Advances in Astrophysics

8

Authors: V.U.M.Rao, M.Vijaya Santhi, N.Sandhya Rani

Spatially homogeneous axially symmetric cosmological models filled with barotropic fluid and dark energy are obtained in a scalar tensor theory of gravitation proposed by Brans and Dicke (1961). In these models one fluid is the radiation distribution which represents the cosmic microwave background and the other fluid is the perfect fluid representing the matter content of the universe. Also some important features of the models, thus obtained, have been discussed.

11

Authors: Jaiyeola Sefinat. B., Abdulrazaq Abdulraheem, Titiloye, Emmanuel O.

This research work investigates the effect of Poynting-Robertson (P-R) drag on the stability of the triangular libration points of the Restricted Three Body Problem (RTBP) when the primaries are considered to be oblate spheroid as well as sources of radiation. We established the equations of motion, which incorporated the perturbing forces, for the system. Using linear approximations, we obtained the triangular libration points in terms of the perturbing parameters and found that they were affected by them. Due to the nature of the characteristics equation corresponding to the variational equations of motion of the system obtained, we employed Murray’s criteria and concluded that the triangular libration points remained unstable.

21

Authors: Joseph J. Smulsky

In light of the latest research developments, this paper describes the fundamental principles of the astronomic theory of climate change. It comprises three problems: the evolution of the orbital motion, the evolution of the Earth’s rotational motion and the evolution of the insolation controlled by the evolutions of those motions. All the problems have been solved in a new way and other methods. The paper demonstrates geometric parameters of the Earth’s insolation by the Sun, and explains a new insolation theory. Its results are identical to the results of the previous theory. The equations of orbital movement are established, is told about their solution and the results for the different periods of time are submitted. These results improve the results of the previous theories: the planets’ and the Moon’s orbits are stable and the Solar system is stable. In much the same way, the problem of the Earth’s rotation is described. Unlike the previous papers, this problem is solved here without simplification. The calculations demonstrate significant oscillation of the Earth’s axis. These results were confirmed with other three independent solutions of the Earth’s rotation problem. The oscillations of the Earth’s axis result in such oscillations of insolation that explain the paleoclimate changes. The material in this paper is presented in a format intelligible for a broad audience.