THE PROPERTIES OF STRANGE STARS IN THE QUARK MASS– DENSITY–DEPENDENT MODEL

Abstract

We study the general properties of compact objects made up of strange matter in the framework of a new equation of state in which the quark masses are parametrized as functions of the baryon density, so that they are heavy (light) at low (high) densities. This has been called the "quark mass-density-dependent model." In this approximation, the strange matter equation of state is rather similar to the corresponding to the MIT Bag Model, but it is significantly stiffer at low densities. Such a property modifies the structure of strange stars in a sizeable way. In this framework, we calculate the structure of strange stars (mass, radius, central density, gravitational redshift, moment of inertia, and total baryon number) finding that the resulting structures are rather similar to those obtained in the MIT Bag model, although some important differences appear. Comparing to the standard bagged case (with a bag constant in the range of B = 60 - 80 MeV fm-3), we find that these objects may be more massive and may show gravitational redshifts larger (up to ≈ 10%) than in the bag case. The moment of inertia and total baryon number may be larger than in the bagged case up to a factor of three. We also calculate the first three radial pulsation modes of these objects, finding that the relation of period vs. gravitational redshift is rather similar to the bag case. Also, we present an analytical treatment for such modes in the low-mass strange stars regime, which is in reasonable agreement with the numerical results.