bluuebunny/crossref_metadata_2025 huggingface dataset:
prior to surface appearance of sunspot flux tubes and magneto‐thermal pulsation of the Sun
Authors: Yoshimura H.
Published: July 2007

We found an evidence that the luminosity of the Sun systematically decreased about 20 days before sunspot surface appearance by analysing time‐lag correlation of time derivatives of running mean time profiles of the data of the Active Cavity Radiometer Irradiance Monitor (ACRIM) I experiment on board of Solar Maximum Mission (SMM) and of the data of the daily sunspot number. This indicates that sunspot flux tube cooling and heat transport blocking by the flux tubes start to take place in the interior of the solar convection zone well before the sunspot surface appearance. From this finding and our previous finding that the luminosity of the Sun systematically increased and the blocked heat appeared on the surface about 50 days after the sunspot surface appearance, a new view of sunspot formation and dynamics and a new view of the luminosity modulation emerged. (i) Sunspots of a solar cycle are formed from clusters of flux tubes which can be seen in the running mean time profile of the sunspot number as a peak with duration on the order of 100 to 200 days. (ii) Heat flow is blocked by the cluster of sunspot flux tubes inside the convection zone to decrease the luminosity about 20 days before the surface emergence of the sunspot cluster. (iii) The blocked heat appears on the surface about 50 days after the surface emergence of the cluster of sunspot flux tubes to heat up the surface. This appears as a thermal pulse in the running mean time profile of the ACRIM dat in between the peaks of the sunspot running mean time profile. This process of heating the surface makes the temperature gradient less steep and weakens the buoyancy of sunspot flux tubes below the surface. (vi) The radiative cooling of the surface layer by the excess heat release steepens the temperature gradient so that the buoyancy of the sub‐surface magnetic flux tubes becomes stronger to cause the next surge of emergence of a cluster of sunspots and other magnetic activities, which creates a peak in the time profile of the sunspot number. We call this peak a magnetic pulse of the Sun and the coupled process of alternating pulsed appearance of heat and sunspots the magneto‐thermal pulsation of the Sun.
A spectrum of the veiled T Tauri star CY Tau
Authors: Stüwe J. A. , Schulz R.
Published: July 2007

We present a flux calibrated spectrum of the star listed as CY Tau in the “General Catalogue of Variable Stars 4th ed.” (Kopolov et al. 1987) in the spectral range 3700 Å ⩽ λ ⩽ 6400 Å with a resolution of ≈︁ 15 Å showing the Balmer‐Series from Hβ to H10 as well as the Call H (in blend with Hα) and K lines in emission. Apart from the emission. Apart from the emission lines the spectrum is composed of a continuum equivalent to that of an ordinary pre‐main sequence star (i.e. a “naked” T Tau) of spectral type M2 V with emission lines plus a “blue” veiling continuum that can be described as black body radiation of temperature Tbl ≈︁ 7000 K due to accretion onto a boundary layer at a rate of Macc ⪆ 2.8 10−8 M⊙ a−1.
Photographic photometry for stellar statistics with Tautenburg Schmidt telescope
Authors: Andruk V. , Kharchenko N. , Schilbach E.
Published: July 2007

Photometric properties of deep Tautenburg Schmidt plates in the UBV system over the whole field and over a wide range of stellar magnitudes are discussed. Different reduction models based on the calibration curve alone and with additional terms containing colour and plate coordinates are considered.

With the filter‐emulsion combinations used the Johnson UBV system can be reproduced quite well by the Tautenburg telescope. The accuracy of photometric data can be improved if geometrical terms are taken into account. For deep plates with a significant effect of background nebulosity a supplementary term is to be included in the reduction model. The polynomial coefficients vary in dependence on spectral bands and individual properties of each plate.
Schmidt plate survey in the galactic centre direction. 1. Investigation of open clusters in the Sagittarius‐Carina spiral arm
Authors: Kharchenko N. , Schilbach E.
Published: July 2007

A study of four open clusters on Tautenburg Schmidt plates in the direction to the Galactic Centre (l = 17.0°, b = +0.8°) is presented. In a field of 8.95 square degrees proper motions and B, V magnitudes were determined for about 36 500 stars up to the limiting magnitudes B = 17m.9, V = 16m.8. For stars brighter than B = 16m an accuracy of about 3 mas/year has been estimated for proper motions. The rms errors of stellar magnitudes and (B—V) colours is about 0.1 mag.

There are two open clusters already known in this sky area: Trumpler 32 (C 1814‐133) and NGC 6611 (C 1816‐138). By the inspection of the plates two additional anonymous clusters were identified near the double star ADS 11285 or BD −14°5014 (C 1819‐146) and near the star BD −14°5016 (C 1820‐146). The cluster membership determination was carried out using information on spatial and proper motion distributions of stars in the field. The colour‐magnitude diagrams up to the limiting stellar magnitude were constructed. For each cluster interstellar extinction AV, diameters of the core and corona, ages and spatial velocity components (V, W) relative to the LSR in the Y, Z‐galactic directions were derived.

