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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.
| Analysis of photoelectric light curves of V448 CYG taking the Roche geometry into account
Three-color photoelectric UBV light curves of the close binary systemV448 Cyg obtained at the Abastumani Astrophysical Observatory areanalyzed using a new code by Djurasevi. A new value for the ratio of themasses of the components, which is the fundamental parameter fordetermining the absolute elements of the system, has recently beenpublished. The parameters obtained in our analysis differ substantiallyfrom those published previously because the new mass ratio has beenemployed. The location of the components of V448 Cyg on a mass-logg plotshows that this system, similarly to XZ Cep and V382 Cyg, is in a phasesubsequent to a rapid transfer of mass.
| Beobachtungssergebnisse Bundesdeutsche Arbeitsgemeinschaft fuer Veraenderliche Sterne e.V.
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| 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.
| An Apparent Descriptive Method for Judging the Synchronization of Rotation of Binary Stars
The problem of the synchronous rotation of binary stars is judged byusing a synchronous parameter Q introduced in an apparent descriptivemethod. The synchronous parameter Q is defined as the ratio of therotational period to the orbital period. The author suggests severalapparent phenomenal descriptive methods for judging the synchronizationof rotation of binary stars. The first method is applicable when theorbital inclination is well-known. The synchronous parameter is definedby using the orbital inclination i and the observable rotationalvelocity (V1,2 sin i)M. The method is mainly suitable for eclipsingbinary stars. Several others are suggested for the cases when theorbital inclination i is unknown. The synchronous parameters are definedby using a1,2 sin i,m1,2 sin3 i, the mass function f (m) andsemi-amplitudes of the velocity curve, K1,2 given in catalogue ofparameters of spectroscopic binary systems and (V1,2 sin i)M. Thesemethods are suitable for spectroscopic binary stars including those thatshow eclipses and visual binary stars concurrently. The synchronousparameters for fifty-five components in thirty binary systems arecalculated by using several methods. The numerical results are listed inTables 1 and 2. The statistical results are listed in Table 3. Inaddition, several apparent descriptive methods are discussed.
| Catalogue of averaged stellar effective magnetic fields. I. Chemically peculiar A and B type stars
This paper presents the catalogue and the method of determination ofaveraged quadratic effective magnetic fields < B_e > for 596 mainsequence and giant stars. The catalogue is based on measurements of thestellar effective (or mean longitudinal) magnetic field strengths B_e,which were compiled from the existing literature.We analysed the properties of 352 chemically peculiar A and B stars inthe catalogue, including Am, ApSi, He-weak, He-rich, HgMn, ApSrCrEu, andall ApSr type stars. We have found that the number distribution of allchemically peculiar (CP) stars vs. averaged magnetic field strength isdescribed by a decreasing exponential function. Relations of this typehold also for stars of all the analysed subclasses of chemicalpeculiarity. The exponential form of the above distribution function canbreak down below about 100 G, the latter value representingapproximately the resolution of our analysis for A type stars.Table A.1 and its references are only available in electronic form atthe CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/407/631 and Tables 3 to 9are only available in electronic form at http://www.edpsciences.org
| Photoelectric Observations of V448 CYGNAE
The research literature on the star V448 Cyg is reviewed in more detail.An analysis of three color photoelectric observations made at Abastumaniis reported in detail with corresponding tables and graphs. Inparticular, the gaseous structure and evolutionary status of the systemare discussed. Newly published spectroscopic data suggest that our lightcurves might be interpreted by more modern nonclassical methods assuminga new model. Thus, comparing data obtained in this fashion with the newspectroscopic data may help improve the evolutionary status and modelfor the V448 Cyg system. It is also seems possible to obtain bettervalues of the physical parameters for circumstellar structures andobtain more precise information on the physical conditions in theatmospheres of the stars and on the structure of the circumstellarshells.
