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New Times of Minima of Eclipsing Binary Systems and of Maximum of SXPHE Type Stars
We present 64 photoelectric minima observations of 31 eclipsingbinaries. We also report three new times of maxima of three SXPHE typepulsating stars.
| 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.
| Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
Not Available
| 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 Eclipsing Binary Systems
We present 45 photoelectric minima observations of 20 eclipsingbinaries.
| Variable Depths of Minima of the Eclipsing Binary V685 Cen
According to data by HIPPARCOS and ASAS 3 the depths of minima of V685Cen are smaller than according to older photometry by van Houten et al.The reason of it might be the precession of the orbital plane in atriple system. If the third light is allowed when the light curves aresolved, better fit and more acceptable parameters of the binary result.
| Tidal and rotational effects in the perturbations of hierarchical triple stellar systems. I. Numerical model and a test application for Algol
A new numerical integrator has been developed for studying the orbitaland spin evolution of hierarchical triple stellar systems. The codeincludes equilibrium tide approximations with arbitrary direction ofrotational axes. The variation of the orbital elements (e.g. theinclination of the close - eclipsing - binary) and its observationalconsequences according to the distorted models with differentmass-distributions of the stars, as well as with and without dissipationare studied in the case of the well-known eclipsing triple systemAlgol. We found that, in the absence of the tidaldissipation, the presence of the third star may cause suddenfluctuations in the orbital elements and the stellar rotation of thebinary members even in the previously synchronized case, too. Thedissipation can eliminate these fluctuations, nevertheless somevariations which would produce observable effects in the same orderwhich have been measured in several eclipsing binaries are also present.Appendices are only available in electronic form athttp://www.edpsciences.org
| Photoelectric Minima of Selected Eclipsing Binaries
Not Available
| New Times of Minima of Eclipsing Binary Systems
We present 58 photoelectric minima observations of 19 eclipsingbinaries.
| New Times of Minima of Eclipsing Binary Systems
Not Available
| Photoelectric Minimum Times of Some Eclipsing Binary Stars
We present 12 minimum times of 6 eclipsing binaries observed in theyears from 1996 to 1999.
| Refinement of third body parameters and new photometric results for the early-type multiple system IU Aurigae
The massive eclipsing binary system IU Aurigae is re-analyzed in thecontext of new photometric observations and an improved treatment of itslong-term period changes (O-C diagram) derived from new times of minima.The best-fit of the O-C curve reveals that the third component isorbiting around the system with a period of 293.3 days in a highlyeccentric orbit (e = 0.62). A solution of the most recent UBV lightcurves obtained during 1997/1998 showed a third light contribution of~23% and continuation of the orbital plane precession of IU Aurigae.Since the revised mass of the third component deduced from the analysisof the O-C curve of m3=14.2 Msun would imply alarger fraction of third light than suggested by the value of 23%derived from the light curve analysis, the third body is possiblycomposed of two components. A q-search test applied to the UBV lightcurves yields a minimum chi 2 value at q=0.67 +/- 0.02, whichconfirms previous photometric and spectroscopic solutions.Based on the first observational data of a new optical observatory inTurkey, Çanakkale Onsekiz Mart University Observatory, operatedby the Çanakkale Astrophysics Research Center (ÇAAM), URL:http://physics.comu.edu.tr/caam.html
| On the detectability of long period perturbations in close hierarchical triple stellar systems
We study the possibility of the detection of the low amplitude long (P')period perturbative effect of a distant third companion on the motion ofa close binary. We give a new, more accurate analytical formula for thiskind of perturbation affecting the moments of the times of minima ineclipsing binaries. The accuracy of this formula is tested by numericalintegrations carried out for several initial configurations. We alsodescribe a numerical method based on a non-linear Levenberg-Marquardtalgorithm which makes it possible to separate this dynamical effect fromthe pure geometrical light-time effect in the eclipsing O-C diagram. Thecapabilities of this new method are demonstrated by the analysis ofnumerically simulated O-Cs for test systems having physical parametersvery similar to Algol and IU Aur.The results show that the above mentioned effect would be detectable inthese systems nowadays, observing almost each minima events in a 1-2year-long interval.
| 149 Bedeckungssterne der BAV-Programme. Eine Analyse der Beobachtungstatigkeit seit den Angangen.
