Study of Microflares through SOXS Mission

Journal of astrophysics and astronomy

Nipa Upadhyay³  Vishal Joshi²  Yoichiro Hanaoka¹  Rajmal Jain1²  T. Sakurai¹ 

[1] National Astronomical Observatory of Japan (NAOJ), Mitaka, Tokyo, Japan.$$;Physical Research Laboratory, Navrangpura, Ahmedabad 380 009, India.$$;C. U. Shah Science College, Ashram Road, Ahmedabad 380 014, India.$$

关键词: X-ray detectors;    coronal 100 ps;    solar flares;    microflares;    hard X-ray emission.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

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 2 × 1049 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.

【 授权许可】

Unknown