The distances to the clusters were obtained to 1720 pc, 2260 pc, 2130 pc and 2130 pc for Trumpler 32, NGC 6611, C 1819‐146 and C 1820‐146, respectively. All clusters are situated in the Sagittarius‐Carina spiral arm. Their spatial location confirms the assumption that galactic spiral arms are close to logarithmic spirals with a characteristic angle of about 20 degrees.
Coherence between Seyfert galaxies and their surroundings
Authors: Mahtessian A. P. , Khachikian E. Ye. , Tiersch H.
Published: July 2007

A sample of galaxy groups is investigated for the occurence of Seyfert objects within them. The velocity dispersion in groups with Seyfert galaxies is significantly larger than in groups without Seyfert galaxies. But there was not found any correlation between the galaxy density within the groups and the content of Seyfert galaxies.
Eléments Orbitaux Definitif de I'Etoile Double Visuelle ADS 5871 — STF1037
Authors: Scardia M.
Published: July 2007

Aus einer Gesamtheit von 315 Beobachtungen wurden die Bahnelemente des visuellen Doppelsternes ADS 5871 — STF 1037 wiederberechnet. Die nach der Methode von KOWALSKY erhalten vorläfigen Elemente wurden mit der Differenzenmethode von HELLERICH korrigiert und die dynamische Parallaxe und Gesamtmasse berechnet.
Density and Radial Velocity Strucutre of the Hydra I Cluster of Galaxies
Authors: Baier F. W. , Oleak H.
Published: July 2007

The investigation of the distributions of number densities, radial velocities and morphological types in the Hydra I cluster led us to the conclusion that this cluster possesses dominant substructures. This result is in agreement with former conclusions of different authors that substructures are a typical phenomenon for a high percentage of all clusters of galaxies. The galaxies inside the radius 60 from the cluster centre giv ea mean cluster redshift 3332±102 km/s and a velocity dispersion 679 ± 87 km/s.
Iterative and Direct Determinations of the Gravitational Potential of Axisymmetric Mass Distributions in Spherical Coordinates
Authors: Tschaepe R.
Published: July 2007

Highly flattened objects may appear in early stages as well as in late stages of stellar evolution. The calulation of their axisymmetric gravitational potential in spherical coordinates requires a lot of computer time. In this paper we compare iterative solutions of the Poisson differential equation with direct evaluations of the Poisson integral with respect to accuracy and time consumption. further, we derived a fast direct method which is superior in computer time to the discussed methods whereas its accuracy remains nearly unchanged.
Beobachtungen Kleiner Planeten. III
Authors: BÖrngen F. , Kirsch K.
Published: July 2007

Es wird eine Übersicht über die im Jahr 1982 auf Tautenburger Schmidtaufnahmen gefundenen Kleinen Planeten gegeben. Es wurden 229 Objekte entdeckt und für sie 643 Positionen gerechnet. Für zehn, 1982 numerierte Planeten haben Tautenburger Beobachtungen einen Beitrag geleistet. Der von uns entdeckte Planet (2424) erhielt den Namen Tautenburg.
Luminosity Profiles of 6 Dwarf Galaxies in the M 81/82 Group
Authors: Karachentseva V. E. , Schmidt R. , Richter G. M.
Published: July 2007

The main photometric parameters of six very low surface brightness dwarf galaxies of the M81 group are obtained. For the first time the luminosity profiles of extreme dwarfs outside the local group are given. The profiles are much more consistent to the exponential law than to the r1/4 law. No significant differences in profile between irregulars and sphericals could be found.
A Catalogue of Extremely Young, Massive and Compact Infrared Objects (Mitteilungen der Universitäts‐Sternwarte zu Jena Nr. 165)
Authors: Henning Th. , Friedemann C. , Gürtler J. , Dorschner J.
Published: July 2007

Ausgehend vom Becklin‐Neugebauer‐Objekt in der Orion‐Molekülwolke I als Prototyp wird anhand zahlreicher Beobachtungsmerkmale eine Klasse von kompakten Infrarotquellen abgegrenzt, von denen man annehmen kann, daß sie junge massereiche von optisch dicken Staubhüllen umgebene Sterne sind. Ein Katalog gibt für 34 Objekte ausführliche Informationen, u. a. über Infrarot‐ und Radiospektren, das Vorhandensein von Masern und Ausströmungserscheinungen.
Photometric and Spectroscopic Study of the Variable Star ET And
Authors: Gerth E. , Scholz G. , Panov K. P.
Published: July 2007

Spectroscopic and photometric observations of the variable ET And were carried out in the years 1981/82. In addition to the known periodical variation of the radial velocities of 48.308 days produced by a companion and the photometric period of 1.61883 days probaly resulting from the rotation of the star some other periodical variations exist. The radial velocities vary further with a period of 0.1989 days and the photometric data with the half of this value, i.e. with 0.0994 days. The minima of the light coincide with the extrema of the radial velocity. The radial velocity curve deviates somewhat from a pure harmonic, more precisely, the values increase more rapidly than they decrease. The same behaviour also appears for the corresponding part in the light curve.
Scale Factor of Isotropic Homogeneous Universe
Authors: Popic R. V.
Published: July 2007

Four fundamental expressions of isotropic homogeneous universe lead to the scale factor equations. Their solution is achieved by developing the factor as a power series of time, establishing the recursion relations among its coefficients, performing the summation of this power series and obtaining the scale factor as a function of time in a closed form. This one should be used in comparison to observational data with different cosmological models, generally present within this formalism.
Pre‐main sequence stellar activity
Authors: Belvedere G.
Published: July 2007

Models of stellar activity based on the α–ω dynamo have recently been proposed by BELVEDERE et al. (1980c, 1981b) for main sequence and giant late type stars.