Not Available
| Optical spectroscopy of XMEGA targets in the Carina Nebula - III. The multiple system Tr 16-104 (≡CPD -59° 2603)
We discuss the orbital elements of the multiple system Tr 16-104 whichis usually believed to be a member of the open cluster Trumpler 16 inthe Carina complex. We show that Tr 16-104 could be a hierarchicaltriple system consisting of a short-period (2.15d) eclipsing O7V+O9.5Vbinary bound to a B0.2 IV star. Our preliminary orbital solution of thethird body indicates that the B star most probably describes aneccentric orbit with a period of ~285 or ~1341d around the close binary.Folding photometric data from the literature with our new ephemerides,we find that the light curve of the close binary exhibits rather narroweclipses indicating that the two O stars must be well inside their Rochelobes. Our analysis of the photometric data yields a lower limit on theinclination of the orbit of the close binary of i>=77°. Thestellar radii and luminosities of the O7 V and O9.5 V stars aresignificantly smaller than expected for stars of this spectral type. Ourresults suggest that Tr 16-104 lies at a distance of the order of 2.5kpcand support a fainter absolute magnitude for zero-age main-sequence Ostars than usually adopted. We find that the dynamical configuration ofTr 16-104 corresponds to a hierarchical system that should remain stableprovided that it suffers no strong perturbation. Finally, we also reportlong-term temporal variations of high-velocity interstellar Caiiabsorptions in the line of sight towards Tr 16-104.
| 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.
| 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
| Dynamical Stability of Triple Stars
The dynamical stability of 38 observed hierarchical triple stars withknown orbital elements of the internal and external binary subsystemsand component masses is considered. Four different criteria of dynamicalstability are used. The observed stability parameters and their criticalvalues are calculated by taking into account errors in the orbitalelements and component masses. Most triple systems are stable. Accordingto some criteria, several triple stars (ADS440, xi Tau, lambda Tau,ADS3358, VV Ori, ADS10157, HZ Her, Gliese 795, ADS15971, and ADS16138)may be dynamically unstable. This result is probably associated withunreliability of the empirical stability criteria and/or with errors inthe observed quantities.
| The Cessation of Eclipses in SS Lacertae: The Mystery Solved
The 14.4 day period eclipsing binary SS Lacertae in the open cluster NGC7209 is unusual in that the eclipses stopped completely about the middleof this century, giving rise to considerable speculation as to thecause. Disruption of the binary through a collision with another memberof the cluster and, more likely, gravitational perturbations from athird star in the system have been proposed to explain the phenomenon.We present here the results of our intensive radial velocity monitoringof the object, which show clearly that there is indeed a third star inthe system in a slightly eccentric orbit with a period of about 679days. We also reanalyze the historical light curves of SS Lac todetermine the properties of the system early in the century. We discussthe implications of our findings in terms of changes in the inclinationangle of the close pair. An analysis of available times of eclipse forSS Lac together with the new velocity information has also revealedapsidal motion in the system, ω=0.0137d cycle-1,corresponding to an apsidal period of about 1000 yr. We argue that thethird star is probably responsible for this effect also. Some of theobservations reported here were obtained with the Multiple MirrorTelescope, a joint facility of the Smithsonian Institution and theUniversity of Arizona.
