bluuebunny/crossref_metadata_2025 huggingface dataset:
Turbulent viscosity, magnetic diffusivity, and heat conductivity under the influence of rotation and magnetic field
Authors: Kitchatinov L. L. , Pipin V. V. , Rüdiger G.
Published: July 2007

The old problem of turbulent diffusion is addressed to define the influence of rotation and magnetic field ‐ the usual ingredients of astrophysical bodies ‐ on the effective transport coefficients. Either rotation and magnetism produce the anisotropy and quenching. The tensorial structures of the diffusivities and their dependences on the angular velocity and the field strength are explicitly defined. An example of application of the theory to the global stellar circulation model is given and the implications for cosmic dynamos are briefly discussed.
Investigation of the kinematics and structure of the Galaxy in the vicinity of the North galactic pole
Authors: Kharchenko N. , Schilbach E. , Scholz R.‐D.
Published: July 2007

In the framework of the programme of studying the meridional section of the Galaxy (MEGA) the absolute proper motions of more than 11000 stars with respect to 3000 galaxies and their stellar magnitudes in the B, V Johnson system are determined in two sky regions near the North Galactic Pole (NGP) by means of Tautenburg Schmidt plates. The limiting and completing apparent stellar magnitudes are B = 20.4 and 18.3 mag, the overall and the investigated sky areas are 16.4 and 14.6 square degrees, respectively. Distances have been determined using the stellar magnitudes, colours, proper motions and reduced proper motions. Stellar kinematics, eccentricities of Galactic orbits, spatial distribution and changes of these characteristics with Z‐distance from the Galactic plane are obtained up to 15 kpc. Four subsystems distinguished in the NGP direction, respectively with semithicknesses of 0.25, 0.38, 0.67, 1.48 kpc and density ellipsoid axial ratios of 0.09, 0.20, 0.28, 0.49 show mean velocities in the Galactic rotation direction relative to the LSR of 5.6 ± 0.6, − 11.0 ± 0.6, − 62.5 ± 1.2, − 181.6 ± 4.4 km/s, and ages of 0.1, 0.4, 0.9, 1 of the Galaxy age.
Autocorrelation function bias owed to a limited number of de‐trended observations. Applications to autoregressive models with noise
Authors: Andronov I. L.
Published: July 2007

Analytical expressions were derived for the expectation of the autocorrelation function (ACF) corresponding to lowfrequency least squares fits and deviations from them in the case of a limited number of observationsN. A vector of values of the autocovariation function may be obtained by multiplication of aN . NmatrixZ(dependent on concrete basic functions used for trend determination) by a vector of the unbiased ACF. Because much computational time is needed to obtain such a matrix, its components are to be computed once for concreteNand basic functions, and then stored as a file. An algorithm is proposed for determining the contribution of the correlated signal to the ‘signal+noise’. The expressions are written for general form of the ACF, and illustrated by the application to autoregressive models. The statistical properties of the model parameters are studied. The method is applied to cataclysmic binaries AM Her and TT Ari. The precise expressions allow us to obtain reliable results and to avoid misinterpretation being possible when using the approximate methods.
Cr 135 revisited
Authors: Amieux G. , Röser S.
Published: July 2007

In this paper we combine information on photometry, radial velocities and proper motions to study the nature of the suspected open cluster Cr 135. For the first time we introduce proper motions of a large number of stars in the region of Cr 135 into the discussion. The proper motions taken from the PPM catalogue favour the hypothesis that Cr 135 is a real open cluster with at least 12 members at a distance of 300 pc having a space motion U, V, W of (−11, −13, −15) km s−1. But still more accurate observations are needed to separate it from the field stars without any doubt.
Scalar field instability in multi‐dimensional cosmology
Authors: Bleyer U. , Zhuk A.
Published: July 2007

The scalar field theory on the background of cosmological models with n(n ≥ 1) spaces of constant curvature is considered. We take the integrable case of Ricci flat internal spaces. The coupling between the scalar and the gravitational fields includes the minimal coupling as well as the conformal case. In the ground state of the scalar field we find the conditions for vacuum instability realized for most of the possible solutions to Einstein's equations if the coupling parameter takes appropriate values. For the excited states of the scalar field we show the induction of massive modes and discuss their properties.
Generalized de Sitter solution in multi‐dimensional cosmology with static internal spaces
Authors: Zhuk A.
Published: July 2007

A multi‐dimensional cosmological model with space‐time consisting of n(n ≥ 2) Einstein spaces Mi is investigated in the presence of a cosmological constant λ and a homogeneous minimally coupled free scalar field. A generalized de Sitter solution was found for λ > 0 and a Ricci‐flat external space for the case of static internal spaces with fine tuning of parameters.
Size scale of the R Coronae Borealis variables
Authors: Rosenbush A. E.
Published: July 2007

The radius of R CrB is estimated to 90–100 radii of the Sun. The dust layer, which is the cause of the deep minimum in the visible light of R Coronae Borealis‐type stars, has a radius of about 6 radii of the star. This follows from the delay of the infrared light increase after the visual minimum and also from the analogy with the dust formation in novae. The emission lines appearing in the minimum have an origin analogous to the metal emissions in the comets of 1882 II and 1965 VIII in which they were observed at a distance of 20–30 R⊙. The permanent dust shell has a radius about of 26 stellar radii.
Revealing of periodicities in the variations of differential rotation of the Sun
Authors: Gigolashvili M. Sh. , Gogoladze N. A. , Khutsishvili E. V.
Published: July 2007

It is presumed that a north‐southern asymmetry of a solid‐body rotation of large spots, depending on even and odd solar activity cycles (Gigolashvili and Khutsishvili 1 1989, 1990) may possibly be explained by the asymmetry of the appearance of large structures with strong magnetic fields in the corresponding hemispheres.

