Enlarged M_G−M_B plane for V₁ = 0.03 GeV and G₂ = 0.010 GeV⁴ close to the maximum mass configurations. In each constant-entropy curve, the rounded dot indicates the appearance of the quark matter core. The squared points a, b and c indicate the maximum mass configuration for s ≃ 1, s ≃ 2 and s = 0, respectively. The squared dot d indicates the initial configuration that evolves, through a constant baryonic mass vertical line, to the maximum mass configuration of the curve s ≃ 2. Only for proto-HS with baryonic masses , a constant baryonic mass vertical line can be drawn across the dots f, e and c and the three isentropic curves. Thus, such stars will remain stable, surviving the evolutionary process towards a cold HS.