bluuebunny/crossref_metadata_2025 huggingface dataset:
New exact solutions for power‐law inflation Friedmann models
Authors: Schmidt H.‐J.
Published: July 2007

We 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

Models 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

The 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

For 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

Tetrads 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

Within 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.
Quantum string theory in curved space‐times
Authors: Sánchez N.
Published: July 2007

A 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

In 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.
Conformally coupled Abelian gauged Q balls
Authors: Wolf C.
Published: July 2007

A conformally coupled Abelian gauged Q ball is studied in curved space. The mass of the Q ball is calculated in terms of the conserved Q charge and the parameters in the lagrangian and a brief discussion is given on the effects produced by the conformal couplings.
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

The 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

For 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

Using 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

In 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

The 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

Solar 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

On 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.
A possibility to classify local radio sources by fluctuation power spectra
Authors: Burov V. A. , Kozlovsky V. D.
Published: July 2007

TNA–1500 radio telescope observations data of radio emission from local sources of different types have been examined. The established quantitative peculiarities of spectral and integral characteristics of fluctuations can be used for forecasting flare activity by means of pattern recognition technique.
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

It 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

The 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

In 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.
On boundaries among magnetic structures at the sun
Authors: Ishkov V. N. , Linke J.
Published: July 2007

The analysis of the characteristics of a large number of developed large complex active regions (CAR) leaded to the understanding of the fact that at the lower solar atmosphere are existing boundaries of special kinds. These boundaries are the places of separation of magnetic structures, which are developed independent in the first order.
Fiber bursts and related phenomena
Authors: Mann G.
Published: July 2007

Fiber bursts occur as special fine structures in solar type–IV radio bursts. They represent an important diagnostic tool for the coronal plasma, especially for determining magnetic field strengths in the solar corona. In this paper the physical understanding of this fine structure and related phenomena is briefly reviewed.
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

Results 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.
Evidences of whistler manifestations in fine structure of type IV radio emission
Authors: Chernov G. P.
Published: July 2007

Different regimes of an whistler instability yield divers elements of fine structures: millisecond pulsations or different stripes in emission and absorption, moreover zebra–stripes can convers into fiber bursts and inversely.
Mesures d'étoiles doubles. I. Faites au grand refracteur de Nice
Authors: Gili R.
Published: July 2007

204 binaries were observed with the great refractor of the Cǒte d'Azur observatory at Nice to confirm their orbits.
Electric currents and Lorentz forces derived by vector magnetographic measurements 1. Electric currents in a flux bundle
Authors: Hofmann A.
Published: July 2007

We 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

The 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

Es 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

Minor 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

New 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

The 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.
Metallicities of open clusters
Authors: Strobel Andrzej
Published: July 2007

The main aim of this paper is (i) to examine the available metallicity data of open clusters, (ii) to gather a large set of homogeneous estimations of the characteristics, and (iii) to check whether open cluster metallicities are related to spatial and age distribution of these objects.
Determination of proper motions in the Pleiades Cluster
Authors: Schilbach E.
Published: July 2007

For 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

The 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

We 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

We 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.
Remarks on anisotropy of inertia in an anisotropic cosmos
Authors: Treder H.‐J.
Published: July 2007

Mach's relativity of inertia does not necessarily imply an anisotropy of inertial masses in an anisotropic universe and the Mach‐Einstein doctrine is compatible with the isotropy of mass in each cosmos.
Photographic positions of Minor Planets
Authors: Debehogne H. , Scardia M.
Published: July 2007

Photographic precise positions of minor planets, obtained with the G.P.O. astrograph at ESO (La Silla ‐ Chile) and with the ZEN astrograph at Merate, are given
A comparison of the measuring machines APM and MAMA for astrometric application
Authors: Schilbach E. , Scholz R.‐D.
Published: July 2007

Measurements 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

We 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 parametric resonance in a thin disk galactic dynamo
Authors: Kuzanyan K. M. , Sokoloff D. D.
Published: July 2007

