Constraints on the a − λ plane, resulting from M_max > 2  M_⊙, obtained assuming an SR EOS of baryon matter and a quark core starting at P₁ = 31  MeV  fm^-3. Each line is an upper boundary of the region of (a_CFL,λ_CFL) consistent with M_max > 2  M_⊙. The solid lines are obtained for quark cores composed of a 2SC layer (P₁ < P < P₂) and a CFL core starting at P₂ = 45  MeV  fm^-3. These lines are labeled by the density jump at the B-2SC interface λ_2SC = 1.05,1.15,1.30. We used a_2SC = 0.3 (Agrawal 2010). The dashed line is obtained for purely CFL cores (no 2SC layer) starting at P₂ = 45  MeV  fm^-3, and the dotted line corresponds to purely CFL cores starting at P₁, i.e., replacing the 2SC with the CFL phase. Open circles correspond to EOSs presented in Fig. 3. (This figure is available in color in the electronic form.)