Trigger of successive filament eruptions observed by SDO and STEREO

Using multi-wavelength observation from SDO and STEREO, we investigated the mechanism of two successive eruptions (F1 & F2) of a filament in active region NOAA 11444 on 27 march, 2012. The filament was inverse `J' shaped and lying along a quasi-circular polarity inversion line (PIL). The first part of the filament (F1) erupted at ~2:30UT on 27 March 2012, the second part of the filament (F2) erupted at around 4:20 UT on the same day. A precursor/pre-flare brightening was observed below filament's main axis about 30 min prior to F1. The brightening was followed by a jet-like ejection below filament, which triggered the eruption. Before the eruption of F2, the filament seems to be trapped within the overlying arcade loops almost for $\sim$1.5~hr before its successful eruption. Interestingly, we observed simultaneously contraction (~12km/s) and expansion (~20km/s) of arcade loops in the active region before F2. HMI magnetograms show the converging motion of the opposite polarities resulting in flux cancellation near PIL. We suggest that flux cancellation at PIL resulted jet-like ejection below filament's main axis, which triggered the eruption F1 similar to tether-cutting process. The eruption F2 was triggered by removal of the overlying arcade loops via reconnection process. Both filament eruptions produced high speed (~1000km/s) CMEs.
Comment: 25 pages, 14 figures, accepted to Solar Physics Journal