Contact Binaries with Additional Components. I. The Extant Data
We have attempted to establish observational evidence for the presenceof distant companions that may have acquired and/or absorbed angularmomentum during the evolution of multiple systems, thus facilitating orenabling the formation of contact binaries. In this preliminaryinvestigation we use several techniques (some of themdistance-independent) and mostly disregard the detection biases ofindividual techniques in an attempt to establish a lower limit to thefrequency of triple systems. While the whole sample of 151 contactbinary stars brighter than Vmax=10 mag gives a firm lowerlimit of 42%+/-5%, the corresponding number for the much better observednorthern-sky subsample is 59%+/-8%. These estimates indicate that mostcontact binary stars exist in multiple systems.
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Evolution of interacting binaries with a B type primary at birth
We revisited the analytical expression for the mass ratio distributionfor non-evolved binaries with a B type primary. Selection effectsgoverning the observations were taken into account in order to comparetheory with observations. Theory was optimized so as to fit best withthe observed q-distribution of SB1s and SB2s. The accuracy of thistheoretical mass ratio distribution function is severely hindered by theuncertainties on the observations. We present a library of evolutionarycomputations for binaries with a B type primary at birth. Some liberalcomputations including loss of mass and angular momentum during binaryevolution are added to an extensive grid of conservative calculations.Our computations are compared statistically to the observeddistributions of orbital periods and mass ratios of Algols. ConservativeRoche Lobe Over Flow (RLOF) reproduces the observed distribution oforbital periods but fails to explain the observed mass ratios in therange q in [0.4-1]. In order to obtain a better fit the binaries have tolose a significant amount of matter, without losing much angularmomentum.
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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.
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Times of Minima for Neglected Eclipsing Binaries in 2005
Times of minima obtained at Rolling Hills Observatory during 2005 for anumber of neglected eclipsing binaries are presented.
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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.
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Times of Minima for Neglected Eclipsing Binaries in 2003
Times of minima for a number of neglected eclipsing binaries arepresented.
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Catalogue of the field contact binary stars
A catalogue of 361 galactic contact binaries is presented. Listedcontact binaries are divided into five groups according to the type andquality of the available observations and parameters. For all systemsthe ephemeris for the primary minimum, minimum and maximum visualbrightness and equatorial coordinates are given. If available,photometric elements, (m1+m2)sin3i,spectral type, parallax and magnitude of the O'Connell effect are alsogiven. Photometric data for several systems are augmented by newobservations. The quality of the available data is assessed and systemsrequiring modern light-curve solutions are selected. Selectedstatistical properties of the collected data are discussed.
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Determination of the consistent and interdependent values of the basic characteristics of eclipsing variable systems components
An approximate approach for determining consistent and interdependentwith each other principal characteristics as well as the equatorialrotational velocity and the inclination angle of rotation axis of arotator to the line - of - sight for components of eclipsing variablesystems is suggested.
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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
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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.
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V606 Centauri: an early-type eclipsing contact binary
We present a spectroscopic and photometric analysis of the early-typeeclipsing binary V606 Cen. Based on new high-resolution CCD spectra thefirst radial velocity curve of this system is given, which allows for anaccurate determination of radial velocity amplitudes (K_1=181.8 km s(-1), K_2=345.2 km s(-1) ) and the spectroscopic mass ratio q_spec=0.527.Moreover, equivalent widths are listed. The line strengths of He i 4922show strong variations with the orbital phase, related to the so-called(and hitherto unexplained) ``Struve-Sahade effect". In this context,some aspects concerning the determination of equivalent widths in closebinary systems are discussed, with special reference to the influence ofthe ellipsoidal light variations. For the first time, photoelectric UBVlight curves of V606 Cen are presented, which were solved with the MOROcode, based on the Wilson-Devinney model. The first set of solutions wasachieved with effective temperatures according to the previous spectralclassification B1-2 Ib/IIb, but the derived absolute dimensions, surfacegravities, as well as an investigation of the equivalent widths led to arevision of the spectral type. We now suggest B0-0.5 V for the primary,and B2-3 V for the secondary component, respectively. Using thecorresponding effective temperatures, another light curve analysis wasperformed, yielding the following absolute dimensions: M_1=14.7 M_sun,M_2=8.0 M_sun, R_1=6.8 R_sun, R_2=5.2 R_sun, log L_1/L_sun=4.48, and logL_2/L_sun=3.74. In all cases, a contact configuration is found. Theevolutionary state of V606 Cen is discussed in the light of modernevolutionary grids. It turns out that this contact system was formedduring the slow phase of case A mass transfer after reversal of its massratio. In this respect it is similar to other early-type contactbinaries such as V382 Cyg, V701 Sco or RZ Pyx. Based on observationscollected at the European Southern Observatory, La Silla, Chile
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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.
