive solar flares is presented. Low-frequency electromagnetic plasma waves excited by the Electron Firehose Instability (EFI) can account for the acceleration of ions up to 1 MeV amu−1 energies as a single stage process. The EFI arises as a direct consequence of the free energy stored in a temperature anisotropy (T e ‖ > T e ⊥) o...
متن کاملThe shock reprocessing model of electron acceleration in impulsive solar flares
We propose a new two-stage model for acceleration of electrons in solar flares. In the first stage, electrons are accelerated stochastically in a post-reconnection turbulent downflow. The second stage is the reprocessing of a subset of these electrons as they pass through a weakly compressive fast shock above the apex of the closed flare loop on their way to the chromosphere. We call this the "...
متن کاملParticle acceleration in solar flares: observations versus numerical simulations
Solar flares are generally agreed to be impulsive releases of magnetic energy. Reconnection in dilute plasma is the suggested trigger for the coronal phenomenon. It releases up to 1026 J, accelerates up to 1038 electrons and ions and must involve a volume that greatly exceeds the current sheet dimension. The Ramaty High-Energy Solar Spectroscopic Imager satellite can image a source in the coron...
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ژورنال
عنوان ژورنال: International Astronomical Union Colloquium
سال: 1989
ISSN: 0252-9211
DOI: 10.1017/s0252921100031821