bluuebunny/crossref_metadata_2025 huggingface dataset:
Neutrinooszillationen in Neutronensternmaterie
Authors: Haubold H. J.
Published: July 2007

Gemäß einem Vorschlag von T. J. Mazurek (1979) könnten Neutrinooszillationen im kollabierenden Stern (M ≥ 10M) einen beträchtlichen Teil leptonischer Energie auf die nichtrelativistischen Baryonen transferieren. Der Adiabatenindex crreicht dann Werte γ ≥ 4/3; das ist die Bedingung für die Umkehr des dynamischen Kollaps in eine Explosion. Wir leiten aus der Theorie der Neutrinooszillationen von B. Pontekorvo (1967) die Oszillationslänge L der Neutrinos im Vakuum und eine charakteristische Oszillationslänge L* der Neutrinos mit Berücksichtigung des Brechungsindex ne der Neutronensternmaterie ab. Der Vergleich beider Oszillationslängen zeigt, daß für Dichten, charakteristisch für Neutronensternmaterie, immer L ≫ L* gilt und somit Neutrinooszillationen keinen Einfluß auf das Szenarium der Neutrinoemission des Neutronensterns haben.
Estimates of Chandler's Component of Polar Motion as Derived from Various Data Sets
Authors: Wilson C. R. , Vicente R. O.
Published: July 2007

Des groupes de données provenant de plusieurs combinaisons de techniques classiques et modernes (Doppler et laser vers des satellites artificiels) ont été analysés par des méthodes autoregressives, simsoidales et autorégressives avec moyenne mobile (ARMA) pour obtenir des estimations de la fréquence de Chandler et du facteur de qualité de cette composante du mouvement du pǒle. La mδthode ARMA présente des avantages sur les autres méthodes et les résultats obtenus ne mettent pas en évidence une variation temporelle des paramètres du mouvement du pǒle. Les inconvénients du lissage des groupes de données et de l'utilisation de courts intervalles de temps pour les données sont clairement démontrés. L'importance est placée sur un besoin pour des séries d'observations longues et régulières avec techniques modernes.
A Spectrographic Study of the Shell Star EW Lac (217050)
Authors: Scholz G.
Published: July 2007

Die Untersuchung von 38 Zeemanspektrogrammen des Be Sterns EW Lac, die in den Jahren 1978, 1979 und 1980 erhalten wurden, gibt keine Beweise für die Existenz eines globalen Magnetfeldes größer als 150 Gauß. Die zeitlichen Variationen der Radialgeschwindigkeiten der Balmer und Metallinien zeigen ein Verhalten, das auf eine von den inneren zu den äußeren Teilen der Hülle sich fortpflanzende Störung hindeutet. Variationen der Linienbreiten und Äquivalentbreiten der Metallinien weisen auf merkliche Änderungen der physikalichen Parameter der Hülle hin. Diese Resultate sowie die gemessen Variationen der Radialgeschwindigkeiten und Intensitäten der Emissionslinien von Hβ können durch einen dicken elliptischen Ring um EW Lac erklärt werden.
Die Herabsetzung der Schwärzungsgradieten astronomischer Aufnahmematerialilen durch das FAH ‐ Verfahren
Authors: Högner W. , Ziener R.
Published: July 2007

Photographyische Astroplatten werden FAH‐vorbehandelt, um Entwicklungseffekten bei der Verflachung zu steiler Schwärzungsgradienten vorzubeugen. Die dabei entstehende Beeinflussung der photometrischen Genauigkeit wird untersucht.
Method for the Determination of the Inclination Angle between the Comentary Tail and the Radius Vector
Authors: Tóth I. , Eötvös L.
Published: July 2007

If the angle ϵ between the radius vector and the axis of the comet tail is known one can determine the velocity component of the solar wind pointing into the direction of the radius vector. This paper describes a geometrical method to determine the orientation of cometary tails (it will be represented by l). If n is the normal vector of the cometary orbit, ϱ is the geocentrical position vector of the cometary nuclei and ϱ* is the geocentrical direction vector towards the direction of an indicated arbitary point of the cometary tail (and the equality |ϱ|; = |;ϱ|;* holds) then by means of the factor k where k = nϱ/nϱ* the vector l = kϱ* – ϱ can be calculated. The factor k is indefinite when nq* = o that means when the Earth passes through the orbit of the comet. At that time ϵ must be determined in other ways for example by means of dynamical methods or ϵ must be interpolated between two neighbouring observed data which are sufficiently near in time. A continuous ϵ‐time function must be assumed.
Approximate Function for the Equation of Time
Authors: Claussnitzer H.
Published: July 2007

Ausgehend von den von Schaub (1950) angegebenen Gleichungen ist es möglich, durch Hinzufügen geeigneter Korrekturglieder einen einfachen mathematischen Ausdruck zu finden, der es gestattet, für beliebige Zeitpunkte Werte von g = α – α mit für viele Zwecke ausreichender Genauigkeit zu ermitteln. So betragen die maximalen Abweichungen von den wahren Werten für das Ausgangsjahr etwa ±0s3 und für die beiden folgenden Jahre ungefähr ±0s7 and 1s5.

