Impulsive and hot thermal solar flares

✍ Scribed by Saku Tsuneta

• Publisher: Springer
• Year: 1987
• Tongue: English
• Weight: 563 KB
• Volume: 113
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00147680

✦ Synopsis

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 x 1O r K) plasma, and unusually weak ruicrowave 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.