MHD Seismology of a loop-like filament tube by observed kink waves

Abstract

We report and analyze observational evidence of global kink oscillations in a solar filament as observed in Hα by instruments administered by National Solar Observatory (NSO)/Global Oscillation Network Group (GONG). An M1.1-class flare in active region (AR) 11692 occurred on 2013 March 15 and induced a global kink mode in the filament lying towards the southwest of AR 11692. We find periods of about 61–67 minutes and damping times of 92–117 minutes at positions of three vertical slices chosen in and around the filament apex. We find that the waves are damped. From the observed period of the global kink mode and damping timescale using the theory of resonant absorption, we perform prominence seismology. We estimate a lower cut-off value for the inhomogeneity length scale to be around 0.34–0.44 times the radius of the filament cross-section.