In the present work we extend the theoretical analysis to the pre‐main sequence fully convective phase of stellar evolution. As a measure of magnetic activity we assume the intensity of the toroidal magnetic field Bt. The results show that Bt decreases with the increasing effective temperature along the evolutionary track of a star of given mass. It is stressed the crucial dependence of the intensity of the magnetic field on the rotation rate.

Comparison with the observations of pre‐main sequence stellar activity in the very young galactic cluster NGC 2264 is briefly discussed.
The effect of a weak magnetic field on stellar oscillations
Authors: Roberts P. H.
Published: July 2007

The effect of a weak magnetic field on the otherwise radial pulsations of a star are discussed.
Secondary α‐effect in the nearly symmetric dynamo
Authors: Cupal I.
Published: July 2007

An attempt has been made to examine the role of the secondary α‐effect in the nearly symmetric dynamo. The tensor form of the effect has been found and it is concluded that this effect only plays a role under special assumption of the disturbance velocity field. The secondary alfa effect can amplify the generation of the azimuthal field from the poloidal field in the α2‐dynamo rather than in the αω‐dynamo.
Bestimmung absoluter Eigenbewegungen in einem KSZ‐Feld mit zwei Astrographen
Authors: Dick W. R.
Published: July 2007

In the field No. 153 of the KSZ program relative proper motions of 144 stars up to 15m.0 are presented as well as parameters for the reduction to absolute with reference to 6 galaxies. The external error of one proper motion is 0.014″/y. It is shown that in a small field the statistical method for the estimation of the magnitude error is not able to give significant results due to the variance of the proper motion. It is concluded that in practice the long focus and the wide angle astrographs of the Main Observatory of the Ukrainian Academy of Science in Kiev can be combined for the derivation of proper motions.
Eine neue Methode zur Bestimmung der statistischen Zählverluste bei Photonenzählern
Authors: Hildebrandt G. , Lange D.
Published: July 2007

A simple method for the determination of statistical pulse losses of photon counting photometer in dependence on the pulse intensity was deveoloped. The slowly decereasin brightness of the clear sky in the dusk serves a light source. With the help of neutral filter one gets two different pulse rates for two intensities. From a series of such measurements with different intensities one can derive the correction in dependence on pulse density in form of a power sequence.
A constraint on the past star formation rate from the kinematics of nearby stars
Authors: Meusinger H.
Published: July 2007

The age dependence of the velocity dispersions σv(τ) of the nearby stars is considered under distinct assumptions on the history of the star formation rate. The velocity distributions N¦U¦, N¦V¦, N¦W¦ are derived from this by means of the diffusion theory using the standard case by WIELEN AND FUCHS (1983a) and are compared with the observed distributions of a kinematically unbiased sample of nearby stars. The best agreement is found for a nearly constant star formation rate.
On the influence of density and temperature fluctuations on the formation of spectral lines in stellar atmospheres
Authors: Stahlberg J.
Published: July 2007

Es wird eine Methode zur Berücksichtigung von Temperatur und Druckschwankungen, die durch das Geschwindigkeitsfeld bedingt sein sollen, angegeben. Um das so beeinflußte Linienprofil zu erhalten, werden die Größen einer statischen Atmosphäre durch gemittelt und fluktuierende Anteile ersetzt. Die auftretenden Korrelationen werden über bekannte Gleichungen der Hydrodynamik berechnet Es resultiert, daß in gewöhnlichen Sternatmosphären, in denen nur kleine Werte des Dichte‐ und Druckgradienten sowie der mittleren stochastischen Geschwindigkeit vorkommen, die optischen Linienprofile nur schwach durch diese Effekte beeinflußt werden.
An analytic model for phase transitions in the early Universe
Authors: Diósi L. , Lukács B. , Keszthelyi B. , Paál G.
Published: July 2007

A simplified model of the very early Universe is presented for studying the effects of the GUT phase transition on the cosmic evolution and vice versa. An exact description of a strongly first order phase transition is given. Both inflationary and non‐inflationray solutions are obtained. The cosmological scale factor and the temperature are determined and graphically depicted. The self‐consistency of our simplifying assumptions needed to get analytic solutions are checked. Contrary to expectations spread in the literature, the strongly first order character of the phase transition in itself is found to be insufficient to solve the monopol problem inherent in most GUT cosmologies.
Search for dwarf galaxies in the IC 342 complex of galaxies
Authors: Börngen F. , Karachentseva V. E.
Published: July 2007

A survey of dwarf galaxies was carried out in the inner part of the IC 342 complex of galaxies, which is a subgroup of the M81 group, in an area of about 42 sq. degrees by means of Tautenburg 52‐in. Schmidt plates. Fifteen new dwarf candidates and four extended “cloudy” objects of very low surface brightness not yet classified were discovered. Coordinates, linear dimensions as well as remarks on the nature of the cloudy objects are given. A deeper analysis with 6‐meter plates is planned to study a part of the new objects more exactly.
On the properties of very young massive infrared sources (Mitteilungen der Universitäts‐Sternwarte zu Jena Nr. 169)
Authors: Gürtler J. , Henning T. H. , Dorschner J. , Friedmann C.
Published: July 2007

The data compiled for 34 very young massive compact infrared source (Becklin‐Neugebauer objects) in a separately published catalogue serve as the basis for an investigation of their general properties.

