Multiwavelength Observations of a Partial Filament Eruption on 13 June 2011

In this paper, we report the multiwavelength observations of the partial filament eruption associated with a C1.2 class flare in NOAA active region 11236 on 13 June 2011. The event occurred at the eastern limb in the field of view (FOV) of Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) spacecraft and was close to the disk center in the FOV of Extreme-UltraViolet Imager (EUVI) onboard the Behind Solar Terrestrial Relations Observatory (STEREO) spacecraft. During eruption, the filament splits into two parts: the major part and the runaway part. The major part flows along closed loops and experiences bifurcation at the loop top. Some of the materials move forward and reach the remote footpoint, while the remainder returns back to the original footpoint. The runaway part flows along open-field lines, which is evidenced by a flare-related type-III radio burst. The runaway part also undergoes bifurcation. The upper branch escapes the corona and evolves into a jet-like narrow coronal mass ejection (CME) at a speed of ∼ 324 km s −1 , while the lower branch falls back to the solar surface. A schematic cartoon is proposed to explain the event and provides a new mechanism of partial filament eruptions.