Panel a: quiescent (in black) and flaring (in orange) spectra of the star AU Microscopii, obtained from the coronal model. Panel b: quiescent (in black) and flaring (in orange) spectra of the Sun (used as a proxy for HD 209458), based on measurements by the TIMED/SEE spacecraft. The flaring spectrum is the mean of four strong solar flares (see text). The quiescent spectrum is the mean of the spectra recorded a few minutes before onset of the flares. Panel c: quiescent and flaring spectra of the star used as a proxy for HD 189733. The quiescent spectrum (in black) is obtained from the coronal model applied to the star ϵ Eridani. Two different flaring spectra are constructed using spectral shapes from solar flares (in orange) and the modelled AU Mic flare (in red) – both flaring spectra are scaled to match X-ray observations of flares on the star HD 189733 (see text for further details).