Equatorial Circular Orbits and the Motion of the Shell of Dust in the Field of a Rotating Naked Singularity

The astrophysical and observational consequences of the (possible) existence of Kerr naked singularities (NSs) are examined, and the circular geodesic orbits in the equatorial plane of a rotating NS are studied. It is shown that, owing to the existence of negative-energy orbits, the extraction of rotational energy from these NSs is astrophysically plausible for both the dissipative processes (by gravitational radiation or by viscous heating of accretion disks) and the Penrose process. In addition, the motion of the shell of incoherent matter in the field of a rotating NS is investigated; the shell, initially spherical, is found to become prolate along the symmetry axis during the fall, and to be oblate when the shell returns to infinity.