An Observational Study of the Recurring Formation and Dissipation of a Dynamic Filament

Abstract

Based on observations at the $\mbox{H}\upalpha$ wavelength from the Hinode spacecraft, we report here the detailed process of a dynamical filament that showed repeated appearance and dissipation in a filament channel. First, $\mbox{H}\upalpha$ short fibrils spreading in the pre-formed filament channel joined into longer threads. The joining process was found to be accompanied by small-scale brightening activity, indicating the possible involvement of magnetic reconnection. The forming filament was thickened by merging the neighboring dark threads that were nearly parallel to the axis and also those adjacent to its main endpoints. The formed filament as a single coherent structure only existed for tens of minutes, immediately followed by the dissipation. The dissipation appeared to start with expansion of the filament body, ascending and stripping away of the filament threads, and mass drainage along the legs of the filament. The formation–dissipation process of the filament was repeated three times within the four-hour observational window of Hinode. These observations indicate that the filament structure is highly dynamic. This study provides the observational evidence to confirm the hypothesis of Martin et al. (Ann. Geophys. 26, 3061, 2008) on the irreversible build-up of magnetic fields in the corona by discrete threads or groups of threads ascending bodily into the corona.