bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations of Eclipsing Dwarf Novae
Authors: Wood J. 
Published: July 2016

AbstractHigh Speed Photometry of four eclipsing dwarf novae, Z Cha, OY Car, HT Cas and IP Peg, is used to determine the orbital parameters and the masses of the two stars in each system. The mass ratio, q, and inclination, i, are found by constraining theoretical stream trajectories (Lubow and Shu 1975) to pass through the observed light centre of the bright spot eclipse. The light centre is defined as the point corresponding to the half flux points in the ingress and egress of the eclipse of the compact part of the bright spot. The theoretical stream width indicates that the centre of the stream must intersect the bright spot close to this point.
Continuum Distributions and Line Profiles of UX UMa-Type Novalike Systems
Authors: Haug K. 
Published: July 2016

AbstractCombined UV, optical and, in part, IR continuum distributions of the UX UMa-systems CPD-48°1577, V3885 Sgr, RW Sex and of the recently discovered cataclysmic system PHL 227 were determined from multi-wavelength spectroscopic and photometric data to search for general characteristics of these systems. The observed variations of the UV to IR spectral indices are qualitatively very similar for all systems, whereas the absolute values show significant differences in the far and near UV ranges. The wavelength dependence of the optical and IR spectral indices as well as the variations of the Balmer line profiles lie within the range of model spectra of optically thick and stationary accretion disks with stellar atmosphere characteristics. The different behavior of the far UV spectral indices can be explained by the excess radiation from an extended and optically thick boundary layer, which depends mainly on the orbital inclination.
The Ultrashort Period Dwarf Nova SW Ursae Majoris
Authors: Shafter A.W. , Hill J.A. , Robinson E.L. , Szkody P. , Thorstensen J.R. , Wood M.A. 
Published: July 2016

AbstractSW UMa is an unusual dwarf nova in several respects. Recent observations by Robinson et al. (1986) have established that SW UMa is an SU UMa system, while Shafter, Szkody, and Thorstensen (1986) have presented evidence suggesting that SW UMa may be a DQ Her system as well. If the DQ Her classification is confirmed then SW UMa will be the only system to have this dual classification. Finally, time resolved spectroscopy of SW UMa has revealed the presence of an S-wave component in the Ha emission which has an unexpected phasing relative to the line wings.
Red Spectroscopy of IP Pegasi
Authors: Martin J.S. , Jones D.H.P. , Smith R.C 
Published: July 2016

AbstractTime resolved spectroscopy of the dwarf nova IP Pegasi in the range λλ 7670–8320Å shows absorption lines originating from the cool secondary. A radial velocity curve for this component has been derived by cross-correlation with a normal M star. The curve has semi-amplitude K2 = 288.3 ± 4 km s−1, and is slightly distorted. This distortion is equivalent to an orbit with an apparent eccentricity of 0.075 ± 0.024. The mass function of the primary is 0.394 ± 0.016M⊙. From this we derive constraints on the component masses of 0.62 < M1 < 1.14M⊙ and 0.17 < M2 < 0.71M⊙. The red star has a radius in the range 0.32 < R2 < 0.51R⊙ and is probably on the main sequence.
Spectroscopic Evolution of Nova Vul 1984 No. 1 (PW Vul) and No. 2
Authors: Rosino L. , Iijima T. 
Published: July 2016

AbstractSpectroscopic observations of two novae (Nova Vul 1984 No. 1 and No. 2) have been carried out at the Asiago Observatory from the moment of their discovery up to now. A short preliminary description of the spectral characteristics and evolution of these two novae is reported together with a brief comparison of their properties.
X-Ray Observations of Cataclysmic Variables
Authors: Osborne J.P. 
Published: July 2016

AbstractThe X-ray observatory EXOSAT spent over 1000 hours observing cataclysmic variables. Some of the major results reviewed here are: soft X-ray light curve changes in AM Her objects, orbital effects in the X-ray light curves of intermediate polars and U Gem, regular behaviour in the inter-outburst X-ray flux of VW Hyi, and X-ray emission from the tenuous remnant of the recent recurrent nova RS Oph. The ability of EXOSAT to make long uninterupted observations at high sensitivity over a broad spectral range and to react quickly to cosmic events has yielded a dataset of a quality that will not be surpassed for many years.
A Simultaneous X-Ray and Optical Study of TT Arietis
Authors: Hudec R. , Valníček B. , Peřesty R. , Wenzel W. , Richter G.A. , Goetz W. , Hacke G. , Huth H. , Schult R. , Pfau W. , Reimann G.-H. , Stecklum B. , Tremko J. , Mrkos A. , Schpitshka I.V. , Kojevnikov V.P. , Kumshiashvili M.I. , Oprescu G. , Dumitrescu A. , Cristescu C. , Bojack W. , Patkós L. , Toth I. , Oláh K. 
Published: July 2016

