Mass M vs. radius R for non-rotating NS models calculated using different assumptions concerning the structure of dense matter for ρ > 2ρ₀. Dotted segments of M(R) curves: configurations unstable with respect to small radial perturbations. N – nucleon matter, Argonne V₁₈+TBF nucleon interaction (Schulze & Rijken 2011). B – baryon matter, EOS calculated using hyperon-nucleon and hyperon-hyperon potentials Nijmegen ESC08 (Rijken et al. 2010a,b). Open circles – configurations of maximum allowable mass, with central density given in units of ρ₀. BQ – hybrid stars with quark cores, when reconfinement is not allowed. – hybrid stars with stable quark cores, when the condition is always satisfied and the high-density reconfinement is allowed. Analytical EOS of quark matter in the CFL state with ρ₂ = 2.35ρ₀, a_CFL = 0.5, λ_CFL = 1.2. Enlarged rectangle: vicinity of the high-density first-order phase transition Q→B (reconfinement). (This figure is available in color in the electronic form.)