First, the correlations of the strength of the ice and silicate bands at 3.1 μm and 10 μm, resp., with each other and with other parameters of the sources are investigated. In accordance with theoretical expectations the strengths of both bands are not well correlated with each other. The ratio τ10/τ3 of their optical depths veries from 0.85 to 8 (and possibly up to 22). That implies for the number densities of the grains that (naked) silicate grains always are considerably more abundant than ice grains (grains with ice mantles). It follows from the discussion of the relationships between τ10, the temperature parameter of the sources, and their luminosity that relations between τ10 and temperature and possibly between τ10 and the luminosity exist.

Stellar wind models for the ionized region around the embedded star are favoured after the analysis of the intensities of the hydrogen infrred emission lines and the radio continuum.

The limited observational data do not yet allow a decision on a correlation between the silicate band depth and energy content and/or the velocity of the bipolar outflow detected in a number of sources.

The BN objects are clearly more frequently associated with H2O masers than OH masers. The linear separations of the infrared peaks from the masers are compatible with models where the H2O masers are situated near the edges the gas‐dust shells of the BN objects.
Analytic solution to the problem of nuclear energy generation rate in a simple stellar model
Authors: Haubold H. J. , Mathai A. M.
Published: July 2007

This paper deals with complete analytic solution to the problem of evaluating the total net rate of nuclear energy generation and the basic integral of the luminosity of a purely gaseous star in hydrostatic equilibrium. It is assumed that the total energy production is proportional to certain powers of the density and temperature and that the density inside the star is a nonlinear function varying from the centre to the surface.
Polar motion estimates from linear combinations of independent series
Authors: Vicente R. O. , Wilson C. R.
Published: July 2007

This paper describes methods for combining independent observations of polar motion into a single time series, and applies these methods to satellite laser ranging, Doppler, and astrometric polar motion data taken over the period 1981‐‐1983. The polar motion data are treated as complex valued time series, yielding one estimate of the noise level for each series, rather than a separate estimate for X and Y components. Estimates of the noise level which take advantage of the existence of simultaneous observations are preferred. Linear combination of the data may be performed in both the time and the frequency domain, and examples of each are present. The results of analyzing three years of observations show little difference between the Allan and conventional variance. Present day Doppler determinations do not show marked improvement compared to classical astrometric results. Thus, the astrometric observations are still useful.
Observations of minor planets
Authors: Geffert M. , Tucholke H.‐J. , Dettmar R.‐J.
Published: July 2007

The PDS 2020 GM‐microdensitometer of the University of Münster has been used to determine 115 positions of minor planets observed with the astrograph and the double refractor of Hoher List Observatory.
Cataclysmic variables and the amplitude‐cycle length relationship
Authors: Richter G. A.
Published: July 2007

After a survey of the latest state of knowledge on cataclysmic variables in general (Chapter 1) and recurrent novae in particular (Chapter 2), the amplitude‐cycle length relationship (A‐C relation) is rederived (Chapter 3) after statistical correction for published incorrect values of C. While the A‐C relationship of dwarf novae is of the form A = ‐0.40 + 2.50 log C, it is, presumably for physical reasons less sharply defined for the few known recurrent novae.
Induced causality
Authors: Bleyer U. , Liebscher D.‐E.
Published: July 2007

Alternatives to General Relativity with respect to its causal structure are deeply connected with Mach's hypothesis of the cosmic origin of inertial properties. We consider the main features of a theoretical scheme to construct such alternatives and show that observable effects may be estimated without full construction of a theory. From the point of these alternatives, the light cone of Special Relativity is highly degenerated, and any deviation from General Relativity in the direction considered will reduce this degeneracy. Therefore the effects possible in the alternatives considered provide tests already on the level of Special Relativity.
The linear problem for the five‐dimensional projective field theory
Authors: Matos T.
Published: July 2007

A linear problem is given for the five‐dimensional projective theory when the metric depends only on two coordinates. The symmetries of this problem are investigated.
Gravitationally induced supercurrents in the Schwarzschild field
Authors: Zimdahl W.
Published: July 2007

Using the jellium model the behaviour of electronic properties in solids in external gravitational fields is investigated. The charge carriers are influenced by the gravitational field both directly and via the gravitationally induced lattice deformations. As an example we treat London superconductors on circular orbits in the Schwarzschild field of the earth. This motion induces alternating supercurrents with frequencies of the order 0,3 s−1. There exists a general relativistic difference of the oscillation frequencies in different directions. Its relative value is of the order 10−9.
Early star formation and galaxy formation triggered by the evolution of large‐scale density perturbations
Authors: Mücket J. P.
Published: July 2007

The evolution of small‐scale density perturbations on the background of increasing large‐scale perturbations of supercluster size will be considered. In the case that the characteristic length scales of both perturbation modes differ significantly, the interaction between both modes has to be taken into account already within lowest order of approximation. It will be shown that in this case an effective amplification for the smaller‐scale perturbations occurs. For these perturbations the characteristic times of evolution decreases in dependence on the considered mass‐scales more or less rapidly. Therefore, the growth of adiabatic density perturbations on mass‐scales up to galaxy masses seems to be triggered by the density evolution of superclusters which the smaller‐mass perturbations are embedded in. A model for the formation of observed condensed matter distribution will be proposed.
Green's functions of the induction equation on regions with boundary. II. Spherical regions
Authors: Bräuer H.‐J. , Rädler K.‐H.
Published: July 2007

