bluuebunny/crossref_metadata_2025 huggingface dataset:
On spinor field equations of BUCHDAHL and WÜNSGH
Authors: Illge R.
Published: July 2007

The field equations of BUCHDAHL and WÜNSCH for the description of fields of particles with nonzero rest mass and arbitrary spin in curved space‐times are considered. The Lagrangian, the field equations and the energy‐momentum tensor for fields of integer spin are formulated by means of real tensor fields.
The formation of primordial stars triggered by the evolution of large‐scale density perturbations
Authors: M$Uucket J. P. , Haubold H. J.
Published: July 2007

This paper summarizes the basic idea of coupling of density perturbation modes in Newtonian cosmology and the formation of primordial stars. The way of deriving the second‐order differential equation governing the growth of two coupled adiabatic density perturbation modes in the matter era is briefly discussed. A Jeans criterion for the growth of short wavelength perturbations is given. A mechanism is proposed for the cosmological origin of Population III stars.
Fluctuations in contracting objects
Authors: Salié N.
Published: July 2007

By a general relativistic fluctuation theory developed recently following ideas by LANDAU and LIFSHITZ, hydrodynamical fluctuations in a simple model of a contracting star are considered. It can be shown that there are always regions in which the fluctuations and mean square values of basic physical quantities are increasing.
Semiregular variable RX Bootis: Double‐period optical variation of a cosmical maser?
Authors: Andronov I. L. , Kudashkina L. S.
Published: July 2007

Periodogram analysis of 349 photovisual observations showed the peaks corresponding to periods 352 ± 5d, 179.1 ± 0.3d and 162.4 ± 0.8d. The first value is very close to 1 year, so it might not be justified by the present observations. The other two values obtained by ‘two‐parameter’ search seem to be independent periods, but not the effect of ‘observational windows’. No other significant peaks were detected in the interval from 65d to 100d.
Analysis and results of cooperative magnetographic measurements. I. Correction, comparison and discussion of measurements
Authors: Hofmann A. , Grigorjev V. M. , Selivanov V. L. , Klvana M.
Published: July 2007

On June 24, 1983 cooperative magnetographic measurements were made with the vectormagnetographs of the Sayan Observatory (Irkutsk) and the Potsdam Solar Observatory “Einsteinturm” and with the longitudinal magnetograph of the Ondrejov Observatory. Additionally, the maximum field strengths in the sunspot were measured with the photographic method. Using the photographically measured field strengths as reference values we provide a method to eliminate the influences of stray light in a time series of vectormagnetograms. A comparison of nearly simultaneous magnetograms shows a good correspondence in general. The deviations of the zero points as well as the scales are comparable with the results of other authors. Regarding the magnetic field distribution the magnetograms reflect a substantial nonsymmetric structure in the spot under study. The magnetic field lines tend to concentrate into several flux tube clusters. In one region of the penumbra we find a magnetic field with nearly longitudinal character in close neighbourhood of a strong, nearly horizontal flux tube bundle. This indicates a strong nonradial horizontal field gradient in the penumbra.
Particle content and degrees of freedom of a gravitational field in 4th order theories of gravity
Authors: M$Oubius K.
Published: July 2007

In gravitational theories of 4‐th order, the influence of certain properties of the field equations (tracelessness, conformal invariance, scale in variance respectively their breaking) for the “particle content” (number of degrees of freedom, mass, spin) is investigated. Using the plane‐wave ansatz valid in linearized theory it is possible to determine the mass content of the theory, but one cannot get assertions about the number of degrees of freedom and the spin states corresponding to the field quanta. In the linearized theory, this can be done with a spin projection formalism.

Using the Cauchy initial value problem and a counting method first developed by EINSTEIN one can get, however, a useful definition of the concept of the degrees of freedom for the full nonlinear theory. This is due to the fact that this method allows to incorporate the concrete structure of the field equations (and thus their nonlinearities). Analysing different general‐relativistic field theories via these approaches the influence of the various structures of nonlinearities is discussed. It is, in particular, shown that those results obtained by the spin projection formalism can be reproduced by “nonlinear methods”.
Analysis and results of cooperative magnetographic measurements. II. Comparison and interpretation of the current densities
Authors: Hofmann A. , Grigorjev V. M. , Selivanov V. L.
Published: July 2007

We compare and interpret distributions of vertical electric current densities derived from nearly simultaneous vector measurements by the magnetographs of the Sayan Observatory (Irkutsk) and the Potsdam Solar Observatory. The derived distributions of current densities of the different observations are in good agreement referring to the scaling factors and the morphological structure. The zero points differ within the noise level amounting to 0.8 * 10‐3 Am‐2 for the Sayan observation and to 1.3 * 10‐3 Am‐2 for the Potsdam observation. In the spot under study we found several current filaments indicating that the spot is clustered by several flux bundles. An azimuthal current between (5.9 ± 1.4) * 1011 A and (6.8 ± ± 1.5) * 1011 A flowing around a (relatively isolated) flux bundle can be derived from the observations.
Catalogue of Abell clusters of galaxies with published photometric data
Authors: Baier Potsdam‐Babelsberg F. W. , Ziener Tautenburg R. ,
Published: July 2007

This catalogue is a compilation of references of publications with photometric data in and around Abell clusters of galaxies.

