bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantum string theory in curved space‐times
Authors: Sánchez N. 
Published: July 2007

AbstractA general method to quantize strings in curved space‐times is exposed. It treats the space‐time metric exactly and the string excitations small as compared with the energy scale of the geometry.The method is applied to cosmological (de Sitter) and black‐hole (Schwarzschild) geometries. The critical dimension decreases in one for de Sitter and stays unaltered for black‐holes as compared with flat space‐time values. Bogoliubov transformations in the context of string theory are derived and the Bogoliubov coefficients describing elastic and inelastic scattering and excitation of modes are computed explicitely.The string‐black‐hole cross section is derived and a pair mode creation phenomena is found. The quantization and scattering of strings in shockwave geometries (ultrarelativistic boosted black‐holes or Aichelburg‐Sexl space time) is found to be exactly solvable.
Physical consequences of intrinsic dilation currents
Authors: Soleng H. H. 
Published: July 2007

AbstractIn the Einstein‐Carten theory only the traceless part of the torsion field can be related spin. Here we generalize the Einstein‐Cartan theory by allowing iutrinsic dilation currents, which couple algebraically to the torsion trace. This implies implies a variable gravitational coupling, G.
The quasar population density as a result of the formation rate and the evolutionary pathes II. Adaption to the observation
Authors: Boller T. , Liebscher D.‐E. , Lorenz H. 
Published: July 2007

AbstractThe continuity equation of CAVALIERE et al. (1971) generalized to age‐dependent luminosity evolution (BOLLER and LIEBSCHER 1989) is used to calculate quasar luminosity functions. For some combinations of source functions S(L, t) and evolutionary pathes M(L) we discuss the resulting N — m relations and the amount of the X‐ray background and compare them with actual results of observation. We can exclude certain models, (S(L, t), M(L)). We cannot yet decide what the actual source function and the actual evolutionary path are.
An investigation of the subflare‐microwave burst connection
Authors: Maksimov V. P. , Zubkova G. N. , Borovik A. V. 
Published: July 2007

AbstractFor a number of active regions with a different character of development, a study is made of the dependence of the degree of subflare‐microwave burst connection on subflare characteristics and the stage of development of the active region. The earlier conclusion is confirmed that the degree of connection depends weakly on time charactersistics of subflares, their area, and position in a sunspot group, but depends strongly on brightness. It is shown that the degree of subflare‐burst connection is a rather sensitive indicator of the state of the active region. In disturbed periods characterized by the appearance in the active region of flares of importance 1B and higher, the degree of connection is very high. Also, it begins to increase approximately 24 hours before the onset of a disturbed period and remains high still on the next day after its end.
Effect of noise on sunspot magnetic field parameters
Authors: Linke J. , Utrobin V. G. 
Published: July 2007

AbstractUsing a perturbated (noised) dipole model of a sunspot magnetic field structure we simulated the influence of background noise or apparent noise (unresolved small‐scale magnetic field structure) on sunspot magnetic field parameters.We evaluated mean values of the vertical and horizontal electric current densities |j|∥ and |j|⊥, respectively, of the force‐free parameter α and of the Lorentz force |F|. For comparison we estimated |j⊥| and |F| of a standard sunspot magnetic field model (return‐flux model, OSHEROVICH 1982). Furthermore, we compared our results with those from observations resulting in estimated values of |j|∥ for quiet sunspots. Our investigation led to the following results: the estimated values of 〈|F|〉 show clearly that due to the noise the axisymmetric magnetic dipole model is clustered into several subsystems of fluxbundles. The latter are connected with a system of electric current densities of the order of |j|∥ ∼ 10−3 Am−2 and |j|⊥ = 10−1 Am−2, i.e., this system is a noise‐generated nonaxisymmetric magnetohydrostatic model.
Present status of projective unified field theory and its physical predictions
Authors: Schmutzer E. 
Published: July 2007

AbstractIn this article we shortly present the basic equations of our 5–dimensional Projective Unified Field Theory and their physical interpretation. Our main intention is to confront this theory with physical experience. For this reason we treat the Einstein effects (including the exact solutions for a central body) in detail. Further we once more discuss the first order effects on the quasi–Newtonian level with respect to the equivalence principle.
The gradual type SXR flares
Authors: Antalová A. , Viktorínová B. 
Published: July 2007

