| Solar flare is a solar activity phenomena that in the local areas dramatically brightens of the solar atmosphere,It also is one of the most intense solar activity ever observed in the solar atmosphere.A large amount of high-energy electromagnetic radiation and high-energy particle stream released in the process of solar flare eruption will affect the heliosphere environment and the life of human beings on earth to a great extent.Therefore,it is of great significance to study the eruption mechanism and evolution of solar flares and to give a possible prediction method.On September 6,2017,NOAA AR12673,located southwest of the solar,frequently produced more than a dozen flares,including two large x-class flares,during the 8:00-12:00 UT period.For the location of the eruptive flare,we conducted a careful statistical study on the active region data observed by SDO/AIA at channel 1700 A,it was found that during this period(8:00-12:00 UT),a total of about 57 flare blocks were formed in the active area(large flares can be composed of several or even dozens of flare blocks).We've plotted the locations of these patches with asterisks on the same map,the results show that the distribution of these flares has obvious regularity,thirty of them are in a north-south strip,and twenty more in an east-west strip.By comparing this distribution with the vector magnetic map observed by SDO/HMI,it is easy to find that the north-south distribution zone almost coincides with the magnetic neutral line of the active region,and the east-west distribution has no significant correspondence with the characteristics of the magnetic map.However,by comparing the evolution of the active region from September 1 to September 6,we found that the distribution zones of the two flares were located in the new emerging magnetic region.In order to further understand the flare eruption mechanism,we obtained the vector magnetic map of the active region based on SDO/HMI,and calculated the current distribution of the active region by using the ampere loop integration algorithm.By comparing the position of the flare patch and the current distribution,it is found that the flare site has a very good correspondence with the strong current: The line-of-sight current distribution shows that there is a pair of conjugate strong current bands with opposite polarity at the corresponding position of the magnetic neutral line,and the positions of the flare patches on the north-south flare patches distribution ribbon mostly correspond to the strong electric current area;in addition,the location of the flare patches distribution ribbon in the east-west direction also shows an extremely strong electric current distribution area.This correspondence indicates that the flare eruption is closely related to the current distribution in the solar activity region.According to the above correlation,a reasonable explanation may be that the strong current region in the active region stores a high density of free energy.Once this free energy is released,it may rapidly heat the plasma in the region,and lead to the flares eruption.The strong current structure can be calculated using vector magnetic maps prior to the flare,therefore,we can infer the possible location of the flare according to the position of the strong current band before the flare.According to the relationship between the flare and the current distribution,we propose a feasible method to predict the location of the flare.In this paper,Chapter 1 mainly introduces the stratified structure of the solar and the phenomenon of solar activity in the active region.Chapter 2 mainly introduces the research progress of solar flare,magnetic fluid equation(MHD),magnetic reconnection model,current sheet formation and flare theory model.Chapter 3 introduces the measurement theory of magnetic field and the calculation method of electric current.Chapter 4 is our main work,that is,the statistical study of the flare location and current distribution. |
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