Die Arbeit enthält eine Zusammenstellung der Publikationen mit photometrischen Daten für Abell‐Haufen und ihre Umgebung.
Numerical simulation of colour equations for the uvby system
Authors: Reimann H. G. , Böhm M. , Pfau W.
Published: July 2007

The results of numerical simulation of colour equations of uvby photometry for filter‐defined bandpasses are presented. It is shown that linear transformation equations to the standard system are valid for instrumental systems deviating by no more than 2.5 nm in peak transmission wavelengths. The comparison with the results of observations is satisfying.

Im Ergebnis einer numerischen Farbgleichungssimulation im uvby‐System wird nachgewiesen, daß für Instrumentensysteme mit Abweichungen der Wellenlängen maximaler Transmission bis zu 2.5 nm gegenüber den Standardwerten eine lineare Transformation möglich ist. Der Vergleich mit Beobachtungsresultaten zeigt eine gute Übereinstimmung.
Beobachtungen Kleiner Planeten. VIII
Authors: Börngen F.
Published: July 2007

Es wird eine Übersicht gegeben über die im Jahr 1987 auf Tautenburger Schmidtplatten gefundenen Kleinen Planeten. Es wurden 290 Objekte entdeckt und für diese 845 Positionen gerechnet. Es handelt sich um 75 numerierte Objekte, von denen drei auf der kritischen Liste von EMP 1988 stehen, sowie um 215 Planetoiden mit provisorischen Bezeichnungen. Von letzteren erhielten 191 neue Bezeichnungen. Für 17 im Berichtszeitraum numerierte Planeten haben Tautenburger Beobachtungen einen Beitrag geleistet. Darunter sind zwei in Tautenburg entdeckte Planetoiden: 1967 GF1 erhielt die Nummer (3539) und den Namen Weimar, der Trojaner 1973 UF5 die Nummer (3540) und den Namen Protesilaos.

A summary is given about the Minor Planet survey performed in 1987 on Tautenburg Schmidt plates. There were discovered 290 asteroids and calculated 845 positions for them. These are 75 numbered objects and 215 asteroids with provisional designations, 191 of them have new designations. Tautenburg observations could give a tribute to 17 planets numbered in the period of this report, including two asteroids discovered in Tautenburg: 1967 GF1 received the number (3539) and the name Weimar, the Trojans 1973 UF5 the number (3540) and the name Protesilaos.
Cosmic strings and strings in gravitational waves
Authors: Schmidt H.‐J. , Semmelmann U.
Published: July 2007

We consider strings with the Nambu action as extremal surfaces in a given space‐time, thus, we ignore their back reaction. Especially, we look for strings sharing one symmetry with the underlying space‐time. If this is a non‐null symmetry the problem of determining ihc motion of the string can be dimensionally reduced. We get exact solutions for the following cases: straight and circle‐like strings in a Friedmann background, straight strings in an anisotropic Kasner background, different types of strings in the metric of a gravitational wave. The solutions will be discussed.

Wir betrachten Strings mit der Nambu‐Wirkung als Extremalflächen in einer gegebenen Raum‐Zeit, d. h., wir ignorieren ihre Rückwirkung. Wir interessieren uns dabei besonders für solche Strings, die eine Isometrie mit der unterliegenden Raum‐Zeit gemeinsam haben. Handelt es sich dabei um eine nicht‐lichtartige Symmetrie, so läß Bt sich das Problem der Bestimmung der Stringbewegung dimensionsreduzieren. Wir erhalten exakte Lösungen für die folgenden Fälle: gerade und kreisrunde Strings im Friedmann‐Hintergrund, gerade Strings im anisotropen Kasner‐Hintergrund sowie verschiedene Stringtypen in der Metrik einer Gravitationswelle. Die Lösungen werden diskutiert.
A note on some unusual velocity values of the Be star o And
Authors: Scholz G. , Lehmann H.
Published: July 2007

Radial velocities of Ca II (K), Na (D), and Balmer lines have been determined for the Be star o And. The temporal variations of the velocity, especially of the Ca II (K) line, may be explained by the existence of a companion.
On the discovery of the Apollo object 1987SB
Authors: Elst E. W. , Ivanova V. , Shkodrov V.
Published: July 2007

On september 22nd, 1987, a fast moving object of 17th magnitude was discovered at the Bulgarian National Observatory by ELST, IVANOVA, and SHKODROV (1987). Due to international collaboration the Apollo‐type asteroid 1987SB could be followed up to the 15th January 1988.
K 23 — a spatially isolated low surface brightness dwarf galaxy?
Authors: Bronkalla W. , Richter G. M. , Karachentsev I. D. , Karachentseva V. E.
Published: July 2007

The attention is called to a relatively rare case of an apparently “isolated” dwarf spheroidal galaxy K 23 (α = 02h40m.5, δ = +16·31'). The large‐scale plates obtained with the 6 m telescope have been scanned, and the photometric data and King model parameters determined. According to these data K 23 is similar to the well‐known prototypes in the Local Group and M 81 group.

