Solar flares at submillimeter wavelengths

  • Säm KruckerEmail author
  • C. G. Giménez de Castro
  • H. S. Hudson
  • G. Trottet
  • T. S. Bastian
  • A. S. Hales
  • J. Kašparová
  • K.-L. Klein
  • M. Kretzschmar
  • T. Lüthi
  • A. Mackinnon
  • S. Pohjolainen
  • S. M. White


We discuss the implications of the first systematic observations of solar flares at submillimeter wavelengths, defined here as observing wavelengths shorter than 3 mm (frequencies higher than 0.1 THz). The events observed thus far show that this wave band requires a new understanding of high-energy processes in solar flares. Several events, including observations from two different observatories, show during the impulsive phase of the flare a spectral component with a positive (increasing) slope at the highest observable frequencies (up to 405 GHz). To emphasize the increasing spectra and the possibility that these events could be even more prominent in the THz range, we term this spectral feature a “THz component”. Here we review the data and methods, and critically assess the observational evidence for such distinct component(s). This evidence is convincing. We also review the several proposed explanations for these feature(s), which have been reported in three distinct flare phases. These data contain important clues to flare development and particle acceleration as a whole, but many of the theoretical issues remain open. We generally have lacked systematic observations in the millimeter-wave to far-infrared range that are needed to complete our picture of these events, and encourage observations with new facilities.


Sun: flares Sun: radio observations 



The authors thank the International Space Science Institute (ISSI), Bern, Switzerland, for supporting the preparation of this review. We also would like to thank the anonymous referee for his comments, which helped to improve our review.


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Copyright information

© Springer-Verlag Berlin Heidelberg 2013

Authors and Affiliations

  • Säm Krucker
    • 1
    • 3
    Email author
  • C. G. Giménez de Castro
    • 2
  • H. S. Hudson
    • 3
  • G. Trottet
    • 4
  • T. S. Bastian
    • 5
  • A. S. Hales
    • 5
  • J. Kašparová
    • 6
  • K.-L. Klein
    • 4
  • M. Kretzschmar
    • 7
  • T. Lüthi
    • 8
  • A. Mackinnon
    • 9
  • S. Pohjolainen
    • 10
  • S. M. White
    • 11
  1. 1.Institute of 4D Technologies, School of EngineeringUniversity of Applied Sciences and Arts Northwestern SwitzerlandWindischSwitzerland
  2. 2.CRAAMUniversidade Presbiteriana MackenzieSão PauloBrazil
  3. 3.Space Sciences LaboratoryUniversity of CaliforniaBerkeleyUSA
  4. 4.Observatoire de Paris, LESIACNRS-UMRMeudonFrance
  5. 5.National Radio Astronomy ObservatoryCharlottesvilleUSA
  6. 6.Astronomical Institute of the Academy of Sciences of the Czech RepublicOndřejovCzech Republic
  7. 7.LPC2EUMR 6115 CNRS et Université d’OrléansOrléans Cedex 2France
  8. 8.Leica Geosystem AGHexagon MetrologyUnterentfeldenSwitzerland
  9. 9.DACE/Department of Physics and AstronomyUniversity of GlasgowGlasgowUK
  10. 10.Department of Physics and Astronomy, Tuorla ObservatoryUniversity of TurkuPiikkiöFinland
  11. 11.Space Vehicles Directorate, AFRLKirtland AFBAlbuquerqueUSA

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