Spectral analysis of the observational data shows the presence of cyclic variations of differential rotation of large‐ and middle‐sized spots. Variations of differential rotation of small spots are either absent or overlapped by noise.

It is also supposed that the discovered and most frequently realized component of the spectrum of solar differential rotation variations — a four‐years periodicity — may be either a real phenomenon or the result of overlapping of multiple quasi bi‐annual variations.
On the Behaviour of Test Matter in the Neighbourhood of Caustics of Homogeneous Cosmological Models
Authors: Paul H. G.
Published: July 2007

Using power asymptotes for the metric of the metric of the BIANCHI types I, V, VIIO, VIII and IX the intensity of geodesic focused scalar test matter is calculated in the neighbourhood of the caustic singularity of these space‐time models. In all considered BIANCHI types there is a caustic diffraction field bounded by regions of extinction depending on the structure of the gravitational lense.
New Light Curve Analyses for the Eclipsing Binaries u Her and UV Leo
Authors: Giuricin G. , Mardirossian F. , Mezzetti M.
Published: July 2007

Using WOOD's (1972) model we have analyzed two sets of photoelectric observations as yet unsolved, i.e., ROVITHIS' and ROVITHIS‐LIVANIOU's (1980) B and V light curves of the semi‐detached system u Her and BROGLIA's (1961) three‐colour observation of the detached system UV Leo.

The observations of u Her have yielded solutions in which the secondary's radius exceeds its ROCHE lobe. On the other hand, our new elements of UV Leo confirm the most recent investigations, thus giving for the primary eclipse an unexpected occulatation solution which hardly permits a simple picture of UV Leo.
Positionen Kleiner Planeten
Authors: Gressmann M.
Published: July 2007

The table contains topocentric positions of several minor planets. The coordinates are given for the epoch 1950.0.
Limits to Intergalactic Neutral Hydrogen from Photoionization Absorption in Ultraviolet Quasar Spectra
Authors: Dautcourt G.
Published: July 2007

Measurement of the continuum beyond the LYMAN limit in the spectra of highly redshifted quasars allows to put upper limits to intergalactic neutral hydrogen which are comparable to those derived from the GUNN‐PETERSON‐SCHEUER‐SCHKLOWSKI test. The data apply to a weighted average of neutral hydrogen along the whole line of sight to the quasar, not to a small region around the quasar as in the GPSS test. Some conclusions are derived for a possible clumped component of neutral hydrogen in different FRIEDMAN models.
Die MARKARJAN‐Galaxienkette im Sterbild Virgo
Authors: Litzroth E.
Published: July 2007

Den von MEURERS untersuchten zwei Strukturvarianten der MARKARJAN‐Galaxienkette im Sternbild Virgo wird eine dritte, wahrscheinlichere Variante hinzugefügt. Eine Untersuchung der Abstands‐Geschwindigkeits‐Beziehungen dieser Variante zeigt, daß von den acht Galaxien der Kette sieben zu demselben kinematischen Kettensystem gehören. Dieses rotiert wie ein starres Gebilde mit gleicher Winkelgeschwindigkeit, wobei es sich zugleich mit einer Geschwindigkeit von etwa 700 km/s von uns entfernt. Die Galaxie NGC 4374 am Rand der MARKARJAN‐Kette gehört offenbar nicht zu diesem einheitlich rotierenden Kettensystem, da sie nicht in die Abstands‐Geschwindigkeits‐Struktur dieses Systems paßt.
Stress‐Energy Density Tensor of Isotropic Homogeneous Universe
Authors: Popić R. V.
Published: July 2007

The relation between timelike and spacelike components of the stress‐energy density tensor is obtained from EINSTEIN equations in ROBERTSON‐WALKER metrics. The timelike component of the stress‐energy density tensor is developed as a power series of cosmological scaling radius. FRIEDMANN cosmology is recognized as a part of a more general cosmology.
Koordinateninvariante Erhaltungssätze in der Schwarzschildgeometrie
Authors: Burghardt R.
Published: July 2007

Die Einsteinschen Feldgleichungen für das Schwarzschildfeld werden so umgeschrieben, daß in ihnen nur meßbare Größen vorkommen. Die Austdrücke sind völlig koordinateninvariant, jedoch vom Beobachter abhängig. Verallgemeinerte Lorentztransformationen im Sinne von TREDER vermitteln zwischen den Meßwerten verschiedener Beobachtersysteme. Die Feldgleichungen enthalten einen Ausdruck für die Energie und die Spannungen des Gravitationsfelds, die kovariante differentielle Erhaltungssätze erfüllen.
A Second‐order Correlation Approximation for Thermal Conductivity and Prandtl Number of Free Turbulence
Authors: Eschrich K.‐O. , Rüdiger G.
Published: July 2007

By means of a linearizing approximation we determine the scalar thermal eddy conductivityχTin its dependence on the spectral function of the (given) turbulence and the microscopic conductivityχ. The discussion of the profileχT(χ) reveals the importance of the shape of the frequency spectrum of the velocity fluctuations. Spectra which decrease with increasing frequency produce eddy conductivities which decrease with increasingχ. A distinct peak in the frequency spectrum corresponds to a non‐trivial maximum of theχT‐profile. These general findings are confirmed by examples some of which are numerical. Very small molecular diffusivities generally lead to a turbulent PRANDTLnumber of 0.4in rough accordance whith most of the measurements. For large diffusivities, however, the turbulent PRANDTLnumber behaves inversely to the molecular PRANDTLnumber. We have to doubt thus the general belief that eddy conductivity always exceeds eddy viscosity. For the effective PRANDTLnumber of the Sun we find an upper limit of 0.3. An application of our theory to the smallscale motions in the upper Earth core yields values of 0.4.
The Light Curve Changes of VW Cephei
Authors: Kotarska I. , Glownia Z.
Published: July 2007

