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Rapid apsidal motion in eccentric eclipsing binaries: OX Cassiopeia, PV Cassiopeia, and CO Lacertae
Aims.Double-lined eclipsing binaries are a traditional tool to test thecapability of the stellar evolutionary models. If such binaries showapsidal motion, it is also possible to check, in addition to theirabsolute dimensions, some aspects of their internal structure. In orderto perform this additional test, we monitored the times of a minimum ofthree eclipsing binaries with accurate absolute dimensions. Methods:Approximately thirty new precise times of minimum light recorded withCCD photometers were obtained for three early-type eccentric-orbiteclipsing binaries OX Cas (P = 2.49°, e = 0.041), PV Cas (1.75°,0.032), and CO Lac (1.54°, 0.029). O-C diagrams were analyzed by theLacy's method using all reliable timings found in the literature, andthe elements of apsidal motion were improved. On the other hand, stellarmodels computed for the precise observed masses of the three systemswere used as theoretical tools to compare with the observed shift in theperiastron position. Results: We confirm very short periods of apsidalmotion of approximately 38.2, 91.0, and 43.4 years for OX Cas, PV Cas,and CO Lac, respectively. The relativistic effects are negligible, beingup to 6% of the total apsidal motion rate in all systems. Thecorresponding observed apsidal motion rates are in good agreement withthe theoretical predictions, except for the case of PV Cas, whosecomponents seem to be more mass concentrated than the models predict.
| B.R.N.O. Contributions #34
Not Available
| A new catalogue of eclipsing binary stars with eccentric orbits
A new catalogue of eclipsing binary stars with eccentric orbits ispresented. The catalogue lists the physical parameters (includingapsidal motion parameters) of 124 eclipsing binaries with eccentricorbits. In addition, the catalogue also contains a list of 150 candidatesystems, about which not much is known at present.Full version of the catalogue is available online (see the SupplementaryMaterial section at the end of this paper) and in electronic form at theCDS via http://cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/MNRAS/(vol)/ (page)E-mail: ibulut@comu.edu.tr
| Mass-luminosity relation for massive stars
A catalog of massive (⩾10 M ȯ) stars in binary andmultiple systems with well-known masses and luminosities has beencompiled. The catalog is analyzed using a theoretical mass-luminosityrelation. This relation allows both normal main-sequence stars and starswith peculiarities: with clear manifestations of mass transfer, massaccretion, and axial rotation, to be identified. Least-squares fittingof the observational data in the range of stellar masses 10Mȯ ⩽ M ≲ 50 M ȯ yields therelation L ˜ M 2.76.
| Apsidal motion in eccentric eclipsing binaries: CW Cephei, V478 Cygni, AG Persei, and IQ Persei
Aims.About thirty new times of minimum light recorded with photoelectricor CCD photometers were obtained for four early-type eccentric-orbiteclipsing binaries CW Cep (P=2.73d, e=0.029), V478 Cyg ( 2.88d, 0.016),AG Per ( 2.03d, 0.071), and IQ Per ( 1.74d, 0.076). Methods:.Their O-C diagrams were analysed using all reliable timings found inthe literature, and elements of apsidal motion were improved.Results: .We confirm relatively short periods of apsidal motion of about46, 27, 76, and 124 years for CW Cep, V478 Cyg, AG Per, and IQ Per,respectively. The corresponding internal structure constants, log k_2,are then found to be -2.12, -2.25, -2.15, and -2.36, under theassumption that the component stars rotate pseudosynchronously. Therelativistic effects are negligible, being up to 8% of the total apsidalmotion rate in all systems. Using the light-time effect solution, wehave predicted a faint third component orbiting with a period of about39 years for CW Cep.
| 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.
| 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.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
| The massive binary CPD - 41° 7742. II. Optical light curve and X-ray observations
In the first paper of this series, we presented a detailedhigh-resolution spectroscopic study of CPD - 41°7742, deriving for the first time an orbital solution for bothcomponents of the system. In this second paper, we focus on the analysisof the optical light curve and on recent XMM-Newton X-ray observations.In the optical, the system presents two eclipses, yielding aninclination i77°. Combining the constraints from the photometrywith the results of our previous work, we derive the absolute parametersof the system. We confirm that the two components of CPD -41° 7742 are main sequence stars (O9 V + B1-1.5 V) withmasses (M_118 Mȯ and M_210 Mȯ)and respective radii (R_17.5 Rȯ and R_25.4Rȯ) close to the typical values expected for such stars.We also report an unprecedented set of X-ray observations that almostuniformly cover the 2.44-day orbital cycle. The X-ray emission fromCPD - 41° 7742 is well described by atwo-temperature thermal plasma model with energies close to 0.6 and 1.0keV, thus slightly harder than typical early-type emission. The X-raylight curve shows clear signs of variability. The emission level ishigher when the primary is in front of the secondary. During the highemission state, the system shows a drop of its X-ray emission thatalmost exactly matches the optical eclipse. We interpret the mainfeatures of the X-ray light curve as the signature of a wind-photosphereinteraction, in which the overwhelming primary O9 star wind crashes intothe secondary surface. Alternatively the light curve could result from awind-wind interaction zone located near the secondary star surface. As asupport to our interpretation, we provide a phenomenological geometricmodel that qualitatively reproduces the observed modulations of theX-ray emission.
