Line profile evolution of Hα, D3 He I and Na D vs. the pulsation phase from minimum R_min to maximum R_max of the photospheric radius. The apparition of the strongest Hα emission near 0.89 at R_min corresponds to the emergence of the main shock from the subphotospheric layers. The letter e means that an emission is present within the Hα line profile (yellow). The blueshifted and redshifted absorption components are shown in blue and red. A P Cygni profile is shown in green. The shock velocity corresponds to an average velocity deduced from Fig. 8 of Gillet et al. (2019). For D3, the dotted area indicates that no emission or absorption line could be detected. The scale and phases are approximate.