bluuebunny/crossref_metadata_2025_split huggingface dataset:
An interpretation of the variations of the magnetic core‐mantle coupling torques and the core drift rate
Authors: Greiner‐Mai H. 
Published: July 2007

AbstractThe influence of recently computed axial magnetic core‐mantle coupling torques on the Earth's rotation was investigated. These torques derived from poloidal geomagnetic field within the mantle and at the core‐mantle boundary are retarding torques. An accelerating torque due to the action of unknown parts of the core field was estimated by inverse solution of the equation of the mantle rotation for the periodic variations of the quantities of the magnetic field and the length of day. The variations of the drift rate of the Earth's core were compared with those of the mantle rotation velocity for a force‐free Earth. The time constants of the coupling process were estimated and discussed in connection with the magnetic coupling of the mantle with an upper core layer.Der Einfluß kürzlich berechneter axialer Kern‐Mantel‐Kopplungsmomente auf die Erdrotation wurde untersucht. Diese Lorentz‐Drehmomente, abgeleitet vom poloidalen geomagnetischen Feld im Mantel und an der Kern‐Mantel‐Grenze, sind retardierende Momente. Ein beschleunigendes Drehmoment, das der Wirkung unbekannter Feldanteile zugeordnet wird, wurde durch inverse Lösung der Mantelrotationsgleichung für die periodischen Variationen der Magnetfeldgrößen und der Tageslänge abgeschätzt. Die Variationen der Kerndriftgeschwindigkeit wurden mit denen der Mantelrotationsgeschwindigkeit für eine kräftefreie Erde verglichen. Die Zeitkonstanten des Kopplungsprozesses wurden ermittelt und im Zusammenhang mit der magnetischen Kopplung des Mantels mit einer oberen Kernschicht diskutiert.
The programme “Milky Way”: the physical and kinematical investigation of galactic structures
Authors: Guseva N. G. , Kharchenko N. V. , Schilbach E. 
Published: July 2007

AbstractThe programme “Milky Way” for a complex study of the structure, kinematics and evolution of the Galaxy is outlined. In the framework of the programme new astrometric and astrophysical observations are carried out. Preliminary results concerning the structure of regions of star formation, the motions and the structure of the local spiral arm as well as the dependence of the kinematic parameters of stellar groups on the distance from the galactic plane are presented. These investigations were based on the new observations within the programme “Milky Way” and data from previously published catalogues.
A method for modelling the surface of irregular celestial bodies
Authors: Wiebicke H.‐J. 
Published: July 2007

AbstractThe surface function R(9) of irregular celestial bodies (small satellites like Phobos and Deimos, cometary nuclei or small asteroids) is expanded in terms of spherical harmonics. A method is given to determine the expansion coefficients by comparing the calculated contours with the contours extracted from a series of images of the body. With given expansion coefficients this method can be applied to orientation systems of the spacecraft approaching the body. Furthermore, physical quantities like volume, centre‐of‐mass coordinates, moments of inertia and the gravitational field of the body can be calculated analytically. Under the assumption that the gravitational potential can be determined experimentally a method is described to calculate the radial mass density profile of the body.
The quasar population density as a result of the formation rate and the evolutionary pathes. I. Analytical formulas and numerical simulations
Authors: Boller T. H. , Liebscher D.‐E. 
Published: July 2007

AbstractThe continuity equation of CAVALIERE et al. (1971) is generalized to age‐dependent luminosity evolution. We show that some simple cases (monomial forms of the formation rate) are integrable and compare some important features. Test procedures and the adaption to the observations are considered in the following parts.
Note on the orbit of the magnetic star 53 Cam
Authors: Oetken L. 
Published: July 2007

AbstractBased on the known spectroscopic orbital elements of 53 Cam the positions of the companion for times of speckle observations were predicted and compared with the observed positions. Taking into account the ambiguity in speckle interferometry the observations can be represented fairly well by an inclination of approximately 45° between orbital and tangential plane.
On the relation between activity and rotation in main‐sequence stars
Authors: Teplitskaya R. B. 
Published: July 2007