| Evolution of Wolf-Rayet Stars in Binary Systems: An Analysis of the Mass and Orbital-Eccentricity Distributions
We have undertaken a statistical study of the component mass ratios andthe orbital eccentricities of WR + O close binary, detachedmain-sequence (DMS), contact early-type (CE), and semidetached (SD)systems. A comparison of the characteristics of WR + O systems and ofDMS, CE, and SD systems has enabled us to draw certain conclusions aboutthe evolutionary paths of WR + O binaries and to demonstrate that up to90% of all known WR + O binaries formed as a result of mass transfer inmassive close O + O binary systems. Since there is a clear correlationbetween the component masses in SD systems with subgiants, the absenceof an anticorrelation between the masses of the WR stars and O stars inWR + O binaries cannot be considered evidence against the formation ofWR + O binaries via mass transfer. The spectroscopic transitionalorbital period P tr sp corresponding to the transition from nearlycircular orbits (e sp<0.1) to elliptical orbits (e sp≥0.1) is14d for WR + O systems and 2d 3d for OB + OB systems. Theperiod range in which all WR + O orbits are circular &$(1mathop dlimits_. 6 ≤slant P ≤slant 14(d) ); is close to the range for SD systems with subgiants, &0mathop dlimits_. 7 ≤slant P ≤slant 15(d); . The large difference between the P tr sp values for WR + O and OB +OB systems suggests that a mechanism of orbit circularization additionalto that for OB + OB systems at the DMS stage (tidal dissipation of theorbital energy due to radiative damping of the dynamical tides) acts inWR + O binaries. It is natural to suggest mass transfer in the parent O+ O binaries as this supplementary orbit-circularization mechanism.Since the transitional period between circular and elliptical orbits forclose binaries with convective envelopes and ages of 5×109 yearsis &P_{tr} = 12mathop dlimits_. 4$; , the orbits of most known SD systems with subgiants had enough timeto circularize during the DMS stage, prior to the mass transfer. Thus,for most SD systems, mass transfer plays a secondary role incircularization of their orbits. In many cases, the initial orbitaleccentricities of the O + O binary progenitors of WR + O systems arepreserved, due to the low viscosity of the O-star envelopes and theshort timescale for their nuclear evolution until the primary O starfills its Roche lobe and the mass transfer begins. The mass transfer inthe parent O + O systems is short-lived, and the number of orbitalcycles during the early mass-transfer stage is relatively low (lowerthan for the progenitors of SD systems by three or four orders ofmagnitude). The continued transfer of mass from the less massive to themore massive star after the component masses have become equal leads tothe formation of a WR + O system, and the orbit's residual eccentricityincreases to the observed value. The increase of the orbitaleccentricity is also facilitated by variable radial mass loss via thewind from the WR star in the WR + O system during its motion in theelliptical orbit. The result is that WR + O binaries can haveconsiderable orbital eccentricities, despite their intense masstransfer. For this reason, the presence of appreciable eccentricitiesamong WR + O binaries with large orbital periods cannot be consideredfirm evidence against mass transfer in the parent O + O binary systems.Only for the WR + O binaries with the longest orbital periods (4 of 35known systems, or 11 %) can the evolution of the parent O + O binariesoccur without filling of the Roche lobe by the primary O star, beinggoverned by radial outflow in the form of the stellar wind and possiblyby the LBV phenomenon, as in the case of HD 5980.
| 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.
| Tomographic Separation of Composite Spectra. IX. The Massive Close Binary HD 115071
We present the first orbital elements for the massive close binary HD115071, a double-lined spectroscopic binary in a circular orbit with aperiod of 2.73135+/-0.00003 days. The orbital semiamplitudes indicate amass ratio of M2/M1=0.58+/-0.02, and yet the starshave similar luminosities. We used a Doppler tomography algorithm toreconstruct the individual component optical spectra, and we appliedwell-known criteria to arrive at classifications of O9.5 V and B0.2 IIIfor the primary and secondary, respectively. We present models of theHipparcos light curve of the ellipsoidal variations caused by the tidaldistortion of the secondary, and the best-fit model for a Roche-fillingsecondary occurs for an inclination of i=48.7d+/-2.1d. The resultingmasses are 11.6+/-1.1 and 6.7+/-0.7Msolar for the primary andsecondary, respectively, so both stars are very overluminous for theirmass. The system is one of only a few known semidetached, Algol-typebinaries that contain O stars. We suggest that the binary has recentlyemerged from extensive mass transfer (possibly through a delayed contactand common-envelope process).
| Beobachtungsergebnisse Bundesdeutsche Arbeitsgemeinschaft fur Veraenderliche Sterne e.V.