AbstractPrelimary results of an extended program of coordinated X-ray and optical observations of TT Ari are presented. The object was observed on August 21/22 1985 both in X-rays (EXOSAT) and optical range, about 100 days after the return to the active state. The first detailed simultaneous study of TT Ari in active state indicates the presence of strongly absorbing structure in the system.
Implications from the Shape of the Viscosity-Surface Density Relation
Authors: Meyer-Hofmeister E. 
Published: July 2016

AbstractWe present results of new vertical structure computations for cool, convective accretion disks. The influence of the uncertainty in the low temperature opacities on the cool branch of the viscosity-surface density relation is investigated. We discuss how the shape of this relation allows a prediction of temperatures in the accretion disk during the onset of an outburst and we compare this with observations for VW Hydri by Hassall (1984).
White Dwarf Models of Supernovae and Cataclysmic Variables
Authors: Nomoto K. , Hashimoto M. 
Published: July 2016

AbstractIf the accreting white dwarf increases its mass to the Chandrasekhar mass, it will either explode as a Type I supernova or collapse to form a neutron star. In fact, there is a good agreement between the exploding white dwarf model for Type I supernovae and observations. We describe various types of evolution of accreting white dwarfs as a function of binary parameters (i.e, composition, mass, and age of the white dwarf, its companion star, and mass accretion rate), and discuss the conditions for the precursors of exploding or collapsing white dwarfs, and their relevance to cataclysmic variables. Particular attention is given to helium star cataclysmics which might be the precursors of some Type I supernovae or ultrashort period X-ray binaries. Finally we present new evolutionary calculations using the updated nuclear reaction rates for the formation of O+Ne+Mg white dwarfs, and discuss the composition structure and their relevance to the model for neon novae.
Possible Role of the White Dwarf in Grain Formation in Cataclysmic Variable Systems
Authors: Albinson J.S. , Evans A. 
Published: July 2016

AbstractWe consider the possibility that carbon, in the form of the allotrope carbyne, might form in the atmosphere of the white dwarf in a cataclysmic variable system, and be expelled from the system by radiation pressure. It seems that, under some circumstances, cataclysmic variable systems may indeed have carbon dust in their vicinity.
Optical Short-Time Variations in GK Persei during the 1983 Outburst
Authors: Steinle H. , Pietsck W. 
Published: July 2016

AbstractDuring the August 1983 outburst of the old nova GK Persei observations with EXOSAT showed for the first time a 351 second periodicity in X-rays.Our fast photometry (U(B)V with 25 sec time resolution) was made at the end of the outburst in the nights of September 29 , and October 1–3 , using the 2.2 meter telescope at Calar Alto (Spain).Optical variations up to 10% in U and 4% in V with periodicities in the range 350 to 360 seconds were found, lasting only for few cycles.A comparison with the extrapolated prediction of the X-ray maxima did not show a coincidence, but rather an anticoincidence in several cases. This supports a model of reprocessed X-rays at the inner edge of an accretion disk.
The Nature of Recurrent Novae
Authors: Webbink R.F. , Livio M. , Truran J.W. , Orio M. 
Published: July 2016

AbstractThe observational properties and outburst histories of each member of the small class of recurrent novae are reviewed, with the objective of identifying the outburst mechanisms for these systems. Examples are found of both accretion-powered outbursts (T CrB and RS Oph) and thermonuclear-powered outbursts (T Pyx and U Sco). Outburst properties which might be used in future to distinguish between these mechanisms are identified. Many erstwhile recurrent novae (VY Aqr, RZ Leo, V616 Mon, V1195 Oph, V529 Ori, WZ Sge, and V1017 Sgr) appear to be misclassified examples of other types of cataclysmic variables.
Observational Evidence for the Two Types of Dwarf Nova Outbursts
Authors: Smak J. 
Published: July 2016

AbstractObserved characteristics of outbursts of eight dwarf novae are compared with those predicted for the two types of outbursts by the disk instability theory. OY Car, U Gem, VW Hyi, and WX Hyi are identified as Type A, while RX and, SS Cyg, AH Her, and CN Ori - as Type B.
Zeeman Features from Accretion Columns in AM Herculis-Type Systems
Authors: Wickramasinghe D.T. , Tuohy I.R. , Visvanathan N. 
Published: July 2016