In an earlier paper the evolution of a magnetic field was considered which permeates an electrically conducting fluid and its non‐conducting surroundings. It was shown how the tensorial Green's function of the initial value problem posed by the governing equations can be constructed. The present paper gives a more detailed analysis of the case where the fluid occupies the interior of a sphere. The construction is carried out for arbitrary motions of the fluid. More special results are derived for differential rotation with angular velocity depending only on the radius, and explicit expressions of Green's functions are given for rigid body rotation.
Calculations of comet orbits from observations of 1982/83
Authors: Buffoni L. , Manara A. , Scardia M.
Published: July 2007

From observations published in Smithsonian Astrophysical Observatory and MPC circulars corrected orbits of 30 comets have been calculated.
An astrometric model for Tautenburg Schmidt plates
Authors: Yatsenko A. I. , Kur'Yanova A. N. , Dick W. R.
Published: July 2007

The major principles of establishing a statistical model for plates of the Tautenburg Schmidt telescope (134/200/400) are described. The model is intended to be used for the Monte Carlo simulation of the determination of coordinates and proper motions. It has been tested with orthogonal polynomials by determining positions of stars. Under certain conditions linear equations are sufficient for the reduction of measured to standard coordinates when using the AGK3 as the reference system.
Measures of 104 faint common motion pairs of LUYTEN'S NLTT catalogue on prints of the Palomar Sky Survey
Authors: Gellera D.
Published: July 2007

For 104 faint common motion pairs of the New Luyten Catalogue of stars with proper motions larger than two tenth of an arcsec (NLTT) position angles and separations have been measured on prints of the Palomar Observatory Sky Survey. For each pair a finding chart is given.
A Programme to derive from terrestrial observations the rotation of the HIPPARCOS system with reference to the inertial system
Authors: Dick W. R. , Ruben G. , Schilbach E. , Scholz R.‐D.
Published: July 2007

The connection of the HIPPARCOS system with a quasi‐inertial system can be reached by transforming the HIPPARCOS proper motions to absolute proper motions. The Tautenburg Schmidt telescope provides such proper motions with respect to extragalactic objects with an accuracy of 0″.6/100a. The telescope as well as the measuring and reduction technique are described. The accuracy of the link of the HIPPARCOS system to extragalactic objects depends on the accuracy of the transformation matrix which represents the time‐depending part of the rotation matrix to be applied to the whole HIPPARCOS catalogue. To obtain a reliable estimate for the error of transformation we used the error propagation law. An accuracy of 0″.12/100a for the transformation can be achieved with six Tautenburg fields.
On the structure of the low surface brightness dwarf galaxies in the M81 group
Authors: Karachentseva V. E. , Karachentsev I. D. , Richter G. M. , von Berlepsch R. , Fritze K.
Published: July 2007

A detailed photometry of spheroidal dwarf galaxies in the M81 group has been carried out. The integral characteristics and the structural parameters of the spheroidal dwarfs has been determined. Their luminosity profiles are well fitted to a King law. The investigated spheroidal dwarfs together with the prototypes of the Local Group form a common sequence according to their main parameters. The observational data presented show that dSphs are not linked evolutionary with normal E and dE galaxies, but probably form a separate branch together with irregular low surface brightness dwarfs.
Spacetimes admitting a universal redshift function
Authors: Dautcourt G.
Published: July 2007

The conditions are given for a velocity congruence in a Riemannian spacetime admitting a universal redshift function R. This function allows to calculate in a simple way (as a quotient ofR values taken at the emission and registration event) the redshift or blueshift connected with an emitter and observer both following the congruence. Spacetimes and congruences with an universal redshift function are shortly discussed.
A note on the linear stellar model
Authors: Anderson J. W. , Mathai A. M. , Haubold H. J.
Published: July 2007

For a purely gaseous self‐gravitating stellar configuration with linear matter density distribution the total power generated by nuclear reactions is considered. The analytic connection between physical parameters of the macroscopic and microscopic levels of the stellar equilibrium configuration is revealed.
Precession and the long‐time magnetic variables
Authors: Lehmann H.
Published: July 2007

The model of forced precession of a star gravitationally influenced by a companion is tested for a small group of stars having time‐scales of magnetic changes in the order of some years up to some decades. Results show that the observed secular periods cannot be reduced to a common time‐scale of regular precession. The main difficulty is the evident discrepancy between the oblateness of the stars required by the model and that attainable from rotational or magnetic flattening. Only the observed behaviour of the star 52 Her could be interpreted as a precessional motion.
The binary system 53 Cam
Authors: Scholz G. , Lehmann H.
Published: July 2007

The orbital elements of the spectroscopic binary 53 Cam were revised using 136 radial velocity measurements. The positions in the vicinity of the periastron predicted for the secondary under the assumption of the spectroscopic orbital elements do not agree with those found by speckle interferometric observations. Nevertheless, we try to estimate the mass of the secondary and the dimensions of the binary system.
Local effects in pure astronomical refraction
Authors: Kurzyńska Krystyna
Published: July 2007

On the grounds of a ten‐year material of aerological soundings for Pozna$ (φ = 52° 24′, $LD = 1h 07m.5, h0 = 85 m) a statistical analysis is made of both temporal and local effects in the pure astronomical refraction. No appreciable effects of temporal variations of higher layers of the local atmosphere have been recorded so that the instantaneous local pure refraction can be approximated accurately enough by the average local pure refraction calculated for an instantaneous value of the refractive index n0 at the ground level. A systematic difference is recorded, however, between the standard pure refraction calculated for a given value of n0 and the local one. This difference is proved to be rather sharply defined, so it is reasonable to introduce the notion of local correction to the standard pure refraction. For Poznan, this correction is negative and amounts 0″.01 atz0 = 60°, 0″.1 at z0 = 77°, 1″ at z0 = 85°, and 3″ at z0 = 87°. At z0 = 82° it overestimates the variance of stochastic refraction anomalies (image motion) integrated over time 60 s. The paper answers the long time discussed question whether we should apply the notion of local pure refraction and if yes, in what way.
Higher order curvature terms in theories with creation
Authors: Wolf C.
Published: July 2007