| Observational Tests and Predictive Stellar Evolution. II. Nonstandard Models
We examine contributions of second-order physical processes to theresults of stellar evolution calculations that are amenable to directobservational testing. In the first paper in the series, we establishedbaseline results using only physics that were common to modern stellarevolution codes. In this paper we establish how much of the discrepancybetween observations and baseline models is due to particular elementsof new physics in the areas of mixing, diffusion, equations of state,and opacities. We then consider the impact of the observationaluncertainties on the maximum predictive accuracy achievable by a stellarevolution code. The Sun is an optimal case because of the precise andabundant observations and the relative simplicity of the underlyingstellar physics. The standard model is capable of matching the structureof the Sun as determined by helioseismology and gross surfaceobservables to better than a percent. Given an initial mass and surfacecomposition within the observational errors, and no current observablesas additional constraints for which the models can be optimized, it isnot possible to predict the Sun's current state to better than ~7%.Convectively induced mixing in radiative regions, terrestriallycalibrated by multidimensional numerical hydrodynamic simulations,dramatically improves the predictions for radii, luminosity, and apsidalmotions of eclipsing binaries while simultaneously maintainingconsistency with observed light element depletion and turnoff ages inyoung clusters. Systematic errors in core size for models of massivebinaries disappear with more complete mixing physics, and acceptablefits are achieved for all of the binaries without calibration of freeparameters. The lack of accurate abundance determinations for binariesis now the main obstacle to improving stellar models using this type oftest.
| Close binary stars in ob-association regions i. preliminary investigation
We performed a sample of O- and B-eclipsing binary stars inOB-association regions and obtained the preliminary list of 147 binariesin 45 OB-association regions. We tried to elucidate the question whether(or not) the close binaries belong to corresponding OB-associations,from the commonness of their proper motions, radial velocities anddistances. Based on the completeness of the data,the binaries aredevided into three groups and the scheme for calculation of degree ofbelonging of stars to OB-associations is developed. Necessary data arenot available for nine systems and they are given in a specific table.For 12 cases, the binaries project onto the regions of two associations.We show that 33 (22.3%) close binary stars are members, 65 (43.9%) areprobable members and 39 (26.4%) are less probable members of theOB-associations. We find that 11 binaries belong to the Galaxybackground. The comparison of the distributions of orbital periods forthe binaries in OB-associations and for O-, B-binaries of the Galaxybackground shows their considerable differences in the vicinity of thetwo-day period.
| New Times of Minima of Some Selected Eclipsing Binary Systems
Not Available
| Photoelectric Minimum Times of Some Eclipsing Binary Stars
We present 15 minimum times of 8 eclipsing binaries observed in theyears from 2001 to 2003 and in 1998 only for V436 Per.
| Masses and other parameters of massive binaries
Binary stars provide us with the means to measure stellar mass. Here Ipresent several lists of known O-type stars with reliable mass estimatesthat are members of eclipsing, double-lined spectroscopic binaries. Themasses of young, unevolved stars in binaries are suitable for testingthe predictions of evolutionary codes, and there is good agreementbetween the observed and predicted masses (based upon temperature andluminosity) if the lower temperature scale from line-blanketed modelatmospheres is adopted. A final table lists masses for systems in awide variety of advanced evolutionary stages.
