Ca II K line of different epochs of HD 21620. The spectra that are plotted in the panels at the top and lower left were obtained with HERMES. Lower right panel: median spectra of the indicated period and telescope. FEB-like events appear at ∼16 km s⁻¹ and tentatively at zero (blue-shifted, top left panel) and 50 km s⁻¹ (red-shifted, bottom right). The events of January 2016 appear to present some dynamical evolution. Vertical red- and grey-dashed lines show the stellar and ISM radial velocities, respectively.