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OB-type binaries: Models versus observations
Recently published models on close binary evolution for massive stars (Mgreater than 5 solar mass) are compared to a set of detached andsemidetached OB binaries. For the majority of the detached systems, wefind good correspondence between theoretical and observedcharacteristics for stars with masses between 4.5 sola mass and 17 solarmass. We explore the origin of semidetached systems, and discussanomalies between models and observed characteristics. An initial massratio of around 0.6 seems to be preffered for this group. Finally, webriefly examine a number of massive (marginal) contact systems. Thelatter systems all seem to evolve according to case A of mass transfer.
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Catalogue of astrophysical parameters of binary systems
Not Available
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Properties and nature of Be stars. XV - Light variations of LQ And and its check stars revisited
Results of an analysis of 624 UBV observations of LQ And made at sixobservatories between 1980 and 1988 have been used to find a period of0.30952 or 0.61904 days, with a full amplitude of about 0.025 m. Noevidence of multiperiodicity is found, and the only variation other thanthe periodic one at 0.6 or 0.3 days is the suspected decline inbrightness between 1951 and 1988, probably connected with physicalchanges in the Be envelope. A new period of 3.5112 days is derived forLQ And light and color variations, and it is suggested that this hot CPstar is an oblique rotator.
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Stellar masses and radii based on modern binary data
Accurate data on absolute dimensions of eclipsing binaries published inthe astronomical literature since 1980 are collected and analyzed.Simple approximation formulas relating the effective temperature withother basic physical parameters (mass, radius, bolometric magnitude) arederived. Mean and extreme values of these parameters for each spectraltype are also tabulated. The implication of improved data for theproblem of critical rotational periods and equatorial velocities ofearly-type stars is discussed.
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The gravity-darkening of highly distorted stars in close binary systems. VI - Practical analysis of early-type contact systems with spectral types later than B1
The observed ellipticity effect is analyzed to deduce empirical valuesof the exponent of effective gravity-darkening, alpha, for early-typecontact systems with spectral types later than B1 for which the effectof radiation pressure may be neglected. It is found that the alphavalues for all contact systems as a whole increase with the meaneffective temperature of both components. It is shown that the alphavalues increase slightly with the mass ratio in early-type contactsystems, whereas they decrease with mass ratio in W UMa type contactsystems.
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On OB-type close binary stars
Masses, radii, effective temperatures, and luminosities for thecomponents of 31 binary systems with spectral types in the O-B5 rangeare given. Comparison of the data for the 16 detached systems in thesample with main-sequence models for individual stars supports theprevious suggestion that convective overshootng and stellar-wind massloss should be included in evolutionary models. An empiricalmass-luminosity relation is derived from these detached components forthe 3.5-20 solar mass range. Eight of the remaining systems are insemidetached configurations and seven are in marginal-contact states.The results suggest that all the systems in this sample have evolved orwill evolve through a case A mass-transfer process.
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RZ Pyxidis - an early-type marginal contact binary
The first modern photometric and spectroscopic study of the early-typebinary RZ Pyx is presented. The analysis suggests that the system is ina marginal contact configuration with components on the zero-age mainsequence. The masses and radii of the two components are found to be 5.3+ or - 0.4 and 4.3 + or - 0.2 solar masses and 2.61 + or - 0.10 and 2.44+ or - 0.06 solar radii, respectively. The age estimate for the systemis less than 2 Myr. The system may have evolved into contact within thisperiod of time or have arrived on the main sequence in a contactconfiguration.
