Context. Flares and coronal mass ejections (CMEs) are important for the evolution of the atmospheres of planets and their potential habitability, particularly for planets orbiting M stars at a distance <0.4 AU. Detections of CMEs on these stars have been sparse, and previous studies have therefore modelled their occurrence frequency by scaling up solar relations. However, because the topology and strength of the magnetic fields on M stars is different from that of the Sun, it is not obvious that this approach works well. Aims. We used a large number of high-resolution spectra to study flares, CMEs, and their dynamics of the active M dwarf star AD Leo. The results can then be used as reference for other M dwarfs. Methods. We obtained more than 2000 high-resolution spectra (R ~ 35 000) of the highly active M dwarf AD Leo, which is viewed nearly pole on. Using these data, we studied the behaviour of the spectral lines Hα, Hβ, and He I 5876 in detail and investigated asymmetric features that might be Doppler signatures of CMEs. Results. We detected numerous flares. The largest flare emitted 8.32 × 1031 erg in Hβ and 2.12 × 1032 erg in Hα. Although the spectral lines in this and other events showed a significant blue asymmetry, the velocities associated with it are far below the escape velocity. Conclusions. Although AD Leo shows a high level of flare activity, the number of CMEs is relatively low. It is thus not appropriate to use the same flare-to-CME relation for M dwarfs as for the Sun.

Flares and CMEs are very powerful events in which energetic radiation and particles are ejected within a short time. These events thus can strongly affect planets that orbit these stars. This is particularly relevant for planets of M-stars, because these stars stay active for a long time during their evolution and yet potentially habitable planets orbit at short distance. Unfortunately, not much is known about the relation between flares and CMEs in M-stars as only very few CMEs have so far been observed in M-stars. In order to learn more about flares and CMEs on M-stars we monitored the active M-star EV Lac spectroscopically at high resolution. We find 27 flares with energies between 1.6 × 1031 and 1.4 × 1032 erg in $\rm H\alpha$ during 127 hours of spectroscopic monitoring and 49 flares with energies between 6.3 × 1031 and 1.1 × 1033 erg during the 457 hours of TESS observation. Statistical analysis shows that the ratio of the continuum flux in the TESS-band to the energy emitted in $\rm H\alpha$ is 10.408 ± 0.026. Analysis of the spectra shows an increase in the flux of the He ii 4686 Å line during the impulsive phase of some flares. In three large flares, we detect a continuum source with a temperature between 6 900 and 23 000 K. In none of the flares we find a clear CME event indicating that these must be very rare in active M-stars. However, in one relatively weak event, we found an asymmetry in the Balmer lines of $\sim 220\, \rm km\, s^{-1}$ which we interpret as a signature of an erupting filament.

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