Échelle diagram representing the observed frequencies (filled black symbols) as well as the model frequencies (open red symbols) corresponding to a representative best-fitting model. No interpolation was used and so this correspondsto a specific model in the grid. The circles, triangles, and squares indicate the modes of angular degree ℓ = 0 (radial modes), ℓ = 1 (dipole modes), and ℓ = 2 (quadrupolemodes), respectively.