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| The post-Newtonian effects due to rotation of stars on the variation of orbital elements of the component in binary system
The author examined continuously the post-Newtonian effects due torotation of stars on the variation of the orbital elements for thecomponent in binary system in PPN formalism. The secular and periodicperturbation effects are both given. The results show that there existonly the periodic variations in semi-major axis and eccentricity, andexist the periodic and secular variations in longitude of periastron andmean anomaly of epoch. In addition, the author applied the obtainedresults to calculate the post-Newtonian effects of rotation to sixbinary stars (EK Cep?GT Cep?NY Cep?V448 Cyg?V1143 Cyg?V451 Oph)on thevariation of the Orbital elements of components and discussed. Thenumerical results are given in Tablel-3. It shows that thepost-Newtonian effect caused by the two rapid rotating massivecomponents is not negligible.
| 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.
| 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
| Variations of the orbital periods in semi-detached binary stars with radiative outer layers
A detailed analysis of the period changes of sixteen semi-detachedbinaries which contain only stars with radiative outer layers(ET-systems) has been performed and their respective O-C diagrams arebrought and discussed. It was found that the course of the periodvariations is monotonic and in some systems the period is even constant.This detailed analysis of extensive sets of timings covering severaldecades brings a strong support to an earlier finding of te[Hall(1989)]{hal89} and develops it further. We show that all systems withthe orbital periods shorter than nine days display constant period orits increase, with the exception of an uncertain case of V 337 Aql. Thecourse of the period variations in TT Aur appears more complex but thecyclic term can be plausibly explained by the third body. A search forgeneral relations between the parameters of the systems and the periodchanges was undertaken. The mass ratio q appears to play a role in theperiod variations. Clear changes in systems with orbital periods shorterthan 9 days were detected only for q>0.4 while constant periods arecommon in systems with q<0.4 in this period range. The sense of thesecular changes in most systems is in accordance with the dominantconservative mass transfer in evolved binary and corresponds to the slowphase. The role of the evolutionary scenarios (case A versus B) and theinfluence of changes of the rotational angular momenta of the componentsare discussed.
| Interacting OB star binaries: LZ Cep, SZ Cam and IU AUR
New spectroscopic observations of three O+O binary stars (LZ Cep, SZ Camand IU Aur), obtained over a number of years at the DominionAstrophysical Observatory, are analysed using state-of-the-artcross-correlation techniques to produce radial velocity curves. Theseresults are combined with new (LZ Cep) and published (SZ Cam and IU Aur)photometry to yield masses, temperatures, radii and luminosities. Wefind that LZ Cep is a semi-detached system, in agreement with theresults of Howarth et al., with the secondary star filling its Rochelobe. We find a distance modulus of 9.6+/-0.2, which is slightly smallerthan the distance modulus to Cep OB2 (=9.9).The reddening of LZ Cep isalso at the lower end of the cluster range, suggesting that the binaryis located on the near side of the cluster. SZ Cam is a triple system,and we are able to measure the radial velocities of the three componentsthat are observed in the absorption lines. A light-curve solutionemploying our new mass ratio shows that the short-period binary isdetached. The third body emits about 40 per cent of the radiation fromthe system, and is probably a binary itself. The distance modulus for SZCam (=9.88) is in good agreement with that of its parent cluster NGC1502 (=9.71). IU Aur is another triple system, although we are unable tofind spectroscopic evidence for the tertiary. The close binary issemi-detached, with the secondary filling its Roche lobe. The distancemodulus of the system is 11.0, which is in approximate agreement withthat of the Aur OB1 association (=10.6+/-0.2). We note that the currentmodels for interacting massive binaries all assume case B mass transfer,in which the mass-loser becomes a Wolf-Rayet star. Case A mass-transfermodels (in which the mass-loser fills its Roche lobe while still on themain sequence) are required in order to see whether or not they canexplain the observed properties of these interacting systems.
| 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.
