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.
|
Automatic classification of eclipsing binaries light curves using neural networks
In this work we present a system for the automatic classification of thelight curves of eclipsing binaries. This system is based on aclassification scheme that aims to separate eclipsing binary systemsaccording to their geometrical configuration in a modified version ofthe traditional classification scheme. The classification is performedby a Bayesian ensemble of neural networks trained with Hipparcos data ofseven different categories including eccentric binary systems and twotypes of pulsating light curve morphologies.
|
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
|
Beobachtungsegebnisse Bundesdeutsche Arbeitsgemainschaft fur Veranderliche Sterne e.V.
Not Available
|
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.
|
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
|
Stars with the Largest Hipparcos Photometric Amplitudes
A list of the 2027 stars that have the largest photometric amplitudes inHipparcos Photometry shows that most variable stars are all Miras. Thepercentage of variable types change as a function of amplitude. Thiscompilation should also be of value to photometrists looking forrelatively unstudied, but large amplitude stars.
|
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.
|
Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
Not Available
|
Radio emission from Algol-type binaries. I. Results of 1992-1993 VLA survey
In this paper we report on a 5 GHz survey of 26 Algol-type binaries. Sixsystems were detected. We combine the new results with previouslypublished data to derive some radio characteristics of Algols and tocompare them with those of other active binaries. The radio detectionrate of 30 %, a factor that is somewhat smaller compared to the case ofRSCVn-type, does not seem to be due to a reduced coronal activity. Infact, Algols share many similarities with the radio behavior of RS CVnsand the 5 GHz luminosity functions of both kind of systems look quitesimilar. Among the different possibilities, the high radio variabilityand distances, which, on average, are larger than those of RS CVns, seemto be the most reasonable explanation for the apparently reducedactivity at radio wavelengths.
|
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.
|
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
|
On the nature of the AM phenomenon or on a stabilization and the tidal mixing in binaries. I. Orbital periods and rotation.
The paper casts a questioning eye on the unique role of the diffusiveparticle transport mechanism in explaining the Am phenomenon and arguesthat the so-called tidal effects might be of great importance incontrolling diffusion processes. A short period cutoff at =~1.2d as wellas a 180-800d gap were found in the orbital period distribution (OPD) ofAm binaries. The existence of the former can be ascribed to the state ofthe primaries with the almost-filled Roche lobes. The latter couldresult from the combined effects of the diffusion, tidal mixing andstabilization processes. Because the tidal mixing might surpassdiffusion in the binaries with the orbital periods P_orb_ less thanseveral hundred days and might thus sustain the He convection zone,which would otherwise disappear, no Am stars should lie below thisboundary. The fact that they are nevertheless seen there implies theexistence of some stabilization mechanism (as, e.g., that recentlyproposed by Tassoul & Tassoul 1992) for the binaries with orbitalperiods less than 180d. Further evidence is given to the fact that theOPD for the Am and the normal binaries with an A4-F1 primary arecomplementary to each other, from which it stems that Am stars are closeto the main sequence. There are, however, indications that they haveslightly larger radii (2.1-3 Rsun_) than expected for theirspectral type. The generally accepted rotational velocity cutoff at=~100km/s is shown to be of little value when applied on Am binaries ashere it is not a single quantity but, in fact, a function of P_orb_whose shape is strikingly similar to that of the curves of constantmetallicity as ascertained from observations. This also leads to thewell known overlap in rotational velocities of the normal and Am starsfor 402.5d.We have exploited this empirical cutoff function to calibrate thecorresponding turbulent diffusion coefficient associated with tidalmixing, having found out that the computed form of the lines of constantturbulence fits qualitatively the empirical shape of the curves ofconstant metallicity. As for larger orbital periods(20d55km/s found by Burkhart(1979) would then be nothing but a manifestation of insufficientlypopulated corresponding area of larger P_orb_.
