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.
KeywordsFlare Solar Flare Release Mode Plasma Heating Impulsive Phase
Unable to display preview. Download preview PDF.
- Bai, T., and Dennis, B. R.: 1985, Astrophys. J. 287, 179.Google Scholar
- Kai, K.: 1985b, Proc. Cosmic Radiation Symposium (ISAS, Tokyo), p 69.Google Scholar
- Kondo, I.: 1982, in Y. Tanaka et al. (eds.) Proc. Hinotori Symposium on Solar Flares (ISAS, Tokyo), p. 3.Google Scholar
- Kundu, M and Woodgate, B (eds.): 1986, Energetic Phenomena on the Sun (NASA CP-2439), p. 2–19.Google Scholar
- Ogawara, Y: 1988, in these proceedings.Google Scholar
- Tsuneta, S: 1984, in J.-C. Pecker and Y. Uchida (eds.) Proc. Japan-France Seminar on Active Phenomena in the Outer Atmospheres of Stars and the Sun, Paris p. 243.Google Scholar