| Massive stars
We describe the present state of massive star research seen from theviewpoint of stellar evolution, with special emphasis on close binaries.Statistics of massive close binaries are reasonably complete for theSolar neighbourhood. We defend the thesis that within our knowledge,many scientific results where the effects of binaries are not included,have an academic value, but may be far from reality. In chapter I, wesummarize general observations of massive stars where we focus on the HRdiagram, stellar wind mass loss rates, the stellar surface chemistry,rotation, circumstellar environments, supernovae. Close binaries can notbe studied separately from single stars and vice versa. First, theevolution of single stars is discussed (chapter I). We refer to newcalculations with updated stellar wind mass loss rate formalisms andconclusions are proposed resulting from a comparison with representativeobservations. Massive binaries are considered in chapter II. Basicprocesses are briefly described, i.e. the Roche lobe overflow and masstransfer, the common envelope process, the spiral-in process in binarieswith extreme mass ratio, the effects of mass accretion and the mergingprocess, the implications of the (asymmetric) supernova explosion of oneof the components on the orbital parameters of the binary. Evolutionarycomputations of interacting close binaries are discussed and generalconclusions are drawn. The enormous amount of observational data ofmassive binaries is summarized. We separately consider the non-evolvedand evolved systems. The latter class includes the semi-detached andcontact binaries, the WR binaries, the X-ray binaries, the runaways, thesingle and binary pulsars. A general comparison between theoreticalevolution and observations is combined with a discussion of speciallyinteresting binaries: the evolved binaries HD 163181, HD 12323, HD14633, HD 193516, HD 25638, HD 209481, Φ Per and silon Sgr; theWR+OB binary V444 Cyg; the high mass X-ray binaries Vela X-1, Wray 977,Cyg X-1; the low mass X-ray binaries Her X-1 and those with a black holecandidate; the runaway ζ Pup, the WR+compact companion candidatesCyg X-3, HD 50896 and HD 197406. We finally propose an overallevolutionary model of massive close binaries as a function of primarymass, mass ratio and orbital period. Chapter III deals with massive starpopulation synthesis with a realistic population of binaries. We discussthe massive close binary frequency, mass ratio and period distribution,the observations that allow to constrain possible asymmetries during thesupernova explosion of a massive star. We focuss on the comparisonbetween observed star numbers (as a function of metallicity) andtheoretically predicted numbers of stellar populations in regions ofcontinuous star formation and in starburst regions. Special attention isgiven to the O-type star/WR star/red supergiant star population, thepulsar and binary pulsar population, the supernova rates.
| Interacting O-star binaries: V382 Cyg, V448 CYG and XZ CEP
New spectroscopic observations of three interacting O+O-star binaries(V382 Cyg, V448 Cyg and XZ Cep), obtained at the Dominion AstrophysicalObservatory, are analysed in conjunction with published photometry, toyield masses, temperatures and radii. We determine masses of 26.0+/-0.7and 1903+/-0.4Msolar for V382 Cyg, 25.2+/-0.7 and 14.0+/-0.7Msolar forV448 Cyg, and 15.8+/-0.4 and 6.4+/-0.3 Msolar for XZ Cep. We find thatV382 Cyg is a contact system, resulting from evolutionary expansion ofthe components during their main-sequence lifetimes (case A masstransfer). V448 Cyg is an evolved binary that has undergone late case Aor early case B mass transfer, with the mass loser now filling its Rochelobe and transferring mass more slowly to the gainer. The distancemodulus for V448 Cyg of 11.4 agrees well with that of its parent clusterNGC 6871, while the cluster age (7Myr) places a tight constraint on theevolutionary status of this system. XZ Cep closely resembles V448 Cyg,although its mass is somewhat lower.
| The calculation of critical rotational periods in three typical close binary systems based on synchronization theory.
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| Measurement and study of rotation in close binary stars (III) Statistical analysis of synchronization.
