On Expanding MACH-EINSTEIN Universes

The “telescopic” gravodynamics of the MACH -EINSTEIN -Doctrine gives expanding “MACH ian clouds” as world models. The universe becomes a closed system (according to the classical statistical mechanics) if and only if the total energy H of this cloud, i.e. its HAMILTON ian, vanishes. This cloud is the MACH ian equivalent to the EINSTEIN-de SITTER universe of general relativity (or of “NEWTON ian cosmology”). However, the MACH ian cloud with H = o describes a linearly expanding universe.     

Non-vacuum solutions of Bianchi type VI0 universe in f(R) gravity

In this paper, we solve the field equations in metric f(R) gravity for Bianchi type VI ₀ spacetime and discuss evolution of the expanding universe. We find two types of non-vacuum solutions by taking isotropic and anisotropic fluids as the source of matter and dark energy. The physical behavior of these solutions is analyzed and compared in the future evolution with the help of some physical and geometrical parameters. It is concluded that in the presence of isotropic fluid, the model has singularity at [(t)\tilde]=0\tilde{t}=0 and represents continuously expanding shearing universe currently entering into phantom phase. In anisotropic fluid, the model has no initial singularity and exhibits the uniform accelerating expansion. However, the spacetime does not achieve isotropy as t→∞ in both of these solutions.     

Flare-associated coronal expansion phenomena

Two classes of coronal expansion phenomena have been studied in Sacramento Peak coronal movies: Slow, slightly decelerated expansion phenomena (v=∼10− =∼ 2 km/sec) and fast, accelerated, quasi-exploding arches (v =∼ 10 - > 100 km/sec). The various phenomena were found to be associated with flares in different ways: The slow expansions were long lived post-flare phenomena initiated by the flare; the accelerated expanding arches were either (a) arches expanding prior to and apparently exploding at flare onset, or (b) arches apparently emerging from the flare (probably in its initial phase) and rapidly expanding and exploding, or (c) the expansion and disruption of (originally stable) coronal arches during occurrence of a distant flare. These expansions may be considered as evidence for corresponding flare associated changes in the coronal magnetic field. Mitteilung aus dem Fraunhofer Institut Nr. 96.     

Width of Radio-Loud and Radio-Quiet CMEs

In the present paper we report on the difference in angular sizes between radio-loud and radio-quiet CMEs. For this purpose we compiled these two samples of events using Wind/WAVES and SOHO/LASCO observations obtained during 1996 – 2005. We show that the radio-loud CMEs are almost twice as wide as the radio-quiet CMEs (considering expanding parts of CMEs). Furthermore, we show that the radio-quiet CMEs have a narrow expanding bright part with a large extended diffusive structure. These results were obtained by measuring the CME widths in three different ways.     

Optical depth effects on the formation of spectral lines in rotating and expanding spherical atmospheres

We have investigated the effects of increasing optical depths on spectral lines formed in a rotating and expanding spherical shell. We have assumed a shell whose outer radius is 3 times the inner radius, with the radial optical depths equal to 10, 50, 100, 500. We have employed a constant velocity with no velocity gradients in the shell. The shell is assumed to be rotating with velocities varying as 1/_ρ, where_ρ is the perpendicular distance from the axis of rotation, implying the conservation of angular momentum. Two expansion (radial) velocities are treated: (1)V = 0 (static case) and (2)V = 10 mean thermal units. The maximum rotational velocities areV _rot = 0, 5, 10 and 20. In the shell where there are no radial motions, we obtain symmetric lines with emission in the wings forV _rot = 0 and 5 while forV _rot ≥ 10 we obtain symmetric absorption lines. In the case of an expanding shell, we obtain lines with central emission.     

Expanding clusters of galaxies as components of a relativistic hierarchical cosmology

Approximate metries for clusters embedded in an expanding Robertson/Walker background (Section 1) indicate that in general clusters of galaxies cannot remain uninfluenced by the expansion. The potential for an expanding cluster (Section 2) is seen to suggest that clusters as presently observed are not in static equilibrium and that the missing mass problem can be elucidated via use of the virial theorem (Section 3) given certain density conditions in compact clusters. Non-compact clusters can be treated similarly, and it is found that the behaviour of a low-density cluster is equivalent to that of a domain of a Friedmann (k=0) model Universe (Section 4). The treatment of compact clusters (Section 5) is based on approximate metrics for clusters embedded in a Robertson/Walker background. These comparisons lead to information on the evolution of non-compact clusters and compact clusters (Section 7), and to observable consequences that seem to be borne out successfully (Section 8). Data on clusters themselves tend to show that there exists an expanding supercluster and/ or that >0 (Section 9). Several tests of the hypothesis of expansion of clusters (Section 10) are proposed.     

