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Test Bodies (test + body)

Distribution by Scientific Domains
Physics and Astronomy75%

Selected Abstracts

Azimuthally symmetric theory of gravitation , I. On the perihelion precession of planetary orbits

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2010
G. G. Nyambuya
ABSTRACT From a purely non-general relativistic standpoint, we solve the empty space Poisson equation (,2,= 0) for an azimuthally symmetric setting (i.e. for a spinning gravitational system like the Sun). We seek the general solution of the form ,=,(r, ,). This general solution is constrained such that in the zeroth-order approximation it reduces to Newton's well-known inverse square law of gravitation. For this general solution, it is seen that it has implications on the orbits of test bodies in the gravitational field of this spinning body. We show that to second-order approximation, this azimuthally symmetric gravitational field is capable of explaining at least two things: (i) the observed perihelion shift of solar planets; (ii) the fact that the mean Earth,Sun distance must be increasing (this resonates with the observations of two independent groups of astronomers, who have measured that the mean Earth,Sun distance must be increasing at a rate between about 7.0 ± 0.2 m century,1 and 15.0 ± 0.3 m cy,1). In principle, we are able to explain this result as a consequence of the loss of orbital angular momentum; this loss of orbital angular momentum is a direct prediction of the theory. Further, we show that the theory is able to explain at a satisfactory level the observed secular increase in the Earth year (1.70 ± 0.05 ms yr,1). Furthermore, we show that the theory makes a significant and testable prediction to the effect that the period of the solar spin must be decreasing at a rate of at least 8.00 ± 2.00 s cy,1. [source]

Spinning test particles in a Kerr field , II

MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 4 2007
K. Kyrian
ABSTRACT The motion of small spinning free test bodies is usually treated within the ,pole,dipole' approximation, which , in general relativity , leads to Mathisson,Papapetrou (MP) equations. These have to be supplemented by three side constraints in order to provide a unique solution. Several different ,spin conditions' have been proposed and used in the literature, each leading to different worldlines. In a previous paper, we integrated the MP equations with the p,S,,= 0 condition numerically in Kerr space,time and illustrated the effect of the spin,curvature interaction by comparing the trajectories obtained for various spin magnitudes. Here we also consider other spin conditions and clarify their interrelations analytically as well as numerically on particular trajectories. The notion of a ,minimal worldtube' is introduced in order to judge the individual supplementary conditions and to expose the limitations of the pole,dipole approximation. [source]

The gravitomagnetic clock effect and its possible observation

ANNALEN DER PHYSIK, Issue 12 2006
H. Lichtenegger
Abstract The general relativistic gravitomagnetic clock effect involves a coupling between the orbital motion of a test particle and the rotation of the central mass and results in a difference in the proper periods of two counter,revolving satellites. It is shown that at ,,(c -2) this effect has a simple analogue in the electromagnetic case. Moreover, in view of a possible measurement of the clock effect in the gravitational field of the Earth, we investigate the influence of some classical perturbing forces of the terrestrial space environment on the orbital motion of test bodies along opposite trajectories. [source]

Multi-dimensional inhomogeneity indicators and the force on uncharged spheres in electric fields

MATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 7 2009
Dirk Langemann
Abstract Uncharged droplets on outdoor high-voltage equipment suffer a non-vanishing total force in non-homogeneous electric fields. Here, the model problem of a spherical test body is considered in arbitrary dimensions. A series expansion of inhomogeneity indicators is proven, which approximates the total force in local terms of the undisturbed electric field. The proof uses the ideas of generalized spherical harmonics without referring to the particular choice of the orthonormal system. The fast converging series expansion establishes a relationship between the solutions of two partial differential equations on different domains. Copyright © 2008 John Wiley & Sons, Ltd. [source]