The secular variations in the restricted problem's sixth-order theory and stability: An explicit numerical approach

In this paper, we develop and implement an explicit numerical technique for studying equilibrium solutions concerning the secular variations in the restricted problem of three bodies, and their stability. In this implementation, we employ a sixth-order theory for the secular terms.     

Geosystem as an object of landscape study

GeoJournal - Systems' ideas are organically inherent in the integrational potential of geography. Analysis of evolution of understanding of a “geosystem” witnesses for ecologization...     

Structure-distortion of polytropic stars by differential rotation: Third-order perturbation theory

In order to specify the structure of a rapidly and differentially rotating gaseous polytrope, we extend Chandrasekhar's perturbation theory to include third-order terms in the perturbation parameter. In the present paper, the theory developed is required for a subsequent numerical treatment of the structure-determination.This research was supported by the Research Development Project of the University of Patras, Greece.     

Rotational evolution of solar-type stars

The aim of the present investigation has been to consider rotational evolution of solar-type stars simulated by a polytropic model that possesses differential rotation of Clement's type. A properly defined reduction factor moderates the effects of such a rotation. The present treatment is based upon the general Eulerian equation, governing nonuniform (i.e., nonrigid-body) rotation, which has been set up in a previous investigation. Nonconservative terms, arising when stellar wind torque is under consideration, are taken into account. Data available for the viscosity of the Sun are used to construct a plausible viscosity model. Certain assumptions are made that remove the mathematical difficulties and simplify the physical ground. The obtained results are compared to corresponding estimates of recent observations.     

Zatrikean pregeometry: simple cosmological scenarios

In this paper basic cosmological consequences of zatrikean pregeometry are studied. It is shown that many universal quantities can be calculated with simple applications of this theory. An equation directly linking the angular velocity of the universe, the Hubble constantH and the mean density of the universe is derived. The relation between the massM and the radiusR of the universe is examined. This relation leads to various cosmological scenarios, including variations in physical constants and/or violation of the mass conservation and/or variable geometrical properties.     

Implementation of an explicit numerical method to the study of stability of asteroids with large eccentricities and inclinations

In this paper, we consider the secular variations in the restricted three bodies problem by implementing an explicit numerical technique for studying stability of equilibrium solutions. In the present case, the three bodies are the Sun, the Jupiter and an asteroid. Our results arise from studying some maximum stable orbital elements corresponding to the stable equilibrium solutions of the particular problem.     

White dwarfs with magnetic field and differential rotation

We compute classical white-dwarf models distorted by magnetic field and differential rotation. In the computations we implement a complex-plane strategy and a multiple-partition technique, which have been developed recently by the first author.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain.     

The effect of toroidal magnetic field and differential rotation on self-gravitating polytropic models

In this paper we construct a polytropic model distorted by toroidal magnetic field and differential rotation. We then compute states of critical rotation of this model. In the computations we implement the so-called complex-plane strategy and multiple partition technique which are numerical methods deviced recently by the first author.     

Physical characteristics of critically distorted or almost spherically shaped rotating magnetic polytropic models

We use the so-called complex plane iterative technique (CIT) to the computation of polytropic stars distorted by rotation (either rigid or differential) and magnetic fields (both toroidal and poloidal). We give emphasis on computing(i) critically rotating configurations, and (ii) configurations that – dueto the counterbalancing of the effects of rotation and poloidal magnetic field with the effects of toroidal magnetic field – obtain an almost spherical shape. This revised version was published online in July 2006 with corrections to the Cover Date.