In two theories involving continuous creation higher order curvature terms are added to the field equations. At high gravitational curvatures the creation of matter depends critically on these extra terms.
Entropy production in a non‐conservative gravitational theory
Authors: Wolf C.
Published: July 2007

The production of entropy is calculated in a Friedman Universe governed by a non‐conservative gravitational theory permitting the creation of matter. The calculation has two motivations, the first is that it represents a mechanism to generate the large entropy per baryon observed, and secondly, it simulates the ten dimensional mechanism for entropy production by the out‐of‐equilibrium condition between massive string modes and massless modes with the added condition of energy non‐conservative gravitation.
A search for the age‐dependency of Ap star parameters
Authors: RÖdiger G. , Scholz G.
Published: July 2007

Some observational data of the sample of the magnetic chemically peculiar stars (MCP stars) are investigated statistically. For the MCP stars of spectral types later than A2 both the frequency distribution and the R ⋅ sin i‐values suggest the existence of a linear relation between stellar diameter and rotation period. The MCP stars of spectral types earlier than B9 show an overpopulation of small R ⋅ sin i which may indicate the existence of a second group with smaller radius in this sample. The equatorially symmetric rotator is used as the magnetic model. With respect to its temporal behaviour the effective magnetic field is separated into dipolar and quadrupolar contribution. Both signs of the axisymmetric quadrupole moment appear with equal frequency. The dipole moment which produces the amplitude of the Beff(t) curve forms for longer periods two groups which are separated by a distinct gap. Both of the groups exhibit magnetic fields which are the stronger the greater the stellar radius is, contrary to what is expected for frozen‐in fields. The dominance of magnetic curves without polarity reversal for longer‐period stars is in accordance with predictions of the dynamo theory.
Charged black holes in compactified higher‐dimensional Einstein‐Maxwell theory
Authors: Heinrich O.
Published: July 2007

A solution of the higher‐dimensional Einstein‐Maxwell‐dilation equations with a Ricci‐flat internal manifold and a 4‐geometry describing a non‐rotating charged black hole is presented. The black hole carries a scalar hair formed by a linear combination of the dilaton and the internal scale factor.
Simultaneous creation of electron‐positron pairs and photons due to their interaction in Robertson‐Walker universes
Authors: Lotze K.‐H.
Published: July 2007

The influence of the electromagnetic interaction upon particle creation in expanding Robertson‐Walker universes is investigated applying an S‐matrix scheme. We discuss all processes contributing to the number density of created particles up to second order in the coupling constant. One process is of particular importance being the only source of photons. It is considered in more detail and evaluated explicitly for a time‐symmetrically expanding radiation‐dominated Friedman universe as well as statically bounded expansions.
Galactic evolution with bimodal star formation. I. A simple model
Authors: Meusinger H.
Published: July 2007

Models for the history of the star formation rate are presented which essentially follow three assumptions: (i) high‐mass star formation is mainly initiated by collisions of molecular clouds while low‐mass stars are formed in a spontaneous mode; (ii) the bimodal IMF is responsible for the structure in the present‐day mass function of nearby stars; (iii) the global molecular gas density can be described in terms of the total gas density and the metal abundance. Some properties of these models are confronted with observations in the Solar neighborhood (total density, gas fraction, OB star formation rate, star formation efficiency, present‐day mass function, age‐metallicity relation, white dwarf luminosity function). Special attention is given to the question of the nature of dark matter in the galactic disk within the frame of these models.

Es werden Modelle für die zeitliche Entwicklung der Sternentstehungsrate vorgestellt, die im wesentlichen von drei Annahmen ausgehen: (i) Die Entstehung massereicher Sterne wird durch Kollisionen von Molekülwolken initiiert, während masseärmere Sterne spontan entstehen; (ii) Die bimodale IMF ist verantwortlich für die Strukturin der gegenwärtigen Massenverteilung der nahen Sterne; (iii) Die globale Dichte des molekularen Gases kann durch die gesamte Gasdichte und die Häufigkeit schwerer Elemente ausgedrückt werden. Einige Eigenschaften der Modelle werden mit Beobachtungsdaten der Sonnenumgebung konfrontiert (Gesamtdichte, Gasanteil, Entstehungsrate der OB Sterne, Sternstehungseffektivität, gegenwärtige Massenverteilung der Sterne, Alter‐Metallgehalt Relation, Leuchtkraftfunktion weißer Zwerge). Besondere Aufmerksamkeit wird der Frage nach der Natur der dunklen Materie in der galaktischen Scheibe im Rahmen dieser Modelle gewidmet.
Quasars in the field of 88 Leonis
Authors: Erculiani‐Abati L. , Afanasjev V. L. , Spiridonova O. , Lorenz H.
Published: July 2007

