Observational evidence of torus instability as trigger mechanism for coronal mass ejections: the 2011 August 4 filament eruption

摘要: Solar filaments are magnetic structures often observed in the solar atmosphere and consist of plasma that is cooler denser than their surroundings. They visible for days -- even weeks which suggests they equilibrium with environment before disappearing or erupting. Several eruption models have been proposed aim to reveal what mechanism causes (or triggers) these eruptions. Validating through observations represents a fundamental step our understanding We present an analysis observation filament agrees torus instability model. This model predicts flux rope embedded ambient field undergoes when axis reaches critical height depends on topology field. use two vantage points SDO STEREO reconstruct three-dimensional shape filament, follow its morphological evolution determine just eruption. The magnetograms acquired by SDO/HMI used infer derive onset instability. Our shows trigger also find some pre-eruptive processes, such as reconnection during flares cancellation at neutral line, facilitated bringing region where was more vulnerable