bluuebunny/crossref_metadata_2025_split huggingface dataset:
Compactification and cosmic string phenomenology
Authors: Bleyer U. , Heinrich O. , Nikolaenko V. M. 
Published: July 2007

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

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

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

AbstractPreliminary results of observations of narrow drifting bursts (NDB) are presented. The bursts appeared as narrow bright sloping lines both overlaped at the dynamic spectra of type III bursts and at the background of noise storms. The observations were made in 1982–1989 at 45–270 MHz frequency range in Troitsk and Kislovodsk at radiospectrographs with the frequency resolution of 0.2 MHz and the time one of 0.1 s. NDB were observed at 45–180 MHz range. Main parameters of NDB are near to that of drifting pairs. A small part of NDB shows sharp changes of the frequency drift sign (N, V–shape bursts).
Astrophysical effects of a superconducting cosmic string
Authors: Mańka R. , Bednarek I. 
Published: July 2007

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

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

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

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

AbstractWe calculate the binding energy of a Schwarzschild gas sphere in D space time dimensions. To the post‐Newtonian approximation we demonstrate that the interior Schwarzschild solution does not exhibit an instability before the Schwarzschild radius is reached for D = 4. For D = 5, 6 we find binding energy is negativ to the post‐Newtonian approximation. Extending the approximation to the post‐post‐Newtonian approximation we find that the post‐post‐Newtonian contribution to the binding energy of a Schwarzschild gas sphere is positive for the cases D = 4, 5, 6. The effect of the post‐post‐Newtonian contribution to the binding energy on the stability of higher dimensional gas spheres is discussed.
Beobachtungen Kleiner Planeten. XI
Authors: Börngen F. , Schmadel L. D. 
Published: July 2007

AbstractEs wird eine Übersicht gegeben über die im Jahr 1990 auf Tautenburger Schmidtplatten gefundenen Kleinen Planeten. Es wurden 561 Objekte beobachtet und für diese 2104 Positionen gerechnet. Es handelt sich um 430 Planetoiden mit provisorischer Bezeichnung, unter denen 364 neu vergebene Bezeichnungen sind, sowie um 131 numerierte Objekte. Für 160 Tautenburger Objekte wurden erste Bahnen gerechnet. Für 49 im Berichtszeitraum numerierte Planeten haben Tautenburger Positionen einen Beitrag geleistet. Darunter sind sechs in Tautenburg entdeckte Planetoiden (Tab. 3).
Density profiles and luminosity functions of the globular clusters M3 and M92
Authors: Scholz R.‐D. , Schmidt K.‐H. 
Published: July 2007

AbstractTautenburg Schmidt plates with the globular clusters M3 and M92 were measured on the APM facility in Cambridge, mainly for astrometric purposes. The data were used to derive the radial density profiles and the luminosity functions of these clusters. There is a good agreement of our results with formerly ones derived by other authors. In both clusters effects of mass segregation are observed.
Orbits of galactic globular clusters
Authors: Odenkirchen M. , Brosche P. 
Published: July 2007

AbstractNew absolute proper motions of the two globular clusters NGC 4147 and NGC 6218 and a specific model of galactic mass distribution are used to integrate their orbits numerically. The resulting values of orbital parameters and their variation due to the uncertainty of the initial values are discussed. Furthermore, the deviations from the time average of the virial theorem are determined.
Orbits of the visual double stars W.D.S. 03537N5317, 11468N4839 and 14138N3100
Authors: Ling J. F. 
Published: July 2007

AbstractNew orbital elements are presented for the visual double stars W.D.S. 03537N5317, 11468N4839, and 14138N3100. The observations, residuals, ephemerides, dynamical parallaxes, and total masses of each system are also given.
On a two‐body problem with periodically changing equivalent gravitational parameter
Authors: Şaru D. , Cucu‐Dumitrescu C. , Mioc V. 
Published: July 2007

AbstractAssigning to the equivalent gravitational parameter of a two‐body dynamic system, a periodic change of a small amplitude B and arbitrary frequency and phase, the behaviour of an elliptic‐type orbit is studied. The first order (in B) perturbations of the orbital elements are determined by using Delaunay's canonical variables. According to the value of the ratio between oscillation frequency and dynamic frequency, three cases (non‐resonant (NR), quasi‐resonant (QR), and resonant (R) ones) are pointed out. The solution of motion equations shows that only in the QR and R cases there are elements (argument of pericentre and mean anomaly) affected by secular perturbations. The solutions are valid over prediction times of order of pericentre and mean anomaly) affected by secular perturbations. The solutions are valid over prediction times of order B−1 in the NR case and B−1/2 in the QR and R cases.
Beobachtungen Kleiner Planeten. XII
Authors: Börngen F. , Schmadel L. D. 
Published: July 2007

