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Flares on the Sun: Selected Results from HINOTORI

Published online by Cambridge University Press:  12 April 2016

Katsuo Tanaka
Katsuo Tanaka*
Affiliation:
Tokyo Astronomical Observatory, University of Tokyo Mitaka, Tokyo, Japan

Abstract

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The X-ray observations of solar flares by Japanese astronomy satellite Hinotori (ASTRO-A) are reviewed. Detailed results from the X-ray telescope and the soft X-ray spectrometers are given. The hard X-ray images in the 17-40 keV range show a wide variety of source structures. Examples of compact single source, stationary coronal source, and double sources are presented. High resolution spectra in the range 1.7-2.0A indicate strong turbulence and blue-shifted components in the beginning of flares. From the FeXXV and FeXXVI spectra two kinds of thermal plasma are shown to appear. The cooler component of Te=15-20xl06K, which increases in the impulsive phase of the hard X-ray burst, is suggested to be produced by the dissipation of the electron beams. The hotter component of Te=30-50xl06K and Ne=1011-1012 increases towards the flare maximum. This component is also responsible for emitting 17-40keV continuum, and emitted from a very compact source. The results are discussed in comparison with flare loop models. It is shown that evolutionary changes in the loop density realize various source structures in the hard X-ray under the unitary electron beam hypothesis.

Type
Session III: Observed Activity in Related Objects
Information
International Astronomical Union Colloquium , Volume 71: Activity in Red-Dwarf Stars , 1983 , pp. 307 - 320
Copyright
Copyright © Reidel 1983

References

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