Damit ist eine Vorausberechnung der Werte von g ohne Kenntnis der wahren Werte möglich. Wenn die wahren Werte später bekannt sind, lassen sich die Abweichungen durch Hinzufügen meistens nur eines trigonometrischen Korrekturgliedes wieder erheblich reduzieren. Auf diese Weise kann die Näherungsfunktion mehrere Jahre auf einer Genauigkeit von ±1s gehalten werden.
A Model of the 10 Micrometer Silicate Feature in the Spectra of BN‐like IR‐Point Sources (Mitteilungen der Universitäts‐Sternwarte zu Jena Nr. 150)
Authors: Henning Th.
Published: July 2007

A model representing the profile of the silicate absorption band at 9.8 μm in the spectra of BECKLIN‐NEUGEBAUER objects has been developed, solving the equation of radiative transfer. The model based on the condition of radiative equilibrium, on an analytical temperature distribution and on the assumption of constant density in the circumstellar shell allows the evaluation of the optical depth in the band's centre and the investigation of the effect of the temperature variation at the inner boundary of the envelope. The optical depth in the band's centre ist calculated for the BN point source.
Bahnverbesserung des Kleinen Planeten (1019) Strackea
Authors: Landgraf W.
Published: July 2007

In Anschluß an die Beobachtung des Planeten in der Opposition 1980 wurde unter Hinzuziehung teilweise neu reduzierter älterer Beobachtungen die Bahn verbessert und dabei 38 Beobachtungen mit einem mittleren Fehler von 1”.34 dargestellt.
Der gegenwártige Stand der Theorie und der analytischen Auswertung von nichtresonanten thermonuklearen Reaktionsraten
Authors: Haubold H. J. , John R. W.
Published: July 2007

Wir schlagen vor, die Integrationstheorie spezieller Funktionen zur analytischen Auswertung von Reaktionsraten auszunutzen, und zeigen für den speziellen Fall thermonuklearer Reaktionen in einem nichtentarteten nichtrelativistischen Plasma, daß sich die nichtresonante Reaktionsrate sogar geschlossen mittels verallgemeinerter hypergeometrischer Funktionen auswerten láßt und daß sich im Zusammenhang mit dieser geschlossenen Darstellung Differential‐ und Funktional relationen sowie Reihenentwicklungen angeben lassen und Náherungsbetrachtungen durchgeführt werden können.
Computer‐Assisted Reduction of Photographic Two‐Colour Diagrams Application to Field Stars Near IC 348
Authors: Pfau W. , Lehmann H.
Published: July 2007

A computer programme is described which derives amounts of reddening and distances of stars from UBV photometry. I t is based on analytical expressions for the normal line in the two‐colour diagram and for the absolute magnitude as a fucction of the intrinsic colour (Eqns. (I) and (3)). The programme was applied to photographic UBV data of two fields of stars in the vicinity of the galactic cluster IC 348. It is shown that the interstellar dust is concentrated there in a thin slab situated a t about zoo pc to 300 pc distance and giving rise to amounts of reddening, E(B ‐ V ), of about 0.4 mag. and 0.8 mag. for the two fields, resp.
Die Ausbreitung der skalaren Kugelwellen bis zur 2. Náherungsordnung im Gravitationsfeld mit Quadrupolstruktur
Authors: Mankin R.
Published: July 2007

Mittels Störentwicklung nach der Gravitationskonstanten κ – bis 2. Ordnung – wird eine retardierte Lösung der kovarianten Wellengleichung für das Potential des freien, ruhmasselosen skalaren Feldes im axialsymmetrischen Gravitationsfeld (Hintergrundfeld!) einer Punktmasse mit Quadrupolmoment angegeben, als deren 0. Náherung man eine zentralsymmetrische, von einer isolierten Quelle ausgehende Welle wáhlt. Insbesondere zeigt sich, daß der zentralsymmetrische Schweifterm der 2. Náherung in großer Entfernung von der Quelle im wesentlichen von dem durch Gravitationsstrahlung hervorgerufenen Masseschwund verursacht ist, wáhrend sámtliche anderen Schweifterme 2. Ordnung durch entsprechende Modifikation der Grenzbedingungen (in 1. Ordnung) kompensierbar sind.
Orbit Determination of the Ashbrook‐Jackson Comet from Observational Data during the Last Two Apparitions
Authors: Manara A. , Buffoni L. , Scardia M.
Published: July 2007

En considerant les perturbations planetaires, on a calculé les éléments orbitaux corrigés de la comete ASHBROOK‐JACKSON. On a utilisé 196 observations relatives aux derniers deux passages du 1971 et 1978. Enfin on a calculé une éphéméride avec perturbations disponible sur demande.
On the Collapse Dynamics of Cold Stars with a Phase Transition in the Interior
Authors: Kämpfer B.
Published: July 2007

Cold stars can become unstable due to a phase transition in the centre. By small perturbations the collapse is triggered toward a new stable configuration. The features of the collapse are studied by means of a parameter‐independent model with piece by piece uniform density. Possible consequences of such a collapse for neutron stars are: extreme speed‐up, heating and a supernova‐like release of binding energy. The dynamical stability properties of the model are considered in the framework of General Relativity. In particular the very beginning of the collapse can be treated by analytical means. In a certain range relativistic effects can prevent a configuration to collapse.
A Hypothesis on the Hydromagnetic Activity of T Tau, Type Stars and Related Objects
Authors: Gershberg R. E.
Published: July 2007

A hypothesis on the hydromagnetic nature of T Tau‐type stellar activity (GERSHBERG and PETROV, 1976; GERSHBERG, 1978 b) that suggests a way of solving the main energetic problem of these stars is given in detail. In this model it is supposed that the whole surface of a T Tau‐star is covered with structures similar to sunspots, and that the deficit of radiation from these dark spots is carried away by hydromagnetic waves. The assumptions on which the hypothesis rests are shown to be consistent with existing astrohysical and stellar evolutionary ideas. Several consequences of the hypothesis concerning the physical and evolutionary problems of T Tau‐stars, FU Ori‐type Stars, magnetic, antiflare and classical flare star are discussed. Possibilities of testing the hypothesis observationally are considered.
Zur Bestimmung der Gravitationskonstanten und zum Nachweis von Gravitationsstrahlung in einem kosmischen Laboratorium
Authors: Steenbeck M. , Treder H.‐J.
Published: July 2007

