Fast filament eruption on 2017 April 23 detected by the Solar Dynamics Doppler Imager (SDDI)

On 2017 April 23, a fast filament eruption was observed by the Solar Dynamics Doppler Imager (SDDI) in operation on SMART telescope at Hida Observatory. The eruption was captured in a wide spectral window around the H-alpha line center, spanning from -9 to +9 A. In this work we investigate the dynamics of the filament eruption taking advantage of the unprecedented line-of-sight information provided by the SDDI. The spectral analysis reveals signatures of blue-shifted plasma up to -8 A, indicating that the material was ejected with a velocity of ~365 km s^-1 along the line-of-sight. The maximum transversal velocity and acceleration estimated from time-distance measurements are about 450 km s^-1 and 2 km s^-2, respectively, exhibiting a rapid exponential-like rise. Considering the derived kinematics properties, we examine the association of the filament eruption with a fast (~955 km s^-1) coronal mass ejection (CME) observed later on. We also discuss the importance and difficulties of determining the real mass motion of the filament eruption by using H-alpha images especially in direction of the line-of-sight, which is a crucial aspect to predict the occurrence of Earth-affecting CMEs.