AbstractThe temporal variations of the occurrence of the (M–X) LDE flares (with the SXR duration exceeding 2 hours) throughout the 20th and the 21st cycles are considered. The characteristics of the 20th cycle: the maximum value of the observed yearly number of LDE flares was in the 1970 (with the total 225 LDE flares observed). The increased LDE flare activities were observed in the years 1972 and 1974 (see Tab. 1). The characteristics of the 21st cycle: the large occurrence of the (M–X) LDE flares was observed form 1979 to 1982. The yearly numbers of the (M–X) LDE flares in 1980–168, 1981–151 and 1982–135 are comparable. The fast decrease of the whole flare activity begun at 1983. The percentual representation of the (M–X) LDE flares in the occurrence rate of all Hα flares fluctuated between 1–3%.
Analysis of small pre–flare activity from radio observations at 755 MHz and 612 MHz
Authors: Averyanikhina Y. A. , Paupere M. , Eliass M. , Ozolins G. 
Published: July 2007

AbstractSolar pre–flare analysis was carried out before 155 bursts, which are observed with a 10–m radiotelescope at 755 and 612 MHz. 60% of these bursts are preceeded by precursors. The mean appearing time of precursors is about 20 minutes before the radio burst.
Multifrequency radio observations of coronal holes, filaments and cavities on RATAN–600
Authors: Borovik V. N. , Sh. Kurbanov M. 
Published: July 2007

AbstractOn the basis of multifrequency solar radio observations made on RATAN–600 radiotelescope with high spatial resolution at nine wavelengths in the 2–32–wavelength range is shown that filaments and cavities are well detected on the solar scans at short centimeter wavelengths as the regions of low radio brightness with angular dimensions of 25′–80′ in E—W direction. The tendency of decreasing radio sizes for cavities and filaments from 2.0 to 8.0 cm is observed. The coronal hole (CH) is more contrast in the range of 8–32 cm. The radio size of CH in E—N direction increases from 2′ (at 8.2) to 5′.0 (at 31.6 cm). The spectra of the brightness temperature of CH and the quiet Sun are obtained. The brightness temperature of CH is twice lower than that of the quiet Sun at wavelength of 31.6 cm.
On the correlation between the solar gamma–ray line emission, radio bursts and proton fluxes in the interplanetary space
Authors: Chertok I. M. 
Published: July 2007

AbstractIt is shown that the correlation takes place between the 4–7 MeV gamma–ray line flare fluence F4–7 and the intensity of the > 10 MeV proton flux in the interplanetary space as well as between F4–7 and the peak flux density of microwave bursts. Besides, the energy spectral index of protons displays the definite dependence from parameters of the radio burst frequency spectrum. These testify that: a) there is a close physical association between the acceleration of electrons and protons in flares; b) protons, giving gamma–ray lines, and ones, registered in the interplanetary space, belong to the same population.
Dynamics of the solar radio spectra in pre–burst periods related with proton events
Authors: Durasova M. S. , Fridman V. M. , Podstrigach T. S. , Sheiner O. A. 
Published: July 2007

AbstractThe dynamics of the solar radio emission spectra is investigated for periods preceeding the proton flare at six wavelengths within a range from 3 cm up to 3 m. The spectrum shape is shown to be essentially dependent on the type of preburst changes. For the cases of powerful proton events the precursor spectra have two maxima within cm and dm ranges showing independent temporal evolution during the pre–flare period.
Sympathetic radio bursts and the attempt of their finding with RATAN–600 by ‘RELAY’ technique
Authors: Golubchina O. A. 
Published: July 2007

AbstractIn this work the observational results of synchronous changes of relative fluxes of local sources are given. The observations were made with RATAN–600 by ‘RELAY’ TECHNIQUE at λ = 2.3 cm and 4.5 cm. Synchronous changes of the intensity are shown to be frequent. The accuracy of relative fluxes, sizes and brightness temperatures of local sources are given.
The dynamics of two solar millimetre bursts
Authors: Nagnibeda V. G. , Piotrovitch V. V. , Ivanov V. N. , Rozanov B. A. , Solovev G. N. 
Published: July 2007

