Particle acceleration by a solar flare termination shock
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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Supplementary Material
Summary
Materials and Methods
Figs. S1 to S6
Movie S1
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Information & Authors
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Published In
Science
Volume 350 | Issue 6265
4 December 2015
4 December 2015
Copyright
Copyright © 2015, American Association for the Advancement of Science.
Submission history
Received: 24 June 2015
Accepted: 3 November 2015
Published in print: 4 December 2015
Acknowledgments
The authors thank the National Radio Astronomy Observatory (NRAO) staff for their support and E. DeLuca, K. Reeves, H. Tian, J. Lin, A. Warmuth, H. Hudson, A. Caspi, F. Guo, G. Nita, G. Fleishman, and X. Bai for helpful discussions. S. Bourke and G. Hallinan are acknowledged for making their fast radio imaging software AIPSLite available for B.C. A. K. Tolbert and R. Schwartz are thanked for their help in providing the Fermi/GBM detector response for this flare. Z. Wang and M. DeRosa are thanked for their help on the Pfss extrapolations. The NRAO is a facility of the National Science Foundation (NSF) operated under cooperative agreement by Associated Universities, Inc. The VLA data can be accessed at https://archive.nrao.edu/archive/advquery.jsp, using the observing times as the search criteria. The Solar Dynamics Observatory/AIA, RHESSI, Hinode/XRT, and Solar and Heliospheric Observatory/LASCO data are all available through the Virtual Solar Observatory (http://sdac.virtualsolar.org/cgi/search). B.C. acknowledges support by NASA under contract SP02H1701R from Lockheed-Martin to the Smithsonian Astrophysical Observatory (SAO) and contract NNM07AB07C to SAO, and by the NASA Living With a Star Jack Eddy Fellowship (administered by the University Corporation for Atmospheric Research). C.S.’s work was supported by NSF SHINE grants AGS-1156076 and AGS-1358342 to SAO. D.E.G. acknowledges support from NSF grant AST-1312802 and NASA grant NNX14AK66G to the New Jersey Institute of Technology. S.K. and L.G. are supported by NASA contract NAS598033 for the RHESSI spacecraft.
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