A catalogue of eclipsing variables
A new catalogue of 6330 eclipsing variable stars is presented. Thecatalogue was developed from the General Catalogue of Variable Stars(GCVS) and its textual remarks by including recently publishedinformation about classification of 843 systems and making correspondingcorrections of GCVS data. The catalogue1 represents thelargest list of eclipsing binaries classified from observations.
|
Catalogue of Algol type binary stars
A catalogue of (411) Algol-type (semi-detached) binary stars ispresented in the form of five separate tables of information. Thecatalogue has developed from an earlier version by including more recentinformation and an improved layout. A sixth table lists (1872) candidateAlgols, about which fewer details are known at present. Some issuesrelating to the classification and interpretation of Algol-like binariesare also discussed.Catalogue is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/417/263
|
Beobachtungsergebnisse Bundesdeutsche Arbeitsgemeinschaft fur Veranderlichen Serne e.V.
Not Available
|
Archive of Photometric Plates Obtained at Cluj Astronomical Observatory
The archive of photometric plates obtained at the AstronomicalObservatory of Cluj in the period 1952-1974 is presented. The plateinventory is made within the framework of the Wide-Field Plate Databaseproject. The plates were taken in the regions around 110 variable stars(eclipsing variables and RR Lyrae-type stars), as well as in somecomparison stars regions.
|
Optical positions of 55 radio stars from astrolabe observations from the Yunnan Observatory
The observations by the photoelectric astrolabe at Yunnan Observatoryrelative to the Hipparcos Catalogue and the optical positions of 55radio stars were obtained from observations between 1991 and 2000. Theyall resulted from processing the photon counts obtained by means of theastrolabe after the automation of the instrument. There are 46 stars incommon with the Hipparcos Catalogue. Tables \ref{t1} and \ref{t2} arealso available in electronic form at the CDS via anonymous ftpcdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/383/1062.
|
The Origin of Cyclic Period Changes in Close Binaries: The Case of the Algol Binary WW Cygni
Year- to decade-long cyclic orbital period changes have been observed inseveral classes of close binary systems, including Algol, W UrsaeMajoris, and RS Canum Venaticorum systems and the cataclysmic variables.The origin of these changes is unknown, but mass loss, apsidal motion,magnetic activity, and the presence of a third body have all beenproposed. In this paper, we use new CCD observations and thecentury-long historical record of the times of primary eclipse for WWCygni to explore the cause of these period changes. WW Cyg is an Algolbinary whose orbital period undergoes a 56 yr cyclic variation with anamplitude of ~0.02 days. We consider and reject the hypotheses of masstransfer, mass loss, apsidal motion, and the gravitational influence ofan unseen companion as the cause for these changes. A model proposed byApplegate, which invokes changes in the gravitational quadrupole momentof the convective and rotating secondary star, is the most likelyexplanation of this star's orbital period changes. This finding is basedon an examination of WW Cyg's residual O-C curve and an analysis of theperiod changes seen in 66 other Algols. Variations in the gravitationalquadrupole moment are also considered to be the most likely explanationfor the cyclic period changes observed in several different types ofbinary systems.
|
149 Bedeckungssterne der BAV-Programme. Eine Analyse der Beobachtungstatigkeit seit den Angangen.
Not Available
|
Das Brunner Punktesystem.
Not Available
|
Catalogue of Apparent Diameters and Absolute Radii of Stars (CADARS) - Third edition - Comments and statistics
The Catalogue, available at the Centre de Données Stellaires deStrasbourg, consists of 13 573 records concerning the results obtainedfrom different methods for 7778 stars, reported in the literature. Thefollowing data are listed for each star: identifications, apparentmagnitude, spectral type, apparent diameter in arcsec, absolute radiusin solar units, method of determination, reference, remarks. Commentsand statistics obtained from CADARS are given. The Catalogue isavailable in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcar?J/A+A/367/521
|
A Search for Trojan Extrasolar Planets: Planets in V442 Cas and YZ Aql?
