Evolution of a star with 2.8 M_⊙ in the Hertzsprung–Russell diagram with different δ_ov. The δ_ov is set to 0.00, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, and 0.70. A star symbol indicates the point at which the star radius equals the Roche radius, R_L, where a WD mass of M_WD = 1.0 M_⊙ and orbital periods of log(Pⁱ/days) = 0.8 are assumed. The purple line connecting the star symbols represents the equal-radius line in the Hertzsprung–Russell diagram.