AbstractA modified index of the level of stellar chromospheric activity, A'Call, is proposed. It is calculated from the measured emission flux density in cores of Ca II H and K lines; however, unlike the other known indices, it is free from the influence of the colour of a star. Application of the new index leads to amodified activityrotation relationship in lower main‐sequence stars. It is shown that in the coordinate system log A'Call, log Ro (Ro being Rossby number) F‐M stars obey a common relationship corresponding to the parameter α = 1.6. The obtained curve shows no evidence for activity saturation for stars with small Rossby numbers, but in slowly rotating stars with thin convection zones the activity level tends to a constant value.
The estimation of distances to Hyades and Praesepe clusters by a geometrical method
Authors: Loktin A. V. , Matkin N. V. 
Published: July 2007

AbstractThe capability of a geometrical distance estimation method is verified by numerical modelling for the Praesepe cluster. The distance estimated by Hertzsprung's method is r = 175 ± 47 pc. The same method gives for the distance to the Hyades r = 48.4 ± 2.2 pc.
An apparent highly sheared magnetic field structure generated by a subphotospheric current system
Authors: Linke J. , Bachmann G. 
Published: July 2007

AbstractUsing Potsdam vector magnetograms and a force‐free model, we have investigated the magnetic field structure of the active region BBR 18474 of 1982 July 15 and 1982 July 16. By comparison of the azimuths of the current‐free model of magnetic field structure in the central part of this active region with the map of the azimuth values estimated from the observation we find a good qualitative agreement. Additional earlier results have shown that the apparence of highly sheared magnetic field structure near the neutral line in the central part of this active region may be a simulated effect generated by a subphotospheric current system.
Diffuse interstellar bands — an observational review (Review)
Authors: Krelowski J. 
Published: July 2007

AbstractThe paper presents a review of observational data concerning the unidentified diffuse interstellar bands (DIBs). The history of the investigation of these fascinating spectral features is presented together with very recent results obtained with the aid of solid state detectors. The high signal‐to‐noise spectra allowed to divide diffuse bands into at least 3 families defined as sets of these features characterized by constant intensity ratios in every observed spectrum. “Intrinsic” profiles of DIBs, i.e. profiles that originated in single interstellar clouds free of any Doppler splitting were derived from high resolution spectra. The same observations revealed convincingly the Doppler structures inside DIB profiles observed in distant objects. It is shown that DIBs may originate in clouds of very low opacity — their agent(s) being thus resistant against diffuse UV radiation. The agent(s) seems not to be the dust causing the visual extinction as the bands may be absent in some of reddened spectra. Relations between DIBs and other interstellar absorptions are also briefly reviewed.
Determination of dust properties and magnetic fields from polarimetric and photometric observations of stars (Review)
Authors: Voshchinnikov N. V. 
Published: July 2007

AbstractVarious models of the interstellar extinction and polarization are considered. Special attention is devoted to alignment mechanisms of the dust grains, such as Davies‐Greenstein mechanism and suprathermal spinning alignment, and their approximate versions. It is concluded that the grain size and the strength and the direction of the interstellar magnetic field may be estimated from the extinction and polarization data. Applications of the theoretical results to the observations of the stars in the galactic plane are discussed.
uvby photometry of open clusters
Authors: Reimann H. G. 
Published: July 2007

AbstractFür insgesamt 40 Stern im Gebiet des verfärbten offenen Haufens NGC 6871 erhieken wir eine uvby Photometric. 21 dieser Sterne klassifizierten definitely as members. From the photometric results we derived 1.2 × 107 years as the cluster age, 2440 pc as its distance, and E(b ‐ y)) = 0.348 mag as mean reddening of the cluster. From the scatter around this mean colour excess and the deviation of a subgroup of stars by more than twice the standard deviation a varible intracluster reddening in order of 0.1 mag is indicated. The value of the colour excess ratio E(b ‐ y)/E(B ‐ V) = 0.705 for the cluster stars leads us to the conclusion that the very broadband structure (VBS) in the spectra of the cluster stars must be very weak.Für insgesamt 40 Stern im Gebiet des verfärbten offenen Haufens NGC 6871 erhielten wir eine uvby Photometrie. 21 dieser Sterne klassifizieren wir definitiv als Haufenmitglieder. Aus den photometrischen Ergebnissen leiteten wir ein Haufenalter von 1.2 × 107 Jahren, eine Entfernung von 2440 pc und eine Verfärbung E (b ‐ y) = 0.348 mag ab. Aus der Streuung um diesen mittleren Farbexzeß und der Tatsache, daß eine Gruppe von Sternen um mehr als die doppelte Standardabweichung von diesem Wert differiert, läßt sich eine Verfärbung innerhalb des Haufens in der Größenordnung von 0.1 mag vermuten. Aus der Größe des Farbexzeßverhältnisses E(b ‐ y )/E(B ‐ V) = 0.705 schließen wir, daß die Breitbandstruktur (VBS) in den Spektren der Haufensterne nur sehr schwach ausgeprägt sein kann.
Carbon altotropic composition of interstellar grains
Authors: Maron N. 
Published: July 2007