In this project we are exploring the light curves of eclipsing binariesfor the signature of planets that may exist at the L4 and L5 Lagrangepoints of the stellar system. While no binaries are known to exist thatstrictly satisfy the stellar mass ratio constraint for the restrictedthree-body problem, the general solution would allow a planet formed atthe L-point to remain there if there are no major perturbing bodies suchas an additional planet. We have coined such objects "Trojan planets."The advantage of this approach is that the phases of the planetaryeclipses are known. We picked systems with deep primary eclipses, tomaximize the amount of system light eclipsed by the planet when in frontof the hotter star. We also scanned the Finding List for Observers ofInteractive Binary Stars, for G dwarf systems ,but found only a few thatwere high inclination and detached. The target list includes QY Aql, YZAql, V442 Cas, SS Cet, S Cnc, VW Cyg, WW Cyg, RR Dra, RX Gem, RY Gem, VWHya, Y Leo, TV Mon, BN Sct, UW Vir, AC UMa, TX UMa, and GSC 1657. Wehave concentrated on V442 Cas and YZ Aql, based on initial results thatshow anomalies in the light curves near the phases where a Trojan planeteclipse is expected. We present results on these two, as well as initialresults for some of the other systems. We gratefully acknowledge thesupport of the National Science Foundation, through grants AST-9731062and AST-0089248. We also appreciate the support of the Fund forAstrophysical Research. Gregory Shelton and Brenda Corbin, at the U.S.naval Observatory Library, have been indispensable in providingreferences for these binary systems. This research has made use of theSimbad database, operated at CDS, Strasbourg, France
|
Is asynchronism in semidetached binary systems real?
We analyze statistical relationships between the parameters ofAlgol-type binaries with asynchronous rotation of the primary componentsand provide observational evidence for denser, more extended gaseousenvelopes in the eclipsing systems of this group. We conclude thatasynchronism of the primary components in such systems is not real. Thelines that are used to determine the rotational velocities of thesecomponents originate mostly in the part of the atmosphere which acquiresan additional angular momentum during the interaction with the gasstream and produces a transient accretion disk near the equatorialplane.
|
Further discussion of binary star radio survey data
Statistical information on 8280 individual radio observations of binarystars, predominantly at 8.4 GHz using the Parkes 64 m antenna, ispresented. Three main groups are distinguished: (i) RS CVn stars, (ii)classical Algol binaries (EA2s) and (iii) detached pairs of generallyearly type (ETBs). The RS CVn stars more frequently gave rise todetectable fluxes, while the ETBs, in this data, are a small and ratherheterogeneous class. The Algols' emission appears to increase nearconjunction phases, though we cannot clearly distinguish any specialproperty of the Algols' phase-dependent behaviour which is not alsoshared by the RS CVn binaries. Both these categories' data show abimodal, phase-dependent pattern to the distribution of detections,suggesting both binary types share similar underlying physicalproperties, though there could also be other factors at play. The samplesizes of the Algols and particularly the ETB detections are too smallfor effective, discriminatory statistics, however.
|
Magnetic activity and evolution of Algol-type stars - II
We examine the possibility of probing dynamo action in mass-losingstars, components of Algol-type binaries. Our analysis is based on thecalculation of non-conservative evolution of these systems. We model thesystems USge and betaPer where the more massive companion fills itsRoche lobe at the main sequence (case AB) and where it has a smallhelium core (early case B) respectively. We show that to maintainevolution of these systems at the late stages which are presumablydriven by stellar `magnetic braking', an efficient mechanism forproducing large-scale surface magnetic fields in the donor star isneeded. We discuss the relevance of dynamo operation in the donor starto the accelerated mass transfer during the late stages of evolution ofAlgol-type binaries. We suggest that the observed X-ray activity inAlgol-type systems may be a good indicator of their evolutionary statusand internal structure of the mass-losing stellar components.
|
Orbital circularization in detached binaries with early-type primaries
Extending our previous study, the present paper reports on thediscussion of the orbital circularization in 37 detached binaries withearly-type primaries. From comparison of the theoretical predictionswith the orbital eccentricities of our binary systems, we find thatZahn's circularization theories are substantially consistent with theobserved data for overwhelming majority of our samples. However, we alsonote that three binaries of whom both components are asynchronizedrotators possess circular orbits. How to understand the circularism ofthe three systems remains a problem not only to Zahn's theories, but toall other present circularization mechanisms.We think that studies onthe circularization of pre-main-sequence binary systems could providesome clues for the problem.