AbstractEs wird eine Übersicht gegeben über die im Jahr 1991 auf Tautenburger Schmidtplatten gefundenen Kleinen Planeten. Es wurden 533 Objekte beobachtet und für diese 2066 Positionen gerechnet. Es handelt sich um 456 Planetoiden mit provisorischer Bezeichnung, unter denen 324 neu vergebene Bezeichnungen sind, sowie um 77 numerierte Objekte. Für Tautenburger Objekte wurden 250 Bahnen aus einer Opposition gerechnet. Für 54 im Berichtszeitraum numerierte Planeten, darunter befinden sich auch (4999) MPC und (5000) IAU, haben Tautenburger Positionen einen Beitrag geleistet. Neun Tautenburger Planetoiden wurden numeriert (Tab. 3).A summary is given about the Minor Planet survey performed in 1991 on Tautenburg Schmidt plates. 533 asteroids were observed and 2066 positions are calculated for them. These are 456 asteroids with provisional designations (324 of them have new designations) and 77 numbered objects. One‐opposition orbits have been computed for 250 Teutenburg asteroids. Tautenburg observations could give a tribute to 54 planets numbered in the period of this report, among them are (4999) MPC and (5000) IAU, too. Nine Tautenburg asteroids have been numbered (Tab. 3).
Nearby galaxies. II. Luminosity function and spatial distribution
Authors: Schmidt K.‐H. , Boller T. 
Published: July 2007

AbstractA sample of nearby galaxies (Schmidt and Boller 1992, paper I) has been analysed with regard to the luminosity function and the spatial distribution. The main results are as follows: (i) a relation between the slope of the luminosity function of the members of a group of galaxies and the earliest morphological type in this group has been detected which possibly is a new kind of environmental effects; (ii) the virial masses of the groups of galaxies are, on the average, by a factor 3 to 4 greater, only, than the luminous masses derived from the individual galaxy masses; (iii) the nearby galaxies are concentrated in a thin disk‐like layer around the supergalactic plane the thickness of which is a few hundred kiloparsecs, only; (iv) a population of field galaxies with nearly constant density (about 3 per cent of the number density in the supergalactic plane) is extended into the voids on both the supergalactic hemispheres.
Determination of the optical or physical nature of wird visual binaries by means of two‐dimensional conditional probabilities
Authors: Brosche P. , Denis‐Karafistan A. , Denis C. 
Published: July 2007

AbstractA sample consisting of 888 wide visual double stars with known relative proper motions has been processed for the HIPPARCOS input catalogue. Brosche et al. (1992) applied two separate criteria on this list to discriminate statistically between physical and optical pairs. The first of these criteria uses the number density constrast, the second the ratio of the tangential velocity to an estimate of the orbital velocity, assuming the pair to be physical. Here we combine these two separate criteria into a single criterion based on a probability depending on two arguments, i.e. on a conditional probability. Statistically, we are thus led to the conclusion that the sample comprises 545 physical and 343 optical pairs.
The spectrum of Pleione during 1990
Authors: Menchenkova E. V. 
Published: July 2007

AbstractThe results of the observations of Pleione obtained during 1990 with the 6‐m‐telescope SAO (Zelenchukskaja) and the 2.6‐m‐telescope of the Crimean Astronomical Observatory are presented. The spectral type of the star was B8. Variations of the equivalent widths and profiles of the hydrogen lines in the spectrum of Pleione during 1990 were detected. Lines of a secondary component in the spectrum of Pleione were not discovered.
Vilnius photometry of the red horizontal branch stars in the Galactic thick disk
Authors: Tautvaiśienė G. 
Published: July 2007

AbstractThe photometric observations and three‐dimensional classification in the Vilnius system have been carried out for 13 of the red horizontal branch (RHB) stars in the Galactic thick disk identified by Rose (1985). The photometric spectral types, metallicities [Fe/H], effective temperatures, surface gravities and absolute magnitudes are determined. The age of about 10–12 Gyr is evaluated for this group of stars from comparison with model isochrones, indicating that the age of the thick disk is intermediate between the disk globular and the oldest open clusters.
A new family of non‐linear filters for background subtraction of wide‐field surveys
Authors: Shergin V. S. , Kniazev A. Yu. , Lipovetsky V. A. 
Published: July 2007

AbstractIn this paper the definitions and properties of a newly dedicated set of high‐frequency filters based on smoothing‐and‐clipping are briefly described. New applications for the reduction of wide‐field 2048x2048 CCD spectral and direct images of a new deep survey KISS are also presented.
Catalogue of Shakhbazian compact groups of galaxies. VI.
Authors: Stoll D. , Tiersch H. , Braun M. 
Published: July 2007

