bluuebunny/crossref_metadata_2025_split huggingface dataset:
Total‐to‐selective extinction ratio in nearby and distant objects
Authors: Wegner W. 
Published: July 2007

AbstractIn an area of nearly 23.1 square degrees centered at α(1950) = 23h57m and δ(1950) = + 59δ48' magnitudes, colors, and spectral classes were determined for 1419 stars brighter than mpg = 13m.00. Star counts were made in this area for all objects brighter than mpg = mpv = 15m.5. Altogether 50585 stars were included in the pv counts. The original photographic data have been transformed to the B, V system. From star counts the ratio of total‐to‐selective extinction was derived to be R ≉ 4.0 ± 0.2. It depends on the distance to the stars under consideration as well as on the surface density of the objects inside the considered region.In einem Gebiet von annähernd 23.1 Quadratgrad mit den Mittelpunktskoordinaten α(1950) = 23h57m und δ(1950) = 59°48' werden für 1419 Sterne heller als mpg = 13m.00 Helligkeiten, Farben und Spektraltypen bestimmt. Sternzählungen in Helligkeitsintervallen mpg und mpv wurden für alle Objekte heller als mpg = mpv = 15m.5 durchgeführt. Für diese 50585 Sterne wurden die gemessenen photographischen und photovisuellen Helligkeiten in das B, V‐System transformiert. Im Ergebnis dieser Sternzählungen wurde ein Wert von R ≉ 4.0 ± 0.2 abgeleitet. Er hängt sowohl von der Entfernung der betrachteten Objektgruppen als auch von der Flächendichte der Sterne innerhalb der Region ab.
Optical properties of inhomogeneous media: T‐matrix approach (Review)
Authors: Bussemer P. 
Published: July 2007

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

AbstractWe give a review of the present knowledge on the properties of circumstellar silicate dust. After relating the detection story, a survey of objects with silicate features in their spectra is presented. The interdependence between the optical properties of the dust grains and the structure of the circumstellar envelopes in determining the outgoing infrared radiation is analyzed and the more important studies of dust shells with silicate grains are summarized. The optical properties of the circumstellar silicates are discussed. The amorphous structure of the silicates is emphasized. Finally, the relevance of fine structures within the 10‐μm feature observed in several objects is considered.
Star‐forming processes in Cepheus OB2
Authors: Balázs L.G. , Kun M. 
Published: July 2007

AbstractThe properties of IRAS point sources in the region of the “Cepheus bubble” were studied. This bubble is a possible very old supernova remnant which includes the association Cepheus OB2. A large number of sources which are probably low‐ and medium‐mass embedded stars are situated around the bubble. It is concluded that whereas high‐mass stars which have formed in the bubble are already on the main sequence, lower‐mass stars are still embedded in their parent clouds.
Can the ten‐dimensional phase prior to Calabi‐Yau splitting of the super‐string phase generate the primordial entropy of the universe?
Authors: Wolf C. 
Published: July 2007

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

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

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

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

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

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

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

AbstractVarying the step, at which Lorentz signature is introduced in the scheme of applications of general relativity outside the material distribution, new solutions can be obtained. The interpretations of these solutions can be achieved if the field equations Rμv = 0 are written in a wider space than the Riemannian one. A counter example is given in favour of this claim.
Bianchi types of Lie point symmetries arising for differentially rotating stationary axisymmetric fluids
Authors: Grosso R. , Stephani H. 
Published: July 2007

AbstractThe Einstein field equations for a perfect fluid with two commuting Killing vectors, which span the fluid's four‐velocity, are considered. A third space time symmetry, which is a homothetic or a Killing vector, can be used to reduce these equations to a system of ordinary differential equations. This symmetry restricts the form of the differential rotation Ω of the fluid. A Bianchi classification of the resulting Lie algebras is performed and related to the kinematical properties of the fluid.
Some results of solar radio emission observations at the Siberian Solar Radio Telescope
Authors: Zubkova G. N. , Kardapolova N. N. , Lubyshev B. I. , Nefedyev V. P. , Ya. Smolkov G. , Sych R. A. , Treskov T. A. 
Published: July 2007

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

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

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

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

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

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

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

AbstractWe consider the Newtonian limit of the theory based on the Lagrangian \documentclass{article}\pagestyle{empty}\begin{document}$ \ell = (R + \sum\limits_{k = 0}^p {a_k R\square ^k R)\sqrt { - g.} } $\end{document}. The gravitational potential of a point mass turns out to be a combination of Newtonian and Yukawa terms. For sixth‐order gravity (p = 1) the coefficients are calculated explicitly. For general p one gets \documentclass{article}\pagestyle{empty}\begin{document}$ \phi = m/r(1 + \sum\limits_{t = 0}^p {c_i } \exp (&#x02010; r/l_i))\;with\;\sum\limits_{t = 0}^p {c_i} \; = \;1/3 $\end{document}. Therefore, the potential is always unbounded near. The origin.
Drag perturbations in artificial satellite orbital motion based on the Total Density model
Authors: Mioc V. 
Published: July 2007

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

AbstractGeneralized inflationary stages as power‐law solutions result from the addition of R3 and R□R terms to the quadratic gravitational Lagrangian. Both contributions lead to new attractor solutions in the high‐curvature limit. We emphasize the properties of critical values of the curvature scalar in the R3 theory. Contrarily to models with two scalar fields, the higher order curvature terms allow double inflation for special initial conditions only.
Synthetische UBVR‐Photometrien aus flußkalibrierten Spektren
Authors: Gochermann J. 
Published: July 2007

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

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

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

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

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

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

AbstractThe effect of the radiation‐pressure in the problem of the two bodies is analysed. It is found that such an effect is the same as that of reducing the stellar mass, m, by the factor p (0 ≤ p ≤ 1). The case p < 0 leads to stellar instability and, consequently, it is not considered here. The problem of the mass determination from spectroscopic observations is reviewed and an iterative method is recommended.
Flat Galaxy Catalogue
Authors: Karachentsev I. D. , Karachentseva V. E. , Parnovsky S. L. 
Published: July 2007

AbstractA systematic search for disclike edge‐on‐galaxies with a diameter larger than a = 40 arcsec and a major‐to‐minor axis ratio a/b ≥ 7 has been carried out by means of the Palomar Observatory Sky Survey and the ESO/SERC survey. As a result, we present a new catalogue of flat galaxies (FGC) containing 4455 objects and covering about 56% of the whole sky for the first time. The catalogue is assigned to study large‐scale cosmic streamings and other problems of observational cosmology.