Initial density structures corresponding to Case 1 (top), Case 2 (middle) and Case 3 (bottom). In each panel, we indicate the location of the stellar photosphere (arrow with R_⋆ label and vertical line) of the original stellar model. The shaded area for Case (2) corresponds to the dense CSM characterized by a large density scale height before transitioning to a wind solution. The dot marks the location of the photosphere assuming the material is ionized (κ = 0.34 cm² g⁻¹). For details, see Sect. 2.1.