AbstractExtinction curves for core‐mantle and muiticored grains containing two allotropic carbon modifications are compared with far UV extinction observations of the stars R CrB and RY Sgr as well as interstellar extinction. We show that these grain models are consistent with the observed far UV extinction, but it is found that only those particles in which amorphous carbon is surrounded by graphite fit well the interstellar extinction curve and that of the R CrB‐type stars.
Polarized light from circumstellar dust: observations and models
Authors: Šolc M. 
Published: July 2007

AbstractTwo models of a biconical dust nebula with an opaque torus in the symmetry plane are presented: a model containing dust in the whole biconical space (A) and an “empty” model with the dust layer on the surface of this empty space (B). Surface brightness distribution and polarization of the emitted light are computed using the Monte Carlo simulation of photon transport in the nebula. The results have features similar to those observed in several compact reflection nebulae.
Modelling of the radiative transfer in the dust shell around n Carinae
Authors: Men'Shchikov A. B. 
Published: July 2007

AbstractEvolutionary models of structure and spectrum of the dust shell around n Carinae are constructed by means of radiative hydrodynamics calculations. Processes of dust grain growth and destruction are included in the models. The results of the modelling enable us to put some constraints on possible parameters of the object. The theoretical light curve and the spectrum in the visual and infrared are in a good agreement with the observations.
Molecular maser radio emission in the environment of young stellar objects (Review)
Authors: Rudnitskij G. M. 
Published: July 2007

AbstractA brief review of properties of molecular maser sources in star‐forming regions is given. Different types of sources, their structure and variability are discussed. The variability of H2O masers at a timescale of several days observed in the case of the Cep A maser source is difficult to explain in the model of energy diffusion inside a maser cloud. Another possibility is suggested and analysed. An H2O maser flare may be due to amplification of a strong nonthermal radio flare of the magnetically active central young star (possibly, of the T Tauri variability type) by an initially unsaturated H2O maser. An observational test is suggested.
Pumping cycles of cosmic masers: sense and methods of investigation
Authors: Sobolev A. M. 
Published: July 2007

AbstractThe principles of the search and analysis of the routes of population transfer between the energy levels of quantum systems are formulated. Using the Monte‐Carlo technique it is shown that the number of pumping cycles of cosmic masers may be rather large. For example, the pumping mechanism of the H2O JKK. = 616 – 523 line in a two‐temperature gas needs approximately 2 ± 1013 cycles to account for 75% of population transfer between the maser levels. The degree of participation of various types of cycles in the total population exchange between maser levels is suggested as a means for determining the thermodynamical type of the pumping mechanism. The type of a cycle is determined by the nature of residual population transfer in its ascendant (source of energy) and descendant (sink) transitions. The nature of the transition is definite, if the residual transfer caused by the processes of a certain kind greatly exceeds the others. The knowledge of the degrees of participation of individual levels and transitions provides the possibility to decide whether the scheme of levels and transitions is adequate for kinetical investigations.
Molecular clouds and the formation of open clusters
Authors: Stecklum B. 
Published: July 2007

AbstractUsing analytical approximations of the mass spectra of molecular clouds and stellar systems including open clusters and associations a relation between the final star formation efficiency (final SFE) and the initial cloud mass is derived. The dependence of the SFE on cloud mass is estimated for two cases of molecular cloud destruction by stellar winds in spherical geometry. The result of growing SFE with rising cloud mass does not agree with current observations and the above relation. A decrease of the SFE is expected if the fraction of high‐mass stars grows with increasing mass of the cloud.
Populations of Rydberg levels of atoms in the interstellar medium
Authors: Gulyaev S.A. , Nefedov S.A. 
Published: July 2007