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A Review of Early-Type Close Binary Systems
This is a review of close binary systems with very early spectral types(B, O, Of, and WR stars). We limit our selection to systems with Rochemodel photometric solution only. There are 10 contact systems known atpresent. Three of them (V701 Sco, BH Cen, and RZ Pyx) are located in thevicinity of the zero-age contact (ZC) according to a Spectral Type— Period diagram. Only the first two systems have absolutedimensions available. Both of these fall into the ZC zone in thelogP-logm diagram and the logm-logR diagram. The system TU Mus wasthought to be a ZC system is located in the evolved contact zone (EC) inthe above diagrams. Both V701 Sco and BH Cen were thought to be havingmass ratios about unity. With the much improved light curves of BH Cenand new analysis the mass ratio has been revised to 0.84! This resultmay favor Shu's model for early-type zero-age contact systems. Theevolved systems might be undergone Case A mass exchange except for twosystems (V729 Cyg and RY Sct) which might be from Case B. The systemsV367 Cyg was classified by Plavec as a W Ser system may be a evolvedcontact system. It is interesting to note that V729 Cyg (O7f+OfIa), UWCMa(O7f+O) and CQ Cep(WN7+O) are all highly evolved contact systems. TheMax II of UW CMa and CQ Cep are displaced to 0.78 and 0.80 phase,respectively. The displacement for V729 Cyg is not known due to poorcoverage at this phase. The most distinct feature going from Of toWolf-Rayet stars is the increasing domination of emission lines. It issuspected that this phaseshifts reflect the increasing activity ofmass-flow in the common envelope. There are 8 semidetached systems withreliable absolute dimensions. It is believed that 6 of them are derivedfrom Case A while the remaining 2 are from Case B mass exchange.
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Statistics of categorized eclipsing binary systems Lightcurve shapes, periods, and spectral types
The statistics of the light curve morphologies, eclipse depths, orbitalperiods, and spectral types of about 1000 eclipsing binary systems areexamined, after attempting to subdivide these binaries into variousbasic evolutionary categories. The applicability of statisticalcriteria, based on light curve morphologies and eclipse depths, for thecategorization of eclipsing binaries has been found more limited thanpreviously believed. In particular, EW-type light curves turn out to begood indicators of contact systems (though not conversely), while EA-and EB-type light curves have little physical significance. Moreover,the study reveals a strong deficit of short-period noncontact systems inthe whole spectral range, together with an underabundance of early-typecontact binaries (compared with the number of late-type contact pairs).Interestingly, the distribution of evolved Algol-type systems isshifted, on average, to periods longer than those of unevolved detachedsystems in the OB and early A spectral range (and to shorter periods inthe F spectral range).
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A uvby, beta photometric survey of southern hemisphere
A uvby, beta photometric study of southern hemisphere eclipsing binarystars has been undertaken at Cerro Tololo Inter-American Observatory.The standardized colors and V magnitudes for 288 binaries at quadratureand/or at minimum are presented, along with an indication of theaccuracy of the standardization and photometry. Discussions of theresolving time of the pulse-counting photometers and of the atmosphericextinction at CTIO are included.
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BR MUSCAE - A new early-type contact binary
The eclipsing binary system BR Muscae was observed photoelectrically in1980-1982. Four primary and two secondary eclipse curves are welldefined, and eighteen epochs of minimum light and an updated ephemerisare presented. Although the coverage of the light curves has not beencompleted, it is evident that they are of the W UMa-type with typicalfeatures of contact binary systems. Since the observed (B-V) and (U-B)colors are consistent with a reddened main sequence star of spectraltype B3, it is concluded that BR Mus is a new member of the so-called'early-type contact binaries'.
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Times of Minima for Southern Hemisphere Eclipsing Binaries
Not Available
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A catalogue of parameters for eclipsing binaries
Not Available
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Contact binaries . III. Early-type systems.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1978AJ.....83..288E&db_key=AST
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V 701 Scorpii and its place among early contact binaries
Abstract image available at:http://adsabs.harvard.edu/abs/1977A&A....61..137W
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The early-type contact system V1010 Ophiuchi.
Abstract image available at:http://adsabs.harvard.edu/abs/1977ApJ...211..853L
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Eclipsing systems in star clusters. III. Early-type contact system BH Centauri.
Abstract image available at:http://adsabs.harvard.edu/abs/1977ApJ...211..844L
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SV Centauri: an unusual example of mass transfer.
Abstract image available at:http://adsabs.harvard.edu/abs/1976MNRAS.176..625W
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INHABITED SKY
