In this paper, we present an observation of the confined upward motion of core cooler plasma of a filament that remains within a stable magnetic configuration during its activation. Later it exhibits a rapid reformation along the same magnetic channel within ≈2 hours after the eruption on 4 August 2012. Solar Dynamics Observatory/Atmospheric Imaging Assembly (SDO/AIA), Solar TErrestrial RElations Observatory/Sun Earth Connection Coronal and Heliospheric Investigation (STEREO/SECCHI) and Global Oscillation Network Group (GONG)
Hα observations have been analyzed to investigate the physical mechanism of this plasma dynamics of filament, which shows the sinistral magnetic orientation with positive sign of magnetic helicity. From the GONG Hα observations, we find that the filament plasma gets into its dynamic motion at around 11:20 UT from the middle part of the filament towards the north-west direction with an average speed of ≈100 km/s. Small brightening underneath of it shows possibly the signature of low atmospheric reconnection below the filament eruptive part.
In SDO/AIA 171 A images, we observe an activation of right-handed helically A twisted magnetic flux rope that contains the filament material and confines it during its dynamical motion. The motion of the cool plasma of the filament core stops after traveling a distance of around ≈215 Mm from the point of eruption towards north-west. Some of the plasma moves towards right foot point of the flux rope, while most of the plasma returnes back after 12:00 UT towards the left foot point in order to reform the filament with an average speed of ≈60 km/s
within the stable magnetic structure. From the coronal magnetic field decay index n calculation near the flux rope axis, it is evident that the whole filament axis lies within the domain of stability (i.e., n < 1), which infers the filament stability in spite of strong disturbances at its eastern foot point.