An analysis of the spatial galaxy distribution shows, that K 23 is probably placed in the bridge connecting the Local Supercluster and Perseus‐Pisces Supercluster and is not truely spatially isolated.
Equilibrium flavor dynamics during the cosmic confinement transition
Authors: Kämpfer B.
Published: July 2007

The dynamics of the flavor composition of strongly interacting matter during the cosmic confinement transition is followed in a simplified thermodynamical model. Relying on thermal, mechanical, and chemical equilibrium we analyse the strangeness fraction of strongly interacting matter. Due to equilibrium with respect to ΔS = 0 and ΔS = 1 weak interactions the relations between different flavors depend strongly on the poorly known lepton excess. In a universe where the lepton (antilepton) excess is in the same order of magnitude as the baryon excess, the strange quark abundances are suppressed (enhanced). In the hadron phase the strange baryons carry up to a half of the baryon excess.
Influence of rotational darkening on ultraviolet interstellar extinction
Authors: Friedemann C.
Published: July 2007

The influence of rotational darkening on ultraviolet stellar fluxes of fast rotating stars has been rediscussed. For this aim ANS filter‐photometric magnitudes of weakly reddened B stars (E(B ‐ V) 0.1 mag) were corrected for interstellar extinction. The distribution of the stars in the rotationa velocity — colour index diagrams displays a scatter exceeding the photometric errors. The distributions of the stars agree qualitatively with the theoretically calculated colour indices.

The effect of rotational darkening should be taken into account as a possible source for individual deviations of the interstellar extinction from the average law.
Total‐to‐selective extinction ratio in nearby and distant objects
Authors: Wegner W.
Published: July 2007

In an area of nearly 23.1 square degrees centered at α(1950) = 23h57m and δ(1950) = + 59δ48' magnitudes, colors, and spectral classes were determined for 1419 stars brighter than mpg = 13m.00. Star counts were made in this area for all objects brighter than mpg = mpv = 15m.5. Altogether 50585 stars were included in the pv counts. The original photographic data have been transformed to the B, V system. From star counts the ratio of total‐to‐selective extinction was derived to be R ≉ 4.0 ± 0.2. It depends on the distance to the stars under consideration as well as on the surface density of the objects inside the considered region.

In einem Gebiet von annähernd 23.1 Quadratgrad mit den Mittelpunktskoordinaten α(1950) = 23h57m und δ(1950) = 59°48' werden für 1419 Sterne heller als mpg = 13m.00 Helligkeiten, Farben und Spektraltypen bestimmt. Sternzählungen in Helligkeitsintervallen mpg und mpv wurden für alle Objekte heller als mpg = mpv = 15m.5 durchgeführt. Für diese 50585 Sterne wurden die gemessenen photographischen und photovisuellen Helligkeiten in das B, V‐System transformiert. Im Ergebnis dieser Sternzählungen wurde ein Wert von R ≉ 4.0 ± 0.2 abgeleitet. Er hängt sowohl von der Entfernung der betrachteten Objektgruppen als auch von der Flächendichte der Sterne innerhalb der Region ab.
Optical properties of inhomogeneous media: T‐matrix approach (Review)
Authors: Bussemer P.
Published: July 2007

In this paper the problem how to obtain an effective dielectric function (ω) characterizing the optical properties of heterogeneous media is reviewed. For grain sizes smaller than the wavelength of light the quasi‐electro static problem can be formulated as an integral equation that allows the application of the T‐matrix formalism known from solid state theory to calculate. Different approximations for the T‐matrix are discussed leading to different effective‐medium theories as the average T‐matrix approximation (ATA) or the coherent‐potential approximation (CPA).
Properties of circumstellar silicate dust (Review)
Authors: Gürtler J. , Henning T. H. , Dorschner J.
Published: July 2007

We give a review of the present knowledge on the properties of circumstellar silicate dust. After relating the detection story, a survey of objects with silicate features in their spectra is presented. The interdependence between the optical properties of the dust grains and the structure of the circumstellar envelopes in determining the outgoing infrared radiation is analyzed and the more important studies of dust shells with silicate grains are summarized. The optical properties of the circumstellar silicates are discussed. The amorphous structure of the silicates is emphasized. Finally, the relevance of fine structures within the 10‐μm feature observed in several objects is considered.
Observational appearance of circumstellar ionized regions and ultracompact HII regions
Authors: Kravchuk S. G.
Published: July 2007

In the frame of the theoretical model, which describes the dynamics of protostellar envelopes during massive star formation, main stages of the evolution of HII regions are determined. Typical properties of HII region evolution are discussed for forming massive stars of luminosities
Molecules as probes of star‐forming regions (Review)
Authors: Khersonskii V.K.
Published: July 2007

This paper is a brief review of molecular spectroscopy methods for the diagnostics of star‐forming regions. Principal attention is paid to the determination of the kinetic temperature and gas density in dense clouds, the radiation field temperature, the magnetic field, and the spatial and velocity structure of regions of star formation.
On the origin of stellar aggregates in molecular clouds
Authors: Surdin V.G.
Published: July 2007

A method which provides the possibility to connect the global characteristics of the interstellar medium with that of the young stellar population of the Galaxy is proposed.
Star‐forming processes in Cepheus OB2
Authors: Balázs L.G. , Kun M.
Published: July 2007

The properties of IRAS point sources in the region of the “Cepheus bubble” were studied. This bubble is a possible very old supernova remnant which includes the association Cepheus OB2. A large number of sources which are probably low‐ and medium‐mass embedded stars are situated around the bubble. It is concluded that whereas high‐mass stars which have formed in the bubble are already on the main sequence, lower‐mass stars are still embedded in their parent clouds.
Minor planet's positions of the ESO — La Silla
Authors: Debehogne H. , De Mourão R.R. Freitas
Published: July 2007

This paper contains three discoveries and observations of numbered asteroids observed in September and October 1984 at the ESO in La Silla.
The definition of the parsec
Authors: Ruben G. , Treder H.‐J.
Published: July 2007

A new definition is proposed for the parsec, because the distance definition of the IAU is not physically consistent.
Can the ten‐dimensional phase prior to Calabi‐Yau splitting of the super‐string phase generate the primordial entropy of the universe?
Authors: Wolf C.
Published: July 2007