| Analyses of the Currently Noneclipsing Binary SS Lacertae or SS Lacertae's Eclipses
Confirmatory evidence for changing light-curve amplitude of the formereclipsing and current SB2 system SS Lac in the Open Cluster NGC 7209 hasbeen uncovered. Remeasured Harvard plate data and published and compileddata sets reveal that the depth of the primary minimum increased betweenthe 1890s and 1902 and decreased in the 1920s and 1930s. A parabolicfitting of the amplitude with phase predicts a maximum at 1911.5, withan eclipse onset at 1885.3 and eclipse cessation at 1937.8. We confirmthe finding of Lehmann, that the system's inclination varies with timeand that a central eclipse occurred ~1912, and we concur withMossakovskaya that eclipses effectively ceased ~1940. Estimates of SSLac on plates taken at Tashkent between 1937 and 1940 further serve toconfirm the result. Thus, SS Lac belongs to a small but elite class oftriple systems in which changes due to dynamical effects can be seenover a single human lifetime. In order to explore the properties of theSS Lac system, recent radial velocity curves and archival photographicand visual light curves have been analyzed with versions of theWilson-Devinney code, augmented with a simplex routine to test solutionuniqueness. The modeling solutions for the Dugan-Wright light curvesostensibly indicate that the former eclipsing system is composed of twoearly A stars of only slightly differing masses (2.57+/-0.16 and2.59+/-0.19 Msolar) and effective surface temperatures(8750+/-300 [assumed for component 1] and 8542+/-309 K), butsignificantly different radii (2.38+/-0.02 and 3.63+/-0.07Rsolar) and luminosities (30+/-4 and 63+/-9Lsolar) for the hotter and cooler components, respectively.The light-curve solutions are compromised somewhat by variable eclipsedepths over the ranges of dates of the data sets. This is especiallytrue of the most complete light curve, that of Dugan & Wright; theothers also suffer from incompleteness (that of Wachmann) and highscatter (that of Kordylewski, Pagaczewski, & Szafraniec). As aconsequence, small, temporal variations in such system properties as theeccentricity, argument of periastron, modified Roche potentials,luminosities, and third light level, cannot be ruled out from currentlyavailable data. However, solutions with WD95, a self-iterating,damped-least squares version of the Wilson-Devinney program, revealoptimized inclinations for the data sets that project an inclinationvariation of 0.16d yr-1, but no evidence of apsidal motion.We find a distance for the system of 898+/-95 pc, consistent with thevalue of Vansevičius et al. of 1040+/-10 pc, and finally, on thebases of location on the sky, proper motion, radial velocity,photometry, and properties deduced in the present study, we confirm itsmembership in the cluster NGC 7209. Publications of the RothneyAstrophysical Observatory, No. 73.
| Speckle Interferometry of New and Problem HIPPARCOS Binaries
The ESA Hipparcos satellite made measurements of over 12,000 doublestars and discovered 3406 new systems. In addition to these, 4706entries in the Hipparcos Catalogue correspond to double star solutionsthat did not provide the classical parameters of separation and positionangle (rho,theta) but were the so-called problem stars, flagged ``G,''``O,'' ``V,'' or ``X'' (field H59 of the main catalog). An additionalsubset of 6981 entries were treated as single objects but classified byHipparcos as ``suspected nonsingle'' (flag ``S'' in field H61), thusyielding a total of 11,687 ``problem stars.'' Of the many ground-basedtechniques for the study of double stars, probably the one with thegreatest potential for exploration of these new and problem Hipparcosbinaries is speckle interferometry. Results are presented from aninspection of 848 new and problem Hipparcos binaries, using botharchival and new speckle observations obtained with the USNO and CHARAspeckle cameras.
| 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
| 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.