|
Evolutionary scenarios for double degenerate systems
We propose evolutionary scenarios in which double degenerate white dwarfsystems can be produced through one or two phases of stable masstransfer. We consider Algol-type evolution as well as evolutioninvolving first a stage of common-envelope (CE) evolution followed by aphase of stable mass transfer. We also show that the final orbitalperiod of double white dwarf systems depends on the period after thefirst phase of mass transfer, and that there is critical period (thebifurcation period) above which systems evolve to orbital periods of theorder of days and below which systems evolve towards very short orbitalperiods (a few hours). This probably corresponds to the observation thatdouble degenerate systems have periods either of hours or of days. Wealso find a limit on the stability of mass transfer for systems thatfirst go through a phase of CE evolution. We suggest that our newevolutionary scheme involving two stages of stable mass transfer and ourscheme involving first CE evolution followed by stable mass transfershould be included in population synthesis models.
|
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
|
Catalogue of astrophysical parameters of binary systems
Not Available
|
Radial-velocity measurements. V - Ground support of the HIPPARCOS satellite observation program
The paper presents data on 1070 radial velocity measurements of starsdistributed in 39 fields measuring 4 deg x 4 deg. The PPO series ofFehrenbach et al. (1987) and Duflot et al. (1990) is continued using theFehrenbach objective prism method.
|
UBV photometry of AW Pegasi
New UBV observations of the classical Algol system AW Peg werepresented. The photometric minima times were collected and used togetherwith the new determinations in a period study. No sign of any periodchange was found from observations covering more than sixty years. The Band V light curves are analyzed by means of the Wilson-Devinneyapproach. It was verified that the system is semi-detached with a Rochelobe filling secondary.
|
Eclipsing binaries, Pegasus to Sagittarius, in 1972-1987
Photoelectric and visual observations of 34 known and suspectedeclipsing binaries are discussed. Revised light elements are derived forDM Per and Beta Per. EL Sge is confirmed to vary with a period ofapproximately 0.333d. Large deviations from the published elements arereported for BG Peg, AB Per, LS Per, SU Psc, SZ Psc and TU Sge. Thecatalogue period of BQ Peg is probably incorrect.
|
Rotation statistics of Algol-type binaries and results on RY Geminorum, RW Monocerotis, and RW Tauri
Rotation rates and other parameters are estimated from light curves ofthree Algol-type binaries, and rotation statistics based on bothspectral line broadening and light curves are collected for 36 Algolsystems. The statistics suggest that a subset of Algols have primarystars which rotate at the centrifugal limit and that many Algols havesufficient continual mass transfer to maintain nonsynchronous rotation.A formal procedure for estimating the critical rotation rate(centrifugal limit) is described. It is found that RY Gem rotates about14 times faster than synchronously, but not close to its centrifugallimit of about 24 times. For RW Mon, the rotation is about five timessynchronous. For RW Tau it was not possible to estimate the rotationfrom the light curves, but consistency with a published result from linebroadening is found.
|
Accuracy and efficiency in the binary star reflection effect
The geometric and irradiation heating problems for the binary starreflection effect theory are developed in terms of equipotential levelsurfaces and are sufficiently general so as to include eccentric orbitsand nonsynchronous (even centrifugally limited) rotation and to treatmultiple reflection. The requisite physics, mathematics, and logic arethen presented and the computations are organized so that a givenquantity is computed only as often as necessary, emphasizing thedistinction between local surface quantities and aspect-relatedquantities. The local geometric, bolometric, and wavelength-specificquantities are grouped for storage according to how often they need tobe recomputed. Some tests of a computer program based on this reflectionmodel are given in the form of graphs in which program results arecompared to a special exact case, and with results from an earlierprogram. The new program gives intuitively reasonable output for alltests, and the tests give an idea of how accurate the old program is,adopting the detailed reflection computations of the new program as astandard for comparison. A table is given which shows the convergence ofthe multiple reflection computations to a constant distribution ofsurface effective temperature.
|
