Numerical Simulation On The Formation,Evolution And Eruption Of Magnetic Flux Rope In Solar Active Region

The spectacular solar activity in the solar active region is closely related to the surrounding magnetic field structure,but because the coronal magnetic field is difficult to measure directly,there are many unsolved mysteries hidden in it,which has aroused great research interest.The collision-shear process is a new concept of photospheric motion that was only proposed in 2019,and the current research on this process is still in the development stage,and it is basically observational at present,and no relevant numerical simulation research has been found yet.Based on this new concept,we study the formation and evolution of the magnetic flux rope in the active region.We take February 14,2011,AR11158 as the research object.Three-dimensional magnetohydrodynamic numerical simulation is used to simulate the photosphere motion of the magnetic poles in the collisional shearing motion on the photosphere layer,reproduce the whole process of the magnetic rope from the formation to the explosion,and analyze the formation and evolution of the magnetic flux rope in the solar active region.The following conclusions are drawn:(1)Due to the magnetic flux cancellation caused by the collisional shearing motion,the shearing magnetic arch above the photosphere occur magnetic reconnection,and a magnetic flux rope with a helical structure is formed above the photosphere after a few minutes.The magnetic flux rope is injected with a large amount of helicity under the collisional shearing motion of the magnetic poles,and has been storing a large amount of magnetic free energy.(2)After the magnetic flux rope is formed,there is a pair of "J"-shaped magnetic force lines under the magnetic flux rope to occur magnetic reconnection,so that the magnetic flux rope starts to rise from the central part.During the ascending process,the magnetic field lines connecting the four magnetic poles occur magnetic reconnection under the magnetic flux rope to form a complex current sheet.(3)After the magnetic flux rope is formed,it rises under the Lorentz force.The rising process can be divided into a slow rising phase and a pulse phase.Due to the continuous collisional shearing motion,the shear magnetic arch around the magnetic flux rope occur tether-cutting reconnection under the magnetic flux rope,which causes the magnetic flux rope to rise linearly and the speed can reach 30km/s.After the eruption of the magnetic flux rope,the magnetic flux rope enters the pulse phase,the height of the magnetic rope increases exponentially,and the speed can reach 100 km/s.In this process,the second magnetic flux rope will also have the same process,but due to the short polar inversional line between the non-conjugated magnetic poles,the canceled magnetic flux is far less than that of the first magnetic flux rope,so the power is not as good as the first one.magnetic flux rope.