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V. Belinski
I.C.R.A.Net- International Center for Relativistic
Astrophysics Network, University of Rome "La Sapienza"
Title: Equilibrium
confgurations of two charged masses in General
Relativity".
Author: G. Alekseev and V.
Belinski
Abstract: A family of static
asymptotically flat solutions for Einstein-Maxwell equations which describe two
non-rotating
electrically charged massive objects (the Reissner -
Nordstrom sources) in equilibrium is presented. From the exact expressions it
is shown that mutual gravitational interaction of these sources can be balanced
by their electrostatic interaction (without any struts) if the masses, charges
and distance between them satisfy the balance equation. This equation shows
that the equilibrium is not possible for two black holes or for two naked
singularity objects. However, in the case when one of the sources is a black
hole and another one is a naked singularityE the
equilibrium is possibleE for some appropriate distance.E The derived equilibrium condition for large
distances asymptotes the Newtonian condition. It is interesting that for
sufficiently short distances even an uncharged Schwarzshild
black hole can "hang" freely in the field of the Reissner-Nordstrom
naked singularity center.
Donato Bini
Istituto per le
Applicazioni del Calcolo ``M. Picone'', CNR I-00161 Rome, Italy , and ICRA,
University of Rome, I-00185 Rome, Italy
Title talk: Frenet-Serret
formalism for null world lines
Abstract: The Frenet-Serret
curve analysis is extended from nonnull to null
trajectories in a generic spacetime using the
Newman-Penrose formalism, recovering old results which are not well known and
clarifying the associated Fermi-Walker transport which has been left largely
unexplored in the literature.This machinery is then
used to discuss null circular orbits in stationary axisymmetric
spacetimes using the Kerr spacetime
as a concrete example, and to integrate the equations of parallel transport
along null geodesics in any spacetime.
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