Study of microflares through soxs mission |
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Authors: | Rajmal Jain Vishal Joshi Yoichiro Hanaoka T Sakurai Nipa Upadhyay |
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Institution: | (1) Physical Research Laboratory, 380 009 Navrangpura, Ahmedabad, India;(2) National Astronomical Observatory of Japan (NAOJ), Mitaka, Tokyo, Japan;(3) C. U. Shah Science College, Ashram Road, 380 014 Ahmedabad, India |
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Abstract: | We present a study of 10 microflares observed in 4–30 keV by SOXS mission simultaneously with Hα observations made at NAOJ,
Japan during the interval between February and August 2004. The X-ray and Hα light curves showed that the lifetime of microflares
varies between 4 and 25 min. We found that the X-ray emission in all microflares under study in the dynamic energy range of
4–30 keV can be fitted by thermal plus non-thermal components. The thermal spectrum appeared to start from almost 4 keV, low
level discriminator (LLD) of both Si and CZT detectors, however it ends below 8 keV. We also observed the Fe line complex
features at 6.7 keV in some microflares and attempted to fit this line by isothermal temperature assumption. The temperature
of isothermal plasma of microflares varies in the range between 8.6 and 10.1 MK while emission measure between 0.5 and 2x1049 cm-3. Non-thermal (NT) emission appeared in the energy range 7–15 keV with exponent -6.8 ≤γ≤-4.8. Our study of microflares that had occurred on 25 February 2004 showed that sometimes a given active region produces
recurrent microflare activity of a similar nature. We concluded from X-ray and simultaneous Hα observations that the microflares
are perhaps the result of the interaction of low lying loops. It appears that the electrons that accelerated during reconnection
heat the ambient coronal plasma as well as interact with material while moving down along the loops and thereby produce Hα
bright kernels. |
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Keywords: | X-ray detectors coronal 100 ps solar flares microflares hard X-ray emission |
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