AbstractResults of observations of two mm–bursts using the RT–7.5 millimetre radio telescope at 88 GHz are analysed. It is shown that spectral properties of mm–bursts may indicate a possible existence of two different sources for cm– and mm–bursts.
Electric currents and Lorentz forces derived by vector magnetographic measurements 1. Electric currents in a flux bundle
Authors: Hofmann A. 
Published: July 2007

AbstractWe investigate the distribution of vertical electric current densities derived from nearly simultaneous measurements of the photospheric vector magnetic field made by the magnetographs of the Sayan Observatory (Irkutsk) and the Potsdam Solar Observatory. A flux bundle left the spot investigated nearly horizontally and was isolated enough to enable the discovery of two current density contours dominated by azimuthal currents flowing around the bundle. The countours were situated nearly symmetrically on both sides of the strongly inclined axis of the bundle. By means of three assumptions concerning the symmetry of the bundle we give a way to separate from each other the field‐aligned and the azimuthal components of the currents. The analysis of one of the Potsdam magnetograms yielded a current density of (7.2 ± 4.3) · 10‐2 Am‐2 and a current strength of (6.1 ± 3.6) · 1011 A for the azimuthal current.
On the dynamic fine structure evolution in a narrow‐band type IVdm burst
Authors: Aurass H. 
Published: July 2007

AbstractThe dynamic evolution of type IV burst spectral fine structures in a narrow‐band decimetric continuum is analyzed. It points toward the coronal magnetic field as the energy source for the radiating processes. The observation is discussed in terms of the repetitive cyclic action of an instability sequence in the sub‐filamentary current sheet of the two‐ribbon flare. This type of continua could characterize an interuption of the flare current system during the plasmoid ejection.
Beobachtungen Kleiner Planeten. X
Authors: Börngen F. 
Published: July 2007

AbstractEs wird eine Übersicht gegeben über die im Jahr 1989 auf Tautenburger Schmidtplatten gefundenen kleinen Planeten. Es wurden 501 Objekte entdeckt und für diese 1442 Positionen gerechnet. Es handelt sich um 407 Planetoiden mit provisorischer Bezeichnung, unter denen 333 neu vergebene Bezeichnungen sind, sowie um 94 numerierte Objekte. Für 42 im Berichtszeitraum numerierte Planeten haben Tautenburger Beobachtungen einen Beitrag geleistet. Darunter sind acht in Tautenburg entdeckte Planetoiden (Tab. 3).
Positions of minor planets with the GPO at ESO – La Silla
Authors: Debehogne H. , De Mouráo R.R. Freitas 
Published: July 2007

AbstractMinor Planets were observed in February 1985 with the Grand Prisme Objectif (GPO) at ESO – La Silla. They were reduced at Uccle, Uppsala, Turin, Universidade Federal do Rio de Janeiro (Observatório do Valongo), Museu de Astronomia e Ciěncias Afins and ESO Center at Garching. Here we give those computed by the authors.The great number of positions is attained due to the experience of 9 years at La Silla and to the automatic means we have developed for more than 20 years. These means are based on more than 70 years of works at Uccle. The measurements remain very long when performed, for the sake of uniformity, by a single measurer, as in this present publication (175 positions).
Magnetic field measurements of the supergiant v Cep
Authors: Gerth E. , Scholz G. , Glagolevskij Y.U.V. , Romanyuk I.I. 
Published: July 2007

AbstractNew measurements of the effective magnetic field of the supergiant v Cep confirm the earlier finding of the temporary presence of a magnetic field larger than 1000 Gauss. The observations were obtained using photographic and photoelectric methods. Searching for periods yields as the best representation of the Beff values (related to 3 cycles) the period 4.7 years.
Investigations of clusters of galaxies. IV. Properties of the galaxy cluster Abell 1795
Authors: Baier F.W. , Fritze K. , Tiersch H. , Ziener R. 
Published: July 2007

AbstractThe structure of the centre of the galaxy cluster A 1795 and its surroundings, representing different cluster components, has been investigated in several wavelength ranges. A preferred orientation deviating about 10–20° from the north‐south direction has been found for all cluster components. The orientation of the central cD galaxy is in good agreement with this direction, too. There seem to exist hints for antisegregation in luminosity as well as for colour segregation.
Determination of proper motions in the Pleiades Cluster
Authors: Schilbach E. 
Published: July 2007