Spektroskopisch bestätigte Quasare im 25 Quadratgrad großen A1‐Feld bis zu einer Grenzgroße von mB = 18.0 werden untersucht. Die abgeschätzte Quasar Flächendichte von 0.28 ± 0.11 Objekte pro Quadratgrad auf der Grundlage der “vollständigen” Quasar‐Stichprobe im A1 Feld liegt guter Übereinstimmung mit der beobachteten integralen Anzahl‐Helligkeitsbeziehung. Wir betrachten jedoch diese Flächendichte, bedingt durch Selektionseffekte bei der Farbauswahl der Objekte, insbesondere deren Helligkeitsabhängigkeit, nur als Untergrenze. Die Quasar Flächendichte im A1 Feld kann bis zu 30% unterschätzt sein und entspricht damit der kürzlich bestimmten Unvollständigkeit der BQS Durchmusterung.
Galactic evolution with bimodal star formation. II. Expectations and problems
Authors: Meusinger H.
Published: July 2007

Bimodal star formation is an interesting hypothesis from the point of view of galactic evolution. It is believed that bimodal star formation scenarios provide answers to several outstanding problems. In this paper the question is discussed whether by means of LARSON's (1986) bimodal IMF the chemical evolution (D, He, Fe), the nature of the dark matter, the luminosity function of white dwarfs, and the structure in the field star luminosity function in the solar neighborhood can be explained simultaneously.
Long‐term behaviour of the stellar brightness in eclipsing minima of SV Cam
Authors: Hempelmann A. , Rüdiger G.
Published: July 2007

The time dependence of the brightness at both central eclipses of the RS CVn binary SV Cam – observed between 1973 and 1980 by PATKOS – is analysed to check the activity model of this star, which was derived from light variations outside the eclipses by Busso et al. Their detection of a cycle of about 10 years is confirmed by the observations of the primary eclipses, whereas from observations of the secondary eclipses an unambiguous determination of a cycle length was not possible. Obviously, the cycle is superimposed with fluctuating short‐term variations which exist in time scales from days up to months. These fluctuations are observed not only at the primary eclipse but also at the secondary eclipse. Correlations between the fluctuations at these two orbital phases suggest the primary component of SV Cam to be the main contributor to the variations observed.
Photographic observations of the dwarf nova SS UMi
Authors: Richter G. A.
Published: July 2007

Beobachtungen auf 4180 Platten der Sonneberger Himmelsüberwachung ergaben, daß es sich um einen SS‐Cygni‐Stern mit einer Zyklenlänge zwischen etwa 30 … 48 Tagen handelt. Es werden mögliche Bahnumlaufperioden diskutiert.
Binaries in the vicinity of the open cluster IC 4665.I. V 378 Oph
Authors: Kraicheva Z. , Popova M. , Antov A.
Published: July 2007

The first results of the programme for investigation of binary stars, which are possible members of open clusters, are presented. The distribution is given for spectroscopic and eclipsing binaries in the wide vicinity of the open cluster IC 4665.

Results of photometric study of the variable V 378 Oph are also presented. There are controversial data for this object concerning its brightness changes. Our observations confirm that it is a ß Lyrae type binary and its period was determined. A mean light curve is drawn. Some peculiarities are mentioned which demand additional observations, possibly electrophotometric and spectroscopic ones, too. The probability is discussed for V 378 Oph to be a member of Mel 186 (Cr 359) or IC 4665 clusters.
Comet orbits from observations during 1984 and orbital elements for the next perihelion passage
Authors: Buffoni L. , Manara A. , Scardia M.
Published: July 2007

Corrected orbits for 21 comets from observations published in the Minor Planets Circulars have been calculated. Orbital elements for the next perihelion passages of short period comets are also given.
Models of dusty envelopes around Vega‐like stars
Authors: Men'Shchikov A. B.
Published: July 2007

Simple evolutionary models of dust envelopes around Vega, Sun, β Pictoris and Ross 128 are constructed. The infrared spectra of the envelopes are calculated under the assumption that the minimum radii of the particles are determined by the Poynting‐Robertson effect, while their growth to maximum sizes is due to effective coagulation. A comparison with observations of the dust envelopes by IRAS shows that the model can satisfactorily explain the main properties of the protoplanetary disk evolution.
Absolute proper motions of blue objects in the vicinity of M33
Authors: Richter G. A. , Scholz R.‐D.
Published: July 2007

36 objects with mainly negative (U—B) indices were investigated for variability and proper motions. 10 objects with significant or suspected proper motions and 8 variable objects were detected. Using these criteria, it was possible to separate white dwarfs from quasi‐stellar objects to some extent.
Photographic measurements of 320 double stars of POURTEAU remeasured 50 years after their discovery
Authors: Gellera D.
Published: July 2007

The position angle and separation of 320 double stars from Pourteau's Catalogue (18h < α < 19h) measured on the prints of the Palomar Observatory Sky Survey 50 years after their discovery are given.
Beobachtungen Kleiner Planeten. IX
Authors: Börngen F.
Published: July 2007

Es wird eine Übersicht über die im Jahr 1988 auf Tautenburger Schmidtplatten gefundenen Kleinen Planeten gegeben. 386 Objekte wurden entdeckt und für diese 1218 Positionen gerechnet. Es handelt sich um 87 numerierte Objekte sowie um 299 Planetoiden mit provisorischer Bezeichnung. Unter letzteren sind 252 neue Bezeichnungen. Für 40 im Berichtszeitraum numerierte Planeten haben Tautenburger Beobachtungen einen Beitrag geleistet. Darunter sind acht in Tautenburg entdeckte Planetoiden.
Simple methods for orbit determination and identification of asteroids. I
Authors: Kristensen L. K.
Published: July 2007