The absence of a parametric resonance by the generation of a large scale bisymmetric magnetic field in a thin galactic disk with periodically time dependent properties in the frames of the simplest thin disk galactic dynamo model is shown.
On the determination of potential function
Authors: Stavinschi M. , Mioc V.
Published: July 2007

Szebehely'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

Photoelectric 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.
The neighbourhoods of the nearest hickson groups
Authors: Vennik J. , Richter G. M. , Longo G.
Published: July 2007

The comparison of the spatial distribution of galaxies in the surroundings of the nearest compact and loose groups of galaxies confirms that compact groups are very likely to be part of looser groups and shows that loose groups associated to compact groups tend to have higher spatial density than normal ones.
Effectively massive photons within Abelian Higgs galaxies
Authors: Saniga M.
Published: July 2007

We 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

Finding 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

We 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.
A calculation of structural parameters of spherical stellar systems by means of characteristic functions method. I. Theory
Authors: Saiyan A. P.
Published: July 2007

To calculate structural parameters of stellar systems such as an effective radius and central space (or surface) density, the method of characteristic functions is suggested. The characteristic function of the system is a Fourier image of their normalized space density profile f3(r). In the case of spherical symmetry the probability distribution of r (Q3(r) = (3/a3)r2f3(r)) and its orthogonal projections have the same characteristic functions. This fact is used to calculate the effective radii of a few star cluster models (King law, Plummer model and Gausian profile). It is shown, that the characteristic function for King law clusters tends to a finite generalised function if the concentration parameter c is large. The expression for the effective radius (at c ≫ 1) is given. The formula of the effective radius in the Plummer model as well as the relation between the one‐dimensional central velocity dispersion and the root mean square velocity are obtained. It is shown, that in the Gaussian model and for King law clusters the effective radius (half‐mass visual radius) can differ from the effective (harmonic) radius a few times. This fact should be taken into account in estimating the mass‐to‐light ratio from the virial mass of such systems using the King radius.
On the two‐dimensional inverse problem of dynamics
Authors: Pal A. , Anisiu M.‐C.
Published: July 2007

The authors extend the deduction of the equations satisfied by the force fields from inertial to rotating frames, when the curves of a certain family are known to be solutions for the equations of motion. Then Drǎmbâ's equation is obtained as a consequence of this result. The works of Hadamard and Moiseev are proved to be closely related to the inverse problem of dynamics.
Beobachtungen Kleiner Planeten. XV.
Authors: Bōrngen F.
Published: July 2007

A summary is given about the Minor Planet survey performed in 1994 on Tautenburg Schmidt plates. 321 asteroids were observed and 1171 positions are calculated for them. These are 200 asteroids with provisional designations (102 of them have new designations) and 121 numbered objects. Tautenburg observations could give a tribute to 73 planets numbered in the period of this report. Fourteen Tautenburg asteroids have been numbered.
DIVA ‐ An interferometric minisatellite for astrometry and photometry
Authors: Bastian U. , Röserg S. , Hø E. , Mandel H. , Seifert W. , St. Wagner  , Quirrenbach A. , Schalinski C. , Schilbach E. , Wicenec A.
Published: July 2007

We propose a small interferometer on a minisatellite, named DIVA (Deutsches Interferometer für Vielkanalphotometrie und Astrometrie), to perform astrometric and photometric observations of at least one million stars. It would exceed the performance of Hipparcos in all important parameters. With a possible launch in 2002 DIVA would provide for all stars brighter thanV= 10m5

–parallaxes better than 0.8 milliarcseconds (mas) –proper motions better than 2 mas/y –broad‐band photometry with a tyupical accuracy of 0.002 mag –multi‐channel intermediate‐band photometry with a typical accuracy of 0.01 to 0.02 mag For the 100 000 stars observed by Hipparcos, proper motions with a typical accuracy of 0.1 to 0.2 mas/y and parallaxes of 0.3 to 0.5 mas can be obtained in combination with the Hipparcos results. The scientific potential of this mission and a possible layout of its optical system are described in this paper.
Towards a cosmic no hair theorem for higher‐order gravity
Authors: Kluske S. , Schmidt H.‐J.
Published: July 2007