AbstractThe sixth part of the catalogue of Shakhbazian compact groups of galaxies contains the positions and references of all the galaxies of the following 48 groups (north of δ > +2°30''): Shkh 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100, 101, 102, 103, 104, 105, 106, 107. For the estimation of the coordinates the Digitized Sky Survey was used.
Some ideas concerning the problem of anomalous polar E region heating due to Farley‐Buneman turbulence
Authors: Liperovsky V. A. , Kustov A. V. , Meister C.‐V. 
Published: July 2007

AbstractThe energetics of the excitation of the Farley‐Buneman instability is considered, which is recently observed in the auroral and equatorial E regions of the Earth's ionosphere at altitudes between 100 km and 120 km. In the magnetic field of the Earth the Farley‐Buneman instability is excited under the condition of a strong enough external electric field in the case of ion‐neutral collisions with frequencies much larger than the ion gyrofrequency and electron‐neutral collisions with frequencies much below the electron gyrofrequency. It is shown that the linear increase of the wave amplitudes is caused by a small disbalance between the processes of nonlinear energy pumping into the wave from an external electric field and the energy loss because of the collisions of the electrons and ions with the neutral particles. During the nonlinear energy pumping energy of the external electric field is transferred into a nonlinear current of second order, which is connected with the oscillating motion of the electrons in the wave. The oscillating electron motion takes place perpendicular to wave propagation. From the estimations follows that the energy pumped into a Farley‐Buneman wave during one period of pulsation is much larger than the wave energy itself. A new and simply to understand derivation of the anomalous diffusion coefficient is presented, related to the study of the behaviour of a test wave with frequency much above the frequencies of the Farley‐Buneman turbulence in developed stage can cause an additional macroscopic nonlinear Pedersen current directed along the external electric field. It is found that the nonlinear Pedersen current can reach the order of the usual Pedersen current and should contribute to the effective heating of the ionospheric plasma.
The most resonant pulsation frequency of δ Scuti stars
Authors: Kotov S. V. , Kotov V. A. 
Published: July 2007

AbstractPulsation of the Sun with a period of P0 ≈ 160 min discovered about two decades ago, is still waiting explanation. In view of the hypothesis about its cosmological origin, and attempting to find signature of this P0 periodicity among other (short‐period variable) stars, the pulsation frequencies of δ Sct stars are subjected to specific analysis. With a confidence level ≈ 3.8σ it is found that the frequency v0 = P0−1 ≈ 104 m̈Hz, within the error limits, appears indeed to be the most “resonant” one for the total sample of 318 pulsating stars of δ Sct type (the most commensurable, or “synchronizing”, period for all these stars occurs to be 162 ± 4 min). We conjecture that a) the P0 oscillation might be connected with periodic fluctuations of gravity field (metrics), and b) the primary excitation mechanism of pulsations of δ Sct stars, reffected by this “ubiquitous” P0 resonance, must be attributed perhaps to superfast rotation of their inner cores (their rates tend to be in near‐resonance with the “universal” v0 frequency). The arguments are given favouring a cosmoogical nature of the P0 oscillation.
UBV photometry of the WR binary CQ Cephei
Authors: Demircan O. , Ak H. , Özdemir S. , Tanriver M. , Albayrak B. 
Published: July 2007

AbstractPhotoelectric observations of the WR binary CQ Cephei (WN6+O9) are presented. the depths of the eclipses in the light curves are best represented by an inclination of the orbit i = (68°.8±0.6) and the width of the very asymmetric eclipse curves can be represented by only an overcontact configuration (Ω1 = Ω2 = 3.65 ± 0.05, and f = 27%). Simultaneous solution of the light and radial velocity curves strongly supports CQ Cep's membership of the Cep OB1 association. By considering this membership we obtained absolute dimensions of the system, which lead to a consistent physical model for CQ Cephei. The more luminous WR primary turns out to be the hotter but slightly less massive component: MWR = 20.8 M⊙, RWR = 8.2R⊙, Teff(WR) = 43600 K, and Mo = 21.4 M⊙, Ro = 8.3 R⊙, Teff(O) = 37000 K.
The slender solar tachocline: a magnetic model
Authors: Rüdiger G. , Kitchatinov L. L. 
Published: July 2007