A long series of photoelectric observations of the W UMa‐type eclipsing binary VW Cephei collected since 1952 is discussed. The so‐called KWEE effect is examined — regarding the heights of maxima and the depths of minima — in order to detect periodicities i n the light curve changes. The frequency analysis reveals periodicities at the small homogeneous observational domains only, but the power spectrum (in sence of DFT) of all observations is very complicated for exact interpretation. The light curve changes are entirely real much exceeding the possible errors, but they have lost their periodic character in the whole discussed time interval.
Calculations of Comet Orbits from Observations of 1980/81
Authors: Buffoni L. , Manara A. , Scardia M.
Published: July 2007

From observations published in Smithsonian Astrophysical Observatory and MPC circulars corrected orbits of 26 comets have been calculated.
Large‐scale distribution of clusters of galaxies
Authors: Schmidt K.‐H.
Published: July 2007

The redshifts of 576 clusters of galaxies have been compiled from literature. This sample was used to study the large‐scale distribution of clusters up to about z = 0.15. The distribution of the clusters reveals several chains and filaments 50 to 200 h−1 Mpc in size. There are many empty regions and holes, too, some of them known previously.
Secondary maxima in the radial galaxy distribution of clusters of galaxies and subclustering
Authors: Baier F. W.
Published: July 2007

From the structural investigations of 19 clusters of galaxies follows that secondary maxima in their projected radial galaxy distributions can be explained by subclustering. There are no signs for density shells around the cluster centres. Subclustering seems to be a typical phenomenon in clusters of galaxies.
The interstellar 2200 Å band: A second catalogue of equivalent widths and preliminary statistical analysis (Mitteilungen der Universitäts‐Sternwarte zu Jena Nr. 162)
Authors: Friedemann C. , Gürtler J. , Schielicke R. , Dorschner J.
Published: July 2007

A second catalogue of equivalent widths of the interstellar 2200 Å band is presented. It is based on spectrophotometric data obtained with the TD‐1 satellite and supplements a catalogue already published (paper I). Both catalogues list a total of 779 stars. The reliability of the derived parameters is analysed. There is a satisfying agreement with spectrophotometric data obtained with the OAO‐2 satellite. The relationship between the equivalent width of the 2200‐Å band and and the colour excess is discussed, making use of additional data for more strongly reddened stars obtained with OAO‐2 and IUE.
On the Past Star Formation Rate in the Solar Neighbourhood
Authors: Meusinger H.
Published: July 2007

The present day mass function (PDMF) is derived from the data material of the immediate solar neighbourhood. From the comparison of the lower mass part (R<R) and the high mass part of the PDMF it is estimated that the mean past star formation rate related to the present one is in the range 0.08—2.0, supposed the initial mass function (IMF) is time independent. References to probable time dependences of the IMF are summarized. Using the PDMF as a constraint on the temporal variation of the IMF, unplausibilities for the star formation rate result if the IMF monotonously flattens in time uniform over the whole mass range.
Classical Matter Fields in Homogeneous Cosmological Models
Authors: GottlÖber S.
Published: July 2007

The behaviour of classical massive scalar and vector fields as sources of homogeneous world models is examined. The consequence of the violation of the strong energy condition by the massive scalar field for the evolution of an cosmological model is discussed.
Photometrische Untersuchungen im Zentralgebiet der Praesepe (NGC 2632)
Authors: GÖtz W.
Published: July 2007

In Ergänzung der photometrischen Skala in der Zentralregion der Praesepe und ihrer Erweiterung auf schwächere Sterne wurde eine photographische Photometrie im UBV‐System auf Platten der Schmidtkamera (134/200/400 cm) des Karl‐Schwarzschild‐Observatoriums durchgeführt. Die bereits bekannten photometrischen Daten von Sternen, die von HAFFNER, HECKMANN und WEIS erhalten wurden, wurden durch (U – B)‐Farbenindizes vervollständigt. Außerdem wurde eine Anzahl von helleren und schwächeren Sternen, Haufenmitgliedern einschließlich weißer Zwerge und Feldsternen, untersucht, um eine photometrische Skala bis zu V ≈ 18.m9 zu erstellen. Eine Umgebungskarte, in der alle gemessenen Sterne gekennzeichnet sind, wird gegeben.
On Possible Causes of Scatter in the Period‐Luminosity‐Colour Relation of Cepheids
Authors: Zsoldos E.
Published: July 2007

Some possible causes of scatter in the PLC relation of cepheids are investigated and estimates arising from the presence of rotation, magnetic field, and companion star are presented.
Berücksichtigung inhomogenen Hintergrundes bei der Irisblendenphotometrie
Authors: Ziener R.
Published: July 2007

Verschiedene Methoden der Berücksichtigung inhomogenen Hintergrundes bei der Irisblendenphotometrie werden miteinander verglichen. Dabei werden sowohl Meßwerte von SCHAEFER (1979, 1981) als auch eigene Messungen auf Tautenburger Platten herangezogen. Schließlich werden einige Regeln für die Messung von Platten mit Hintergrundinhomogenitäten gegeben.
An Unusual Group of Low Surface Brightness Galaxies in the Region 1046 + 65
Authors: Börngen F. , Karachentseva V. E. , Karachentsev I. D.
Published: July 2007

