There is the long standing conjecture that in the cores of neutron stars the matter resides in a deconfined state (cf. [1] and further references therein). Basing on the speculation of self-bound strange quark matter also pure strange quark stars have been predicted (cf. [2] for a reference list for this topic). The theoretical study of this subject was hampered up to now by the poorly known equation of state at large baryon density. However, recently a considerable progress has been made in calculating the equation of state at vanishing baryon density [3].
In [4] we have shown that the lattice QCD data can be described within a quasiparticle model. This model allows to map the lattice results to finite baryon density. Provided the quasiparticle nature does not change, the equation of state is accessible in such a way. Surprisingly, the numerically obtained results at vanishing temperature can be approximated by p = ae - 4 [B\tilde], where p is the thermodynamical pressure, e the total energy density, a = 3.0 ¼4.5 and [B\tilde]^1/4 = 200 ¼260 MeV. The ranges of a and [B\tilde] are a direct consequence of the yet existing uncertainty of the lattice QCD results.
Exploiting the given parameterization one can integrate the TOV equations to get the masses and radii of cold, pure quark stars in local b equilibrium, as displayed in Figs. 1 and 2. Due to the b equilibrium a large fraction of the quarks occurs as strange quarks.
Of course, the existence of pressure-free deconfined matter is questionable, therefore, one should study hybrid stars by interpolating from our high-density equation of state to nuclear matter densities, where the equation of state is fairly well known.

Fig. 1 The dependence of the mass of pure quark stars with strangeness on the radius for several values of the parameters a and [B\tilde]1/4.	Fig. 2 Maximum masses (upper hatched band, right scale) and corresponding radii (lower hatched band, left scale) of pure quark stars as a function of [B\tilde]1/4. The upper (lower) limit of the bands is for a = 3 (4.5).

¹Dept. of Physics, Brookhaven Nat. Lab., Upton, NY 11973, USA
² Institut für Theoretische Physik, TU Dresden

References

[1] B. Kämpfer, J. Phys. A 14 (1981) L471, Phys. Lett. B 158 (1984) 121

[2] K. Schertler, C. Greiner, J. Schaffner-Bielich, M.H. Thoma, Nucl. Phys. A 677 (2000) 463

[3] F. Karsch, E. Laermann, A. Peikert, Phys. Lett. B 478 (2000) 447

[4] A. Peshier, B. Kämpfer, G. Soff, Phys. Rev. C 61 (2000) 045203  IKH 05/31/01 © B. Kämpfer