We use gravitational Lagrangians R□k √− g and linear combinations of them motivated from trials how to overcome the non‐ renormalizability of Einstein' s theory. We ask under which circumstances the de Sitter space‐ time represents an attractor solution in the set of spatially flat Friedman models. This property ensures the inflationary model to be a typical solution; nowadays, this property is called cosmic no hair theorem because it is analogous to the no hair theorem for black holes.

Results are: for arbitrary k, i.e., for arbitrarily large order 2k + 4 of the field equation, one can always find examples where the attractor property takes place. Such examples necessarily need a non‐ vanishing R2‐ term. The main formulas do not depend on the dimension, so one gets similar results also for 1+1‐ dimensional gravity and for Kaluza‐ Klein cosmology.
Study of the planetary nebula NGC 2438 I. Spectroscopy of the nebula and of some cluster stars
Authors: Pauls R. , Kohoutek L.
Published: July 2007

We found 36 emission lines in the spectrum of the planetary nebula NGC 2438, and we determined its exc. class to be about 6–7. The nebular RVhel = 60.3 ± 3.6 km/s (5 spectra) is in agreement with RVhel = 60.8 ± 4.0 km/s of 4 cluster stars (10 spectra). We conclude that contrary to earlier statements the nebula is probably associated with the cluster.
Phase‐resolved spectroscopy and photometry of the eclipsing polar EP Draconis (=H1907+690)
Authors: Schwope A. D. , Mengel S.
Published: July 2007

We present phase‐resolved optical spectroscopy and CCD photometry of the faint eclipsing polar EP Dra (H1907+690). A revised ephemeris is derived which connects all 32000 binary cycles since its discovery by Remillard et al. (1991). We found no difference between spin and and orbital periods of the white dwarf. Changes in the light curve morphology are attributed to a different beaming behaviour which might change on timescales as short as one or several orbital periods. Optical light curve modelling was used to estimate the co‐latitude of the accretion spot, which must be larger than 40°. We have detected Zeeman absorption lines of Hα originating in an accretion halo in a field of 16 MG. The low‐resolution spectra reveal no indication of resolved cyclotron harmonics, which is also suggestive of a relatively low field strength in the accretion region. The Balmer emission lines contain significant contributions from the UV‐illuminated hemisphere of the companion star, whereas the Hell λ4686 emission originates predominantly from the accretion stream. The emission lines have a multi‐component structure and we could single out a narrow emission line in the Hβ and Hγ lines. It radial velocity amplitude suggests a low mass for the white dwarf, if the lines are interpreted as being of reprocessed origin from the whole illuminated hemisphere of the companion star.
Astronomical refraction: formulas for all zenith distances
Authors: Wittmann A. D.
Published: July 2007

In real‐time applications fast and accurate algorithms for calculating astronomical refraction are required. Some of the most widely‐used expressions are fast, but numerically unstable, and can not be applied where the correction is largest, i.e. close to the horizon. In the present paper a new formula for refraction, which is both fast and numerically stable, is given and compared with previously published refraction formulas. The approximate calculation of refraction 'below the horizon', and of the finite distance correction near the horizon, are also discussed.
Composite lightcurve of asteroid Moskva (787)
Authors: Greve T. R. , Pontoppidan K. M. , Olsen H. J. F.
Published: July 2007

89 CCD frames of the asteroid Moskva (787) were obtained over six nights. Lightcurves have been acquired for each night. We suggest a possible composite lightcurve with a corresponding rotational period of 0.4 days. This is to the knowledge of the authors the first lightcurve of Moskva(787) to be published.
Ultrasoft narrow‐line Seyfert 1 galaxies and X‐ray surveys
Authors: Brandt N. , Boller T.
Published: July 2007

Note from the editor: This article is a re‐print of the original, which appeared in Astron. Nachr. 319 (1/2), 7 (1998). In the original version the figure was ruined in the process of paper production and the scientific content of the paper considerably degraded. Instead of printing only the correct figure, thus loosing the scientific context, we decided to re‐print the whole article.