A complex of 11 objects with a surface brightness of about 26 mag/□” is detected in the direction of the M81 group of galaxies. The argumentes are presented in favour of the fact that they are at the distance of the M81 group; their linear diameters (2 to 3 kpc) and absolute magnitudes (MB = ‐11m to ‐12m) are in agreement with the parameters of the known dwarf galaxies of the Local group. An assumption about the tidal stability of the complex of dwarfs relative to M81 gives an estimation of its summary mass ≳ 1 · 108 M ⊙ and of its mass‐to‐luminosity ratio ℜ/L ≳ 1.2 in the solar units.
Error Analysis for the Astrometric Determination of Absolute Proper Motions by means of a Monte Carlo Simulation
Authors: Hirte S. , Neumann P.
Published: July 2007

For the determination of positions and proper motions of celestial objects until now only corrections of errors caused by the instrument and by the atmosphere have been carried out. Errors of measurement as random errors have not been considered. Therefore a Monte Carlo simulation of the propagation of these random errors in the calculation of the so‐called averaged measurement coordinates and the proper motions were undertaken. As a typical quantity, the corresponding standard deviation was estimated, and its dependence on occuring parameters was studied. With this method, the true values of the considered quantities are known (generated by simulation) so that the errors of the calculated quantities can be directly determined. Inferences to the accuracy of a single measurement were made.
The Physical Nature of the Blue Objects in the Field of BD + 15° 2469 (Virgo Cluster)
Authors: Abati L. E. , Lorenz H.
Published: July 2007

The physical nature of 277 ultraviolet excess objects of the third Asiago field (22 square degrees, 15 ≦ mpg ≦ 18, U–B ≦≦ ‐0.2) is investigated on the basis of objective prism plates. Most of them are stars, 8% are quasar candidates and 7% compact galaxies. The proportions of different kinds of objects changes with the magnitude and U–B colour index. The surface density of quasars is estimated to be between 0.5 Q/sq. deg. and 1.0 Q/sq. deg. for the UVX A3 objects.

The results of the A3 field (located in the Virgo cluster of galaxies) statistically agree with the ones of the A1 field, outside clusters of galaxies.
Mean Magnetic Field in Renovating Random Flow
Authors: Dittrich P. , Molchanov S. A. , Sokoloff D. D. , Ruzmaikin A. A.
Published: July 2007

An integral equation is derived for a mean magnetic field in a random velocity field that renovates after a characteristic time τ. It is shown that in two cases, i.e. when (a) the correlation time is short, τ < l/v0 (where l and v0 are the characteristic scale and velocity), and (b) for long wave components of the field, k−1 ≫ v0τ, the equation is reduced to the differential one, whose form has first been given by STEENBECK, KRAUSE and RÄDLER. Expressions for the equation coefficients are obtained in the two above cases. In a general case the integral equation cannot be reduced to the differential one although its spectral properties are close in a certain sense to those of the SKR‐equation. There are differences, however (specifically, the integral equation yields a higher rate for the field growth), that are shown on the example of the Gaussian distribution (at time renewal) of particles moving along random paths.
Eléments Orbitaux, Presque Definitifs, de l'Etoile Double Visuelle ADS 10075 ‐ SFT 2052
Authors: Scardia M.
Published: July 2007

Orbital elements of the visual binary star ADS 10075 are given. The dynamical parallax and total mass of the system have been calculated.
Theory of stellar magnetic activity: A review
Authors: Belvedere G.
Published: July 2007

The unified sight of solar and stellar activity has revealed a worthwhile concept under several aspects, gaining in the last decade the increasing favour of observers and theorists, and the term solar‐stellar connection has recently been introduced to point out the complementarity of solar and stellar observations in the background of the basic role of the magnetic field.

The great development of ground and space stellar activity observations suggests a much wider scenario than it were possible to imagine even a few years ago, and stimulates theoretical work, most of which is in the framework of the α–ω dynamo theory. Dynamo models of stellar activity in the main sequence, although subjected to different assumptions, do converge in predicting that activity should increase with the increasing angular velocity of rotation ω and colour index (B–V), in agreement with almost all existing observational evidence. However, even if linear dynamo theory seems to have captured the essentials of the mechanism of stellar activity, the complexity of stellar activity phenomenology and operation modes suggests that the future is in the non‐linear approach.

Finally, observational and theoretical uncertainties and difficulties, which affect the present status of dynamo theory, are briefly discussed.
Bimodal mass and angular momentum losses by magnetically controlled winds during stellar evolution
Authors: Castellani V. , Paternò L.
Published: July 2007

In recent times evidence for bimodal distributions of stars in the H–R diagram has reached a striking evidence. These bimodal distributions seem to be correlated with a bimodal distribution of masses and angular velocities. The approach we propose to explain the observed bimodality suggests that this latter is due to a bimodal mass loss by magnetically controlled stellar winds during stellar evolution, owing to different magnetic field configurations. It is assumed a mechanism analogous to that which produces solar wind, with magnetic field generated by dynamo working in the convection zone. Different field geometries (dipole cr quadrupole), which depend on the mode the dynamo operates, can produce different but discrete mass losses during stellar evolution, thus producing bimodal distributions of masses and angular velocities.
Mean‐field dynamo with cubic non‐linearity
Authors: Kleeorin N. I. , Ruzmaikin A. A.
Published: July 2007

The turbulent mean‐field dynamo of αω‐type with a mean helicity quadratically dependent on the magnetic field is investigated. A nonlinear system of ordinary differential equation is derived for the amplitudes of the magnetic field expansion over the eigenvectors of the linear problem.

