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Particle acceleration by a solar flare termination shock

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Science  04 Dec 2015:
Vol. 350, Issue 6265, pp. 1238-1242
DOI: 10.1126/science.aac8467

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Electron acceleration in solar flares

Magnetic reconnection during a solar flare releases energy into the Sun's atmosphere, some of which is converted into accelerated particles in the plasma. Chen et al. combined radio and ultraviolet observations of a solar flare to identify the termination shock region where electrons are accelerated to relativistic speeds.

They confirmed these results with magneto-hydrodynamic simulations. This improved knowledge of the mechanism behind flares improves our understanding of the solar wind and space weather.

Science, this issue p. 1238

Abstract

Solar flares—the most powerful explosions in the solar system—are also efficient particle accelerators, capable of energizing a large number of charged particles to relativistic speeds. A termination shock is often invoked in the standard model of solar flares as a possible driver for particle acceleration, yet its existence and role have remained controversial. We present observations of a solar flare termination shock and trace its morphology and dynamics using high-cadence radio imaging spectroscopy. We show that a disruption of the shock coincides with an abrupt reduction of the energetic electron population. The observed properties of the shock are well reproduced by simulations. These results strongly suggest that a termination shock is responsible, at least in part, for accelerating energetic electrons in solar flares.

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