| Detached double-lined eclipsing binaries as critical tests of stellar evolution. Age and metallicity determinations from the HR diagram
Detached, double-lined spectroscopic binaries that are also eclipsingprovide the most accurate determinations of stellar mass, radius,temperature and distance-independent luminosity for each of theirindividual components, and hence constitute a stringent test ofsingle-star stellar evolution theory. We compile a large sample of 60non-interacting, well-detached systems mostly with typical errorssmaller than 2% for mass and radius and smaller than 5% for effectivetemperature, and compare them with the properties predicted by stellarevolutionary tracks from a minimization method. To assess the systematicerrors introduced by a given set of tracks, we compare the resultsobtained using three widely-used independent sets of tracks, computedwith different physical ingredients (the Geneva, Padova and Granadamodels). We also test the hypothesis that the components of thesesystems are coeval and have the same metallicity, and compare thederived ages and metallicities with the ones obtained by fitting asingle isochrone to the system. Overall, there is a good agreement amongthe different determinations, and we provide a comprehensive discussionon the sub-sample of systems which either present problems or haveestimated metallicities. Although within the errors the published trackscan fit most of the systems, a large degeneracy between age andmetallicity remains. The power of the test is thus limited because themetallicities of most of the systems are unknown. The full version ofTable 6 is only available in the electronic form athttp://www.edpsciences.org
| uvbyβ Photometry of Selected Eclipsing Binary Stars
New uvbyβ observations of 51 eclipsing binary stars are presented,and outside-eclipse averages for 45 of them are given. Many of thesebinaries are detached main-sequence pairs that have been discovered tobe double-lined spectroscopic binaries and appear suitable fordeterminations of accurate absolute dimensions and masses. Photometricproperties are recomputed for 14 of the binaries, for which absoluteproperties have been published previously. Intercomparisons are madewith previous photometry, when available, and notes are given for someindividual systems.
| Determination of the Ages of Close Binary Stars on the Main Sequence from Evolutionary Model Stars of Claret and Gimenez
A grid of isochrones, covering a wide range of stellar ages from thezero-age main sequence to 10 billion years, is calculated in the presentwork on the basis of the model stars of Claret and Gimenez withallowance for convective overshoot and mass loss by the components. Theages of 88 eclipsing variables on the main sequence from Andersen'scatalog and 100 chromospherically active stars from Strassmeier'scatalog are calculated with a description of the method of optimuminterpolation. Comparisons with age determinations by other authors aregiven and good agreement is established.
| Apsidal Motion in Detached Binary Stars: Comparison of Theory and Observations
A list of 62 detached binaries having reliable data on the rotation ofthe line of apsides is considered. Theoretical estimates of the rate ofapsidal motion are obtained. These estimates are compared withobservational data. It is shown that cases in which the theoreticalestimate exceeds the observed value are several times more frequent thancases in which the theoretical value is lower than the observed one.This discrepancy increases when systems with more reliable observationaldata are considered.
| Calculation of the masses of the binary star HD 93205 by application of the theory of apsidal motion
We present a method to calculate masses for components of both eclipsingand non-eclipsing binary systems as long as their apsidal motion ratesare available. The method is based on the fact that the equation thatgives the rate of apsidal motion is a supplementary equation that allowsthe computation of the masses of the components, if their radii and theinternal structure constants can be obtained from theoretical models.For this reason the use of this equation makes the method presented heremodel dependent . We apply this method to calculate the mass of thecomponents of the non-eclipsing massive binary system HD 93205 , whichis suspected to be a very young system. To this end, we have computed agrid of evolutionary models covering the mass range of interest, andtaking the mass of the primary (M 1 ) as the only independentvariable, we solve the equation of apsidal motion for M 1 asa function of the age of the system. The mass of the primary that wefind ranges from for zero-age main-sequence models, which sets an upperlimit for M 1 , down to for an age of 2Myr. Accordingly, theupper limit derived for the mass of the secondary is in very goodagreement with the masses derived for other O8V stars occurring ineclipsing binaries.