We describe systems of satellites giving possibilities for very exact measurements of the gravitational constantfand for searches for gravitation radiation. Our systems are working by gravitational and inertial forces, only.
Rechnergesteuerte schnelle Photometrie am Beispiel der Bedeckung von 57 Orionis durch den Mond. I. (Mitteilungen der Universitäts‐Sternwarte zu Jena Nr. 154)
Authors: Stecklum B.
Published: July 2007

Zur Durchführung von zeitlich hochauflösenden Beobachtungen wurde das System der lichtelektrischen Photometrie modifiziert. Die Ergänzung der Interpreter‐Programmiersprache erlaubt Messungen mit Integrationszeiten bis zu 1 ms bei einer Meßdauer von mindestens 4 s. Es wird auf die Anwendung zur Beobachtung von Sternbedeckungen durch den Mond eingegangen. Ein Ausblick auf den Reduktionsalgorithmus für die dabei erhaltenen Daten wird gegeben.
Investigation of the Orbit of Periodic Comet Ashbrook‐Jackson
Authors: Buffoni L. , Chlistovsky F. , Manara A. , Scardia M.
Published: July 2007

The mechanical energy and planetary perturbations of the periodic comet Ashbrook‐Jackson have been calculated for the time interval from 24th April 1970 to 11th May 1982 which encloses the last two passages through the perihelion.
Perturbations in the Nodal Period of Artificial Satellites Caused by the Terrestrial Infrared Radiation Pressure
Authors: Mioc V. , Radu E.
Published: July 2007

Considering the terrestrial infrared radiaton pressure as a disturbing factor, its influence on the nodal period of an artificial satellite moving in a quasi‐circular orbit is estimated.
Rechnergesteuerte schnelle Photometrie am Beispiel der Bedeckung von 57 Orionis durch den Mond. II. (Mitteilungen der Universitäts‐Sternwarte zu Jena Nr. 155)
Authors: Stecklum B.
Published: July 2007

Die für die Reduktion von Sternbedeckungen durch den Mond benötigten Zusammenhänge werden am Beispiel der Behandlung von 57 Orionis dargestellt. Es erfolgt die Angabe einer Methode zur Berechnung des Objektprofils und eine Diskussion des Einflusses von Rauschprozessen. Die für den spektroskopischen Doppelstern 57 Ori erhaltenen Resultate lassen sich nicht mit den in der Literatur angegebenen Daten erklären.
Hamiltonian dynamics of purely affine fields (EINSTEIN‐SCHRÖDINGER Theory)
Authors: Treder H.‐J.
Published: July 2007

The Lagrangian of the general‐relativistic affine field theory of the non‐symmetric connection field Γikl is Schrödinger scalar density \documentclass{article}\pagestyle{empty}\begin{document}$ H = \frac{2}{\lambda }\sqrt { - \det [R} _{ik} ] $\end{document}, and the field variables (canonical coordinates) are Einstein's affine tensors Umnl = Γlmn ‐ δnlΓrmn. The field equations are the Einstein‐Schrödinger equations

The minors

give by definiton gmn = λ−1 Rmn, and λ becomes the cosmological constant. The Hamiltonian density is the V00‐component of the Einstein energy‐momentum complex

and the tensor‐density components

are the canonically conjugated momentum densities of the field coordinates Ulmn. The canonical equations are

,
and we have no constraints. The affine field theory is invariant with respect to all transformations which preserve the Levi‐Civita parallelism (Einstein's unified T‐A group), and the field equations possess transposition invariance: With Ũlmn = Ulnm we get R̃mn = Rnm, g̃mn = gnm, and Ñmnl = Unml.

The symmetry conditions Γimn = Γinm reduce the space to the general‐relativistic Einstein spaces with Rik = Rki. The equation Rik = λgik yields Γikl = {ikl}, and the pathes of test particles define geodesic world lines of the Einstein spaces.
Turbulence in a rotating magnetized fluid
Authors: Pipin V. V.
Published: July 2007

In a quasilinear approximation, for a special model of initial turbulence the combined effect of the rotation and the largescale toroidal magnetic field was calculated. For large values of parameters of magnetic field strength and rotation rate the intensity of turbulent motions is suppressed in inverse proportion to the product of a mean magnetic field strength and the rotation rate of the medium. With increasing magnetic field strength and rotation rate, the inhomogeneity scale of turbulence increases in the direction of both the magnetic field and the angular velocity vector.

In quasilinearer Annäherung wird für ein spezielles Modell der Ausgangsturbulenz die Gesamteinwirkung der Rotation und des großräumigen toroidalen Magnetfeldes auf die Eigenschaften des turbulenten Mediums berechnet. Für größere Werte der Parameter der Magnetfeldstärke und der Rotationsgeschwindigkeit ist die Intensität der Turbulenzbewegungen umgekehrt proportional zu dem Produkt der Durchschnittsmagnetfeldstärke und der Rotationsgeschwindigkeit des Mediums unterdrückt. Der Maßstab der Turbulenzinhomogenität nimmt mit steigender Magnetfeldstärke und Rotationsgeschwindigkeit zu, sowohl in Richtung des Magnetfeldes als auch in der Richtung des Vektors der Winkelgeschwindigkeit.
On the angular velocity distribution in a nonhomogeneously rotating star
Authors: Gorbatsky V. G.
Published: July 2007

Some results of the calculations of the angular velocity distribution in the equatorial plane of a nonhomogeneously rotating star, in particular of the Sun, are presented. Hence the hypothesis is advanced of the turbulent viscosity as one of the main factors of the angular momentum transport from a rapidly rotating core through the radiative equilibrium region.
A multiple shooting approach for the numerical treatment of stellar structure and evolution
Authors: Reiter J. , Bulirsch R. , Pfleiderer J.
Published: July 2007

