Dynamic Evolution of Magnetic Flux Ropes in Active Region 11429. I. EUV Observations

Studying the formation and dynamic evolution of the magnetic flux rope (MFR) is key to understanding the physics of most solar eruptions. In the present study, we investigate the dynamic evolution of four MFRs, which involve in a major eruption. The MFR1, which represents as filament (F1), first appears about 31 hr before the major eruption. The MFR2 appears as a hot-channel with a small filament (F2) in its east part. The hot-channel becomes intermittently visible about 2 hr before the major eruption. The MFR3 is formed by the reconnection between MFR1 and MFR2. The annular components of MFR3 along the MFR2 part appear as a hollow helical structure from the background with the temperature of several MK after the reconnection. Coronal material then flows along the hollow structure from MFR1 part to MFR2 part to form a new filament (F3), which is hosted by MFR3 and acts as the axial component of MFR3 in the following evolution. The MFR4 appears during MFR3's eruption phase as conjugated extreme ultraviolet (EUV) brightenings. Both brightenings extend outward into irregular ribbons with conjugate EUV dimmings inside. Meanwhile, an erupted hot-channel, which roots in the conjugated brightening, is identified. The morphology of the MFRs are also profiled by four associated flare ribbon pairs. The on-disk observations shed light on our understanding of the topology of the MFRs and their formation and eruption. Further work should lay emphasis on the magnetic environment for the MFR formation and evolution.