In a one‐mode approximation the non‐linear supercritical solution is stable when dγ/dD> 0, where γ is the growth rate of the linear solution andDis the dynamo number.

Non‐linear interation between two modes of dipole and quadrupole symmetry is considered. The conditions are found for the synchronization and beats of these modes under the assumption that the quadrupole mode is weaker than the dipole one.
Some observational results on long‐time variability of stars with magnetic fields
Authors: Scholz G.
Published: July 2007

The intention of this paper is a summary of long‐time phenomena of magnetic stars which we obtained at the Potsdam Observatory. The considered magnetic stars are γ Equ, HD 9996, 53 Cam, 52, Her, and v Cep. Many results have been published already; here, they are compiled and completed by new details.
Accretion with uniform eddy diffusivity I. Polytropic–tube models
Authors: Rüdiger G. , Tschäpe R.
Published: July 2007

We consider accretion onto a two–dimensional polytropic tube. In contrast to the standard papers we apply spatially uniform eddy viscosity (and eddy conductivity in part II resp.). In principle, the resulting rotation law is non–keplerian and proves to be rather flat. Wether the angular velocity increases or decreases inwadly depends on the strength of the torque exerted on the outer surface which is due to the inflow of angular momentum. Large (small) torque cause super–(sub–)rotation. The frictionally originated luminosity varies for various models. It lies one or two orders of magnitude below the total avialable accretion energy. For certain combinations of the Mach numbers the radial inflow profile possesses a sonic point.
General precession computed by numerical integration of ordinary differential equations
Authors: Andersen T. B.
Published: July 2007

It is suggested that the effects of change in the celestial coordinates due to general precession be computed by solving numerically the differential equations for the instataneous rates of change in right ascension and declination. An approximate solution in closed from is given. Similar differential equations may be solved for the complete rotation matrix, requiring only the knowledge of the variations of the two function m and n with time. This suggests the existence of a relation between the classical precessional elements z, ζ0 and Θ, and this relation is derived. Some numerical examples are also presented.
A new representation of Güttler's theory of electromagnetic scattering by a composite sphere
Authors: Shah G. A.
Published: July 2007

The multipole expansion coefficients for electromagnetic scattering by a stratified core‐mantle sphere, suitable for fast and accurate evaluation of the radiation scattering parameters, have been recast.
On static spherical symmetric solutions of the Bach‐Einstein gravitational field equations
Authors: Schmidt H.‐J.
Published: July 2007

For field equations of 4th order, follwing from a Lagrangian “Ricci scalar plus Weyl scalar”, it is shown (using methods of non‐standard analysis) that in a neighbourhood of Minkowski space there do not exist regular static spherically symmetric solutions. With that (besides the known local expansions aboutr= o nadr= ∞ resp.) for the first time a global statement on the existence of such solutions is given. Finally, this result will be discussed in connection with Einstein's particle programme.
Messung der Lichtablenkung während der Sonnenfinsternis am 15. Februar 1961
Authors: Schmeidler F.
Published: July 2007

During the total eclipse, a plate of the stars near the Sun was taken on the Monte Cónero near Ancona in Italy, on which 12 stars were measurable. Comparison with another plate of the same stars taken at night showed strong distortion on the eclipse plate which was very probably due to anomalous refraction. The differences of coordinates between both plates were represented by a general secondorder expression. The value L = I″.98 ± o″.46 was derived for the gravitational deflection on the solar limb.
Zur Interpretation der Messungen der Lichtablenkung am Sonnenrand
Authors: Schmeidler F.
Published: July 2007

The agreement between radiastronomical measurements of the gravitational deflection of light at the solar limb and the theory of relativity is compatible with the exces found by most optical observers. The optical excess is caused by stars so near to the Sun that radioastronomical observations are impossible. Optical and radioastronomical measurements both make it likely that there is an additional term inversely proportional to a power higher than the first of the distance from the Sun. Results found by BOUET indicate that this additional term is of solar origin.
The determination of the gravitational potential of axisymmetric mass distribution in spherical coordinates. II
Authors: Tschaepe R.
Published: July 2007

The numerical computation of gravitational potential of rotational‐symmetric mass distribution in spherical coordinates requires a lot of computing time. We discuss direct methods and present a reduction method which is superior to methods used so far. Results for accuracy which is similar to that of other methods and computing times are given in Fig. 2 and 3.
Measurements of stellar scintillation using photon counting statistics
Authors: Stecklum B.
Published: July 2007

Mittels photonenzählender Photometrie hoher Zeitauflösung wurden Eigenschaften der Intensitätsszintillation untersucht. Die Abhängigkeit der Szintillationsleistung von der Zenitdistanz erwies sich als schwächer als theoretisch vorhergesagt. Die Wellenlängenabhängigkeit der Szintillationsleistung und die Verteilung der Intensitätsfluktuationen gemäß einer logarithmischen Normalverteilung entsprechen den theoretisch zu erwartenden. Das zeitliche Verhalten der Szintillation wird durch Korrelationszeitskalen von weniger als 10 ms bzw. einige 10 s gekennzeichnet, was als Hinweis auf die innere und äußere Skala der atmosphärischen Turbulenz gedeutet werden kann. Es wurden die Einflüsse anderer Vorgänge, die ebenfalls zu Intensitätsschwankungen führen, auf die Messung der Szintillationsleistung untersucht.
Beobachtungen Kleiner Planeten. IV
Authors: Börngen F. , Kirsch K.
Published: July 2007