AbstractFor 458 stars in the Pleiades field from the catalogue of EICHHORN et al. (1970) proper motions were derived on Tautenburg and CERGA Schmidt telescope plates measured with the automated measuring machine MAMA in Paris. The catalogue positions were considered as first epoch coordinates with an epoch difference of ca. 33 years to our observations. The results show good coincidence of proper motions derived with both Schmidt telescopes within the error bars. Comparison with proper motions determined by VASILEVSKIS et al. (1979) displays some significant differences but no systematic effects depending on plate coordinates or magnitudes could be found. An accuracy of 0.3″/100a for one proper motion component was estimated. According to the criterion of common proper motion 34 new cluster members were identified.
On local stellar age distributions and the history of the stellar birthrate in the galactic disk
Authors: Meusinger H. 
Published: July 2007

AbstractThe fraction of nearby stars born at different galactocentric radii is roughly estimated using the epicyclic approximation of stellar orbits in the galactic disk. Especially, the question of a possible burst origin of features in the local stellar age distribution is discussed. If the “bump” at about 4 Gyr in the frequency distribution of stellar isochrone ages (MEUSINGER 1991) is explained by star formation events then they have been locally at the solar galactocentric distance or globally in the whole disk.
Essential properties of the cD galaxy in Abell 1795 — I. General optical and X‐ray structure, dynamics and formation
Authors: Baier F. W. , Kirchner T. M. , Tiersch H. 
Published: July 2007

AbstractWe investigate current problems connected with the formation of cD galaxies. The subject of the present paper is to compare internal properties of the cD galaxy Zw162010 with cluster properties of Abell 1795. This consideration is a first attempt to find commonly valid essential correlations between peculiarities of brightest cluster members as structures and active phenomena and global cluster properties as for instance galaxy populations and concentration degrees. The colours, the X‐ray emission, and the velocity of the cD galaxy are used to discuss the obvious influence of the environment on the evolution of the active nucleus. In a second paper (Kirchner et al. 1992) the radio structure is used to investigate the influence of the surrounding cluster medium onto the development of the active nucleus. Furtheron, various jet ejection scenarios will be quantitatively examined.
Essential properties of the cD galaxy in Abell 1795 — II. Radio structure
Authors: Kirchner T. M. , Baier F. W. , Tiersch H. 
Published: July 2007

AbstractWe consider current problems connected with the evolution of central dominant (cD) galaxies in clusters. In the second part of this series, internal properties of the cD galaxy — in particular its radio structure — are related to the appropriate ones of the cluster. The observations point to an earlier jet ejection along the major axis of the galaxy and a following change of the jet axis.From the existence of “hot‐spot” like regions in different directions it is suggested that the radio engine would have to be intermittent with a relatively short period. Alternatively to the intermittent ejection scenario, the radio morphology of 4C 26.42 can be explained in the frame of the “standard” beam or jet model. The radio structure of 4C 26.42 being an inversion‐symmetric configuration, which is probably due to galactic cannibalism, could be interpreted as a transition at the inner hot spots (at about 1 kpc) from supersonic, stable Fanaroff‐Riley type II jets to subsonic, unstable FR I type structures (“plumes”).A quantitative investigation of the two scenarios for jet interaction with the surroudning interstellar/intercluster medium in 4C 26.42 gives parameter values in reasonable agreement with the ones discussed in the literature for related objects.
A comparison of the measuring machines APM and MAMA for astrometric application
Authors: Schilbach E. , Scholz R.‐D. 
Published: July 2007

AbstractMeasurements of two Tautenburg plates were used for a comparison of the astrometric accuracy of the automatic measuring machines PAM and MAMA. From plate‐to plate solutions a positional accuracy of about 1 μm was achieved for stars with 7 < B < 17 for MAMA and with 11 < B < 17 for APM measurements. A rapid decrease in positional accuracy of fainter stars is caused rather by random effects of the photographic emulsion.A magnitude equation between the plates was obtained to be less than 1 μm over the whole magnitude range. Systematic errors with a small period of 2 cm in the APM measurements as well as a non‐orthogonality and systematic differences between the MAMA and APM coordinate grids were found.A procedure of classifying all real objects measured into stars, galaxies and merged objets is presented for the MAMA measurements and the results are compared with the routine APM classification. Except for merged objects the MAMA and APM classification show a very good agreement for stars brighter than B = 18.5.
Observational evidence for the evolution of cD galaxies
Authors: Baier F. W. , Schmidt K.‐H. 
Published: July 2007