We present a new numerical method for solving the system of partial differential equations describing the structure and evolution of a spherically symmetric star. As usual, we employ the transversal method of lines in order to split the equations into a coupled spatial and temporal part. The novel features of the algorithm are the following: (a) Instead of using the Lagrangian picture we formulate the system of partial differential equations in the Eulerian picture. (b) We reformulate the equations of stellar structure as a multipoint boundary‐value problem. By means of this reformulation the rather clumsy iterative matching procedure of stellar atmosphere and interior is avoided. (c) The multipoint boundary‐value problem is solved by the multiple shooting method. This approach not only ensures a high accuracy of the stellar models calculated at each time step but also allows the free boundaries inside the star due to different energy transport mechanisms to be located exactly. (d) The time derivatives involved in the stellar‐structure equations are discretized implicitly to second order accuracy. Moreover, at each time step, the chemical abundances are determined by using a sophisticated update procedure. In this way, a high accuracy is achieved with respect to the integration in time.

The algorithm has turned out to be exceedingly reliable and numerically accurate. This is shown by the evolution of a 1 M⊙ star up to the hydrogen‐shell burning phase. In this example, the virial theorem, the law of mass conservation, and the law of energy conservation is fulfilled to a hitherto unattainable degree of accuracy.

Since the multiple shooting method, which is at the heart of our approach, is a perfect example of a parallel algorithm, the computational speed of the algorithm might be substantially improved provided easy‐to‐program, high‐performance parallel computers with sufficiently many processors become available in the near future.
New Planetary Nebulae towards the galactic bulge I. Objects in the central area
Authors: Kohoutek L.
Published: July 2007

In the first part of this study of PN towards the galactic centre we present the discovery of 24 new planetary nebulae found on the objective‐prism spectra in three ESO fields (Table 1 ‐ parameters of the survey, Tables 3 and 4 ‐ new objects). The observations of those objects are listed in Table 5. Besides, we give the classification and the positions of known objects in this area (Table 2).
Photometry of groups of galaxies. II. The NGC 972 group
Authors: Vennik J. , Richter G. M.
Published: July 2007

A nearby group of galaxies, centered at the spiral galaxy NGC 972 and conspicuously rich in faint dwarf spheroidal galaxies, has been investigated photometrically on the B and V plates, obtained with the Tautenburg 2m Schmidt telescope. For ten certain and probable group members the equivalent B and V brightness profiles have been extracted. Integrated magnitudes and mean colours of faint group members have been estimated. Typically, the dwarfs show a “subexponential” (i.e. a convex curvature over the linear radius) surface brightness profile and often a central excess. Their equivalent profiles are reasonably well fitted by modified isothermal (King) models.
Variable objects with UV excess in the surroundings of M33
Authors: Richter G. A. , Börngen F. , Afanas'ev V. , Karachentsev I. D. , Kopylov A.
Published: July 2007

13 objects, motly with UV excess, in a field of about 10 square degrees in the surroundings of the Triangulum galaxy were investigated and classified, using photometric, spectroscopic, and proper motion data. 9 of them are probable quasistellar objects, 3 cataclysmic variables, and 1 eclipsing binary.

Die Arbeit enthält für 13 veränderliche Objekte, überwiegend mit UV‐Überschuß, die Ergebnisse der Klassifizierung auf Grund von photometrischen, spektroskopischen und Eigenbewegungs‐aten in einem etwa 10 Quadratgrad großen Feld in der weiteren Umgebung von M33. Unter diesen Objekten sind 9 vermutlich quasistellare Objekte, 3 kataklysmische Doppelsterne und ein Bedeckungsstern.
Ein Vorschlag zur Erzielung hochreflektierender Teleskop‐Optik
Authors: Schmidt‐Kaler T. H.
Published: July 2007

Since 60 years the common method generally used to coat astronomical mirrors is vacuum deposition of pure aluminium by evaporation. Such mirror surfaces degrade very fast resulting in a considerably reduced optical throughput. Protecting layers (oxides like SiO2, fluorides like CaF2) are not applied because their removal, necessary before realuminization, involves damage to the optical surface of the mirror substrate which would necessitate a costly refiguring of that surface. The reduction of the throughput exceeds typically 30 % for a Cassegrain system; it precludes the introduction of excellent optical design solutions in astronomy based on Schwarzschild's theory using four‐reflection optics. In addition, the cost of the conventional procedure of aluminizing and its risks increase tremendously with the size of the mirrors of the very large telescopes now planned or under construction. Here I propose a three‐layer composion in two forms (Fig. 1): a) stopping layer ‐‐ reflecting layer ‐ protecting layer, or b) carrier layer ‐ protecting layer. The stopping layer is supposed to be completely insensitive to the chemical agents dissolving or detaching the protecting (and the reflecting) layers. On the other hand, in modification b), the carrier layer is supposed to be chemically removable from the substrate, thereby detaching also the protecting (and reflecting) layer. As an example for a layer system of type a) experiments are under way with the system gold/silver/quartz on various mirror substrate materials. Quartz can be easily dissolved by fluorid acid without any damage to the gold stopping layer. Dense. pore free Al2O3+SiO2 layers without defects can be expected to protect the silver reflectance R⩾ 0.98 under real observatory conditions effectively for more than 10‐20 years. In addition this protecting layer permits frequent and effective cleaning of the mirror from dust etc. The reflectance of silver exceeds that of fresh conventionally aluminized mirrors with R ≅ 0.87 for all wavelengths λ ⩾ 3370 Å. In the blue the silver mirror realizes with R = 0.995 ideal conditions for Schwarzschild optics. In the V‐IR region it is with ≅ 0.99 by the factor 1.2 better than present‐day mirrors.
Rapid variability of active galactic nuclei: The 160min periodicity in NGC 3516, NGC 4151 and Quasar 3C 273
Authors: Kotov V. A. , Haneychuk V. I. , Lyuty V. M.
Published: July 2007