We describe how recent X‐ray surveys have led to advances in the understanding of ultrasoft narrow‐line Seyfert 1 galaxies. The number of known ultrasoft narrow‐line Seyfert 1s has increased greatly in recent years due to X‐ray surveys, and it is now possible to obtian high quality 0.1–10 keV spectral and variability measurements for a large number of these galaxies. We generalize some of the correlations between X‐ray properties and optical emission line properties,focusing on how the ROSAT band spectral slope appears to be directly connected to the Boroson & Green (1992) primary eigenvector. We discuss how ultrasoft narrow‐line Seyfert 1s may well have extremal values of a primary physical parameter, and we describe new projects that should further improve our understanding of these extreme representatives of Seyfert activity.
Early versus late type galaxies in compact groups
Authors: Shaker A. A. , Longo G. , Merluzzi P.
Published: July 2007

We find a strong correlation between the effective radius of the largest early‐type galaxies in compact groups of galaxies and the velocity dispersion of the groups. The lack of a similar correlation for late type galaxies is supportive of the so called second generation merging scenario which predicts that ellipticals should dominate the internal dynamics of the groups, while late‐type galaxies are mainly recent interlopers which are still in an early stage of interaction with the group potential.
Schmidt plate survey in the Galactic centre and anticentre direction. Luminosity and mass functions of open clusters
Authors: Kharchenko N. , Meusinger H. , Piskunov A. , Schilbach E.
Published: July 2007

The proper motions and stellar magnitudes for more than 20 000 stars distributed in areas around eight open clusters in the directions of the Sagittarius‐Carina and Perseus spiral arms were used to determine the cluster membership. Both spatial‐kinematical and statistical criteria were used for member seletion. The luminosity functions of cluster members were constructed and used for the further data improvement. The safest portions of the luminosity function free both from evolved stars and faint field star contamination were used for mass function construction. The composite mass function was derived from the data on five young clusters with log t < 8.2. A dependence of the mass function slope on the adopted input parameters (mass‐luminosity relation and distance scale) and on member selection procedure was tested. The slope was found to vary in a range from 1.36 to 1.80 for lg M/M⊙ between 0.3 and 1.2. A possible relation between the individual MF slopes and cluster ages was indicated. The results are in good agreement with published data.
Quasar evolution
Authors: Wisotzki L.
Published: July 2007

I present a critical review of recent progress in the field of quasar evolution, concentrating on the methodical issues of constructing and analysing observed quasar samples. In particular, I attempt to trace the origins and shortcomings of the popular concept of ‘pure luminosity evolution’ that has dominated the discussion over the last decade. I discuss results from new surveys showing that this notion should be abandoned, and that quasar evolution is more complex than previously thought.
Aberration and relativity
Authors: Liebscher D.‐E. , Brosche P.
Published: July 2007

The aberration of starlight seems to be one of the simplest phenomena of astronomical observation. However, the story of misunderstandings is long and lasts till now. It is nearly forgotten that the problem of stellar aberration was the cornerstone of the development and the acceptance of relativity. In addition, there seems to be no essentially final point in the discussion of its interpretation, the discussion seems to merely be given up. Of course, with the correct relativistic formulas, there is no need of interpretation any more. The price of this consists in the many incorrect descriptions and interpretations that arise if a textbook tries to explain in words the mere formulas. We try to review the problems discussed in the last three centuries and to give them a final, i.e. geometrical form. We are convinced that this teaches a lot about the geometry of the space‐time union.
The ROSAT Bright Survey: I. Identification of an AGN sample with hard ROSAT X‐ray spectra
Authors: Fischer J.‐U. , Hasinger G. , Schwope A. D. , Brunner H. , Boller T. , Trümper J. , Voges W. , Neizvestny S.
Published: July 2007

