bluuebunny/crossref_metadata_2025_split huggingface dataset:
Photometric catalogue of Shakhbazian compact groups of galaxies. I
Authors: Stoll D. , Tiersch H. , Oleak H. , Baier F. , Macgillivray H. T. 
Published: July 2007

AbstractCompact groups of galaxies are fruitful laboratories to study such processes as dynamical friction, tidal interaction, collision, and galaxy mergers. The largest survey of compact galaxy groups is the one of Shakhbazian, Petrosian, Baier, Tiersch. A programme to evaluate photometrical properties of the galaxies in the Shakhbazian groups has been started using the COSMOS/UKST catalogue of the Southern sky with δ ≤ + 2°30′. About a quarter of the Shakhbazian groups lie south of this declination limit. A list of 24 groups (Shkh 21, 24, 27, 30, 32, 33, 35, 81, 82, 83, 140, 141, 143, 144, 145, 146, 147, 148, 151, 152, 154, 261, 262, 263) is our first result.
Programme of the Galactic meridian: Star counts and Galactic models 2. Distribution of absolute proper motions
Authors: Andruk V. , Kharchenko N. , Schilbach E. , Scholz R.‐D. 
Published: July 2007

AbstractA comparison of the observed distribution of absolute proper motions with a kinematical model of the Galaxy is presented. Proper motions with respect to galaxies were obtained for about 40 000 stars along the main Galactic meridian and in two fields near the North Galactic pole (programme MEGA). The Galaxy is considered as composed of the disk (main sequence and disk red giants), the thick disk and spheroid populations. For each subsystem, spatial velocity components and their dispersions were computed. The distribution of kinematical parameters were modelled for stars located in different directions of the Galaxy.
The Cygnus X region XXI. Radio emission at 1420 MHz from Cyg OB2 stars and two probable cometary HII regions
Authors: Wendker H. J. , Higgs L. A. , Landecker T. L. 
Published: July 2007

AbstractWe have searched our previously published radio surveys of the Cygnus X region for faint radio point sources that may be associated with luminous stars of the Cyg OB2 association. Five positional coincidences have been found between stars and 1420 MHz radio sources. A particularly interesting example is the Wolf‐Rayet star VCLS 146, which has shown a rapid change in 1420 MHz flux density. In addition, sensitive upper limits have been derived for the emission from 14 early‐type stars, which help establish the time history of their non‐thermal radio emission. Two radio features have been detected which have the properties of cometary HII regions, except that they are several arcminutes in size. Their detection provides evidence of recent star formation in Cyg OB2.
Orbital elements of Minor Planets
Authors: Scardia M. , Ghiringhelli D. , Debehogne H. 
Published: July 2007

AbstractOrbital elements of the numbered minor planets 4209 ‐ Briggs, 5177 ‐ Hugowolf and preliminary orbital elements of the unnumbered minor planets 1988 RL4, 1989 CE8 and 1989 DJ are given.
Does the ellipticity of globular clusters correlate with luminosity?
Authors: Schmidt K.‐H. 
Published: July 2007

AbstractUsing the data by Geyer et al. (1983) and by White and Shawl (1987) it has been looked for the dependence of the ellipticity of Galactic globular clusters on luminosity. There is evidence that the moderate bright objects are the roundest, while the most luminous as well as the weaker globulars are more flattened, on the average.
Magnetic field of solar prominences: The procedure of radio observations
Authors: Apushkinskij G. P. , Topchilo N. A. , Tsyganov A. N. , Nesterov N. S. 
Published: July 2007

AbstractThe first successful radio astronomical results of measurements of the magnetic field of solar prominences are presented. The accuracy of polarization and magnetic field observations is 3 · · 10−4 and 2 G, respectively. The observations were made by the 22‐meter radio telescope of the Crimean Astrophysical Observatory at wavelengths of 8 and 13.5 mm. It has been found that the value of the magnetic fields coincides with the optical one (from 7 to 30 G), but the image of radio polarization differs from the intensity.
Catalogue of Shakhbazian compact groups of galaxies. VIII
Authors: Stoll D. , Tiersch H. , Cordis L. 
Published: July 2007