| Observational Tests and Predictive Stellar Evolution
We compare 18 binary systems with precisely determined radii and massesfrom 23 to 1.1 Msolar and stellar evolution models producedwith our newly revised code TYCHO. ``Overshooting'' and rotationalmixing were suppressed in order to establish a baseline for isolatingthese and other hydrodynamic effects. Acceptable coeval fits are foundfor 16 pairs without optimizing for heavy-element or helium abundance.The precision of these tests is limited by the accuracies of theobserved effective temperatures. High-dispersion spectra and detailedatmospheric modeling should give more accurate effective temperaturesand heavy-element abundances. PV Cas, a peculiar early A system, EK CepB, a known post-T Tauri star, and RS Cha, a member of a young OBassociation, are matched by pre-main-sequence models. Predicted massloss agrees with upper limits from IUE for CW Cep A and B. Relativelypoor fits are obtained for binaries having at least one component in themass range 1.7
| 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
| Photoelectric Minima of Selected Eclipsing Binaries and New Elements for Several Stars
Not Available
| Absolute proper motions of open clusters. I. Observational data
Mean proper motions and parallaxes of 205 open clusters were determinedfrom their member stars found in the Hipparcos Catalogue. 360 clusterswere searched for possible members, excluding nearby clusters withdistances D < 200 pc. Members were selected using ground basedinformation (photometry, radial velocity, proper motion, distance fromthe cluster centre) and information provided by Hipparcos (propermotion, parallax). Altogether 630 certain and 100 possible members werefound. A comparison of the Hipparcos parallaxes with photometricdistances of open clusters shows good agreement. The Hipparcos dataconfirm or reject the membership of several Cepheids in the studiedclusters. Tables 1 and 2 are only available in electronic form at theCDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
| Apsidal motion in southern eccentric eclipsing binaries: YY Sgr, V523 Sgr, V1647 Sgr, V2283 Sgr and V760 Sco
Several new times of minimum light recorded with photoelectric meanshave been gathered for the early-type eccentric eclipsing binaries YYSgr (P = 2fd 63, e = 0.16), V523 Sgr (2fd 32, 0.16), V1647 Sgr (3fd 28,0.41), V2283 Sgr (3fd 47, 0.49) and V760 Sco (1fd 73, 0.03). The O - Cdiagrams are analyzed using all reliable timings found in the literatureand improved values for the elements of the apsidal motion are computed.We find more precise periods of apsidal motion of about 290, 202, 531,528 and 38.5 years for YY Sgr, V523 Sgr V1647 Sgr, V2283 Sgr and V760Sco, respectively. The corresponding internal structure constants logk_2 are derived and compared to their theoretical values. Based onobservations collected at the South Africa Astronomical Observatory,Sutherland, South Africa
| Chemical composition of eclipsing binaries: a new approach to the helium-to-metal enrichment ratio
The chemical enrichment law Y(Z) is studied by using detacheddouble-lined eclipsing binaries with accurate absolute dimensions andeffective temperatures. A sample of 50 suitable systems was collectedfrom the literature, and their effective temperatures were carefullyre-determined. The chemical composition of each of the systems wasobtained by comparison with stellar evolutionary models, under theassumption that they should fit an isochrone to the observed propertiesof the components. Evolutionary models covering a wide grid in Z and Ywere adopted for our study. An algorithm was developed for searching thebest-fitting chemical composition (and the age) for the systems, basedon the minimization of a χ2 function. The errors (andbiases) of these parameters were estimated by means of Monte Carlosimulations, with special care put on the correlations existing betweenthe errors of both components. In order to check the physicalconsistency of the results, we compared our metallicity values withempirical determinations, obtaining excellent coherence. Theindependently derived Z and Y values yielded a determination of thechemical enrichment law via weighted linear least-squares fit. Our valueof the slope, ΔY/ΔZ=2.2+/-0.8, is in good agreement withrecent results, but it has a smaller formal error and it is free ofsystematic effects. Linear extrapolation of the enrichment law to zerometals leads to an estimation of the primordial helium abundance ofYp=0.225+/-0.013, possibly affected by systematics in theeffective temperature determination.
| Estimating the ages of eclipsing variable DM-stars on the basis of the evolutionary star models by Maeder and Meynet
A set of isochrones covering a wide range of star ages from5\cdot106 to 1010 yr was built on the basis of thestellar models by A. Maeder and G. Meynet with overshooting and massloss for Population I stars with abundances (X, Y, Z) = 0.70, 0.28,0.02. The isochrones were used to compute the ages of 88 eclipsingvariable stars from the catalog by Andersen which lie on the mainsequence. The influence of initial data errors on the rezultes wasinvestigated. The ages derived are in good agreement with the results ofother authors.
| Apsidal Motion in Double Stars. I. Catalog
A catalog of 128 double stars with measured periods of apsidal motion iscompiled. Besides the apsidal periods, the orbital elements of binariesand physical parameters of components (masses, radii, effectivetemperatures, surface gravities) are given. The agreement of the apsidalperiods found by various authors is discussed.
| 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.
| UBV beta Database for Case-Hamburg Northern and Southern Luminous Stars
A database of photoelectric UBV beta photometry for stars listed in theCase-Hamburg northern and southern Milky Way luminous stars surveys hasbeen compiled from the original research literature. Consisting of over16,000 observations of some 7300 stars from over 500 sources, thisdatabase constitutes the most complete compilation of such photometryavailable for intrinsically luminous stars around the Galactic plane.Over 5000 stars listed in the Case-Hamburg surveys still lackfundamental photometric data.
| Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
Not Available
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Osservazione e dati astrometrici
| Costellazione: | Cigno |
| Ascensione retta: | 20h19m38.75s |
| Declinazione: | +38°20'09.2" |
| Magnitudine apparente: | 8.69 |
| Distanza: | 10000000 parsec |
| Moto proprio RA: | -3.9 |
| Moto proprio Dec: | -7.3 |
| B-T magnitude: | 9.253 |
| V-T magnitude: | 8.737 |
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