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We investigate how higher-order symmetry-energy coefficients of the equation of state (EOS) describing npe core matter impact key neutron star (NS) properties at its crust inner edge, its moment of inertia and corresponding crustal fraction, threshold conditions for direct Urca process, adiabatic index, and related structure observables. Our analysis employs a comprehensive set of CDM3Y-IVF1 equations of state, derived from the M3Y-Paris nucleon-nucleon interaction within a nonrelativistic Hartree-Fock framework, covering a wide range of nuclear matter isoscalar stiffness from soft (K₀=150 MeV) to extremely stiff (330 MeV) regimes. Our analysis reveals that the stiffer EOS characterized by higher isoscalar incompressibility (K₀) and fourth-order symmetry-energy skewness (Q₄) coefficients, coupled with diminished negative values of isoscalar Q₀ and H₀, and isovector K₄, K₄, I₂, ₄, and G₂ coefficients, systematically increase the estimated core-crust transition pressure, density, and charged-particle (p, e, ) fractions, and their threshold values for direct Urca process, as well as the total NS moment of inertia and its crustal fraction, and the central adiabatic index. Simultaneously, they yield less central fraction of p, e, and, and reduced fractional crust thickness and moment of inertia for the maximum NS mass supported by a certain EOS. Conversely, enhanced values of the isoscalar kurtosis I₀ and G₀ symmetry coefficients, and of the higher-order Q₂, H₂, K₆, and K₆ coefficients, combined with diminished negative contributions from K₂ and K₂, produce systematically opposite effects on the mentioned NS quantities, reversing their trends with K₀.
Seif et al. (Thu,) studied this question.