AbstractThe eighth part of the catalogue of Shakhbazian groups contains the positions and references of all the galaxies of the following 48 groups (north of δ > + 2°30'): Shkh 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200, 201, 202, 203, 204, 205, 207, 208, 209, 210, 211, 212, 213, 214, 215. For the estimation of the coordinates the Digitized Sky Survey was used.
Cyclotron spectroscopy of VV Puppis
Authors: Schwope A. D. , Beuermann K. 
Published: July 2007

AbstractWe present phase‐resolved spectrophotometric observations of VV Puppis obtained during two different states of accretion. We confirm the detection of cyclotron lines from emission regions at both poles (Wickramasinghe et al. 1989) having significantly different field strength of B1 ≃ 31 MG and B2 ≃ 54 MG. Our phase‐resolved data allowed the detection of phase‐dependent wavelength shifts of the cyclotron lines from the main accretion pole which is due to the varying aspect of the observer. A corresponding motion of the cyclotron lines from the secondary pole appears likely.Compared to 1984, the cyclotron lines from the main pole appeared redshifted in 1989, during an episode of higher system brightness. This shift can be explained assuming either different locations of the accretion spot and, hence, variations of the magnetic field, or variations of the plasma temperature both triggered by variations of the mass accretion rate.The cyclotron lines from the second pole do not show such changes suggesting that the coupling region for the weakly accreting pole is more or less stationary whereas the coupling region of the main pole varies in space, most likely depending on the mass accretion rate.
Catalogue of Shakhbazian compact groups of galaxies. X
Authors: Stoll D. , Tiersch H. , Cordis L. 
Published: July 2007

AbstractThe tenth part of the catalogue of Shakhbazian groups contains the positions and references of all the galaxies of the following 35 groups (north of δ > +2°30'): Shkh 341, 342, 343, 344, 345, 346, 347, 348, 349, 350, 351, 352, 354, 355, 356, 358, 359, 360, 361, 362, 363, 364, 365, 366, 367, 368, 369, 370, 371, 372, 373, 374, 375, 376, 377. For the estimation of the coordinates the Digitized Sky Survey was used.
A survey of main‐belt asteroids. II. Positions and improved orbital elements for 62 unnumbered asteroids
Authors: Lagerkvist C.‐I. , Hahn G. , Lundström M. , Lagerros J. S. V. , Hernius O. , Tancredi G. 
Published: July 2007

AbstractMore than 7 000 positions of moving objects were detected on 33 films obtained with the Schmidt telescope at the European Southern Observatory in Chile during August and September 1995. The majority of these asteroids are previously unobserved. This paper presents the results for 62 unnumbered asteroids with provisional designations found in the fields. References to the derived positions for these asteroids are given and improved orbital elements have been calculated using all available positions.
Pressure of charged particle flows in ambient magnetic fields
Authors: Ponomarjov M. G. 
Published: July 2007

AbstractThe magnetic field effect on the pressure of charged particle flow is described analytically. Low‐density charged‐particle fluxes, for which a kinetic, rather than fluid description is appropriate, are simulated. Both impulsive and transient injectors of charged particles are considered. Maxwellian and shifted maxwellian velocity distributions of injected particles are dealt with. Obtained results allow (i) to simulate the acceleration of space objects (for instance, space platforms) under the pressure of ion beams, which are focused by the ambient magnetic field, (ii) to calculate the magnetic field, which must be generated for the effective control of influences of a jet from electric rocket engines on a spacecraft and space station.
Spectroscopy of Blue Compact Galaxies
Authors: Esposito A. A. M. , Rafanelli P. , Lipovetskid̊ V. A. 
Published: July 2007

AbstractBlue Compact Galaxies (BCGs) are gas‐rich systems undergoing very massive starburst events which involve the entire galaxy. We performed a spectroscopic study of 12 BCG in order to determine metallicities and helium content. Some objects show presence of broadened emission lines, probably due to internal motion of the interstellar medium, caused by intense stellar winds and supernova explosions.
Spectroscopic analysis of the nuclear and circumnuclear regions of the Seyfert 2 galaxy NGC 7130
Authors: Radovich M. , Rafanelli P. , Birkle K. , Richter G. M. 
Published: July 2007