It is shown that the primordial entropy of the universe can be generated in the residual phase prior to Calabi‐Yau splitting and following the passing to the field theory limit of the heterotic super‐string in ten space‐time dimensions, wherein matter is represented by either a radiative equation of state or the equation of state for stiff matter.
The periodic variations of the core drift rate: global and zonal motions (Mitteilung des Zentralinstituts für Physik der Erde, Nr. 1746)
Authors: Greiner‐Mai H.
Published: July 2007

Toroidal zonal motions at the top of the Earth's core were computed from the observed secular variation and investigated with regard to their time dependence. Previously derived results for a pure westward drifting core could be re‐examined. Additionally, the well‐known 66.7 years period was found to be an oscillation of the zonal velocity field of third degree. With respect to periodic constituents, the total magnetic core‐mantle coupling torque according to the zonal motions is comparable with that derived for a pure westward drifting core. Some differences in period lengthes and amplitudes do not remove previously stated differences between the spectra of the magnetic and mechanical torques on principle.
On real‐time evolution in cosmology
Authors: Perlt H.
Published: July 2007

Real‐time evolution plays an important role to understand the dynamics of the early Universe. It would be of importance to be able to investigate such typical time dependent processes like particle production, reheating, creation and evolution of fluctuations, etc. In this paper we derive the one‐loop renormalized coupled einstein field equations of a scalar field with λϕ4 interaction in a classical curved space‐time of Friedmann‐Robertson‐Walker type. These equations can be used to calculate quantum corrections for the dynamics in the early Universe.
Global stability analysis for scalar‐tensor models
Authors: Amendola L. , Occhionero F.
Published: July 2007

The phase space of a cosmological model with a scalar field coupled to curvature is discussed in detail for any value of the coupling constant ξ and any power law (ϕ2n) potential. The results obtained generalize previous studies with minimal coupling (ξ = 0) and quadratic or quartic potentials to the entire parameter space (ξ, n). In many cases one finds global attractors and inflationary trajectories, with or without the correct Friedmannian limit. If the coupling constant is positive, a forbidden region cuts out a large part of the phase space, while, if it is negative, escaping regions may occur. Semi‐classical instability of vacuum states and singularity‐free trajectories are also discussed.
The formation of the spectrum of preglactic inhomogeneities in the CDM and HDM of the Universe
Authors: Kahniashvili T. A.
Published: July 2007

We consider the evolution of large‐scale cosmological density perturbations in CDM and HDM Universe containing weakly interacting relativistic particles with number density to be the model free paramer. The dependence of parameters of the large‐scale structure on the collisionless particle numbers is discussed. A new cosmological test of the total number of light weakly interacting particles in the Universe is proposed.
A note on harmonic variables for the Brink‐Schwarz covariant superparticle
Authors: Kuusk P.
Published: July 2007

We clarify the geometric meaning of auxiliary variables that were introduced for covariant quantization of the Brink‐Schwarz superparticle (and the Green‐Schwarz heterotic superstring) by KALLOSH and RAHMANOV (1988).
The meaning of gyroscopic invariance for the electromagnetic energy‐momentum tensor
Authors: Kreisel E.
Published: July 2007

The gyroscopic invariance implies the representation of the antisymmetric part of the Hermite‐symmetric metric by a vector potential. Therefore we introduce the six functions of this antisymmetric part in general as derived by two vector potentials. Then Einstein's variational principle leads to a slight modification of the Einstein‐Schrödinger equations, which just encludes Minkowski's form of the energy‐momentum tensor for the electromagnetic field and the gluon field.
Notes on applications of General Relativity in free space
Authors: Wanas M. I.
Published: July 2007

Varying the step, at which Lorentz signature is introduced in the scheme of applications of general relativity outside the material distribution, new solutions can be obtained. The interpretations of these solutions can be achieved if the field equations Rμv = 0 are written in a wider space than the Riemannian one. A counter example is given in favour of this claim.
Deviation of circular geodesics in static spherically symmetric space‐times
Authors: Fuchs H.
Published: July 2007

For static spherically symmetric space‐times the equations of geodesic deviation are solved for circular geodesics. We discuss the connection between the obtained solutions and the stability behaviour of the geodesics. The perihelion shift for test bodies moving on nearly circular geodesics is also derived.
Bianchi types of Lie point symmetries arising for differentially rotating stationary axisymmetric fluids
Authors: Grosso R. , Stephani H.
Published: July 2007

The Einstein field equations for a perfect fluid with two commuting Killing vectors, which span the fluid's four‐velocity, are considered. A third space time symmetry, which is a homothetic or a Killing vector, can be used to reduce these equations to a system of ordinary differential equations. This symmetry restricts the form of the differential rotation Ω of the fluid. A Bianchi classification of the resulting Lie algebras is performed and related to the kinematical properties of the fluid.
Two B and V time series of ET and
Authors: Hempelmann A. , Hildebrandt G.
Published: July 2007

Two time series of B and V observations of the multiple‐periodic variable CP2 star ET And are presented. From both records observed in two consecutive nights, a new period of 180 min is detected.
Some results of solar radio emission observations at the Siberian Solar Radio Telescope
Authors: Zubkova G. N. , Kardapolova N. N. , Lubyshev B. I. , Nefedyev V. P. , Ya. Smolkov G. , Sych R. A. , Treskov T. A.
Published: July 2007

