Podrobný výpis o publikaci

We present influence of cosmological constant on the character of geodesical equatorial circular orbits in the rotating and charged Kerr-Newman black-hole and naked singularity spacetimes. Conditions for the existence of geodesics are determined. Significant limits such as static radius and circular orbits are presented. In the Kerr-Newman-de Sitter spacetime, the existence of two static radii implies different situation in both plus- and minus-family circular orbits in comparison with the Kerr-de Sitter spacetime. Especially, in the naked singularity case, existence of so called plus-family orbits is now restricted by the rotational parameter, minus-family orbits exists not only between the outer static radius and minus-family circular photon orbit but also between the inner static radius and minus-family circular photon orbit.