AbstractPopulations of Rydberg levels of atoms are calculated including effects of lowering the atomic ionization potential. Due to these effects the boundary conditions in bn problem is lim bn = 0. The bn factors were computed for T = 100 K. Ne = 0.1 cm−3 with bn = 0 when n ≧ 3000.The result allows to interpret observational data of the carbon decametric lines without the use of the subthermal dielectronic recombination mechanism. The calculations predict high relative intensities of Cnβ and Cnγ lines.
Continuum beyond the Lyman limit and effective temperatures of the nuclei of planetary nebulae
Authors: Golovatyj V.V. , Pronik V.I. 
Published: July 2007

AbstractUsing published data on Hß‐,λ4471 Hel‐ and λ4686 Hell‐line fluxes for planetary nebulae the energy distribution in their nuclei is calculated in the wavelength range 100–912 Å by supposing that 1) the spectrum inclination is the same in the regions of continuous absorption of Hl, Hel, and Hell atoms; and 2) discontinuities at 504 Å and 228 Å are present in the nuclei spectra.From 40 investigated nebulae, only for two nuclei the distribution in all three intervals 504–912 Å, 228–504 Å and λ ≦ 228 Å corresponds to one and the same temperature of black‐body emission. In 24 cases the emission temperature is the same for the first and the second interval. The energy distribution in the wavelength range shorter than 228 Å corresponds systematically to very high temperatures T* > 100,000 K. It is concluded that the emission temperature over the surface of nuclei is markedly inhomogeneous and/or the nuclei of planetary nebulae possess a hot corona.
Kukarkin‐Parenago relationship, period gap, and cause of dwarf nova outbursts
Authors: Richter G.A. , Bräuer H.‐J. 
Published: July 2007

AbstractIt is shown that it can be useful to incorporate the orbital period P as an additional parameter into the Kukarkin‐Parenago relationship. Then it turns out that the relationship splits into two, one holding for objects above and the other for objects below the well‐known and much‐discussed period gap between 2.2 and 2.8 hoursA = ‐2.03 + 2.26 log C + 8.80 log P for P > 2.2 hA = 2.07 + 2.46 log C ‐ 3.68 log P for P > 2.8 h(A amplitude (mag), C cycle length (d), P orbital period (h)).Future theories of the dwarf nova phenomenon and the origin of the period gap will have to deal with this.
Photoelectric and visual observations of AM Cas
Authors: Richter G.A. , RÖSSIGER S. 
Published: July 2007

AbstractAccording to statistical informations the orbital period of this cataclysmic binary of Z Camelopardalis type should be in the range between 0d.10 and 0d.19. A sole deep minimum was found photoelectrically. It lasted about 40 minutes and had an amplitude of nearly 2 mag in U. For reasons described in detail it can hardly be interpreted as an eclipsing one. Possibly there is no contribution to the light variation of AM Cas from orbital motion.
Motion of the Earth's inner core and related variations of polar motion and the rotational velocity
Authors: Jochmann H. 
Published: July 2007

AbstractCorrelations between the geomagnetic field parameters and polar motion were explained using the hypothesis of an inner core motion. For a number of periodic constituents of both phenomena it could be proved that this model works well. Secular variations of polar motion caused by inner core dynamics are in the same order of magnitude as the secular variation of the pole derived from pole coordinates of the International Latitude Service (ILS).
Magnetic field and radial velocity of the Ap star 52 Her. I. Observations, measurements, results
Authors: Gerth E. 
Published: July 2007

AbstractSince 1971 the magnetic Ap star 52 Her has been investigated with respect to its magnettic field and radial velocity on the observational basis of 140 photographic Zeeman spectrograms obtained at the 2m‐telescope in Tautenburg. Additionally, 47 normal spectrograms were used for the determination of the radial velocity only. The technical foundation for observation and measurement is considered. The main purpose of the paper, however, is the documentation of the observations and the measuring results. Deductions drawn from the material assorted here or taken from other sources are put off to following papers.
Diffussion of a scalar field in a compressible turbulent medium
Authors: Silant'Ev N. A. , Korolkov M. D. 
Published: July 2007