AbstractWe discuss here the spectroscopic properties of the Seyfert 2 galaxy NGC 7130 (= IC 5135). Emission line regions were isolated and line ratios were measured and fitted with photoionization models; this allowed to discriminate between thermal and non thermal ionization in the circumnuclear regions. Massive star formation is likely to occur at projected distances from the nucleus ≫ 2 kpc: line profiles in these regions suggest the presence of outflows of gas due to stellar winds from hot massive stars.
Galaxy activity and interaction: the optical view
Authors: Rafanelli P. , Temporin S. , Baruffolo A. 
Published: July 2007

AbstractThe relevance of interaction to the presence of Seyfert or starburst activity in the nuclei of galaxies is examined. We focus the attention on the close environments of spectroscopically selected samples of Seyfert‐1, Seyfert‐2 and starburst galaxies. In particular the results of a statistical procedure aimed at finding physical pairs are tested with redshift measurements of the identified pairs. Seyfert and starburts galaxies show an excess of physical companions compared to normal galaxies. This excess tends to increase as one moves from Seyfert to starburst galaxies.
Schmidt survey in the Galactic anticentre direction. 1. Investigation of open clusters
Authors: Kharchenko N. , Andruk V. , Schilbach E. 
Published: July 2007

AbstractA study of four open clusters in the direction of the Galactic anticentre (l = 186°, b = +2°) is presented. In a field of 8.32 square degrees proper motions and B magnitudes for about 79 000 stars down to 19.5 were determined on Tautenburg Schmidt plates. For more than 15 500 of them U magnitudes down to 17.3 could be obtained. Additionally, OCA Schmidt plates were used to determine V, R magnitudes in a larger field of 24.45 square degrees for 271 000 stars down to V = 18.2. For stars brighter than V = 15.5 an accuracy of about 1.5 mas/yr has been estimated for proper motions. The rms errors of stellar magnitudes and colour indices are 0.09 – 0.12 mag.Several open clusters have been already known in this direction of the sky, e.g. NGC 2168 or M 35 (C 0605+243), NGC 2158 (C 0604+241) and IC 2157 (C 0601+240). Inspecting the plates and analysing the colour‐magnitude diagrams and published data, we could identify an additional anonymous cluster C 0605+242 with a projection on the sky near the centre of M 35 but at a larger distance from the Sun.The cluster membership determination was carried out using information on spatial and proper motion distributions of stars in the field. The colour‐magnitude diagrams were derived down to the limiting stellar magnitude. For each cluster the interstellar extinction Av, the diameters of the core and corona, the ages and spatial velocity components (V,W) relative to the LSR in the Y,Z – Galactic directions were determined.The distances to the clusters of 960 pc, 2 600 pc, 2 520 pc and 3 700 pc were obtained for M 35, IC 2157, C 0605+242 and NGC 2158. They show the loci of the clusters in the Local and Perseus spiral arms and at external border of Perseus arm, respectively.
Are short‐time variations of the solar S‐component emission identical with microwave bursts?
Authors: Nefedev V. P. , Smolkov G. Ya. , Agalakov B. V. , Krüger A. , Hildebrandt J. 
Published: July 2007

AbstractExtended time series (time resolution about 2–3 min) of spatially resolved observations (≫ 17 arcsec) in one dimension of solar S‐component sources obtained at the Siberian Solar Radio Telescope (SSRT) at 5.2 cm wavelength allow the detection of evolutional features of the growth and decay of active regions in the solar corona. Characteristic slow flux variations with timescales of about 1–2 hours occurring during the decay phase of the radio emission in the low corona above plages and sunspots are compared with recently detected step‐like flux increases on timescales of about 10–20 min followed by quasi‐constant periods appearing in the initial phase of the development of active regions. Superimposed on this basic behaviour, also fluctuations at shorter timescales (or even periodic oscillations) have been observed.As it is well known from emission‐model calculations, the variations of the S‐component radiation can be due to variations of the magnetic field and/or changes of the energy of the radiating particles, which is basically the same emission mechanism as for microwave bursts. Since the “S‐component” is originally defined by its long timescale behaviour derived from whole‐Sun flux density measurements, the presently detected small‐timescale features in S‐component sources require either a revised definition of S‐component emission or must be considered as “burst‐like”.
Proper motions, absolute magnitudes and spatial distribution of Zirconium stars
Authors: Chanturiya S. M. 
Published: July 2007

