The Model of the Simulation

1. t=0 t=170 Ｚ 6*10^4 km Te Te Te 200 200 200 Ｙ 0 0 0 Abstract Coronal Mass ejections(CMEs) are one of the most dynamical phenomena and have been studied theoretically and observationally. But their origins are still unknown. From theoretical views(Kusano, Devore), CMEs have been considered to occur owing to an instability or a loss of a equilibrium of the coronal magnetic field since the coronal gas pressure and the gravity is much lower than the magnetic force. As a process of losing a equilibrium, magnetic arcade which has a large shear and with a converging motion is widely studied. Observations(Feynman & Martin) suggest that the emerging flux has a strong connection with CMEs. As a interpretation to understand both of the results of the theories and the observations, we suggest that the dynamical motion such as a conversing one may be due to the emergence of the flux tube. The aim of our paper is to understand the basic mechanism by which the emerging flux can trigger the filament eruption, which can be a source of CMEs. For this purpose, we performed three-dimensional simulations of the filament eruption caused by the emergence of the magnetic flux tube from the convective zone into the coronal region. Our simulations show that when emerging flux appears near the outer edge of the arcade field, the arcade is deformed strongly by the high magnetic pressure of the flux tube. At the height of the lower corona, where the magnetic force is much higher than the other forces, the distance between the opposite polarity regions of the arcade becomes smaller because the emerging flux push the one of the polarity region to the other. Then the current sheet is made inside the arcade, and the reconnection process starts, which leads to the eruption of the arcade field. These results of our simulations suggest that the emerging flux can be a cause of the CMEs. Ｚ Ｙ Y Z X X Three-Dimensional Filament Eruption driven by a Emerging Flux Tube in the Sun S.Notoya T.Yokoyama (University of Tokyo) K.Kusano,T.Sakurai,T.Miyagoshi,H.Isobe,T.Yamamoto The Model of the Simulation the model of the flux tube The temporal evolution of magnetic field t=140 10^5 km t=140 the model of the arcade field t=170 ・3D resistive MHD equations (no radiation and conduction) cross sections at x=0 ・the anormalous resistivity model It can be seen from these figures that the structure of the arcade is deformed by the magnetic pressure of the emerging flux during its expansion in the corona, and the collapsed arcade gains upward velocity in the process of the magnetic reconnection. In the right panel, the blue plus red line shows the reconnected field line, and the yellow, green lines are un-reconnected lines. ・the initial perturbation at central part of the flux tube ・units

2. thermal+potential+magnetic Poynting Flux 3 t=166 kinetic magnetic Te 1 200 (ｘ25s) 0 (ｘ12 km/s) by the expansion of the emerging flux the eruption of the arcade (ｘ25s) 1.*10^(-6.) O point total force plasmoid -1.*10^(-6.) Summary & Discussion Z 80 200 thermal+potential+magnetic by the expansion of the emerging flux Poynting Flux 1.5 kinetic magnetic no eruption of the arcade t=0 0.3 Te 200 0 t=166 Te 200 0 The upward forces inside the region of the plasmoid Time profile of the Energy of the Erupting Arcade t=166 In the process of the magnetic reconnection, the arcade field collapses and becomes the filamentary structure, and then goes upward because the magnetic energy of the emerging flux is continuously released below the filament. The main upward force is the magnetic pressure, and the downward tension force exists around the o-point inside the filament owing to the unreconnected field lines. the energy differences from the initial states Em(t=0)=6.9,Eth(t=0)=15.0,Epot(t=0)=17.1 With the expansion of the emerging flux, the magnetic energy is stored in the arcade field and released in the process of the magnetic reconnection. The released energy is converted to the thermal, potential, and kinetic energy, and the newly reconnected field lines have upward velocities. t=166 the upward velocity at o-point in the filament The results of the simulation of the case of the wider arcade (twice as large as the former case). ･We studied the process that the emerging flux triggers the filament eruption, which can be a source of CMEs. ･It was found that the arcade was deformed by the high magnetic pressure of the emerging flux, making the current sheet inside the arcade. ･Through the reconnection process, the field lines of the filamentary structure were made from the collapsed arcade, and had upward velocities by the released energy of the emerging flux. ･These results of our simulations suggest that the converging motion which can destabilize the sheared arcade field may be due to the flux emergence which has been observed so far, and the reconnection process can be thought to be a key process for the eruptions. (ｘ12 km/s) (ｘ25s) (ｘ25s) the energy differences from the initial state Em(t=0)=6.9,Eth(t=0)=15.0,Epot(t=0)=17.1 the upward velocity at o-point in the filament In the case of the wider arcade (the density of the magnetic energy is same as the former case), the filament eruption des not occur. Although the arcade is deformed, it does not collapse completely since the arcade itself has more energy than the former case and the reconnection process does not proceed effectively. In other words, the emerging flux has not enough energy to make the arcade collapse, and can not trigger the filament eruption. • References • Kusano & Maeshiro 2004,APJ,610,537 • DeVore 2000,APJ,539,954 • Feynman & Martin 1995,JGR,100,3355