AbstractAbsorption features seen in the bright phase spectra of E1405−451 are identified with Zeeman features of Hα originating from cool (T-104-105 °K) material surrounding the accretion shock. The presence of apparently unshocked material surrounding the cyclotron emission region is surprising and may indicate that accretion occurs onto a larger fraction of the stellar surface than had previously been thought possible.
Changes in the Soft and Hard X-Ray Light Curves of the AM Her Object E1405−451
Authors: Osborne J.P. , Cropper M. , Cristiani S. 
Published: July 2016

AbstractThe preliminary results of EXOSAT and contemporaneous optical observations of E1405−451 (V834 Cen) in 1985 and 1986 are presented. In the latter of the two observations the soft X-ray light curve was observed to be quite different to that seen in all previous observations, but similar to the optical light curve and the new soft X-ray light curve of E2003+225. A phase shift of the broad soft X-ray eclipse was also observed. The hard X-ray and optical light curves have also undergone small changes.
Polarimetry of ST LMi (CW1103+254)
Authors: Cropper M. 
Published: July 2016

AbstractWhite light simultaneous photometry and linear and circular polarimetry is presented for the AM Her variable ST LMi. Linear polarization evident throughout the faint phase is tentatively attributed to electron scattering from gas in the accretion column at heights greater than 5Rwd above the surface. The values of inclination and magnetic colatitude are revised to take into account the height and extent of the cyclotron emitting region which are also determined. A model of two closely connected emitting regions is proposed to account for the asymmetries observed in the light curve and polarization data for this and other AM Her systems. The cyclotron and hard x-ray emitting regions are found to be coincident, which eliminates the region above the shock as the source of polarized light. The shock height is found to be too low and the soft x-ray flux too large for the standard radiative shock model to apply.
Models for Optical and Infrared Polarization from CW1103+254
Authors: Chanmugam G. , Wu K. 
Published: July 2016

AbstractMultiband observations of the AM Herculis-type binary CW1103+254 show significant circular polarization (~ 13%) in the J band. Recently, a model with high temperature (kT ~ 20 keV) and small dimensionless plasma parameter (Λ ~ 10 4) was suggested for the emitting region. However, it gives negligible polarization in the J band. In this paper, a method, in which the J band polarization and the peak frequency v* of the spectrum are taken into account, is used to determine T and Λ. For the viewing angle θ = 80° and the magnetic field B = 30MG, we find that kT = 5.0 keV and Λ = 106. The temperature of the emitting region is close to the value (kT = 8.7 keV) derived for the region emitting cyclotron lines in VV Puppis. If these radiations arise from the post-shock regions, then these temperatures are significantly lower than those predicted by standard accretion models or the shock structure is inhomogenous and more complex than previously assumed.
CCD Observations of X-Ray Binaries
Authors: Steinle H. , Pietsch W. , Gottwald M. , Graser U. 
Published: July 2016

AbstractDuring two observation periods in 1984 and 1985 we monitored the faint optical counterparts of seven X-ray binaries with a CCD camera attached to the Cassegrain-focus of the 2.2 m telescope at Calar Alto , Spain. The observation periods were 1984, September 25–27 , and 1985, August 8–15.The transient sources 4U0042+32 and 4U0115+63 showed no active state.The search for an optical candidate of 4U0142+62 did not reveal any object mv ≤ 24 within the EXOSAT error box.Within the EXOSAT error box of EXO2030+37 the reddest object was found to be very faint in blue in contrast to the blue Palomar plate.The analysis of the other three observed sources 4U1837+04 , 1H1929+509 , and 4U2129+47 is not yet finalized , but no unexpected bright or faint state of the sources has been found. 4U2129+47 is still in its present low state (mv = 18) , lasting at least since 1983.
The Solution of the X-Ray Heating Light Curve for 4U2129+47/V1727 Cyg
Authors: Pavlovski K. 
Published: July 2016

AbstractThe X-ray heating light curve of the binary X-ray source 4U2129+47/V1727 Cgy is synthesized. A reliable solution is obtained only after accounting for the influence of an accretion disk. Model parameters achieved by the best fit are discussed. The solution is also discussed in the context of an extended OFF state.
Theoretical Line Profiles from a Symbiotic System
Authors: Schmid H.M. , Vogel M. 
Published: July 2016