Dark matter-systematics of its distribution

The dynamical masses of dwarf-spheroidals, spiral and elliptical galaxies, dwarf irregular binaries, groups of galaxies and clusters are shown to lie in a band about the M ∼ ρR³ line. The value of ρ is approximately the same as that estimated for unseen matter in the solar neighbourhood. The clusters themselves lie about theM ∼ R ^-3 line derived for a self-gravitating neutrino gas; their masses are distributed around the maximum Jeans-mass, M_Jmax. corresponding to m_v - 10 eV in an expanding universe. The present day length scales of clusters and the dispersion in the velocities observed within them are understood in terms of a 100-fold expansion subsequent to the initial growth of the fluctuations at M_Jmax. These systematics on theR-M plane imply that the initial condensations in the expanding universe are on the scale of the rich clusters of galaxies, these condensations were triggered dominantly by the gravitation of the neutrinos and the constant density of al systems arises naturally due to the embedding of these systems in the large scale neutrino condensations. If the neutrino density falls off asr ^-2 beyond the cluster edge till the distributions from different clusters overlap, then the mean density of the neutrinos approximately equals the closure density of the universe.     

Conformally coupled dark matter

Dark matter is obtained from a scalar field coupled conformally to gravitation, the scalar being a relict of Dirac's gauge function. This conformally coupled dark matter includes a gas of very light (m 2.25 × 10^–34 eV) neutral bosons having spin 0, as well as a time-dependent global scalar field, both pervading all of the cosmic space. The time-development of this dark matter in the expanding F-R-W universe is investigated, and an acceptable cosmological behaviour is obtained.     

Formation of resonance doublet profiles in rapidly expanding envelopes

Generalization of the escape probability method introduced by Sobolev allows us to study the transfer of spectral line radiation for a resonance doublet in rapidly expanding envelopes.For the cases of outward-accelerating (or equivalently inward-decelerating) and outward-decelerating (or equivalently inward-accelerating) envelopes we derive, in the frame of a three-level atom model, the expressions for the spectral radiation fieldsJ ₁₂ andJ ₁₃, for the resulting radiative force F^RE exerted per atom and for the resonance doublet profileE(X)/C _c; we take into account the complex radiative coupling, in both resonance transitions 12 and 13, between distant parts of the atmosphere.For various physical and geometrical conditions prevailing in the expanding media, we illustrate and discuss the behaviours of those quantities as well as their dependence on the parameters of the model. Namely, we deduce criteria under which resonance doublet profiles formed in outward-accelerating and/or outward-decelerating envelopes would appear to be resolved into double P Cygni profiles.We also stress the importance of treating a resonance doublet as being formed by two distinct resonance transitions when evaluating the resulting radiative force F^RE acting on an atom. It is indeed shown that if we use a two-level atom model to represent a resonance doublet-i.e., assigning to it an oscillator strength equal to the sum of the oscillator strengths of both resonance transitions-the amplitude of the resulting radiative force can be underestimated by factors reaching 100% and more in the regions of the expanding envelope which are optically thick to the spectral line radiation. In this context, it would be essential to revise the previous models of radiation-driven winds developed for early-type stars in which the lines belonging to any multiplet were treated as a single line.Also, Aspirant au Fonds National de la Recherche Scientifique (Belgium).     

Viscous fluid cosmological models in the presence of the zero-mass scalar field

The curvature-free (k=0) FRW expanding cosmological model is developed corresponding to interacting viscous fluids and zero-mass scalar fields. In the absence of non-static scalar fields the model exhibits the existence of the initial singularity (Q=0). However, with non-negative coefficient of shear viscosity, in the presence of non-static scalar fields we find thatQ has a minimum value (0). If this epoch is treated as the initial one, it may be said that the presence of scalar fields avoids the initial singularity. Other physical behaviour that the model exhibit has been discussed.     

Circumstellar X-ray emission from SN1978K

We present the X-ray light curve in the 0.2–2.4 keV band based on fiveROSAT observations of SN1978K in NGC 1313. The X-ray emission is believed to arise from the interaction of the reverse shock and the expanding debris from the supernova. The reverse shock becomes established after the outgoing shock runs into circumstellar matter.     

Cosmological considerations and the special theory of relativity

From the special theory of relativity it follows that the Universe is expanding during the expansive evolutionary phase with the limit velocity of the signal propagationc. The discovery of this fact throws a new light on a number of cosmological questions.     

Concerning the instantaneous mass and the extent of an expanding universe

In this article we want to answer the cosmologically relevant question what, with some good semantic and physical reason, could be called the massM _u of an infinitely extended, homogeneously matter‐filled and expanding universe. To answer this question we produce a space‐like sum of instantaneous cosmic energy depositions surrounding equally each spacepoint in the homogeneous universe. We calculate the added‐up instantaneous cosmic energy per volume around an arbitrary space point in the expanding universe. To carry out this sum we use as basic metrics an analogy to the inner Schwarzschild metric applied to stars, but this time applied to the spacepoint‐related universe. It is then shown that this leads to the added‐up proper energy within a sphere of a finite outer critical radius defining the point‐related infinity. As a surprise this radius turns out to be reciprocal to the square root of the prevailing average cosmic energy density. The equivalent mass of the universe can then also be calculated and, by the expression which is obtained here, shows a scaling with this critical radius of this universe, a virtue of the universe which was already often called for in earlier works by E. Mach, H. Thirring and F. Hoyle and others. This radius on the other hand can be shown to be nearly equal to the Schwarzschild radius of the so‐defined mass M _u of the universe. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Some rotating perfect fluid universes coupled with electromagnetic field interacting with gravitation

