Electric Character of Strange Stars

Using the Thomas-Fermi model, we investigated the electric characteristics of a static non-magnetized strange star without crust in this paper. The exact solutions of electron number density and electric field above the quark surface are obtained. These results are useful if we are concerned about physical processes near the quark matter surfaces of strange stars. PACS: 97.60.Gb, 97.60.Jd, 97.60.Sm If strange quark matter in bulk is absolutely stable, there might be strange star [1] consisting almost completely of strange quark matter in the universe. Frustratingly, strange stars are very similar to neutron stars in their many properties, such as mass and radius. Thus, it is suggested that pulsars might be strange stars [1-3]. However, the interesting question about the nature of pulsars (neutron stars or strange stars) has not been answered with certainty even now yet. Strange quark matter mainly consists of up, down, and strange quarks. As strange quark is a little more massive than that of up and down quarks, there are a few electrons in the chemical equilibrium of strange quark matter in order to keep the matter neutral. Hence, electromagnetic interaction as well as strong interaction results in strange quark matter. The electromagnetic force participated in makes the structure of strange quark matter more interesting and attractive. In this paper, we are to investigate this electric peculiarity of strange stars. Previously, some numerical results [1,4] have been given in literature, but no exact analytical result appears. For a static and non-magnetized strange star, the properties of strange quark matter are determined by the thermodynamic potentials Ωi (i = u, d, s, e) which are functions of chemical potential μi as well as the strange quark mass, ms, and the strong interaction coupling constant αc [1,5]. We use units where ∗BAC is CAS-PKU joint Beijing Astrophysical Center †e-mail: [email protected] h̄ = c = 1, physical quantities can be changed to be expressed in units of c.g.s. by using h̄c = 197.327 fm·MeV and c = 2.9979 × 10 cm/s. Assuming weak interaction chemical equilibrium and overall charge neutrality, we come to μd = μs = μ, μe + μu = μ, ne = (2nu − nd − ns)/3, ni = −∂Ωi ∂μi , (1a) and the total energy density ρ reads