| ICCD speckle observations of binary stars. XIX - an astrometric/spectroscopic survey of O stars
We present the results of a speckle interferometric survey made with theCHARA speckle camera and 4 m class telescopes of Galactic O-type starswith V less than 8. We can detect with the speckle camera binaries inthe angular separation range 0.035-1.5 arcsec with delta M less than 3,and we have discovered 15 binaries among 227 O-type systems. We combinedour results on visual binaries with measurements of wider pairs from theWashington Double Star Catalog and fainter pairs from the HipparcosCatalog, and we made a literature survey of the spectroscopic binariesamong the sample. We then investigated the overall binary frequency ofthe sample and the orbital characteristics of the known binaries.Binaries are common among O stars in clusters and associations but lessso among field and especially runaway stars. There are many triplesystems among the speckle binaries, and we discuss their possible rolein the ejection of stars from clusters. The period distribution of thebinaries is bimodal in log P, but we suggest that binaries with periodsof years and decades may eventually be found to fill the gap. The massratio distribution of the visual binaries increases toward lower massratios, but low mass ratio companions are rare among close,spectroscopic binaries. We present distributions of the eccentricity andlongitude of periastron for spectroscopic binaries with ellipticalorbits, and we find strong evidence of a bias in the longitude ofperiastron distribution.
| New times of minima and ephemeris for several OB eclipsing binaries
New times of minimum light were measured for several early-typeeclipsing binaries: V337 Aql, V1182 Aql, V1331 Aql, IU Aur, QZ Car andV382 Cyg. The O-C diagram for these systems is discussed and newephemeris is given for AH Cep; observation of AQ Cir is added. It isshown that the scatter of times of minima is several times larger thanthe measuring errors for most of the binaries studied.
| Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
Not Available
| Interaction of Eclipsing Binaries with their Environment
The interaction of eclipsing binary star systems with the mass around(in the form of star, planet, envelope or disk) affects the orbitalperiod of these systems. Thus, the long-term orbital period changes ofeclipsing binaries which can be deduced by using the observed times ofeclipse minima provide a good tool in understanding the interaction ofeclipsing binaries with their environment. In the present contributionmany examples of the orbital period changes of different eclipsingbinaries are presented and interpreted in terms of the interaction withtheir environment.
| The ``Mass Discrepancy'' for Massive Stars: Tests of Models Using Spectroscopic Binaries
Stellar evolutionary models are often used to infer a star's mass viaits luminosity, but empirical checks on the accuracy of the theoreticalmass-luminosity relation for very massive stars have been lacking. Thisis of particular concern given that modern atmosphere models yieldsystematically smaller masses for massive stars than do evolutionarymodels, with the discrepancy being a factor of 2 for Of stars. Weattempt to resolve this mass discrepancy by obtaining new,high-resolution optical data on seven early-type spectroscopic binaries:V453 Cyg, HD 191201, V382 Cyg, Y Cyg, HD 206267, DH Cep, and AH Cep. Ourstudy produces improved spectral subtypes for the components of thesesystems, which are crucial for evaluating their luminosities andlocations in the H-R diagram. Our radial velocity study utilizes ameasuring method that explicitly accounts for the effects of pairblending. We combine our new orbit solutions with existing data oninclinations and distances when available to compare the orbital masseswith evolutionary models, and we find good agreement in all cases wherethe stars are noninteracting. (The components of V382 Cyg and DH Cepfill their Roche lobes, and in both cases we find masses substantiallylower than the masses inferred from evolutionary tracks, suggesting thatsignificant material has been lost rather than transferred. We confirmthat this same trend exists for other systems drawn from theliterature.) Our own data extends to only 15 Mȯ, althoughphotometric inclination determinations for HD 191201 and HD 206267should prove possible and will provide examples of higher mass systems.We briefly discuss suitable systems from the literature and concludethat orbit solutions provide good agreement with the evolutionary modelsto 25 Mȯ. Beyond this, most known binaries either fill their Rochelobes or have other complications. We also discuss five systems forwhich our improved data and analysis failed to yield acceptable orbitsolutions: EO Aur, IU Aur, V640 Mon (Plaskett's star), LY Aur, and 29 UWCMa all remained intractable, despite improved data.
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| Yükselim: | +34°46'58.2" |
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