This paper gives the main characteristics of the Siberian Solar Radio Telescope as well as some results derived by investigating the s‐component sources and radio bursts on the Sun using the SSRT.
Static spherically symmetric solution (Schwarzschild problem) in isotropic coordinates in Einstein's gravitational theory
Authors: Schmutzer E.
Published: July 2007

In textbooks the full Schwarzschild problem is usually presented in Schwarzschild coordinates. In the Projective Unified Field Theory (PUFT) these coordinates lead to specific difficulties, whereas isotropic coordinates have the advantage to give explicit results for the exterior solution. Up to now the interior solution in PUFT has had to be treated numerically. For such an approach it is useful to know the interior and exterior solution (including matching at the surface of the sphere) of the Schwarzschild problem in isotropic coordinates in the Einstein theory which can be considered a special case of PUFT.
On solar decimeter radio fluctuations
Authors: Aurass H. , Detlefs H. , Eliass M. , Paupere M.
Published: July 2007

In a coordinated fluctuation observing program between the Riga Radioastrophysical Observatory and the Tremsdorf Solar Radio Astronomy Observatory at 755 MHz we found coinciding periods in the range of 30–200s. Further observations are proposed.
Basic results and a perspective for future observations on RATAN–600
Authors: Gelfreikh G. B.
Published: July 2007

The modernization of the radio telescope RATAN–600 for solar observations is intended to improve significantly parameters concerning the spatial, temporal and spectral resolution of the instrument. The main scientific objective of radio observations planned on the RATAN is to study the process of structuring the solar atmosphere and to find out the role of the plasma structures in accumulation, transfer and release of energy in the solar atmosphere. In this paper the results of the study of magnetic fields and different structures both for quiet and active regions on the Sun are summarized. The main problems for future RATAN observations of the Sun are discussed.
Interpretation of the fine spectral structure during solar flare microwave radio emission
Authors: Levin B. N. , Mel'Nikov V. F.
Published: July 2007

Characteristic features of the plasma model of radio emission from the extending fronts of the solar flare energy release are studied. Formation of the electron distribution near the thermal fronts is shown to have the character of stationary beam injection through a boundary into the cold plasma semispace. In quasi–linear approximation the plasma wave accumulation before the thermal fronts is typical of this case. The radio flux density from this regions can reach essential value in the relative narrow frequency band. Possibilities of the flare loop structure analysis based on the narrow band emission parameters are shown.
Various scale structures of the quiet sun emission at 3 mm wavelength
Authors: Nagnibeda V. G. , Piotrovitch V. V.
Published: July 2007

The observations of the Sun during some years with the RT–7.5 millimetre radio telescope are allowed, in particular, to find large scale structures of the quiet Sun emission. It is shown that if even there is no any active region on solar disc latitudinal zones of enhanced brightness exist which coincide with zones of sunspot appearance. Brightness temperature differences between equatorial and latitudinal zones are about 100 K at 3.4 mm wavelength.
Tautenburg proper motion fields
Authors: Scholz R.‐D. , Hirte S.
Published: July 2007

There 70 3° × 3± fields each with at least 4 plates taken with the Tautenburg Schmidt telescope between 1960 and 1970 which can be used as first epoch plates in the determination of proper motions. In the Tautenburg programme of obtaining absolute proper motions of HIPPARCOS stars 10 preliminary fields are included. 17 Tautenburg proper motion fields are being investigated in the programme of the main meridional section of the Galaxy (MEGA). A greater number of fields, particularly for the HIPPARCOS proper motion link to a quasi‐inertial system can be considered if the measuring capacities could be improved. Automated measurements of all objects were carried out in 7 fields each with two pairs of plates with a mean epoch difference of more than 20 years. Further measurements of selected objects for the determination of absolute proper motions were completed in 5 fields.
The Newtonian limit of fourth and higher order gravity
Authors: Quant I. , Schmidt H.‐J.
Published: July 2007

We consider the Newtonian limit of the theory based on the Lagrangian \documentclass{article}\pagestyle{empty}\begin{document}$ \ell = (R + \sum\limits_{k = 0}^p {a_k R\square ^k R)\sqrt { - g.} } $\end{document}. The gravitational potential of a point mass turns out to be a combination of Newtonian and Yukawa terms. For sixth‐order gravity (p = 1) the coefficients are calculated explicitly. For general p one gets \documentclass{article}\pagestyle{empty}\begin{document}$ \phi = m/r(1 + \sum\limits_{t = 0}^p {c_i } \exp (‐ r/l_i))\;with\;\sum\limits_{t = 0}^p {c_i} \; = \;1/3 $\end{document}. Therefore, the potential is always unbounded near. The origin.
Drag perturbations in artificial satellite orbital motion based on the Total Density model
Authors: Mioc V.
Published: July 2007

Analytical expressions for the aerodynamic drag perturbations undergone by five independent orbital elements of an artificial satellite moving in an orbit with small eccentricity, over a nodal period, are established. All three components of the perturbing acceleration are taken into account. The TD model is used to describe the density distribution of the upper atmosphere.
Generalized inflation from R3 and R□R terms
Authors: Gottlöber S. , Müller V. , Schmidt H.‐J.
Published: July 2007

Generalized inflationary stages as power‐law solutions result from the addition of R3 and R□R terms to the quadratic gravitational Lagrangian. Both contributions lead to new attractor solutions in the high‐curvature limit. We emphasize the properties of critical values of the curvature scalar in the R3 theory. Contrarily to models with two scalar fields, the higher order curvature terms allow double inflation for special initial conditions only.
Föppl's repulsive cosmos and hyperbolic Friedmannian matter cosmos
Authors: Treder H.‐J.
Published: July 2007

