1991 Fiscal Year Final Research Report Summary
Detection of 20 million Degree, Superhot Flare Images with a Coronagraph
| Project/Area Number |
63420002
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Astronomy
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| Research Institution | National Astronomical Observatory |
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Principal Investigator |
HIRAYAMA Tadashi National Astron. Obs. Prof., 太陽物理学研究系, 教授 (20012841)
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| Co-Investigator(Kenkyū-buntansha) |
TSUNETA Saku Univ. Tokyo, Fac. Sci. Astron. Center Res. Assoc., 理学部・天文学教育研究センター, 助手 (50188603)
OKAMOTO Tomizo National Astron. Obs. Res. Assoc., 太陽物理学研究系, 助手 (70012862)
KUMAGAI Kazuyoshi National Astron. Obs. Res. Assoc., 太陽物理学研究系, 助手 (50161691)
YAMAGUCHI Asami National Astron. Obs. Assoc. Prof., 太陽物理学研究系, 助教授 (70158096)
WATANABE Tetsuya National Astron. Obs. Assoc. Prof., 太陽物理学研究系, 助教授 (60134631)
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| Project Period (FY) |
1988 – 1991
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| Keywords | Solar Physics / Coronagraph / Flare (Solar eruption) / Prominence |
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| Research Abstract |
The solar flare is transient explosive phenomena often occurring near the sunspots, and it attains to a temperature of some 20 million degree Kelvin. The cause of the high temperature is not known yet in spite of years of research.
In order to understand the physics involved we planned to construct a new coronagraph to be built on the Mt. Norikura Solar Observatory and to obtain white light images of the 10^7K flare which occurs beyond the limb of the Sun. Simultaneous observations were anticipated using this coronagraph and a Japanese scientific satellite, Solar-A, dedicated to study flares with X-ray imaing device.
A fully automated, 10cm aperture coronagraph was completed in 1990 and begun routine operation since Nov. 1990, and the satellite was successfully launched in Aug. 1991. Since then we have acquired a few flare images on both instruments. And we obtained the electron density of 5x10^9 electrons cm^<-3> and the geometrical thickness l=1x10^8-1x10^9cm, of which a value of l=10^8cm is a surprise and an essentially new result because the apparent geometrical size measured perpendicularly to the line of sight is usually 3-6x10^9cm. This must have important bearing upon flare theory, and we have just begun to investigate the problem. Polarimetric observation will also be conducted soon for determination of prominence magnetic fields.
In summary, we can conclude that the aim shown in the title is being achieved from the new coronagraph and further research is being continued with the collaboration of the Yohkoh satellite.
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