Filament eruption and accompanied CME occurring during August 6–8, 2012. (a) and (b) A Hα image and a polarization map including the filament before the eruption taken with the SFT. Red lines in panel (b) show the linear polarization of He I 1083.0 nm; the length of each line indicates the degree of the corresponding linear polarization signal (the line in the inset corresponds to the polarization of 0.01 [1%]), and its direction indicates the orientation of the polarization signal. Only the linear polarization signals >0.1% are shown. The background gray-scape map shows the circular polarization of Si I 1082.7 nm, which provides the photospheric longitudinal magnetic field; the display range is ±1%. (c)–(f) The filament during its eruption observed with the SFT. Panels (c) and (e) show Hα line center images, and (d) and (f) show the Dopplergrams based on the Hα ± 0.05 nm images. Blue and red shifts of the Hα line are indicated by the corresponding colors. (g) A CME seen several hours after the filament eruption observed with the LASCO C2 of SOHO, of which the field of view covers up to 6 solar radii. (h) Schematic representation of the magnetic field structure around the filament before its eruption. The red bar represents the filament material, and helical magnetic field of the flux rope surrounds it. Coronal magnetic loops connect large scale positive and negative polarities on the photosphere.