Föppl's repulsive cosmos and the hyperbolic Friedmannian matter cosmos are compared. Both worlds have positive energy integrals. In the repulsive cosmos no cosmic singularity exists.
Archenhold occultation summary. I. First results
Authors: Guhl K. , Stecklum B.
Published: July 2007

First results of lunar occultation observation and reduction at the Archenhold observatory are presented. Using the 50 cm‐Cassegrain telescope under urban observing conditions acceptable results for 16 events have been obtained including one suspected occultation binary.
Adaptive filtering in astronomical image processing
Authors: Richter G. M. , Böhm P. , Lorenz H. , Priebe A. , Capaccioli M.
Published: July 2007

An adaptive filter for processing of astronomical images is developed and described. The filter recognizes the local signal resolution (which usually varies strongly across the image) and adapts its own impulse response to this resolution.
Synthetische UBVR‐Photometrien aus flußkalibrierten Spektren
Authors: Gochermann J.
Published: July 2007

Since the photometric UBVRI broadband systems of Johnson and Morgan (1951, 1953), Johnson (1955, 1965) and Cousins (1976) were partly illdefined and have partly been modified over the years, their technical realization at different observatories is problematical. Large differences occur especially in measuring objects with peculiar spectra or strong lines. Therefore, firstly an accurate reconstruction of the UBVRI systems of Johnson and the Cousins systems used at the South African Astronomical Observatory (SAAO), at Cerro Tololo Inter‐American Observatory (CTIO) and at Mount Stromlo/Siding Springs Observatory (MSSO) was attempted. The transmissions of the different bands, as well as the possible technical realizations are listed. The data of the Johnson system and the Cousins systems used at SAAO and MSSO were compiled from several publications and new measured transmission curves of the CTIO systems are given. The characteristic wavelengths λ0 have been calculated for all systems. Using flux‐calibrated spectra of 75 early and late type stars in the wavelength range 3200‐8800 Å with a resolution of 10 Å, synthetic photometries of the four described systems and that of Bessell (1990) were derived. The transformation relations from the various systems to the original Johnson system are given in and have been compared to the defined relations. The accuracy of the synthetic photometry is ±0.02 mag in V and (B‐V), ±0.09 mag in (U‐B), and ±0.05 mag in (V‐R). The larger error in (U‐B) is due to the shortwave uncertainties of the U filter transmissions and the missing spectral information because of UV cut‐off of the spectra at λmin > 3200 Å. The uncertainties in (V‐R) are due to the different R filters in the various systems. No synthetic photometry was possible to derive for the I band, because of missing spectral information at λ > 8800 Å.
Peculiarities of gas and dust production rates in comets P/Halley (1986 III), P/Giacobini‐Zinner (1985 XIII), P/Hartley‐Good (1985 XVII) and P/Thiele (1985 XIX)
Authors: Churyumov K. I. , Rosenbush V. K.
Published: July 2007

An IHW narrow‐band photometry of comets P/Halley (1986 III), P/Giacobini‐Zinner (1985 XIII), P/Hartley‐Good (1985 XVII) and P/Thiele (1985 XIX) is presented. Molecular column densities and production rates of CN, C2, and C3 species observed in the coma are calculated in the framework of the Haser model. A comparative analysis of gas and dust production rates in the atmospheres of these comets is given. The effective comet nuclear radii have been estimated by different methods: for comet P/Hartley‐Good Reff ∼ 1·7 km, for P/Thiele Reff ∼ 2 km and for P/Giacobini‐Zinner Reff ∼ 1·3 km.
The action of the satellite 1981 S13, and the optical depth profile of the Encke‐gap ringlet in the Saturn A ring
Authors: Spahn F. , Saar A. , Schmidt St. , Schwarz U.
Published: July 2007

The radial optical depth profile of the Encke ringlet obtained by the occultation experiment of the Voyager photopolarimeter (PPS data) is explained to be caused by the gravitational action of the recently discovered stallite 1981 S13 and a second smaller moonlet orbiting near one of its either libration points — L4 or L5. To this aim the results of previous and new numerical particle simulations as well as an extension of the scattering theory concerning a single moonlet to a pair of satellites have been used leading to a triple‐peaked ringlet near the orbits of the moonlets. The width and the shape of that ringlet and its separate peaks depend on the mass ratio of both moonlets and on their orbital eccentricites. The best resemblance between the PPS data and the theoretical profile is obtained if the mass ratio of the either moonlets takes M2/M1981S13 ≈ (0.8 … 3.0) × 10−2 and the eccentricities hold: e1981S13 < h1981S13; e2 ≈ h2 (the values h are the Hill scales of either moonlets defined by h1981S13/2 ≈ (M1981S13/2/3Mh)1/3, Mh = Saturn mass). Furthermore, our results yield a size of 1981 S13 of < 15 km in diameter.
On diffusion of the tangential fluctuations of the geomagnetic field through the mantle
Authors: Sokoloff D. D. , Zinchenko B. G.
Published: July 2007