The ROSAT Bright Survey (RBS) aims to completely optically identify the more than 2000 brightest sources detected in the ROSAT all‐sky survey at galactic latitudes |b| > 30° (excluding LMC, SMC, Virgo cluster). This paper presents a subsample of 66 bright point‐like ROSAT survey sources with almost hard PSPC spectra, the hardness ratio HR1 is > 0.5 for most of the sources. Teh subsample could be nearly completely identified by low‐resolution optical spectroscopy with the following breakdown into object classes: 31 Seyfert galaxies, 22 BL Lac candidates, 5 clusters of galaxies, 1 cataclysmic variable, and 5 bright stars. Only one object remained unidentified and one X‐ray source was a spurious detection. The redshift distrbution peaks around 0.06 for the Seyferts and around 0.13 for the BL Lac candidates. Observations with medium spectral resolution were obtained for most of the new Seyfert galaxies. A large fraction (20 objects) are type 1 Seyfert galaxies, the other fraction includes Seyfert galaxies of type 1.5 – 1.8 (5 objects), two LINERs, and 4 possible narrow‐line Seyfert 1 galaxies (NLS1). About one third of the new Seyfert's have nearby companion galaxies displaying either emission or absorption lines at the same redshift. Among them are a couple of systems showing direct morphological evidence for interaction. The large fraction of interacting galaxies among our sample suggests a scenario where interaction is the main trigger of AGN activity.
The Solar granulation in different heights
Authors: Balthasar H.
Published: July 2007

Intensity images and Doppler‐velocity maps of the quiet sun in different heights are obtained from simultaneously recorded spectra of different lines. A relation between the intensity images is recognizable up to formation heights of 900 km above continuum, but the correlation coefficient changes sign above 400 km. The core of Hα shows a different pattern without any correlation to the continuum layer. Extreme Doppler velocities as well as the rms‐velocities have minima at a height of 400 km, values of about 2 km/s occur in deep photospheric layers and 2.5 km/s in a height of 900 km. The velocities in the lower and in the upper photosphere are well correlated indicating that the pattern of the velocity field is preserved up to higher layers than the intensity pattern. Hα‐velocities reach values up to 10 km/s and more, they show no correlation with the continuum intensities and almost no with the line core intensities.
Influence of chronic hepatic failure on disposition kinetics of valproate excretion through a phase II reaction in rats treated with carbon tetrachloride
Authors: Khemawoot Phisit , Maruyama Chiharu , Tsukada Hirotaka , Noda Hiroyo , Ishizaki Junko , Yokogawa Koichi , Miyamoto Ken‐ichi
Published: July 2007

The influence of chronic hepatic failure on the disposition kinetics of valproate (VPA) excretion via a phase II reaction was examined in rats treated with carbon tetrachloride (1.0 mg/kg, s.c., 3 times a week) for 2 or 3 months. There was no significant difference in the plasma concentration‐time courses of VPA among the control and two treated groups up to 120 min after i.v. administration of VPA (75 mg/kg), but subsequently the plasma concentrations of the treated groups declined significantly below the control levels. Expression of Mrp2 mRNA in the liver of the treated groups was significantly lower than in the control group; conversely that in the kidney was significantly higher. The enzyme activity of UGTs in the liver of the treated groups decreased significantly, but UGT1A8 mRNA expression in the duodenum was increased about 3‐fold. Cumulative excretion of VPA glucuronide (VPA‐G) in bile of the treated groups was reduced significantly, while that in urine was markedly increased. In conclusion, the area under the VPA plasma concentration‐time curve was decreased significantly in rats with chronic hepatic failure owing to increased excretion of VPA‐G via the kidney as a result of induction of Mrp2, and inhibition of enterohepatic circulation of VPA‐G. Copyright © 2007 John Wiley & Sons, Ltd.