AbstractWe consider current problems connected with the formation of cD galaxies. The subject of this paper is to compare internal properties of cD galaxies such as radial colour distribution, envelope luminosity, and peculiar velocity with mass segregation effects in their parent clusters. This consideration is a forthcoming attempt to find commonly valid essential correlations between peculiarities of brightest cluster members and global cluster properties. We find tight correlations between the discussed properties and conclude that merger processes seem to play an important roll in the formation process of cD galaxies.
On the determination of potential function
Authors: Stavinschi M. , Mioc V. 
Published: July 2007

AbstractSzebehely's renowned equation given in 1974, allowing for potential determination from a given orbit or family of orbits, is proved to be equivalent with an equation deduced in 1963 by Drǎmbǎ. This basic equation in the inverse problem of dynamics, for which the denomination of Drǎmbǎ –Szebehely equation is proposed, is generalized for the motion in the n‐dimensional Euclidean space. A method for the determination of the potential function from motion equations is extended to this space.
Photometric observations of the central star of the planetary nebula NGC 2346 in 1991/1992
Authors: Grothues H. G. , Kohoutek L. 
Published: July 2007

AbstractPhotoelectric UBV observations of the central star of the planetary nebula NGC 2346 obtained during 60 nights between October 1991 and February 1992 are presented (Tables 1 and 2). Four minima have been stated and can be interpreted in terms of occulting dust clouds, probably representing dense condensations of the planetary nebula. We derived R = AV/EB—V = 4.0.
Effectively massive photons within Abelian Higgs galaxies
Authors: Saniga M. 
Published: July 2007

AbstractWe demonstrate that photons emitted by spiral galaxies become effectively massive, if the latter are treated as macroscopic Abelian Higgs topological solitons. The rest mass of a photon is shown to be proportional to the squared amplitude of the Higgs field distribution representing a ‘background’ static cylindrically symmetric magnetic vorto‐source (‐sink). Because the amplitude increases in a monotonous fashion from zero at the center of a spiral to a fixed non‐zero value at its outer boundary, the rest mass (group velocity) of photons emitted at shorter distances from the galaxy' s center is smaller (greater) when compared to that of photons originating at larger distances. A rough estimate shows that for a spiral with a diameter of 60 kpc the maximum attainable mass of photon is of the order of 10−60 g.
Photometric survey near the main Galactic meridian: 2.1. Finding charts and photoelectric U, B, V, R stellar magnitudes in 25 fields
Authors: Andruk V. , Kharchenko N. , Schilbach E. , Scholz R.‐D. 
Published: July 2007

AbstractFinding charts and photoelectric U, B, V, R magnitudes of stars in 25 fields in the Main Galactic Meridian (programme MEGA) are presented. This part of the photometric survey includes fields near the North Galactic pole and fields at southern Galactic latitudes. Together with the finding charts of 2.5° × 2.5° the equatorial coordinates of the stars are given for epoch and equinox 1950.
A colour‐agnitude diagram of the Pisces dwarf galaxy
Authors: Tikhono N. , Makarova L. 
Published: July 2007

AbstractWe present B, V and R band CCD images of the dwarf galaxy LGS‐3 (Pisces dwarf). About 180 stars and diffuse objects were found and processed in these frames. The colour‐magnitude diagram shows a prominent red giant branch and a few blue stars only. Details of the morphological properties and colour‐agnitude diagram indicate to an intermediate (between dIrr and dSph) type of LGS‐3. We estimate the galaxy distance modulus to be about (m ‐ M)0 = 23.9 ± 0.3 mag on the basis of the tip of the red giant branch. We measured the galaxy colour to be about B–V = 0.8 mag and the linear diameter 700 pc, which is the smallest one in the Local group.