Panel a) envelope mass distribution of ZAHB stars produced by the tidally enhanced stellar wind. Panel b) relationship between the envelope mass and effective temperature of ZAHB stars. Panel c) effective temperature distribution of ZAHB stars produced by the tidally enhanced stellar wind. The dashed, solid, and dotted curves in each panel correspond to the model calculations for three different metallicities as in Fig. 1, namely Z = 0.0001, 0.001, 0.02, respectively. The two adjacent solid dots in each curve of these three panels denote a fixed separation interval of Δlog a/R_⊙ = 0.025 (a is the separation of binary system).