Échelle diagram of the frequencies of the models resulting from the optimization procedure. The top panel shows the best model with the BG14₂ correction, the middle panel with the SO15 correction, and the bottom panel with no surface correction. Black symbols with error bars indicate the observed frequencies, green symbols represent the model frequencies without corrections, blue symbols represent the model frequencies with surface corrections, and the orange symbols represent the frequencies of the model constrained using ratios. Circles represent modes ℓ = 0, triangles represent modes with ℓ = 1, and diamonds represent modes ℓ = 2. The dotted gray line indicates the 56 μHZ frequency.