In this paper we develop a statistical approach to resolve the transport problem for the tangential fluctuations of the geomagnetic field in the mantle. For the sake of simplicity we treat the mantle as a thick layer of vacuum and assume in addition that only a radial component of the magnetic field of the core penetrates through the core‐mantle boundary. These assumptions allow us to find exact expressions for the tangential field components throughout the mantle. By using such expressions we construct a correlation tensor of tangential components and then, since the mantle is thick enough, study its asymptotic properties on the Earth surface. Incidentally, the correlation tensor trace happens to be equal to the correlation function of the radial component that was obtained by Pilipenko and Sokoloff (1992). Indeed, we provide a simple boundary problem which initially describes the diffusion functions. We also pay a special attention to transformation properties of the correlation tensor and find here some interesting analogies with secular variation data of the geomagnetic field
The elliptical three‐body problem. Triangular solution
Authors: Todoran I. , Roman R.
Published: July 2007

The restricted three‐body problem with eccentric orbit is reviewed and the positions of the triangular Lagrangian points (L4, L5) are determined. It is put in evidence the fact the fact L4 and L5 are situated at the corners of an isoscales triangle: AB = BC = 1 − e2/)1 + e cos ν )4/3 and AC = 1 − e2/)1 + e cos ν )
The time—delayed correlation of the 100—year modulation of the solar rotation with the long—term modulations of the solar cycle
Authors: Yoshimura H. , Kambry M. A.
Published: July 2007

The time profile of the periodic 100‐year modulation of the solar surface rotation as a whole, which was found in the daily translation data of positions of sunspot groups from 1874 to 1992 obtained by a combination of the Mitaka data of the Tokyo Astronomical Observatory and of the National Astronomical Observatory of Japan from 1943 to 1992 and the Greenwich data of the Greenwich Photoheligraphic Results from 1874 to 1976, is found to have a good correlation with the time profile of the solar cycle amplitude modulation when the time profile of the solar rotation modulation is displaced toward the past by about 23 years. This result indicates that the 100‐year solar rotation modulation is dynamically related with the solar cycle and is real and that the modulation is mainly caused by the Lorentz force of the magnetic field associated with the solar cycle whose effect appears in the rotational modulation after around 23 years. The delay time depends on the level of solar cycle magnitude. The lower the amplitude, the longer the delay time. The delay time of 23 years of the present study is longer than the 20 years of a separate analysis of the Mitaka data of 1963–1992 in which the average level of solar cycle was higher than that during the whole interval of 1874–1992. This result is in consistence with the concept of driving the rotational modulation by the Lorentz force. Weaker Lorentz force needs longer time to modify the flows of the differential rotation.
Photo—gravitational effects in the two—body problem
Authors: Todoran I. , Roman R.
Published: July 2007

The effect of the radiation‐pressure in the problem of the two bodies is analysed. It is found that such an effect is the same as that of reducing the stellar mass, m, by the factor p (0 ≤ p ≤ 1). The case p < 0 leads to stellar instability and, consequently, it is not considered here. The problem of the mass determination from spectroscopic observations is reviewed and an iterative method is recommended.
HS Herculis: Not apsidal motion, but a third body
Authors: Bastian U.
Published: July 2007

Todoran's (1992) postulate of apsidal motion to explain the observed minimum times of HS Her is shown to be physically inconsistent. Instead, a third body in the system is postulated. Minimum timings in the next few years can settle the matter.
Flat Galaxy Catalogue
Authors: Karachentsev I. D. , Karachentseva V. E. , Parnovsky S. L.
Published: July 2007

A systematic search for disclike edge‐on‐galaxies with a diameter larger than a = 40 arcsec and a major‐to‐minor axis ratio a/b ≥ 7 has been carried out by means of the Palomar Observatory Sky Survey and the ESO/SERC survey. As a result, we present a new catalogue of flat galaxies (FGC) containing 4455 objects and covering about 56% of the whole sky for the first time. The catalogue is assigned to study large‐scale cosmic streamings and other problems of observational cosmology.
Photometric catalogue of Shakhbazian compact groups of galaxies. I
Authors: Stoll D. , Tiersch H. , Oleak H. , Baier F. , Macgillivray H. T.
Published: July 2007

Compact groups of galaxies are fruitful laboratories to study such processes as dynamical friction, tidal interaction, collision, and galaxy mergers. The largest survey of compact galaxy groups is the one of Shakhbazian, Petrosian, Baier, Tiersch. A programme to evaluate photometrical properties of the galaxies in the Shakhbazian groups has been started using the COSMOS/UKST catalogue of the Southern sky with δ ≤ + 2°30′. About a quarter of the Shakhbazian groups lie south of this declination limit. A list of 24 groups (Shkh 21, 24, 27, 30, 32, 33, 35, 81, 82, 83, 140, 141, 143, 144, 145, 146, 147, 148, 151, 152, 154, 261, 262, 263) is our first result.
Programme of the Galactic meridian: Star counts and Galactic models 2. Distribution of absolute proper motions
Authors: Andruk V. , Kharchenko N. , Schilbach E. , Scholz R.‐D.
Published: July 2007

A comparison of the observed distribution of absolute proper motions with a kinematical model of the Galaxy is presented. Proper motions with respect to galaxies were obtained for about 40 000 stars along the main Galactic meridian and in two fields near the North Galactic pole (programme MEGA). The Galaxy is considered as composed of the disk (main sequence and disk red giants), the thick disk and spheroid populations. For each subsystem, spatial velocity components and their dispersions were computed. The distribution of kinematical parameters were modelled for stars located in different directions of the Galaxy.
The Cygnus X region XXI. Radio emission at 1420 MHz from Cyg OB2 stars and two probable cometary HII regions
Authors: Wendker H. J. , Higgs L. A. , Landecker T. L.
Published: July 2007