The analysis of all the available data between 1968 and 1991 on rapid variability of optical and X‐ray luminosity of three AGNs, NGC 3516, NGC 4151 and 3C 273, shows the presence of small‐amplitude (˜ 1 %) but statistically confident (≈︁ 5s̀) periodicity of 160.0105 (± 6) min. Within the error limits it coincides with the period P0 = 160.0101 (± 1) min of global oscillations of the Sun. An independence of the observed period on AGN red shift z favours the hypothesis about a cosmological origin of the 160min oscillation.
Black hole stability in multidimensional gravity theory
Authors: Bleyer U. , Melnikov V. N. , Bronnikov K. A. , Fadeev S. B.
Published: July 2007

Exact static, spherically symmetric solutions to the Einstein‐Maxwell‐scalar equations, with a dilatonic‐type scalar‐vector coupling, in D‐dimensional gravity with a chain of n Ricci‐flat internal spaces are considered. Their properties and special cases are discussed. A family of multidimensional dilatonic black‐hole solutions is singled out, depending on two integration constants (related to black hole mass and charge) and three free parameters of the theory (the coordinate sphere, internal space dimensions, and the coupling constant). The behaviour of the solutions under small perturbations preserving spherical symmetry, is studied. It is shown that the black‐hole solutions without a dilaton field are stable, while other solutions, possessing naked singularities, are catastrophically unstable.
Spectroscopic verification of suspected planetary nebulae. III.
Authors: Kohoutek L. , Pauls R.
Published: July 2007

Classification of eight objects as planetary nebulae (Table I/A) was confirmed according to our image tube spectra; as to further two objects (Table 1/B) their status remains unclear. In Table 2 we give estimates of line‐strengths, derived heliocentric radial velocities and their standard deviations.
New mass formula for spherically symmetric stellar configurations
Authors: Bleyer U. , Sh. Grigorian L. , Avakian R. M. , Chubarian E. V.
Published: July 2007

A new formula is derived for the mass of spherically symmetric stellar configurations. An expression will be given where the mass square is connected to an integral over the pressure of gravitating matter. This formula turns out to hold for Newtonian gravity, for Einstein's GRT, for projective and bimetric scalar‐tensor and further theories of gravitation.
Duplicity amongst HIPPARCOS stars
Authors: Brosche P. , Odenkirchen M. , Tucholke H.‐J.
Published: July 2007

Stars observed by the astrometry satellite Hipparcos may be unknown double stars. A subsample of those are dangerous for the extragalactic link of Hipparcos proper motions by long‐term photographic proper motions, if the time base of Hipparcos is too short to detect the orbital motion. The probability of these cases and the typical size of the photocentric orbital motion are estimated by Monte Carlo simulations for the sample of 33 stars used in the Bonn extragalactic link. Both are found to be considerable: about 16% and 9 mas/yr respectively.
Variations of the IMF Bz component over a solar activity cycle for different regimes of solar wind formation
Authors: Kovalenko V. A. , Molodykh S. I.
Published: July 2007

The behavioural features of the IMF Bz component for different solar wind velocity regimes have been studied. The study revealed a significant difference in variations of the Bz component between high‐speed and low‐speed regimes. Formation mechanisms for the IMF meridional component as well as the relationship of Bz with dynamical properties of the large‐scale magnetic fields on the Sun are discussed.
Equations for transfer of radiation in plasma at decay interactions with ionacoustic waves
Authors: Lomadze R. D.
Published: July 2007

Equations for spectral energy densities of waves are obtained describing transfer of high frequency radiation through plasma without magnetic field at the decay of electromagnetic waves into electromagnetic and ionacoustic ones, as well as the decay of Langmuir waves into Langmuir and ionacoustic ones in case of isotropic distributions of all the above waves.
Hierarchical dark matter from fragmenting macroscopic superstrings
Authors: Brosche P. , Tassie L. J.
Published: July 2007

Dark matter is explained within our scenario of the formation of the universe from the decay of macroscopic superstrings. The observed increase of the fraction of dark matter with the hierarchical rank of astronomical objects is explained by assuming that about 90% of superstrings of each rank decay into unbound fragments. The dark matter consists essentially of asteroids and smaller objects which are not bound to stars.
Stream formation in W Serpentis‐type binaries
Authors: Karetnikov V. G. , Menchenkova E. V. , Nazarenko V. V.
Published: July 2007

By the method proposed by Nazarenko (1993) and using observational data obtained by different authors, the physical conditions in the stream in the neighbourhood of the inner Lagrangian point L1 were calculated for three interacting binary systems of W Ser‐type: β Lyr, V367 Cyg, RY Sct. It is shown, that as a result of the evolutional expansion of the mass losing component the deep layers of its atmosphere reach the neighbourhood of the first Lagrangian point L1 and a stream of axial symmetric shape is formed. Its radius is comparable to the dimension of the mass losing component. The rate of the mass transfer increases up to 10−5 M⊙/yr. The calculated parameters of the stream in the neighbourhood of the point L1 explain the main observational properties of the investigated systems (existence of extended circumstellar matter with a developed structure, high mass transfer rate).
Positions of 46 radio stars: Observations of 1984–1985 and 1989–1991
Authors: Tel'nyuk‐Adamchuk V. V. , Molotaj O. A. , Gregul O. Ya.
Published: July 2007

