Multiwavelength Observations of a Partially Eruptive Filament on 2011 September 8

Abstract

In this paper, we report our multiwavelength observations of a partial filament eruption event in NOAA active region 11283 on 2011 September 8. A magnetic null point and the corresponding spine and separatrix surface are found in the active region. Beneath the null point, a sheared arcade supports the filament along the highly complex and fragmented polarity inversion line. After being activated, the sigmoidal filament erupted and split into two parts. The major part rose at the speeds of 90−150 km s −1 before reaching the maximum apparent height of ∼115 Mm. Afterwards, it returned to the solar surface in a bumpy way at the speeds of 20−80 km s −1 . The rising and falling motions were clearly observed in the extreme-ultravoilet (EUV), UV, and Hα wavelengths. The failed eruption of the main part was associated with an M6.7 flare with a single hard X-ray source. The runaway part of the filament, however, separated from and rotated around the major part for ∼1 turn at the eastern leg before escaping from the corona, probably along large-scale open magnetic field lines. The ejection of the runaway part resulted in a very faint coronal mass ejection (CME) that propagated at an apparent speed of 214 km s −1 in the outer corona. The filament eruption also triggered transverse kink-mode oscillation of the adjacent coronal loops in the same AR. The amplitude and period of the oscillation were 1.6 Mm and 225 s. Our results are important for understanding the mechanisms of partial filament eruptions and provide new constraints to theoretical models. The multiwavelength observations also shed light on space weather prediction.Subject headings: Sun: corona -Sun: coronal mass ejections (CMEs) -Sun: flares -Sun: filaments Online-only material: animations, color figures -22 -4. The runaway part, however, separated from and rotated around the major part for ∼1 turn before escaping outward from the corona at the speeds of 125−255 km s −1 , probably along the large-scale open magnetic field lines as evidenced by the PFSS modelling and the type III radio burst. The ejected part of the filament led to a faint CME. The angular width and apparent speed of the CME in the FOV of C2 are 37 • and 214 km s −1 . The propagation directions of the escaping filament observed by SDO/AIA and STA/EUVI are consistent with those of the CME observed by LASCO/C2 and STA/COR1, respectively. 5. The partial filament eruption also triggered transverse oscillation of the neighbouring coronal loops in the same AR. The amplitude and period of the kink-mode oscillation were 1.6 Mm and 225 s. We also performed diagnostics of the plasma density and temperature of the oscillating loops.The authors thank the referee for valuable suggestions and comments to improve the quality of this article. We gratefully acknowledge for inspiring and constructive discussions. SDO is a mission of NASA's Living With a Star Program. AIA and HMI data are courtesy of the NASA/SDO science teams. STEREO/SECCHI data are provided by a consortium of US,

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