Properties of hyperon stars rotating at Keplerian frequency

The structure and properties of a Keplerian rotating hyperon star with an equation of state (EOS) investigated using the relativistic \sigma-\omega-\rho model are examined by employing an accurate numerical scheme. It is shown that there is a clear rotating effect on the structure and properties, and that hyperon star matter cannot support a star with a mass larger than 1.9 M_\odot, even a star rotating at the fastest allowed frequency. The constraints of the two known fastest rotating frequencies (716 Hz and 1122 Hz) on the mass and radius of a hyperon star are also explored. Furthermore, our results indicate that the imprint of the rapid rotation of a hyperon star on the moment of inertia is clear; the backward equatorial redshift, the forward equatorial redshift and the polar redshift can be distinguished clearly, the forward equatorial redshift is always negative; and its figuration is far from a spherical symmetric shape.