No abstract available

[en] Interpenetrating encounters between galaxies may occur frequently in groups and clusters of galaxies, and will be particularly common if most galaxies possess extended massive halos. When the encounter velocity of two galaxies is comparable with the velocity dispersion of the stars they contain, collisions are highly inelastic and may lead to a merger between the two objects. Such mergers can be investigated by direct numerical simulation. The coalescence of two similar 'galaxies' from a bound or parabolic initial orbit usually produces a centrally condensed oblate spheroidal system whose structure depends only weakly on that of the initial objects. Such mergers give rise to galaxies rotating as slowly as observed systems only if the initial impact parameter of the orbit is much smaller than is necessary to produce a strong interaction. (author)

[en] The assumption of a linearly expanding universe for the JBD-cosmological equations generates a set of solutions for the barotropic equations of state p = αrho(α = const.). These solutions turn out to be valid for closed space - except in the case p = rho which is for open space. The 'gravitational constant' which is inversely proportional to the scalar field phi increases with time if α > -1/3 and decreases for α < -1/3. No solution exists for α = 1/3. The Brans-Dicke parameter ω is negative if α < -1/3. (orig.)

No abstract available

[en] All studies of circulation in stars have been based on a linear perturbation analysis. This analysis establishes criteria for the onset of circulation and, if the perturbations remain weak, allows the circulation pattern to be determined

[en] Solutions of the Lane-Emden equation applied to stellar structure theory are derived, and it is concluded that E and M type solutions arise just as piecewise components of F solutions when the customary determination of an F solution holds

[en] The degeneracy of frequencies of nonradial oscillations is resolved in the presence of rotation. (orig./WL)

[en] Red shift and space curature questions are discussed in a isotropic, homogeneous universe

[en] It is shown that viewed from the 'outside', our universe is a black hole. Hence the 'inside' cosmology considered is termed as the Bright Universe Cosmology. The model proposed avoids the singularities of cosmologies of the Big Bang variety, it gives a good account of the redshifts, the cosmic background radiation, the number counts; it also gives a satisfactory explanation of the 'large numbers coincidence' and of the variation in time of fundamental constants. (Auth.)

[en] One of the Friedman's models (the model with hyperbolic co-moving space filled with dustlike matter, the cosmological constant being zero) is considered in two non-co-moving frames of reference. Comparison of the properties and behaviour of the model in three frames of reference (including the co-moving one) shows that such features of the expanding world (of the contracting one as well), as infiniteness or finiteness of the volume of space, of the amount of mass, of the number of particles are not invariant; these quantities are finite in some frames of reference and infinite in other ones. The same is true for the time elapsed from the beginning of the expansion epoch (i.e. for the ''age'' of the expanding universe). Thus the relativity of spatial and temporal finiteness and infiniteness of the world filled with matter has been illustrated. Information allowing to carry out a similar consideration of other cosmological models is also given in the paper