We have searched our previously published radio surveys of the Cygnus X region for faint radio point sources that may be associated with luminous stars of the Cyg OB2 association. Five positional coincidences have been found between stars and 1420 MHz radio sources. A particularly interesting example is the Wolf‐Rayet star VCLS 146, which has shown a rapid change in 1420 MHz flux density. In addition, sensitive upper limits have been derived for the emission from 14 early‐type stars, which help establish the time history of their non‐thermal radio emission. Two radio features have been detected which have the properties of cometary HII regions, except that they are several arcminutes in size. Their detection provides evidence of recent star formation in Cyg OB2.
Orbital elements of Minor Planets
Authors: Scardia M. , Ghiringhelli D. , Debehogne H.
Published: July 2007

Orbital elements of the numbered minor planets 4209 ‐ Briggs, 5177 ‐ Hugowolf and preliminary orbital elements of the unnumbered minor planets 1988 RL4, 1989 CE8 and 1989 DJ are given.
Does the ellipticity of globular clusters correlate with luminosity?
Authors: Schmidt K.‐H.
Published: July 2007

Using the data by Geyer et al. (1983) and by White and Shawl (1987) it has been looked for the dependence of the ellipticity of Galactic globular clusters on luminosity. There is evidence that the moderate bright objects are the roundest, while the most luminous as well as the weaker globulars are more flattened, on the average.
Magnetic field of solar prominences: The procedure of radio observations
Authors: Apushkinskij G. P. , Topchilo N. A. , Tsyganov A. N. , Nesterov N. S.
Published: July 2007

The first successful radio astronomical results of measurements of the magnetic field of solar prominences are presented. The accuracy of polarization and magnetic field observations is 3 · · 10−4 and 2 G, respectively. The observations were made by the 22‐meter radio telescope of the Crimean Astrophysical Observatory at wavelengths of 8 and 13.5 mm. It has been found that the value of the magnetic fields coincides with the optical one (from 7 to 30 G), but the image of radio polarization differs from the intensity.
Catalogue of Shakhbazian compact groups of galaxies. VIII
Authors: Stoll D. , Tiersch H. , Cordis L.
Published: July 2007

The eighth part of the catalogue of Shakhbazian groups contains the positions and references of all the galaxies of the following 48 groups (north of δ > + 2°30'): Shkh 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 207, 208, 209, 210, 211, 212, 213, 214, 215. For the estimation of the coordinates the Digitized Sky Survey was used.
Cyclotron spectroscopy of VV Puppis
Authors: Schwope A. D. , Beuermann K.
Published: July 2007

We present phase‐resolved spectrophotometric observations of VV Puppis obtained during two different states of accretion. We confirm the detection of cyclotron lines from emission regions at both poles (Wickramasinghe et al. 1989) having significantly different field strength of B1 ≃ 31 MG and B2 ≃ 54 MG. Our phase‐resolved data allowed the detection of phase‐dependent wavelength shifts of the cyclotron lines from the main accretion pole which is due to the varying aspect of the observer. A corresponding motion of the cyclotron lines from the secondary pole appears likely.

Compared to 1984, the cyclotron lines from the main pole appeared redshifted in 1989, during an episode of higher system brightness. This shift can be explained assuming either different locations of the accretion spot and, hence, variations of the magnetic field, or variations of the plasma temperature both triggered by variations of the mass accretion rate.

The cyclotron lines from the second pole do not show such changes suggesting that the coupling region for the weakly accreting pole is more or less stationary whereas the coupling region of the main pole varies in space, most likely depending on the mass accretion rate.
Catalogue of Shakhbazian compact groups of galaxies. X
Authors: Stoll D. , Tiersch H. , Cordis L.
Published: July 2007

The tenth part of the catalogue of Shakhbazian groups contains the positions and references of all the galaxies of the following 35 groups (north of δ > +2°30'): Shkh 341, 342, 343, 344, 345, 346, 347, 348, 349, 350, 351, 352, 354, 355, 356, 358, 359, 360, 361, 362, 363, 364, 365, 366, 367, 368, 369, 370, 371, 372, 373, 374, 375, 376, 377. For the estimation of the coordinates the Digitized Sky Survey was used.
A survey of main‐belt asteroids. II. Positions and improved orbital elements for 62 unnumbered asteroids
Authors: Lagerkvist C.‐I. , Hahn G. , Lundström M. , Lagerros J. S. V. , Hernius O. , Tancredi G.
Published: July 2007

More than 7 000 positions of moving objects were detected on 33 films obtained with the Schmidt telescope at the European Southern Observatory in Chile during August and September 1995. The majority of these asteroids are previously unobserved. This paper presents the results for 62 unnumbered asteroids with provisional designations found in the fields. References to the derived positions for these asteroids are given and improved orbital elements have been calculated using all available positions.
Pressure of charged particle flows in ambient magnetic fields
Authors: Ponomarjov M. G.
Published: July 2007

The magnetic field effect on the pressure of charged particle flow is described analytically. Low‐density charged‐particle fluxes, for which a kinetic, rather than fluid description is appropriate, are simulated. Both impulsive and transient injectors of charged particles are considered. Maxwellian and shifted maxwellian velocity distributions of injected particles are dealt with. Obtained results allow (i) to simulate the acceleration of space objects (for instance, space platforms) under the pressure of ion beams, which are focused by the ambient magnetic field, (ii) to calculate the magnetic field, which must be generated for the effective control of influences of a jet from electric rocket engines on a spacecraft and space station.