Solar Physics

, Volume 113, Issue 1–2, pp 35–48 | Cite as

Impulsive and hot thermal solar flares

  • Saku Tsuneta


Some X-class flares (hot thermal flares, HTF) observed with the Hinotori satellite show unique behavior: slow time variability, a compact hard X-ray source containing dense (n > 1011 cm−3) and hot (T > 3 × 107 K) plasma, and unusually weak microwave emission in spite of the intense magnetic field (B > 330 G) required theoretically to sustain the hot plasma. These observations show that HTF's have essentially thermal characteristics throughout the flare evolution, while in impulsive flares, there is a transition in the energy release mode from particle acceleration (impulsive phase) to plasma heating (gradual phase). This behavior can be explained in a unified manner by employing parallel DC electric field acting over large distances.


Flare Solar Flare Release Mode Plasma Heating Impulsive Phase 


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Copyright information

© D. Reidel Publishing Company 1987

Authors and Affiliations

  • Saku Tsuneta
    • 1
  1. 1.Division of SpectroscopyTokyo Astronomical Observatory University of TokyoTokyoJapan

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