The results of observations of 46 radio stars carried out with the Repsold meridian circle of the Kyyiv University Observatory in 1984–1985 and 1989–1991 are presented. The main goal of these observations is to improve the optical positions of radio stars for determination of a relationship between the optical and VLBI reference frames. The standard errors of averaged positions in two catalogues amount to 0.2 arcsec. These results were compared with those obtained with the Bordeaux meridian circle.
Filaments and large‐scale magnetic fields
Authors: Maksimov V. P. , Prokopiev A. A.
Published: July 2007

We have used Stanford magnetic field maps to construct distributions of longitudinal magnetic field gradients in the neighbourhood of polarity inversion lines. The distributions were constructed with proper account of the type of the polarity inversion lines and of the existence or absence of dark filaments above them. It is shown that for polarity inversion lines that pass inside active regions or on their boundary, grad BII distributions for portions of the lines with persisting filament are shifted toward lower values of gradient as compared with grad BII distributions for portions of the lines without filaments. The influence of the spatial resolution of the magnetograms upon polarity inversion line characteristics is discussed.
Brightness profiles of C3 and NH3 in the atmosphere of P/Brorsen‐Metcalf
Authors: Korsun P. P.
Published: July 2007

Spectroscopic observations of Comet P/Brorsen‐Metcalf were made on August 9–13, 1989. Spatial profiles extracted from long‐slit spectra were analyzed to determine the lifetimes of C3 and NH2 radicals and their parents, as well as the tailward acceleration of these radicals. In our investigations we used a Monte Carlo model. The average lifetime for C3 has been found to be 6.3 × 104 s and that for the parent of C3 to 6 × 103 s. The spatial profiles of C3 were almost symmetric and we need only 0.1 cm s−2 as the tailward acceleration. According to our simulations, C3H4 (allene) can be considered as the parent for C3. We obtained the average value 7.6 × 104 s for the lifetime of NH2 and 1.1 × 104 s for the lifetime of the NH2 parent. The tailward acceleration of NH2 was not more than 0.1 cm s−2. This result does not exceed the latest theoretical calculations of NH2 and NH3 lifetimes by a factor of 1.4. So, NH3 may be considered as a parent for NH2 in the atmosphere of P/Brorsen‐Metcalf.
Orbit determination by four observations
Authors: Kahl Kristensen L.
Published: July 2007

An elliptic orbit is determined from two short‐arc pairs of observations at different oppositions by the angular momentum integral. Other methods for initial orbit determination than the classical do exist.
Programme of the Galactic meridian: Star counts and galactic models. 1. Distributions of stellar magnitudes and colours
Authors: Andruk V. , Kharchenko N. , Schilbach E. , Scholz R.‐D.
Published: July 2007

A comparison of observed stellar distributions with a three‐component model of the Galaxy is presented. The analysis is based on photometric and photoelectric data obtained along the main Galactic meridian and in two fields near the North Galactic pole (programme MEGA). The assumed model considers the Galaxy as composed of the disk (main sequence and disk red giants), the thick disk and spheroid populations. To model the observed colour distribution, we distinguish main sequence stars and disk red giants as the disk subsystem; white dwarfs, subdwarfs and intermediate giants as the thick disk subsystem; extreme subdwarfs, spheroid giants and horizontal branch stars as the spheroid subsystem.

A statistical relation between the apparent and absolute magnitudes of stars which make the maximum contribution to the star counts for a given disk subsystem is derived.

In order to achieve the best agreement between the model and observations, we fit the values of the ‘dip’ (aw) of the disk luminosity function, the correction to the absolute magnitude of disk red giants (ΔMVRG) and the expression for interstellar extinction. As the main result, we obtained aw = 0.6 (logarithmic scale) and ΔMVRG = 0.5 mag; the interstellar extinction has to be taken into account by the modified Sandage law.
A refined model for the influence of ocean tides on UT1 and polar motion
Authors: Seiler U. , Wünsch J.
Published: July 2007

Periodic changes in Universal Time and polar motion have been derived from a numerical ocean model for a number of small partial tides. Combined with the results reported earlier our model now includes the 34 most important constituents of degree 2 (measured by the amplitude of the tidal potential). The results show that the terms neglected in all existing models amount to 80 μs in UT1 and to 0.3 mas in polar motion.
Position Angle Variation of the Major Axis of some Galaxies
Authors: Gamaleldin A. I. , Issa I. A.
Published: July 2007

The variation in the direction of the major axis in three ellipticals, five lenticulars and three spirals has been studied using B or V isophotic maps. It is noticed that there is a turn point in most of the curves especially for spirals and lenticulars. This turn point can be used to define the galaxy nucleus region.

There seems to be a correlation between the rotation curve and the position angle curve especially for NGC 2784 and NGC 3640
Stellarstatistische Untersuchungen in der Sonnenumgebung
Authors: Guseva N. G. , Kolesnik L. N. , Metreveli M. D.
Published: July 2007

Space densities for stars given in the „Catalogue of nearby stars”︁ and in „Nearby star data published 1969—1978”︁ were calculated for the stellar groups listed in Table 1 as a function of the distance from the galactic plane. The stars are symmetrically distributed with respect to the galactic plane. Space densities for giant stars nearer than 22 pc were also computed. The comparison between the luminosity functions of stars nearer than 5 pc and 22 pc shows that the number of M dwarfs up to 22 pc is given uncompletely.
Observations of Minor Planets at Dresden Lohrmann Observatory
Authors: Asenjo E. , Böhme D.
Published: July 2007

Observed positions of minor planets from 1980 and 1981 at the Zeiss‐Sonnefeld astrograph 300/1500 of the Lohrmann Observatory at Dresden‐Gönnsdorf are communicated.
Softening Effects in the Equation of State and Influence of General Relativity on the Outcome of Stellar Collapse
Authors: Kämpfer B.
Published: July 2007