AbstractThe computational algorithm to determine the the proper motions of Zirconium stars on the basis of catalogues “Carte du Ciel” and on the recent photographic observations carried out with the 70cm Abastumani meniscus telescope is presented. It allowed to determine the proper motions of 288 stars in the region around α Per with a rms error of ± 0,004 arcsec/yr. Applying the method proper motions of 74 Zirconium stars and 146 control stars have been obtained. The error of proper motions obtained for the North Zone (δ > −2°) 109 AGK3 control stars is ± 0.006 arcsec/yr.On the basis of proper motins absolute magnitudes were separately calculated for the MCLPZS and LASZS.For the MCLPZS the average absolute visual magnitude at maximum, corresponding to the mean period of P = 350 days, equals −3ϕm.9. For the LASZS the mean absolute visual magnitude, corresponding to the apparent median ones equals −1ϕm.9. Low luminosity (Mv = −1ϕmϕ9) Zirconium stars escape rather far (at a distance of up to 2 kpc) to the South from the Galactic plane into the region l ∼ 240 – 260°, where its assumed to be a connection with the Large Magellanic Cloud (LMC) begins to appear. Low luminosity Zirconium stars are weakly correlated with position of the Galaxy spiral arms. The MCLPZS show a somewhat other distribution.
The X‐ray background and the AGN X‐ray luminosity function
Authors: Hasinger G. 
Published: July 2007

AbstractROSAT deep and shallow surveys have provided an almost complete inventory of the constituents of the soft X‐ray background which led to a population synthesis model for the whole X‐ray background with interesting cosmological consequences. According to this model the X‐ray background is the “echo” of mass accretion onto supermassive black holes, integrated over cosmic time. A new determination of the soft X‐ray luminosity function of active galactic nuclei (AGN) is inconsistent with pure luminosity evolution. The comoving volume density of AGN at redshift 2–3 approaches that of local normal galaxies. This indicates that many larger galaxies contain black holes and it is likely that the bulk of the black holes was produced before most of the stars in the universe. However, only X‐ray surveys in the harder energy bands, where the maximum of the energy density of the X‐ray background resides, will provide the acid test of this picture.
Isolated neutron stars in the ROSAT Survey
Authors: Haberl F. , Motch C. , Pietsch W. 
Published: July 2007

AbstractTwo very promising candidates for isolated old neutron stars (IONS) accreting interstellar matter were found so far in ROSAT data. RXJ1856.5–3754 and RXJ0720.4–3125 are soft X‐ray sources with very similar X‐ray spectrum, long term temporal behaviour and faint optical counterpart. In addition RXJ0720.4–3125 shows 8.4 s pulsations which allow to constrain the magnetic field strength of the neutron star. We carried out a search for additional IONS with similar properties in the ROSAT all‐sky survey data of the galactic plane and present RXJ0806.4–4123 as further promising candidate.
Astronomische Nachrichten — Instructions for Authors Using LATEX Markup
Authors: Fritze K. , Schwope A. D. 
Published: July 2007

AbstractThis article gives instructions for authors of Astronomische Nachrichten (AN) how to prepare an article according to the current LATEX style. The source code of this paper may be used by the authors of AN as a template. For further information about the journal please look at the World Wide Web (URL http://www.aip.de:8080/∽astr_n/) where this text and accompanying style files can be obtained from.
Mass distribution in the open cluster NGC 1664
Authors: Missana M. , Missana† N. 
Published: July 2007

AbstractWe start with the hypotheses that the cluster space is limited by an ellipsoid with a semiprincipal axis directed to the observer and that the star density inside of concentric ellipsodal layers remains constant, although varying from layer to layer. It results that the mean star mass at the periphery of the cluster is 0.59 Sun masses smaller than that at the center.
The shapes of Shakhbazian compact groups of galaxies
Authors: Oleak H. , Stoll D. , Tiersch H. , Macgillivray H. T. 
Published: July 2007