AbstractA model for the sharp transition from differential rotation in the solar convection zone to rigid rotation in the radiative interior is presented. Differential rotation in the radiative zone is shown to be quenched efficiently by an internal magnetic field. The poloidal field amplitude, B0, is the input parameter for our model which determines the transition layer thickness and the toroidal field strength. It is illustrated analytically and confirmed numerically that a rather small field, B0 = 10−4 Gauss, suffices to satisfy the helioseismological restrictions on the depth of the differential rotation penetration below the convection zone. The transition layer thickness decreases further with increasing B0. The toroidal field amplitude B ≃ 200 Gauss is almost independent of B0.
The AGN content of ROSAT and ASCA deep surveys
Authors: Griffiths R. E. , Boyle B. J. , Georgantopoulos I. , Shanks T. , Gunn K. , Stewart G. C. , Blair A. , Almaini O. 
Published: July 2007

AbstractThe results of ROSAT deep surveys were well established during the first few years of ROSAT operation (Papers I ‐ XV in this collaboration, and other papers in this Volume). They have allowed us to measure the AGN Luminosity Function and its evolution in soft X‐rays, both for AGN of Type I and for objects classified as AGN Type II/Narrow‐Line X‐ray Galaxy (NXLG). More recently, we have performep surveys with ASCA of some of these same ROSAT fields. Based on coincidences with ROSAT deep survey sources, and further optical spectroscopic identification, we discuss the optical identification content of five of our ASCA deep survey fields. Perhaps not surprisingly, we have observed significant cosmological evolution for Type I AGN in the 2–10 keV energy range, with an evolutionary rate which is consistent with that measured in other passbands. The predicted contribution of Type I AGN to the 2–10 keV X‐ray background (XRB) is about 60%, and the combined contribution from AGN of Types I & II is consistent with 100%.
Sky surveys with ASCA — Large Sky Survey
Authors: Ueda Y. , Takahashi T. , Inoue H. , Tsuru T. , Sakano M. , Ohta K. , Akiyama M. , Ishisaki Y. , Ogasaka Y. , Makishima K. , Yamada T. 
Published: July 2007

AbstractWe have carried out the first systematic wide‐area survey around a Galactic pole region with the ASCA satellite in the 0.7–10 keV energy band (Large Sky Survey; LSS). The observed area amounts to 7 deg2. To make the best use of ASCA capability, we have developed a new source‐detection method where the complicated detector responses are fully taken into account. Applying this method to the entire LSS data independently in three energy bands (0.7–2 keV, 2–10 keV, and 0.7‐7 keV), we detected 104 sources in total (4.5 σ detection). The Log N ‐ Log S relation and spectral properties of faint sources are presented.
The UK ROSAT Deep Survey
Authors: McHardy I. M. , Merrified M. R. , Newsam A. M. , Jones L. R. , Allan D. J. , Ponman T. J. , Mason K. O. , Smith P. J. , Branduardi‐Raymont G. , Carrera F. , Abraham R. G. , Dalton G. B. , Efstathiou G. , Rowan‐Robinson M. , Quenby J. J. , Wegner G. A. , Lehto H. J. , Luppino G. A. 
Published: July 2007

AbstractWe present a summary of the identification content of the UK ROSAT Deep Survey. The survey is based on a 115ksec PSPC observation and comprises a sample of 70 sources to a flux limit of 2 × 10−15 ergs cm−2 s−1 (0.5–2 keV). At bright fluxes the survey is dominated by broad line QSOs, at intermediate fluxes it contains a number of groups and clusters of galaxies, but at faint fluxes the survey contains many galaxies with narrow optical emission lines (NELGs). The average X‐ray spectrum of the NELGs is harder than that of the QSOs and similar to that of the X‐ray background. The NELGs have optical spectra similar to the majority of the field galaxy population in the same redshift range and may simply be the more luminous members of the emission line field galaxy population. Based on optical line ratios and X‐ray/optical ratios, the NELGs, both as a sample and within individual galaxies, appear to be a mixture of starburst galaxies and true AGN.
Results from the ROSAT Deep Cluster Survey
Authors: Rosati P. 
Published: July 2007

AbstractDeep X‐ray surveys of galaxy clusters covering large solid angles offer ideal samples for studying the evolution of the large scale structure in the Universe. I review here some recent results from the ROSAT Deep Cluster Survey (RDCS), particularly, on the study of the evolution of the abundance of galaxy clusters over a large redshift range. The optical identification of RDCS sources have revealed a significant fraction of clusters at >z > 0.5. The observed X‐ray Luminosity Function out to z ⋍ 0.8 and the faint cluster number counts from the RDCS, when combined with previous results of the Einstein Extended Medium Sensitivity Survey, provide a much improved observational picture of the evolution of clusters in the X‐ray band, revealing a slowly evolving population of galaxy clusters since at least z ⋍ 0.8. The theoretical interpretation of these findings in the framework of theories of structure formation will still be subject of much debate in the years to come. The construction of large samples of clusters out to z ∽ 1 and beyond appears to be a challenging task even with the next generation of X‐ray satellites (AXAF, XMM).