AbstractThe diffusion of scalar fields (temperature, density number of some admixture) in a compressible medium showing an isotropic, homogeneous and stationary turbulence is considered. The derived formulae for turbulent diffusivity χT(ξ) hold up to ξ ≈ 1, where ξ = u0 τ0/R0 (u0, τ0, and R0 are characteristic velocity, life‐time, and correlation length of turbulent pulsations, respectively. The velocity field of turbulent motions u(r, t) is assumed to be known and the influence of the scalar field onto u(r, t) is neglected. It is shown that the velocity correlators, which change their signs in dependence on the space corrdinates, may give negative values for ξT(ξ) when ξ ≠ 0.
Relativistic Astrophysics and Gravitation
Authors: Gottlöber S. , Haubold H. J. , Liebscher D.‐E. , Mücket J. P. , Müller V. 
Published: July 2007

AbstractProceedings of the Ninth Potsdam Seminar on Relativistic Astrophysics and Gravitation, held in Wusterhausen, GDR, 1989, October 23–28
New exact solutions for power‐law inflation Friedmann models
Authors: Schmidt H.‐J. 
Published: July 2007

AbstractWe consider the spatially flat Friedmann model

For a ≈ tp, especially, if p ≥ 1, this is called power‐law inflation. For the Lagrangian L = Rm with p = − (m − 1) (2m − 1)/(m − 2) power‐law inflation is an exact solution, as it is for Einstein gravity with a minimally coupled scalar field ϕ in an exponential potential V(ϕ) = exp (μϕ) and also for the higher‐dimensional Einstein equation with a special Kaluza‐Klein ansatz. The synchronized coordinates are not adapted to allow a closed‐form solution, so we write

The general solutions reads Q(a) = (ab + C)f/b with free integration constant C (C = 0 gives exact power‐law inflation) and m‐dependent values b and f: f = −2 + 1/p, b = (4m − 5)/(m − 1). Finally, special solutions for the closed and open Friedmann model are found.
The early Universe with quantum non‐conformal fields
Authors: Baibosunov M. B. , Gurovich V. T. , Imanaliev U. M. 
Published: July 2007

AbstractModels for the early Universe with the combined influence of scalar fields and vacuum polarization are discussed using phase plane portraints. The results concern the probability of the birth of the Universe, different de Sitter solutions and expressions for scalar perturbations.
Laboratory tests for the constituents of dark matter
Authors: Mostepanenko V. M. , Yu. Sokolov I. 
Published: July 2007

AbstractThe problem of dark matter in astrophysics is discussed. As the probable hypothesis about the nature of dark matter the suggestion is examined that it consists of light hypothetical elementary particles which are predicted in the frame of united gauge theories, supersymmetry and supergravity. The new restrictions are obtained on the constants of long‐range forces decreasing with distance by the degree low. The different restrictions are analysed on the characteristics of constituents of dark matter obtained from the gravitational experiments, Casimir effect and atomic force microscopy.
Reduced Hamiltonian formalism for general‐relativistic adiabatic fluids and applications
Authors: Schäfer G. , Garching  
Published: July 2007

AbstractFor the dynamics of general‐relativistic adiabatic fluids a reduced Hamiltonian formalism is presented. For slowly moving fluids an approximation scheme is defined. The first steps of the scheme are worked out explicitly. Radiation damping and emission, and backscattering are discussed. The usefulness of the formalism for numerical relativity is pointed out.
Paralleltransport and geodesic deviation in static spherically symmetric space‐times
Authors: Fuchs H. 
Published: July 2007

AbstractTetrads which are parallelpropagated along time‐like geodesics in static spherically symmetric spce‐times are constructed. Its connection with the geodesic precession is explained. Moreover, we express the solution of the equations of geodesic deviation in terms of the Killing vectors and the fourvelocity.
Quantum radiation of a charged particle in a Schwarzschild field
Authors: Fil'Chenkov M. L. 
Published: July 2007

AbstractWithin the framework of quantum mechanics in a curved space‐time the transitions between energy levels of a charged particle (elementary particle, atomic nucleus) being in a Schwarzschild field are considered. The DeWitt conservative self‐force acting on the charge is taken into account. Energy and intensity of the electric dipole radiation are calculated for charged particles in the field of miniholes with masses ranging from 1014 to 10−5 g.