Theoretical pulsation spectrum for the M = 1.863 M_⊙, X = 0.739 model. The dark grey lines that vertically span the plot are the observed pulsations (modes f₁ to f₇). Their thicknesses are proportional to the observed amplitudes. The light grey lines of different heights are the theoretical pulsations computed from the model. The red line segments correspond to identified island (or mixed gravito-island) modes, assumed to correspond to the observed modes. Meridional cross-sections of these 6 modes, labelled with the letters “a” to “f”, are shown in Fig. B.1. We note that no island pulsation mode was clearly identified around 18 c/d, probably as a result of an avoided crossing.