Onset mechanism of solar eruptions

Solar eruptions are the most energetic phenomena observed in the solar system observed as flares, coronal mass ejections (CMEs) and filament/prominence eruption. The helically twisted flux tube is widely thought to be the source and driver of solar eruptions and to carry the plasma into the interplanetary space. Those may eventually reach the magnetosphere and cause strong disturbances of the geomagnetic field. Therefore, the understanding of the onset of solar eruptions is important not only in the framework of solar physics but also for the space weather forecast. In this paper, we report on new insight into the onset mechanism of solar eruptions recently obtained from our new studies. We perform the studies in terms of the observational approach with state-of-the-art solar physics satellites and the numerical one with the latest super computer system. We specified two types of small magnetic perturbations of the photospheric magnetic field. These can enhance the magnetic reconnection in the pre-existing non-potential magnetic field, which produces a large flux tube and then drives the eruption. We further confirmed that this reconnection is a key process for the eruption in our latest data-constrained simulation. We report our latest results and our interpretation of the onset mechanism of solar eruptions.