AbstractA model for a symbiotic system is presented which is not spherically symmetrical. The system consists of a cool, mass losing giant and a hot star. The stellar wind from the cool star is radiatively ionized by the hot companion, and the resulting nebular lines are emitted mainly close to the cool star. Due to the elliptical orbit, the line fluxes change with time because of the varying separation of the stars. The line profiles vary from symmetrical to asymmetrical, depending on the angle between the line of sight and the axis of symmetry. The calculated line profiles are compared with observed UV lines of the symbiotic star HBV 475.
Periodic Variations in the Symbiotic Star Spectra
Authors: Mikolajewska J. 
Published: July 2016

AbstractPeriodic variations of emission line intensities and radial velocities in three S-type symbiotic stars: BF Cyg, CI Cyg and AX Per are presented and discussed. The behavior of emission lines is different in these objects and suggests that significant differences in physical conditions and geometry may occur in these seemingly similar systems.
AG Pegasi: the Episode of Minimum 1985
Authors: Boyarchuk A.A. , Belyakina T.S. , Tarasov A.E. , Glagolevski Yu.V. 
Published: July 2016

AbstractThe profiles of the emission lines of Hα, HeI 587 6 and HeII 5411 in the spectrum of AG Peg obtained in the minimum of 1985 are described. The light curves in UBVRI system are presented. No indication for the presence of a magnetic field exceeding the error of observations (200 gauss) has been found.
System of Astronomical Constants in Hindu Astronomy
Authors: Bandyopadhyay Amalendu , Bhatnagar Ashok Kumar 
Published: July 2016

AbstractAstronomical constants such as the length of the solar year, sidereal and synodic periods of revolutions of the Moon and five brighter planets have been computed using the system of astronomy in ancient and mediaeval India and a comparison made with their modern values. The modern values of the Moon’s inequalities have been compared with that of the earlier Hindu astronomical reckonings. Also, the Equation of the Centre of the Sun as determined in the period 500 A.D. to 1150 A.D. has been discussed in relation to corresponding modern values.
Analysis of Images with the APM System at Cambridge
Authors: Kibblewhite E. , Bridgeland M. , Bunclark P. , Cawson M. , Irwin M. 
Published: July 2016

The Automated Photographic Measuring (APM) system at Cambridge was started many years ago to analyse Schmidt plates, and its progress has been reported at a number of these conferences. Only brief details of its design will be given in this paper.The system consists of a very accurate laser-beam scanning microdensitometer connected to a series of on-line computers. The microdensitometer (Figure 1) uses a 5500 kg x-y table to position the plate. The plate transmission is digitised to 12-bit accuracy at a rate of one sample every 4 microseconds, although the image processing hardware limits this speed in practice. Special-purpose hardware exists to convert the transmission measurements into density or intensity estimates, to smooth the spot-size digitally, to measure the background and to compute image parameters.
M.A.M.A. Project: A New Measuring Machine in Paris
Authors: Guibert Jean , Charvin Pierre , Stoclet Patrick 
Published: July 2016

SummaryA new photographic measuring machine is under construction at Paris Observatory. The amount of transmitted light is measured by a linear array of 1024 photodiodes. Carriage control, data acquisition and on line processing are performed by microprocessors,a S.E.L. 32/27 computer, and an AP 120-B Array Processor. It is expected that a Schmidt telescope plate of size 360 mm square will be scanned in about one hour with pixel size of ten microns.
Images From Large Schmidt Telescopes
Authors: Brown D.S. , Dunlop C.N. , Major J.V. 
Published: July 2016

AbstractCalculations have been made of the intensity distribution of star images formed at the focal surface of large Schmidt telescopes. The calculations take account of atmaspheric seeing, aperture diffraction, manufacturing errors, chromatic errors in the corrector plate, scattering in the emulsion, photographic response and grain structure. The results are expressed in terms of simulated microdensitometer scans across the processed emulsion.Results are given for a system S1(1.24m, f/2.5) similar to the 48" U.K. Schmidt (with both singlet and achromat corrector plates) for several combinations of correctors and filters using Illa-J emulsion for recording. The improvement in performance expected from the use of larger Schmidt telescopes is discussed and results are given for two designs with 2.5 metres aperture, S2(2.5m, f/2.5) and S3(2.5m, f/3).
The Hipparcos Image
Authors: Gall J-Y. Le , Saisse M. 
Published: July 2016

