Multiwavelength observation of a large-scale flux rope eruption above a kinked small filament

We analyzed multiwavelength observations of a western limb flare (C3.9) that occurred in AR NOAA 111465 on 30 April 2012. The high-resolution images recorded by SDO/AIA 304, 1600 Å and Hinode/SOT Hα show the activation of a small filament (rising speed ~40 km s-1) associated with a kink instability and the onset of a C-class flare near the southern leg of the filament. The first magnetic reconnection occurred at one of the footpoints of the filament and caused the breaking of its southern leg. The filament shows unwinding motion of the northern leg and apex in counterclockwise direction and failed to erupt. A flux-rope structure (visible only in hot channels, i.e., AIA 131 and 94 Å and Hinode/SXT) appeared along the neutral line during the second magnetic reconnection that occurred above the kinked filament. The formation of the RHESSI hard X-ray source (12−25 keV) above the kinked filament and the simultaneous appearance of the hot 131 Å loops associated with photospheric brightenings (AIA 1700 Å) indicates the particle acceleration along these loops from the top of the filament. In addition, extreme ultraviolet disturbances or waves observed above the filament in 171 Å also show a close association with magnetic reconnection. The flux rope rises slowly (~100 km s-1), which produces a very large twisted structure possibly through reconnection with the surrounding sheared magnetic fields within ~15−20 min, and showed an impulsive acceleration reaching a height of about 80–100 Mm. AIA 171 and SWAP 174 Å images reveal a cool compression front (or coronal mass ejection frontal loop) surrounding the hot flux rope structure.