General aspects of hard X-ray flares observed by Hinotori: Gradual burst and impulsive burst

✍ Scribed by K. Ohki; T. Takakura; S. Tsuneta; N. Nitta

• Publisher: Springer
• Year: 1983
• Tongue: English
• Weight: 566 KB
• Volume: 86
• Category: Article
• ISSN: 0038-0938
• DOI: 10.1007/bf00157203

✦ Synopsis

We survey here the observational results on five gradual and four impulsive type events from the hard X-ray imaging (SXT) and spectrometer (HXM) instruments on the Hinotori satellite. A set of differences are clearly recognized between the gradual and impulsive type bursts. These are: (i) Hard X-ray images show the existence of a large coronal source for each gradual burst and a wide variety of source structures for impulsive bursts. (2) The source heights of the impulsive bursts appear to be low.

(3) All gradual bursts show power-law spectra while impulsive bursts show exponential thermal spectra at least before the maximum phase. (4) Energy-dependent peak delays are observed only in gradual bursts. From these differences we suggest that two different acceleration and emission mechanisms are involved with these two kinds of hard X-ray bursts.