AbstractOne presents hereafter the HIPPARCOS satellite payload which is mainly constituted by a Schmidt telescope; a possible way to approximate the Schmidt mirror elliptic deformation profile is explained. Then, the signal expected from the optical chain is briefly described and one displays a residual chromatic effect which may introduce errors in the measure. To conclude, numerical values of this effect are given and one shows the necessity to take it into account in the data reduction process.
Discovery of New Bright Peculiar Stars of the Northern Sky
Authors: Bidelman William P. 
Published: July 2016

AbstractI am now engaged in an objective-prism program directed toward the discovery of new peculiar and interesting stars in most of the northern sky. The plates utilized are 20-min. blue exposures taken with the Warner & Swasey Observatory’s Burrell Schmidt telescope, now located on Kitt Peak. The dispersion of the spectra is 108 A/mm at Hγ, the limiting magnitude about mpg =10.5, and the plate quality generally excellent. This paper discusses the history and status of the project and gives examples of the variety of objects being found.
La Mesure Des Vitesses Radiales Avec Un Prisme Objectif Associe A Un Telescope De Schmidt
Authors: Fehrenbach Ch. , Burnage R. 
Published: July 2016

AbstractRadial velocity measurements with an objective-prism mounted on a Schmidt telescope.A 62 cm diameter objective-prism is mounted on the CNRS-University of Liège Schmidt telescope at the Haute Provence Observatory. The field is 4 x 4° and the limiting magnitude is 12.5 on IllaJ hyper-sensitised plates. The dispersion is 200 A mm-1 at 4220 A. The plates are measured with a special machine and data are reduced by means of a computer with a correlation method. Stars of all spectral types are measured. The probable error is of some 4 km sec -1 over a mean of at least 3 plates. Already several lists of radial velocities of stars belonging to field situated at -30° of galactic latitude have been published. We have also started radial velocity observations for the Hipparcos Program.
Surface Photometry of Pure Disk Galaxies
Authors: Carignan C. 
Published: July 2016

AbstractSurface photometry from U.K.S.T.U. plates in U, BJ and RF is presented for the three Sculptor Group galaxies NGC 7793, NGC 247 and NGC 300. Their photometric parameters are derived and compared to those of M33. Our color maps are used to sort out the data into blue and red pixels where the blue pixels profiles are expected to be rather irregular, representative of the clumpy locations of areas of recent star formation while the red pixels profiles should approximate the smoother distribution of the old disk population.
The Optical Variability of 3C 446
Authors: Barbieri C. , Cristiani S. , Romano G. 
Published: July 2016

3C 446 is one of the most violently variable quasars.Its optical variability has been studied for instance by Barbieri et al. (1978), by Pollock et al. (1979) and by Miller (1981). The quasar exibits periods of prolonged activity, with amplitude exceeding 3 mag, and with intraday significant variations. We observed 3C kkG in the last month of Aug. 1983, finding the quasar of unpreceeded brightness.Three plates were obtained with the 67/92 cm Schmidt telescope on Aug. k, 9 and 11, and in all three the quasar is seen at B=15.1, the brightest value ever recorded. We have only one previous plate of low quality taken on July 31, and 3C kkG is fainter by approximately 0.7 mag. Finally, on two plates taken the 27th of Aug. with the 182 cm telescope at Cima Ekar we see it again down to B=16.2.
The Physical Nature of the Blue Objects in the Field Of BD+15°2469 (Virgo Cluster)
Authors: Erculiani L. Abati , Lorenz H. 
Published: July 2016

This is the second Asiago blue objects field studied to determine the physical nature of ultraviolet excess objects (UVX) at high galactic latitudes using low dispersion objective prism plates. As the first of this series ( Abati 1982 )this work has a double aim: 1.to determine the proportions in the component populations of UVX objects selected by the two-colour method on Schmidt telescope plates;2.to determine the surface density of quasars down to a limiting magnitude m = 18 mag.
Optical Identifications of Radio Sources with Accurate Positions Using the UKST IIIa-J Plates
Authors: Savage Ann , Jauncey David L. , Batty Michael J. , Gulkis S. , Morabito D.D. , Preston R.A. 
Published: July 2016

SummaryThree radio identification programmes are described which are drawn from radio samples with accurate radio positions (< 2" arc rms). Optical identifications are being made on the basis of radio-optical positional coincidence alone, without regard to colour or morphology, using the UKST IIIa-J sky survey to a limiting magnitude of 22.5. Some preliminary results are presented.