The many discoveries of main belt asteroids with insufficient observations for reliable orbits cause special difficulties for identifications and data storage; mainly because of the mixing of objects due to their motion in α and δ. This problem may be reduced by substituting positions by slowly and smoothly varying quantities. A rational system of preliminary designations will be proposed, and surveys and compact ephemerides are discussed. All computations are very simple and performed on a small, programmable pocket computer.
Compactification and cosmic string phenomenology
Authors: Bleyer U. , Heinrich O. , Nikolaenko V. M.
Published: July 2007

A U(1) model of gravitational, Higgs and, gauge fields is analysed. Two phases of the system are considered. In the case with broken symmetry we have the Nielsen‐Olesen configuration. In the symmetric phase we find a space‐time metric S2 × E12. This appears in full analogy to the Freund‐Rubin compactification due to an antisymmeric tensor field. The connection of these structures with cosmic string phenomenology is analysed.
Triviality of λϕ4 theory in 3+1‐dimensional spatially flat Robertson‐Walker space in Gaussian approximation
Authors: Pohle Leipzig H.‐J.
Published: July 2007

We investigate λϕ4 theory within the Gaussian approximation in spatially flat Robertson‐Walker space in 3+1 dimensions. After having performed an adiabatic expansion for one of the ansatz functions we find that the renormalization of the energy‐momentum tensor provides two additional constraints which have to be satisfied by bare couplings. These conditions force the theory to be trivial after renormalization.
Is there a news function for an infinite cosmic string?
Authors: Bičák J.
Published: July 2007

A special form of the Bondi news function can be associated with an infinite static cosmic string. In case of a radiaing isolated system pierced by an infinite cosmic string, the total news function will be composed of two parts — one characterizing the radiation field, the other the string. Some examples are discussed and related to a recently given solution, which was interpreted as an outgoing gravitational wave due to the splitting of an infinite cosmic string.
Unusual events at the fine structure of the solar meter radio emission
Authors: Gorgutsa R. V.
Published: July 2007

Preliminary results of observations of narrow drifting bursts (NDB) are presented. The bursts appeared as narrow bright sloping lines both overlaped at the dynamic spectra of type III bursts and at the background of noise storms. The observations were made in 1982–1989 at 45–270 MHz frequency range in Troitsk and Kislovodsk at radiospectrographs with the frequency resolution of 0.2 MHz and the time one of 0.1 s. NDB were observed at 45–180 MHz range. Main parameters of NDB are near to that of drifting pairs. A small part of NDB shows sharp changes of the frequency drift sign (N, V–shape bursts).
A simple fragmentation law: all possible partitions of a given mass be equi‐probable
Authors: Fröhlich H.‐E.
Published: July 2007

Mixing of all possible partitions of a given mass with equal weights leads to a Bose‐Einstein mass spectrum.
Astrophysical effects of a superconducting cosmic string
Authors: Mańka R. , Bednarek I.
Published: July 2007

The physics of the superconducting cosmic string appearing in the superstring theory with E8 × E8, gauge group was considered. The possible interpretation of such astrophysical objects as quasars, the new class of supernova remnanis, 0.511 MeV intense annihilation line and the exotic binary system SS 433 has been given basing on this string theory.
Spot model of a peculiar brightening of the RS CVn variable SV Cam
Authors: Hempelmann A. , Patkos L.
Published: July 2007

The unusual brightening of the RSCVn‐type variable SV Cam reported by PATKOS (1982a) is analysed. We base our analysis on the assumption of a temporarily existing bright spot which appeared on the primary star of the binary system. A location near the stellar equator and a spot radius of 70° are derived. According to our analysis, the temperature difference between the spot and its surroundings was up to 110 K. The spot's existence is related to an observed change of the orbital period. Both findings are interpreted as caused by mass exchange resp. accretion.
On the discovery of minor planet 3631 = 1987 BV1 = Sigyn
Authors: Elst E.W.
Published: July 2007

During an extensive search for new asteroids with the GPO instrument at ESO a rather bright asteroid was discovered on the night of 23/24 February 1987. The orbital elements from the treatment of the initial observations by means of an improved method of the variation of geocentric distances is compared with the osculating elements deduced from all available observations.
The rotation of (51) Nemausa
Authors: Kristensen L.K.
Published: July 2007

The problem of interpretation of lightcurves and pole determination is illustrated by a discussion of all observations of (51) Nemausa from 1887 to 1990. A new concept is the introduction of a fictitious convex body which can in principle be directly determined from the observations. The importance of the first and third harmonics in the lightcurves is demonstrated. Different oppositions are connected by the synodicperiod 7.h78293 and the proposed pole is: 19h45m + 41° (1950). The rotation is probably retrograde and there are indications of a red spot.
The binding energy of a Schwarzschild sphere in D space‐time dimensions
Authors: Wolf C.
Published: July 2007

We calculate the binding energy of a Schwarzschild gas sphere in D space time dimensions. To the post‐Newtonian approximation we demonstrate that the interior Schwarzschild solution does not exhibit an instability before the Schwarzschild radius is reached for D = 4. For D = 5, 6 we find binding energy is negativ to the post‐Newtonian approximation. Extending the approximation to the post‐post‐Newtonian approximation we find that the post‐post‐Newtonian contribution to the binding energy of a Schwarzschild gas sphere is positive for the cases D = 4, 5, 6. The effect of the post‐post‐Newtonian contribution to the binding energy on the stability of higher dimensional gas spheres is discussed.