|
TRY Geminorum - Revised Elements
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....114..800S&db_key=AST
|
The IUE Spectrum of the Binary Nucleus of the Planetary Nebula NGC 1514
Archival IUE low-dispersion spectra and the first ultraviolethigh-dispersion spectrum of the binary nucleus of NGC 1514 have beenanalyzed. Both SWP and LWR low-dispersion spectra show variability by asmuch as a factor of two in the continuum level between the years 1978and 1989. Weak P Cygni features for OV lambda 1371 and C IV lambda 1549yield terminal wind velocities of -105 plus or minus 25 and -960 plus orminus 150 km s$^{-1}$, respectively. No nebular emission lines weredetected, but several photospheric and interstellar absorption featureswere observed. Absorption lines of Fe VII are suspected. The He IIlambda 1640 absorption line has a radial velocity of +49 plus or minus 3km s$^{-1}$ and is in good agreement with optical data. The peculiarenergy distribution of the SWP continuum for NGC 1514 can be synthesizedby the coaddition of spectral type A0 - A3 III plus hot subdwarf IUEspectra. (SECTION: Stars)
|
Synchronization in the early-type detached binary stars.
With a set of homogeneous and refined rotational velocities, we discussthe synchronism in the "normal" (all the particular stars, such as Ap,Am and Of, are excluded) early-type detached binaries. Being differentfrom previous statistical studies, the present paper not onlyinvestigates the rotational synchronism of each component, but alsoestimates its age from new stellar evolutionary grids, and calculatesits synchronization time scale with Zahn's dynamically tidal theory.Significantly, we find that the dynamically tidal synchronizationmechanism is substantially compatible with the observed data from thecomparison of the rotational properties of our components with thetheoretical predictions.
|
Matter stream formation in close binaries
The dependence of the matter stream structure on the Coriolis force andthe overflow degree has been calculated using numerical hydrodynamicalmethods. A comparison is made with analytical dependences. Using thesecalculations, the possible mass transfer rate variations due toeccentricity of the orbital motion are determined.
|
The calculation of critical rotational periods in three typical close binary systems based on synchronization theory.
Not Available
|
Measurement and study of rotation in close binary stars. (V) Orbital circularization.
Not Available
|
Rotation of Algol binaries - a line profile model applied to observations.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996MNRAS.283..613M&db_key=AST
|
Optical positions of radio stars. I.
The optical positions of 31 radio stars obtained from the observationswith the photoelectric astrolabe at Yunnan Observatory are presented inthis paper. These are all the stars in the astrometric catalogue ofradio stars observable by our astrolabe.
|
Doppler Tomography of Accretion Disks in Algol Binaries
Doppler tomography of H alpha spectra of four Algol-type binaries TTHya, SW Cyg, U CrB, and U Sge has revealed quasi-stable accretion disksaround the mass gaining star in each system. In the tomograms, theseaccretion structures are nearly symmetric distributions of gas betweenthe stellar surface and the Roche lobe around the mass gainer. The diskis most stable in TT Hya and SW Cyg, which have orbital periods greaterthan 4.5 days. However, the morphology of the accretion structures inthe shorter period systems, U CrB and U Sge, can change from a disklikedistribution to a streamlike distribution. During a streamlike epoch ofthese systems, the gas stream in the Doppler tomogram closely followsthe predicted free fall path from the inner Lagrangian point toward themass gainer. However, during the disklike stage, the intensity of thedisk is comparable to that of the gas stream. These tomograms displaythe first maps of accretion disks in the Algol-type class of interactingbinaries.
|
R Canis Majoris---Revisited
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996ApJ...458..371S&db_key=AST
|
Measurement and study of rotation in close binary stars (IV) Comparison between observation and predictions of two theories.
Not Available
|
Measurement and study of rotation in close binary stars (III) Statistical analysis of synchronization.
Not Available
|
Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
|
Radio continuum emission from stars: a catalogue update.
An updated version of my catalogue of radio stars is presented. Somestatistics and availability are discussed.
|
Measurement and analysis of rotation in close binaries. II. Calculation of synchronism.
Not Available
|
Measurement and Analysis of Rotation in Close Binary Stars - Part One - Observations and Results
Not Available
|
INHABITED SKY