Hydrodynamical evolution of a collapsing stellar core is followed to test the influence of general relativity and of softening effects in the equation of state. The general relativistic treatment of the collapse does not show any spectacular deviation from the Newtonian treatment. In particular there is no indication within the standard scenario for potential barrier penetration and continued collapse to a black hole. In the case of strong electron capture during the collapse the nuclear matter equation of state is of importance. A softening according to a phase transition below the bounce density is found to reduce the shock strength, but the shock is strong enough to cause the usual blowing‐off.
REDUCE programs for algebraic computation in general relativity
Authors: Dautcourt G. , Jann K.‐P.
Published: July 2007

REDUCE programs for algebraic computation in General Relativity are presented which use the metric tensor as input. The programs calculate — according to the user's option — the CHRISTOFFEL symbols, the RIEMANN tensor, the RICCI tensor, the RICCI scalar, the EINSTEIN tensor and the WEYL tensor.
Eléments Orbitaux de cinq Etoiles Doubles Visuelles
Authors: Scardia M.
Published: July 2007

We have calculated the orbital elements, the dynamical parallax, and the total mass of the binary stars ADS 1615, 3341, 3472, 3573, and 5464.
Zeitlich periodische Variationen des solaren Neutrinoflusses und das Standardmodell der Sonne
Authors: Haubold H. J. , Gerth E.
Published: July 2007

Die FOURIER‐Transformation der von DAVIS gemessenen 37Ar‐Erzeugungsrate im solaren Neutrinoexperiment weist auf zeitliche Variationen des Neutrinoflusses mit Perioden von 100.0, 58.8, 35.7, 25.6, 19.6, 15.2, 8.8 und 6.3 Monaten hin. Wir diskutieren physikalische Voraussetzungen des Standardmodells der Sonne, die nicht allgemein mit den Beobachtungen übereinstimmen und führen Pulsationen des solaren Neutrinoflusses mit der Zeitskala von Jahren auf im Sonneninneren angeregte Schwerewellen zurück.
On Eccentricities of Globular Cluster Galactocentric Orbits
Authors: Ninković S.
Published: July 2007

By use of a modified HOUSE and WIEGANDT method orbital eccentricities of globular clusters are calculated. A discussion concerning the duration of the evolution contraction of the Galaxy is presented as well.
Modulation of Solar Constant by Active Regions during 1980
Authors: Pap J.
Published: July 2007

Irradiance records of the Nimbus‐7 and SMM satellites indicate a systematic downward trend of the solar constant of the order of a few hundredths of a percent and a slow variation of the solar constant on a time scale from days to weeks. The reason for the downward trend is not known as yet; it seems that the slow variation of the solar constant is linked with the solar rotation period via the effect of solar active regions.

This paper deals with the connection between the solar constant variation and the age of the solar active regions. It seems that decreases in the solar constant took place when sunspot groups developing quickly in time and space with complex structure occurred on the solar disk. On the other hand, when the “older” groups with simple structure were dominant the value of the solar constant increased slightly or these groups could reduce the effects of “younger” groups.
Advantages and Disadvantages of the MERIT Campaigns
Authors: Vicente R. O.
Published: July 2007

The campaigns of the programme of international cooperation, called MERIT, for the determination of the earth rotation parameters are reviewed, especially about the difficulties to infer results about polar motion from such short intervals of observations. It is pointed out the need to employ the same models and standards in order to facilitate the comparison of data obtained by classical and modern techniques.
On the Structure of the Perseus Cluster of Galaxies
Authors: Baier F. W.
Published: July 2007

The investigation of the distribution of number densities and radial velocities in the Perseus cluster led us to the conclusion that this cluster possesses dominant substructures. This result is in agreement with a corresponding result for the Hydra‐I cluster and with former conclusions of different authors that substructures are a typical phenomenon for a high percentage of all clusters of galaxies. The complex of the Perseus cluster has a diameter of 60–80 minutes of arc.
Investigation and Experimental Observations on the Two‐Channel Stellar Electrophotometer
Authors: Kakhiani V. O. , Totochava A. G.
Published: July 2007

Test observations with the new two‐channel photometer performed on the 125 cm telescope of Abastumani Observatory are described.
Two‐Color Observations of AM Her
Authors: Totochava A. G. , Kakhiani V. O.
Published: July 2007

Observations and light curves of the variable star AM Her observed in the b and v proper color system of the Abastumani two‐channel photometer are presented.
On the Structure of the Coma Cluster of Galaxies
Authors: Baier F. W.
Published: July 2007

The investigation of the distributions of number densities and radial velocities in the Coma cluster led us to the conclusion that this cluster possesses substructures. This result is in agreement with corresponding results for the Hydra I cluster and the Perseus cluster and with former conclusions by different authors that substructures are a typical phenomenon for a high percentage of all clusters of galaxies.
Solar magnetism: Observation and theory
Authors: Stix M.
Published: July 2007

This introductory review consists of four parts. The first is a discussion of the concentration of magnetic flux into small elements, the large electrical conductivity and the superadiabatic stratification as the main reasons for these “flux tubes”, their relationship to the mean field, and the observational evidence of the latter. The second briefly repeats the approximations and merits of kinematic mean field dynamos. In the form of the αω‐dynamo, this theory esplains the reversals, latitude migration, dipolar parity and other properties of the mean solar field. The third part treats the question of flux loss from the bottom of the convection zone, or in a transition layer beneath it. The last part discusses further dynamic aspects of the Sun's magnetism, e.g. models of limit cycles and models with chaotic behaviour and in particular the question of phase stability of the solar cycle.
The energy flux number and three types of planetary dynamo
Authors: Stevenson D. J.
Published: July 2007