Some new interesting solutions, the dynamics, behaviour and phenomena of rotating charged perfect fluid models are investigated, and their physical and geometrical properties are studied in order to substantiate the possibility of the existence of such astrophysical bodies in this Universe. The nature and role of the metric rotation Ω(r,t) as well as that of the matter rotation ω(r,t) are studied for uniform and non-uniform motions. The reactions of the gravitational and charged fields with respect to the rotational motion are studied and possible results are explored for real astrophysical situations, and in some solutions we find the spatial restrictions on the models for realistic conditions. Rotating models which are expanding are obtained in which the rotational motions are decaying with time.     

Circumstellar matter in the symbiotic binary EG and

We present a quantitative model of a proposed common slowly expanding envelope corotating with a symbiotic binary system. The geometry of the envelope is defined by the equipotential surface containing the Lagrangian pointL ₂. The model was applied to the symbiotic binary EG And. The orbital inclination,i = 45°, and mass ratio of the cool to the hot component,q = 2.8–3.0, are determined. The nature of the primary as well as the secondary minima in the light curves, development of the line profiles, radial velocities and equivalent widths of the H line through an orbital revolution are explained by this model.     

Self-consistent stability analysis of spherical shocks

In this paper, we study self-similar solutions, and their linear stability as well, describing the flow within a spherical shell with finite thickness, expanding according to a power law of time, t ^q , where q>0. The shell propagates in a medium with initially uniform density and it is bounded by a strong shock wave at its outer border while the inner face is submitted to a time-dependent uniform pressure. For q=2/5, the well-known Sedov–Taylor solution is recovered. In addition, although both accelerated and decelerated shells can be unstable against dynamic perturbations, they exhibit highly different behaviors. Finally, the dispersion relation derived earlier by Vishniac (Vishniac, E.T. in Astrophys. J. 274:152, 1983) for an infinitely thin shell is obtained in the limit of an isothermal shock wave.     

Topology and Dynamics of the 12 December 1980 Magnetic Cloud Event

In this work we have performed an analysis of the interplanetary magnetic field and plasma parameters associated with the 12th December 1980 shock–magnetic cloud event. The study was complemented by including a detailed analysis of the energetic particles fluxes, spectral indexes and directional information. Locally, the magnetic cloud had a latitude of 48°, longitude of 220° and a radius of 0.15 AU. The maximum approach of the ISEE-3 spacecraft to the magnetic cloud axis was 0.047 AU. Moreover, our results suggest that, when encountered by the spacecraft, the magnetic cloud was expanding at a rate of roughly r ₁/r ₀=1.5 (r ₁ is the final radius and r ₀ the initial one) and that it had been expanding during 59 hr. We have also found evidence which indicates that the particle injection inside the cloud depended on the particle energy and pitch angle. These features also suggest that the energetic particle bi-directional fluxes could not be produced by mirroring in the magnetic cloud feet. Instead we think that these fluxes could be generated by the intrinsic properties of the injection mechanism.     

The dynamical behaviour of aN-shell model for an expanding universe

We consider a homogeneous expanding universe consisting of dust which is represented byN concentric massive spherical shells. We assume an explosive perturbation of the innermost shell at some instant of time. The effect of shell crossing and exchange of energy is investigated by deriving the equations of motion and obtaining their stationary and quasi-stationary solutions. Existing equilibrium stages and the density distribution for theN-shell system are discussed. Gravodynamics is a primary source for an understanding of gravitational clustering.     

Comoving frame calculations of spectral lines formed in rapidly expanding media with the partial frequency redistribution function for zero natural line width

Comoving frame calculations have been used to compute the spectral lines formed in rapidly expanding spherical media. We have employed the angle-averaged partial frequency redistribution functionR _I with a two-level atom model in non-LTE atom approximation. A linear velocity law increasing with radius has been employed with maximum velocity at Τ=0 being set equal to 30 mean thermal units. It is found that one obtains almost symmetric emission line profiles at large velocities similar to those found in quasars.     

Lines formed in rotating and expanding atmospheres

Spectral lines formed in a rotating and expanding atmosphere have been computed in the frame of the observer at infinity. Two kinds of velocity laws are employed: (i) a uniform radial velocity of the gas and (ii) velocity increasing with radius (i.e. velocity gradients). The atmosphere has been assumed to be rotating with constant velocity. We have considered maximum radial and rotational velocities to be 10 and 3 mean thermal units respectively in an atmosphere whose geometrical thickness is 10 times the stellar radius. The total radial optical depth at line centre is taken to be about 100. In all cases, Doppler profile and a source function which is varying as 1/r ² have been used. Generally, the lines are broadened when rotation is introduced. However, when radial motion is also present, broadening becomes asymmetric and the red emission and blue absorption are enhanced.