Es wird eine Übersicht über die im Jahr 1983 auf Tautenburger Schmidtplatten gefundenen Kleinen Planeten gegeben. Es wurden 147 Objekte entdeckt und für sie 272 Positionen gerechnet. Für vierzehn im Berichtszeitraum numerierte Planeten haben Tautenburger Beobachtungen einen Beitrag geleistet. Der in Tautenburg entdeckte Planet 1981 VL 2 erhielt die permanente Bezeichnung (2861). Er bekam zu Ehren von Prof. HERMANN LAMBRECHT († 4. 6. 1983) den Namen Lambrecht.
A magnetic neutral sheet as cause of the flare productivity of a δ sunspot group
Authors: Seehafer N.
Published: July 2007

Flare observations in the solar activity complex HR 16862, 16863, 16864 at the end of May 1980 are compared with the structure of force‐free magnetic fields calculated from photospheric magnetograph measurements. A series of homologous flares connected with a δ configuration in HR 16864 was possibly caused by a magnetic neutral sheet. The δ configuration consisted of the large preceding spot of HR 16864 and a small satellite of opposite polarity. All magnetic flux from the satellite is connected to the main spot, and at the outer edge of the satellite, away from the main spot, a magnetic neutral sheet is found. This agrees with the observation that all penumbra was situated between parent spot and satellite, which is typical of such † configurations. It is suggested that the flare productivity of these configurations is generally caused by magnetic neutral sheets at the penumbra‐free outer boundary of the satellites.
On the inhomogeneous structure of the chromosphere‐corona transition region above sunspot umbrae
Authors: Staude J.
Published: July 2007

Multiple wavelength observations of sunspot umbrae can only be expalined by an inhomogeneous, two‐component model for the structure of the umbral transition region and lower corona. The ‘Wroclaw‐Ondrejov sunspot model’ was a first step in this direction. This working model has now been improved using analytic expressions for the atmospheric structure in each component and fitting the free parameters to recent sunspot observations, particularly in EUV lines. The main component has a shallow transition region and a deep‐set corona. The second, ‘active’ component has a vast transition region in relatively cool fine structure elements embedded in the coronal main component. The spatial filling factor of this active component amounts to 5–10% in sunspots with bright EUV plumes, but is is more than ten times smaller in sunspot without such plumes. Observations with high spatial and temporal resolutions are necessary to understand in more detail the basic physical processes.
The search for possible time variations in Davis' measurements of the argon production rate in the solar neutrino experiment
Authors: Haubold H. J. , Gerth E.
Published: July 2007

With the gradual accumulation of experimental data in the solar neutrino experiment of DAVIS and collaborators (runs 18–74 for 1970–1982), the question, whether there are time variations of the solar neutrino flux, is of renewed interest. We discuss the mathematical‐numerical methods applied to the statistical analysis of DAVIS' argon‐37 production rate up till now known in the literature. These methods are characterized by the arbitrary arrangement of the DAVIS data in a time series. We perform a certain Fourier transformation for unequally‐spaced time series of the measuring data of the argon‐37 production rate, discuss the discovered periods and give significance criteria with respect to each period. We find that all periods discussed in the literature are contained in our series of periods. Pointing out the more mathematical character of the time series analysis we emphasize the predominant significance of the detected periods.
Photometric and spectroscopic observations of the variable star ET And. II
Authors: Scholz G. , Gerth E. , Panov K. P.
Published: July 2007

New spectroscopic and photometric observations of the variable Ap star ET And carried out 1982 and 1983 confirm once again the existence of short‐time variations. For the radial velocity variations a period of 0.19771 days and for the light variations a period of 0.0989 days was found. Some spectrograms show a velocity progression of the Balmer lines. The gradient is of such a kind that the radial velocity values increase from the line Hγ to H15. Different models for the interpreation of the velocity progression are discussed.
An analytic approach to the connection between stellar structure parameters and the neutrino emission rate in a simple stellar model
Authors: Haubold H. J. , Mathai A. M.
Published: July 2007

In order to obtain the internal structure of a main‐sequence star such as the Sun usually one has to solve the detailed structure equations numerically. This paper is an attempt to construct analytic models for the stellar nuclear energy generation. We give closed‐form analytic results for the stellar luminosity and stellar neutrino emission rate when the radial matter density of the spherical star under consideration is linear. For the numerical estimation of the neutrino flux of a specified stellar nuclear reaction we take into account parameters of the standard solar model. The present paper gives for the first time the connection between stellar structure parameters and neutrino fluxes in an analytic stellar model.
Brightness variability investigation of V586 Orionis
Authors: Pugach A. F. , Kovalchuck G. U.
Published: July 2007

Photoelectric UBVR observations of the young irregular variable star V586 Ori are presented and discussed.
The position of ET And in the Hertzsprung‐Russell diagram
Authors: Scholz G.
Published: July 2007

The interstellar lines of Call (K) and NaI (D) are the main means used to estimate the distance of the Ap star ET And to derive its position in the HRD, because the classical methods for the determination of M are affected by some restrictions. By these means the star lies distinctly above the main sequence. The post‐main sequence evolutionary stage suggests to assume that pulsations are the reason for the observed short‐time spectroscopic and photemetric variations. Possibly, the 1.61‐day period is also caused by pulsations.
Statistical “Z” parallaxes
Authors: Jaschek C.
Published: July 2007