It is proposed that the existence and nature of a planetary dynamo can be characterized by a dimensionless number Φ ≡ FeR/ϱλ2ω, called the energy flux number, where Fe is the energy flux available for dynamo generation, R is the core radius (or thickness of the dynamo generating region), ϱ is the fluid density, λ is the magnetic diffusivity and ω is the angular velocity. For Φ ≲ 1, there is no dynamo. For 1 ≲ Φ ≲ 102.5 there is an “energy‐limited dynamo”, in which Fe is insufficient to enable the dynamo to reach the dynamically desirable state A ≡ B2/8πϱλω ∼ 1, where B is a typical field amplitude (in Gauss). For 102.5 ≲ Φ ≲ 105, there is a dynamically determined dynamo (Λ ∼ 1) in which the magnetic Reynolds number of turbulent eddies is small. For Φ ≳ 105, there is a turbulent dynamo. Probable planetary examples of these three dynamo states are Mercury (Φ ∼ 102‐103), Earth (Φ ∼ 104) and Jupiter (Φ ∼ 1011), respectively.
Theory of magnetic stars
Authors: Mestel L.
Published: July 2007

The principal observational facts on the early‐type magnetic stars are summarized, and interpreted in terms of the oblique rotator model. In the theoretical discussion of the interaction between a large‐scale magnetic field and the star's thermal, gravitational and rotation fields, emphasis is laid on effects that are relevant to both fossil and dynamo theories of the origin of the magnetic field.
Photometry and spectrophotometry of magnetic stars
Authors: Stępień K.
Published: July 2007

A review of selected photometric and spectrophotometric properties of magnetic stars is given. It is shown that unreddened B–V of magnetic stars around B9 type can be transformed to log Te using the calibration for normal stars and no systematic errors are introduced. Mechanisms of light variability are discussed. It is concluded that different mechanisms must be operating in different stars.

Recently obtained photometric observations of short‐period variability by KURTZ and Hβ variability by MADEJ et al. are discussed. An information about internal structure and the atmospheric structure of these stars can be derived from these observations.
The redshift distribution law of quasars revisited
Authors: Depaquit D. , Pecker J.–C. , Vigier J.–P.
Published: July 2007

Can observational selection effects, tied with the existence of strong lines, explain the observed log (1 + z) periodicity of the quasar's histogram, as sometimes claimed? A first approach shows that one must distinguish radio from optical quasars. In the former case spectroscopic selection due to strong lines is investigated from the study of homogeneous samples. Then, the role played by pairs of strong lines in the redshift's determination is evaluated and it shows that teh spectroscopic selection cannot explain the observed periodicity of the radio quasar's histogram. The study of the complete sample confirms this conslusion.
Strong gravity effects in the temperature profile of accretion disks
Authors: Paul H. G.
Published: July 2007

The temperature profile of accretion disks moving axially symmetric in the static, spherically symmetric field of a compact, massive object is calculated without specifiing the gravitational theory. Using the covariantly written viscous, fluiddynamical equations of motion, the α viscosity law and free‐free radiation of a cooling region is obtained under very general assumptions about the behaviour of the external gravitational field. The used gravitational theory is reflected by inner boundary processes taking place in the region of strong gravity; the cooling region could give a significant „bremsstrahlung”︁ correction to the ”︁cool'' part of the spectrum radiated away from the outer, weak gravity region of the disk.
Beobachtungen der Geminiden und Quadrantiden
Authors: Rendtel J. , Rendtel I. , Otto F. , Koschack R.
Published: July 2007

Geminiden und Quadrantiden werden wahrscheinlich erst seit etwa 100 Jahren beobachtet. Infolge von Bahnstörungen unterliegen sie schnellen Veränderungen. Eine Verformung des Geminiden‐Ratenprofiles läßt sich jedoch nicht finden.

Beobachtungen der Geminiden und Quadrantiden durch den Arbeitskreis Meteore werden mit den Perseiden verglichen. Bei allen drei Strömen wird zum Maximum der Gesamtaktivität auch eine Zunahme der Zahl heller Meteore festgestellt. Zum gleichen Zeitpunkt sinkt der Populationsindex r für Perseiden und Quadrantiden, während der der Geminiden steigt. Daraus wird eine Abschätzung der Zunahme der Teilchenzahl zu schwächeren Helligkeitsklassen gewonnen.
Solutions of the linearized Bach‐Einstein equation in the static spherically symmetric case
Authors: Schmidt H.‐J.
Published: July 2007

The Bach‐Einstein equation linearized around Minkowski space‐time is completely solved. The set of solutions depends on three parameters; a two‐parameter subset of it becomes asymptotically flat. In that region the gravitational potential is of the type φ = ‐m/r + ε exp (‐r/l) m and ε being small parameters.

Because of the different asymptotic behaviour of both terms, it became necessary to linearize also around the Schwarzschild solution φ = ‐m/r. The linearized equation resulting in this case is discussed using qualitative methods. The result is that for m ≤ 2l the asymptotic behaviour is φ = ‐m/r + εr−m/l exp (‐r/l) u, and for m ≧ 2l φ = ‐m/r + εr−2 exp (‐r/l) u, where u is some bounded function; m is arbitray and ε again small. Further, the relation between the solution of the linearized and the full equation is discussed.
Spherical simulations of large‐scale structure of the Universe
Authors: Mücket J. P.
Published: July 2007

We consider a spherical‐smmetric perturbation in an initially homogeneous dust filled universe within the frame‐work of the Bondi‐Tolman solution. The decoupling of the perturbed region from the background evolution naturally leads to shell‐crossing in a certain outer environment, which describes energy relaxation. In the approximation of Newtonian gravity it can be analytically determined the behaviour of the outgoing front shell and different parameters of the shell‐crossing region. On the basis of the obtained results we give a possible explanation for the “large voids” in the observed galaxy distribution.