Solar Physics

, Volume 290, Issue 12, pp 3573–3591 | Cite as

Impulsive Heating of Solar Flare Ribbons Above 10 MK

  • P. J. A. SimõesEmail author
  • D. R. Graham
  • L. Fletcher
Solar and Stellar Flares


The chromospheric response to the input of flare energy is marked by extended extreme ultraviolet (EUV) ribbons and hard X-ray (HXR) footpoints. These are usually explained as the result of heating and bremsstrahlung emission from accelerated electrons colliding in the dense chromospheric plasma. We present evidence of impulsive heating of flare ribbons above 10 MK in a two-ribbon flare. We analyse the impulsive phase of SOL2013-11-09T06:38, a C2.6 class event using data from Atmospheric Imaging Assembly (AIA) on board of the Solar Dynamics Observatory (SDO) and the Reuven Ramaty High Energy Solar Spectroscopic Imager (RHESSI) to derive the temperature, emission measure and differential emission measure of the flaring regions and investigate the evolution of the plasma in the flaring ribbons. The ribbons were visible at all SDO/AIA EUV/UV wavelengths, in particular, at 94 and 131 Å filters, sensitive to temperatures of 8 MK and 12 MK. The time evolution of the emission measure of the plasma above 10 MK at the ribbons has a peak near the HXR peak time. The presence of hot plasma in the lower atmosphere is further confirmed by a RHESSI imaging spectroscopy analysis, which shows resolved sources at 11 – 13 MK that are associated with at least one ribbon. We found that collisional beam-heating can only marginally explain the power necessary to heat the 10 MK plasma at the ribbons.


Sun: flares Sun: particle emission Sun: X-rays, gamma rays 



The authors would like to thank Paul Boerner for providing updated SDO/AIA temperature response functions and Iain Hannah for making the DEM regularised inversion software freely available. The research leading to these results has received funding from the European Community’s Seventh Framework Programme (FP7/2007-2013) under grant agreement no. 606862 (F-CHROMA), from STFC grant ST/I001808/1 (PJAS, LF) and ST/L000741/1 (LF), and from an STFC ‘STEP’ award to the University of Glasgow (DRG).


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Copyright information

© Springer Science+Business Media Dordrecht 2015

Authors and Affiliations

  • P. J. A. Simões
    • 1
    Email author
  • D. R. Graham
    • 1
    • 2
  • L. Fletcher
    • 1
  1. 1.SUPA School of Physics and AstronomyUniversity of GlasgowGlasgowUK
  2. 2.INAF-Osservatorio Astrofisico di ArcetriFirenzeItaly

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