A new method for deriving statistical parallaxes is proposed. The method uses the symmetry in the distribution of the Z‐component of the stellar space velocity vectors. It should be suited to derive the statistical parallaxes of stars of population II, for which the usual method fails.
Magnitudes of standard stars for IHW cometary photometry
Authors: Pfau W. , Stecklum B.
Published: July 2007

For stars to be used as flux standards and solar type analogues magnitudes in the system of the International Halley Watch (IHW) filters are given.
Beobachtungen Kleiner Planeten. V
Authors: Börngen F. , Kirsch K.
Published: July 2007

Es wird eine übersicht über die im Jahr 1984 auf Tautenburger Schmidtplatten gefundenen Kleinen Planeten gegeben. Es wurden 84 Objekte entdeckt und für sie 205 Positionen gerechnet. Darunter sind 17 numerierte Planeten, 16 bereits früher beobachtete und 51 neue Planeten mit provisorischen Bezeichnungen. Für sieben im Berichtszeitraum numerierte Planeten haben Tautenburger Beobachtungen einen Beitrag geleistetet. Der in Tautenburg entdeckte Planet 1964 EC erheilt die permanente Beziechnung (3181). Er bekam zu Ehren von Dr. PAUL AHNERT (*22. 11. 1897) den Namen Ahnert.
Positions of extragalactic objects in the vicinity of M3 and M31 (5C3 radio field) and in the 5C1 radio field
Authors: Dick W. R. , Lorenz H. , Notni P. , Schilbach E. , Scholz R.‐D. , Richter G. A.
Published: July 2007

We have determined the positions of 65 compact extragalactic objects with magnitudes between 16m and 21m.7. The mean error of one position is about 0″.3 in α cos δ and in δ. Some hitherto unpublished redshifts are also listed.
Eigenschaften singularitätenfreier, statischer, zentralsymmetrischer Lösungen gewisser Gravitationsfeldgleichungen 4. Ordnung
Authors: Schmidt H.‐J. , Fiedler B. , Günther M.
Published: July 2007

Von FIEDLER und SCHIMMING (1983) wurde bewiesen, daß die von TREDER vorgeschlagenen Gravitationsfeldgleichungen 4. Ordnung mit einer Linearkombination des Bachtensors und des Einsteintensors auf der linken Seite statische, zentralsymmetrische Lösungen besitzen, welche in einer Umgebung des Symmetriezentrums analytisch und nicht flach sind. Die zunrchst nur in einer kleinen Umgebung von r = o gesicherten Existenz dieser Lösungen (r Radius) läßt sich nun mit Hilfe des abstrakten Satzes über inverse Funktionen auf Intervalle o ≦ r ≦ α mit beliebig groß vorgegebenem α ausdehnen. Ferner wird gezeigt, daß die Schwarzschildmetriken in einem gewissen Sinn die einzigen um r = +∞ analytischen, asymptotisch flachen, statischen, zentralsymmetrischen Lösungen obiger Gleichungen sind.
Extended thermodynamics in the early Universe
Authors: Lukács B. , Martinás K. , Pacher T.
Published: July 2007

It is a general belief that in some early stages of the evolution of the Universe unequilibrium situations played important role. In order to incorporate some deviations from thermal equilibrium into the description of the evolution, here an extension of the thermodynamic formalism is given, where, using the notion of ekaentropy, new terms are introduced into the Gibbs‐Duhem relation for representing the deviation. Two situations are investigated in simplified models: the primordial thermalisation in the symmetric phase of GUT, and the development of a nonthermal distribution for massive neutrinos.
The Determination of the Gravitational Potential in Spherical Coordinates III: Radial recursive integration of the Poisson integral
Authors: Tschaepe R.
Published: July 2007

Radial recursive integration improves the Legendre representation of the gravitational potential of axisymmetris mass distribution and reduces the number of operations form nN2M needed earlier formerly to nNM.
Effective resonant formation of 20Ne in stars
Authors: Md. Khairozzaman A. E.
Published: July 2007

The resonant reaction rates of 16O(α, γ)20Ne have been determined for the 5.64(3‐) MeV 5.8(1‐) MeV excited states of 20Ne under strong screening conditions utilizing the temperature‐density plots of the helium plasma after ITOH et al. (1977). The screened reaction rates were found to be many times greater than the unscreened ones. It has been found that the most effective resonant formation of 20Ne takes place at density 108 g cm‐3. As the density increases beyond 108 g cm‐3 with corresponding rise of temperature the screened reaction rates (i. e. effective reaction rates) decrease. Such a decrease affects the presupernova yields from massive stars drastically The giant and dwarf stage of stellar evolution under pycnonuclear density conditions (108‐‐109 g cm‐3) will be retarded beyond the density of 108 g cm‐3 in stellar interiors.
Deviation of the Cosmic Background Radiation from a black‐body spectrum due to axion‐electromagnetic coupling
Authors: Wolf C.
Published: July 2007

The low energy coupling of the electromagnetic field to the axion leads to two distinct dispersion relations for the electromagneticaxion oscillations. The one frequency being the normal electromagnetic (E. M.) oscillation while the other represents a coupled oscillation. When a non‐zero chemical potential is associated with the axion‐electromagnetic oscillation and the spectrum of the two oscillations are super‐imposed, a formula emerges that suggests how the Cosmic Background Radiation (C.B.R.) might differ from that of a black body if axions do in fact couple to the background radiation.
Photographische Positionen des Kometen Halley (1982i)
Authors: Börngen F.
Published: July 2007