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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.
| Matter flow formation in semidetached eclipsing binaries of AO Cassiopeiae type
We determined, by means of calculations in the frame of nonstationaryhydrodynamics in Euler's formulation using the method of large particlesand taking into account our analysis of observational data, theproperties of the matter flow near the first Lagrangian point for thesemidetached systems AO Cas, V448 Cyg, and XZ Cep. A flow of matter inthe direction of the second component arises when one of the system'scomponents expands and the inner layers of its atmosphere reach thefirst Lagrangian point. This flow has axial symmetry, its size is about20 percent that of the star of its origin, and the matter exchange rateis about 10 exp -7 solar mass/yr. Such parameters of the matter flowfrom AO Cas type stars are considerably lower than those for W Sereclipsing binaries.
| Measurement and analysis of rotation in close binaries. II. Calculation of synchronism.
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| CH(+) in the interstellar medium
This paper describes observations of interstellar CH(+) along the linesof sight to O and B stars with E(B-V)s up to +1.13. Along some lines ofsight with strong detections of CH(+), we find distinct radial velocityshifts between the CH(+) lines and other neutral species, such as Ca Iand CH. The shifts are small but are predicted by shock models of CH(+)formation in which the shock is inclined with respect to the observer.We have also found no column densities exceeding approximately1013.8/sq cm. When these data are examined along with theother CH(+) data collected from the literature, the previously seentendency of CH(+) column density to increase with E(B-V) does notcontinue beyond reddenings of about +0.6. These findings offer supportto the shock model of CH(+) formation for at least some lines of sight.
| Measurement and Analysis of Rotation in Close Binary Stars - Part One - Observations and Results
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| New rotational velocities for eclipsing binaries, and a comparison of spectroscopic and photometric rotations
Rotational velocities are determined spectroscopically for 38 eclipsingbinaries, including many long-period, nominally semidetached, systems.We note that spectroscopic rotations may differ from rotations derivedfrom light-curve modeling using the Wilson-Devinney program. In'direct-impact' mass-transferring systems, or in most systems withperiods smaller than about 7 days, observations suggest that the tworotations are usually about the same. In cases where the stream missesthe gainer and an accretion disk forms, however, photometric rotationestimates often exceed spectroscopic determinations. The possiblephysical significance of this situation is briefly discussed. Doubt iscast on the likelihood that the rotation of the hot component of U Sgehas changed detectably in the last 30 years.
| Structure of the gas envelope in the interactive binary V448 CYG
The structure of the gas envelope in the interactive binary V448 Cyg isstudied on the basis of 11 spectra in the H-alpha-line region obtainedwith the aid of a CCD matrix with an SNR of about 100 and a resolutionof about 20,000, and three photographic spectra with a dispersion of 14A/mm. It is shown that emission of the H-alpha line is formed in theenvelope region connected with the B-component near the L2 point.Circumstellar envelope parameters are determined.
| Structure of the gaseous envelope of the interacting binary V448 Cyg
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| Galactic OB associations in the northern Milky Way Galaxy. I - Longitudes 55 deg to 150 deg
The literature on all OB associations was reviewed, and their IRAS pointsource content was studied, between galactic longitude 55 and 150 deg.Only one third of the 24 associations listed by Ruprecht et al. (1981)have been the subject of individual studies designed to identify thebrightest stars. Distances to all of these were recomputed using themethod of cluster fitting of the B main sequence stars, which makes itpoossible to reexamine the absolute magnitude calibration of the Ostars, as well as for the red supergiant candidate stars. Also examinedwas the composite HR diagram for these associations. Associations withthe best defined main sequences, which also tend to contain very youngclusters, referred to here as OB clusters, have extremely few evolved Band A or red supergiants. Associations with poorly defined mainsequences and few OB clusters have many more evolved stars. They alsoshow an effect in the upper HR diagram referred to as a ledge byFitzpatrick and Garmany (1990) in similar data for the Large MagellanicCloud. It is suggested that the differences in the associations are notjust observational selection effects but represent real differences inage and formation history.
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Observation and Astrometry data
| Constellation: | Schwan |
| Right ascension: | 20h06m09.95s |
| Declination: | +35°23'09.6" |
| Apparent magnitude: | 8.126 |
| Distance: | 3571.429 parsecs |
| Proper motion RA: | -3.2 |
| Proper motion Dec: | -5.9 |
| B-T magnitude: | 8.529 |
| V-T magnitude: | 8.16 |
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