AD Leo spectral observations

We observed the dMe star AD Leo using the 2-meter Perek telescope at Ondrejov observatory, with simultaneous photometric light curves. In analogy with solar flares, we model the H{alpha} line emergent from an extensive arcade of cool flare loops and explain the observed asymmetries using the concept of coronal rain. We solve the non-LTE radiative transfer in H{alpha} within cool flare loops taking into account the velocity distribution of individual rain clouds.

For a flare occurring at the center of the stellar disc, we then integrate radiation emergent from the whole arcade to get the flux from the loop area. We observed two flares in the H{alpha} line that exhibit red wing asymmetry corresponding to velocities up to 50km/s during the gradual phase of the flare. Synthetic profiles generated from the model of coronal rain have enhanced red wings quite compatible with observations.