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We investigate systematically the quark-hadron mixed phase in dense stellar matter and its influence on compact star structures. The properties of quark matter and hadronic matter are fixed based on various model predictions. Beside adopting constant values, the surface tension Σ for the quark-hadron interface is estimated with the multiple reflection expansion method and equivparticle model. To fix the structures of quark-hadron pasta phases, a continuous dimensionality of the structure is adopted as proposed by Ravenhall et al. The corresponding properties of hybrid stars are then obtained and confronted with pulsar observations. It is found that the correlation between radius and tidal deformability in traditional neutron stars preserves in hybrid stars. For those permitted by pulsar observations, in almost all cases, the quark phase persists inside the most massive compact stars. The quark-hadron interface plays an important role in hybrid star structures once quark matter emerges. The surface tension Σ estimated with various methods increases with density, which predicts stiffer equation of states (EOSs) for the quark-hadron mixed phase and increases the maximum mass of hybrid stars. With or without the emergence of quark matter, the obtained EOSs of hybrid star matter are close to each other at densities n≲0.8 fm-3, while larger uncertainty is expected at higher densities. [ABSTRACT FROM AUTHOR]

We study the interface effects of a quark-hadron mixed phase in compact stars. The properties of nuclear matter are obtained based on the relativistic-mean-field model. For the quark phase, we adopt a perturbation model with running quark masses and coupling constant. At certain choices of parameter sets, it is found that varying the quark-hadron interface tension will have sizable effects on the radii (ΔR≈600  m) and tidal deformabilities (ΔΛ/Λ≈50%) of 1.36 solar mass hybrid stars. These provide possibilities for us to constrain the quark-hadron interface tension with future gravitational wave observations as well as the ongoing NICER mission. [ABSTRACT FROM AUTHOR]