There are represented 25 positions of the comet Halley between 1985 Aug. 21 and Oct. 22 determined from plates of the Tautenburg Schmidt telescope 1340/2000/4000.
On the space‐time structure and its relation to quantum mechanics
Authors: Kasper U.
Published: July 2007

The Weyl covariant formulation of Dirac's equation by means of a rest mass the Weyl type of which is — 1, implies the introduction of a Riemann structure in addition to the Weyl structure. The Ehlers‐Pirani‐Schild attempt to specify the space‐time structure and the lowest order of the WKB approximation are compatible with each other. Only the requirement that the connection to which the Dirac field couples minimally is identical to the connection the autoparallels of which are the world lines of structure‐less test particles, leads to a reduction of the Weyl structure to the Riemannian one.
Gauge‐invariant perturbations in generalized inflation
Authors: Matarrese S.
Published: July 2007

One considers the birth and evolution of scalar and tensor gauge‐invariant perturbations in “generalized inflationary models”, that is cosmological models with a suitable early phase of accelerated expansion. In this frame the classical analysis that BARDEEN et al. performed for the standard de Sitter inflation is extended to a more general context.
The conformal potential of the stationary axisymmetric vacuum
Authors: Perjés Z.
Published: July 2007

In a stationary axisymmetric vacuum gravitational field, the conformal structure of the 3‐space is determined by the symmetric, trace free and divergence‐less tensor Yir. Using the Killing vector Ki of the axisymmetry, the conformal potential U can be defined by U,i = εijkKjYkrKr. Conversely, the tensor Yik is given algebraically in terms of the gradient U,i of the conformal potential. An attempt is made here to re‐formulate the field equations Rλμ = 0 in terms of the conformal potential. Introducing the Ernst potential as a complex coordinate, the cylindrical radius can be eliminated from the field equations.
Duality rotations and type D solutions of Einstein‐Born‐Infeld theory
Authors: Salazar H. , Garcia D. A. , Plebanski J. F.
Published: July 2007

Within the non‐linear electrodynamics of Born‐Infeld type, constrained by the condition that admits the freedom of the duality rotations the explicit type D solutions, which generalize the charged Taub‐NUT metric with cosmological constant, are constructed. The obtained type D solution exhausts all solutions within the considered class, assumed that the real eigenvectors of the electromagnetic field are aligned along the geodesic and shear‐free principa null directions.
Cometary dust coma models. II. Computer experiments
Authors: Gottlöber S. , Liebscher D.‐E. , Mücket J. P. , Müller V.
Published: July 2007

Computer simulations of a cometary dust coma are presented which take into account different distribution functions of the ejected material as well as anisotropic ejection due to the rotation of the nucleus and single active regions on its surface.
Zur Metallhäufigkeit in offenen Sternhaufen
Authors: Götz W.
Published: July 2007

Es wurde die starke Streuung der Einzelwerte in der Metallhäufigkeit offener Sternhaufen untersucht und nachgewiesen, daß bei Sternhaufen mit |z| ≦ 0,3 Kpc neben der Abhängigkeit der Metallhäufigkeit vom galaktozentrischen Abstand (RGC) auch eine Beziehung zur galaktischen Länge der Objekte wirksam ist. In offenen Sternhaufen großer Abstände von der galaktischen Ebene (|z| ≧ 0,3 Kpc) gilt jedoch diese Beziehung nicht. Hier ist die Metallhäufigkeit neben ihrer Kopplung mit dem galaktozentrischen Abstand mit der jeweiligen |z|‐Distanz in Verbindung zu bringen.
On the definition of asteroid magnitudes
Authors: Kristensen L. K.
Published: July 2007

The problem of a sharp definition of two photometric parameters for asteroids in the presence of empirical phase functions is discussed. In a rational magnitude system advantage should be taken of the nearly linear phase curve.
Some regularization in the N‐body problem
Authors: Diacu F. N.
Published: July 2007

We consider the simultaneous collision of n bodies in the general N‐body problem, 2 ≤ n ≤ N, in the k‐dimensional Euclidian space and eliminate the singularities which arise from that collision in the equations of motion by suitable coordinates and time transformations. The singularity of that solution is removed by throwing the collision instant to infinity. The new equations of motion are therefore defined in the large and they give a better description of the motion near the collision.
How to get an unbiased estimate of Hubble's constant?
Authors: Fröhlich H.‐E.
Published: July 2007

An unbiased estimating function for Hubble's constant, appropriate to the case that both radial velocity and absolute magnitude contribute to the scatter is proposed.
On the detectability of distant clusters of galaxies
Authors: Von Berlepsch R. , Fröhlich H.‐E. , Schmidt K.‐H.
Published: July 2007

J‐magnitude limits (KRON'S J) which have to be reached to detect a cluster of galaxies of given redshift (up to z ≊ 1) and richness class against the background of field galaxies are given.
The forest of QSO absorption lines and cosmological models with unstable dark matter
Authors: Müller V. , Mücket J. P. , Haubold H. J.
Published: July 2007

Indications on clustering features in the two‐point correlation function of Ly α line separations in published high‐resolution spectra of quasars are presented. They are in contradiction to the self‐similar hierarchical clustering model, but they could be explained by a first generation of small‐scale pancakes in a model with unstable dark matter. A characteristic scale of velocity dispersion Δv ≈ 150 km/s of absorption clouds within pancakes is described by corresponding coherent regions of positive correlation, while the structure adjacent on the lines of sight are separated by a comoving distance of (18 ± 6) Mpc (H0 = 50 km/s Mpc). The appropriate coherence length of the fluctuation spectrum may result from the free streaming length of (unstable) neutrinos of (100 … 200) eV rest mass.