Power spectra of the radial velocity for the four stellar simulations ref (top left), boost1d1 (top right), boost1d2 (bottom left), and boost1d4 (bottom right) at depth r = 0.494 R_tot ≃ r_conv − 2H_p,conv. They were obtained via mode projection on the spherical harmonics basis and a temporal Fourier transform of the radial velocity. Velocities are not rescaled, and the magnitudes represented by the colour bar are different for each simulation.