AbstractWe have completed an investigation (preliminary results for which were reported in Oleak et al. 1995) into the shapes of Shakhbazian compact groups of galaxies. Ellipticites for 299 groups in the Shakhbazian survey have been examined using the technique proposed by Rood (1979) for deriving the average “flatness” of a large sample of objects. The distribution of the apparent axial ratios (g = b/a) for the groups is found to be broad with a mean of< b/a > ∽ 0.5. This distribution is compared with randomly generated spherical and elliptical model systems. The results confirm the findings of our earlier study: the frequency distribution of axial ratios for Shakhbazian groups is represented soley by a population of prolate spheroids with low intrinsic axial ratios, < q > = 0.3, σ = ∽0.17 (assuming random true orientations in 3D space). This now provides further strong evidence that the Shakhbazian groups are more highly flattened than either rich clusters or elliptical galaxies, and represent the most elongated systems yet found. The result also provides confirmation of the reality of the groups, since in the case of systems of chance line‐of‐sight superpositions of galaxies we would expect to see much higher axial ratios.
Application of principal component analysis to radio properties of Quasars
Authors: Denis‐Karafistan A. 
Published: July 2007

AbstractThe principal component analysis method has been applied to two samples of nearby and distant quasars with well known radio data. Relationships between physical parameters pertinent to radio morphology has been searched and the significant number of dimensions of the manifold has been found to be two. The results of this analysis confirm the existence of a redshift luminosity correlation for a subset of 36 nearby, but to a lesser extent for 43 distant, quasars. An anticorrelation seems to exist between luminosity and linear sizes for the last sample. On the other hand, application of this analysis to the above samples indicates no correlation between the viewing angle and the other physical parameters.
A review of diagnostic emission line ratios in the Narrow Line Region of Active Galactic Nuclei
Authors: Radovich M. , Hasinger G. , Rafanelli P. 
Published: July 2007

AbstractThe availability of new observing facilities both from ground and space such as the Keck 10m telescope and the Hubble Space Telescope is casting new light on the spectroscopic investigation of emission line galaxies. In particular, it is now possible to detect spectra with a significantly improved signal to noise ratio in a very wide wavelength range, from the ultraviolet to the near infrared (HST, Keck) and beyond (ISO is unveiling the far infrared domain). As we move to high redshifts, however, it is more likely that the observed spectra are given by the contribution of different components in the galaxy: in particular, this may be the case if an Active Galactic Nucleus (AGN hereafter) emitting a power‐law continuum is surrounded by regions with strong star formation activity. The identification of the source which ionizes the line emitting regions is then complicated by the fact that we are observing the integrated spectrum from regions which are ionized by different sources. In this paper we wish to review which line ratios may be used in order to discriminate between photoionization by young stars and power‐law continuum in the wavelength range from 1200 Å to 100 μm. To this aim we used the photoionization code Cloudy (Ferland 1996) to present a series of diagnostic diagrams showing the dependence of emission line ratios on the main input parameters of photoionization models in the case of one component models with gaseous clouds ionized by (1) a stellar continuum typical of an HII region and (2) a power‐law continuum typical of an AGN: these line ratios are plotted as isoratio maps for different values of the hydrogen density, ionization parameter and slope of the power‐law continuum. We then show how the results may be affected by more realistic assumptions about the environment of the ionized gas: to this aim, we show the effects on selected line ratios of (a) the presence of two populations of clouds with different densities and (b) an AGN surrounded by regions with strong star formation activity.
On the completeness of the lists of Compact Galaxy Groups
Authors: Tovmassian H. M. , Cardena O. , Tiersch H. 
Published: July 2007

AbstractIt is shown that the lists of Shakhbazian Compact Galaxy Groups (SCGGs) are not complete. The number of the detected groups in the strip between b = ±30° and b = ±20° is by four to five times smaller than expected. The most probable reason is that during the search for SCGGs it was hard to distinguish images of compact galaxies from that of stars on the POSS prints in dense areas of the sky at lower galactic latitudes. There is some deficit of the detected groups between 60° and 40° of the north galactic latitudes. The surface density of SCGGs in the southern galactic hemisphere between b = −50° and b = −30° is by about three times less than it is expected. Obviously, the southern sky has not been searched properly. The list of Hickson's groups is complete down to galactic latitude ±30°. However, some excess of HCGs is found in the southern hemisphere, where the surface density of the found groups is by about two times higher than that of in the northern hemisphere.