The phase state of dense matter in the intermediate density range ( 1-10 times the nuclear saturation density) is both intriguing and unclear and can have important observable effects in the present gravitational wave era of neutron stars. As matter density increases in compact stars, the sound velocity is expected to approach the conformal limit ( ) at high densities and should also fulfill the causality limit ( ). However, its detailed behavior remains a prominent topic of debate. It was suggested that the sound velocity of dense matter could be an important indicator of a deconfinement phase transition, where a particular shape might be expected for its density dependence. In this work, we explore the general properties of the sound velocity and the adiabatic index of dense matter in hybrid stars as well as in neutron stars and quark stars. Various conditions are employed for the hadron-quark phase transition with varying interface tension. We find that the expected behavior of the sound velocity can also be achieved by the nonperturbative properties of the quark phase, in addition to a deconfinement phase transition. Moreover, it leads to a more compact star with a similar mass. We then propose a new class of quark star equation of states, which can be tested by future high-precision radius measurements of pulsar-like objects.

中等密度范围（核饱和密度的 1-10 倍）的致密物质的相态既有趣又不清楚，在当前的中子星引力波时代具有重要的可观测效应。随着致密恒星中物质密度的增加，声速预计会在高密度时接近共形极限 ( )，并且还应该满足因果极限 (）。然而，它的详细行为仍然是一个重要的争论话题。有人提出，致密物质的声速可能是解除限制相变的一个重要指标，在这种转变中，可能会因密度依赖性而出现特定的形状。在这项工作中，我们探索了混合星以及中子星和夸克星中致密物质的声速和绝热指数的一般性质。具有不同界面张力的强子-夸克相变采用了各种条件。我们发现，除了去约束相变之外，还可以通过夸克相的非微扰特性来实现声速的预期行为。此外，它会导致具有相似质量的更紧凑的恒星。然后我们提出了一类新的夸克星状态方程，