Abstract We conducted the 31-night time-resolved simultaneous optical spectroscopic and pho-tometric observations of the mid M dwarf flare stars YZ CMi, EV Lac, and AD Leo, using APO 3.5m and SMARTS 1.5m telescopes. Among the 41 detected flares, 7 flares showed clear blue wing asymmetries in Balmer lines, with various correspondences in flare properties (e.g., flare durations are 20 min – 2.5 hours). The line-of-sight velocities of the blue-shifted components range from − 73 to − 122 km s − 1 . Assuming that the blue-shifts were caused by prominence eruptions, the mass of upward moving plasma was estimated to be 10 15 − 10 19 g, which are roughly on the relation between flare energy and erupting mass expected from solar coronal mass ejections (CMEs). Although further investigations are necessary for understanding the observed various properties, these possible prominence eruptions on M-dwarfs could evolve into CMEs, assuming the similar acceleration mechanism with solar eruptions.
Notsu et al. (Sun,) studied this question.