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Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
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| CCD Times of Minima of Selected Eclipsing Binaries
374 CCD minima observations of 187 eclipsing binaries are presented. Theobserved stars were chosen mainly from catalogue BRKA of observingprogramme of Variable Star Section of CAS.
| The Case for Third Bodies as the Cause of Period Changes in Selected Algol Systems
Many eclipsing binary star systems show long-term variations in theirorbital periods, evident in their O-C (observed minus calculated period)diagrams. With data from the Robotic Optical Transient Search Experiment(ROTSE-I) compiled in the SkyDOT database, New Mexico State University 1m data, and recent American Association of Variable Star Observers(AAVSO) data, we revisit Borkovits and Hegedüs's best-casecandidates for third-body effects in eclipsing binaries: AB And, TV Cas,XX Cep, and AK Her. We also examine the possibility of a third bodyorbiting Y Cam. Our new data support their suggestion that a third bodyis present in all systems except AK Her, as is revealed by thesinusoidal variations of the O-C residuals. Our new data suggest that athird body alone cannot explain the variations seen in the O-C residualsof AK Her. We also provide a table of 143 eclipsing binary systems thathave historical AAVSO O-C data with new values computed from the SkyDOTdatabase.
| 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.
| Minima Kurt Locher 2004-2005
Minima observed 2004..2005 by Kurt Locher visually, not accepted by IBVSas part of BBSAG Bulletin.
| 164. List of Timings of Minima Eclipsing Binaries by BBSAG Observers
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| 163. List of Minima Timings of Eclipsing Binaries by BBSAG Observers
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| Catalogue of Algol type binary stars
A catalogue of (411) Algol-type (semi-detached) binary stars ispresented in the form of five separate tables of information. Thecatalogue has developed from an earlier version by including more recentinformation and an improved layout. A sixth table lists (1872) candidateAlgols, about which fewer details are known at present. Some issuesrelating to the classification and interpretation of Algol-like binariesare also discussed.Catalogue is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/417/263
| Archive of Photometric Plates Obtained at Cluj Astronomical Observatory
The archive of photometric plates obtained at the AstronomicalObservatory of Cluj in the period 1952-1974 is presented. The plateinventory is made within the framework of the Wide-Field Plate Databaseproject. The plates were taken in the regions around 110 variable stars(eclipsing variables and RR Lyrae-type stars), as well as in somecomparison stars regions.
| Orbital Period Studies of Two Algol-Type Eclipsing Binary Systems: TY Pegasi and X Trianguli
O-C curves of two EA-type eclipsing binaries, TY Peg and X Tri, areformed and studied in detail based on all available times of lightminimum. For TY Peg, it was discovered that the general trend of the O-Ccurve showed a downward parabolic variation, which indicates a secularperiod decrease with rate at dP/dt=-1.16×10-6 daysyr-1. When the secular decrease is removed from the O-Ccurve, the residuals can be described by several linear ephemerides,suggesting several sudden period jumps. For the other one, X Tri, it isfound that the general O-C trend also indicates a secular perioddecrease (dP/dt=-1.42×10-7 days yr-1), andseveral irregular period jumps are found to superpose on the long-timeperiod decrease. This kind of period change, irregular sudden jumpssuperposed on secular decrease, is typical for many other Algol-typebinary systems such as TU Her, UU And, Z Per, Y Psc, BO Mon, FH Ori, RTPer, and TX UMa. The period changes of these systems may be caused byorbital angular momentum loss via variable magnetic coupling and gravitycoupling between the components.
| Minima of binary stars
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| The Origin of Cyclic Period Changes in Close Binaries: The Case of the Algol Binary WW Cygni
Year- to decade-long cyclic orbital period changes have been observed inseveral classes of close binary systems, including Algol, W UrsaeMajoris, and RS Canum Venaticorum systems and the cataclysmic variables.The origin of these changes is unknown, but mass loss, apsidal motion,magnetic activity, and the presence of a third body have all beenproposed. In this paper, we use new CCD observations and thecentury-long historical record of the times of primary eclipse for WWCygni to explore the cause of these period changes. WW Cyg is an Algolbinary whose orbital period undergoes a 56 yr cyclic variation with anamplitude of ~0.02 days. We consider and reject the hypotheses of masstransfer, mass loss, apsidal motion, and the gravitational influence ofan unseen companion as the cause for these changes. A model proposed byApplegate, which invokes changes in the gravitational quadrupole momentof the convective and rotating secondary star, is the most likelyexplanation of this star's orbital period changes. This finding is basedon an examination of WW Cyg's residual O-C curve and an analysis of theperiod changes seen in 66 other Algols. Variations in the gravitationalquadrupole moment are also considered to be the most likely explanationfor the cyclic period changes observed in several different types ofbinary systems.
| Possible Mass and Angular Momentum Loss in Algol-Type Binaries. IV. UU Andromedae and Z Persei
The orbital periods of two Algol-type binaries, UU And and Z Per, arestudied based on the analysis of the O-C data. It is discovered that theorbital period of UU And shows seven irregular jumps while it undergoesa secular decrease with rate of dP/dt=-4.76×10-7 daysyr-1. For Z Per, seven irregular period jumps are also foundsuperposed on a rapid period decrease (dP/dt=-1.54×10-6days yr-1). Meanwhile, the orbital period changes of twoother systems, BO Mon and Y Psc, studied in Paper II of this series, arereinvestigated by combining our previous data with earlier publishedtimes of light minimum. The secular period decrease rates of the twosystems are revised, and apart from the sudden jumps proposed in PaperII, additional period jumps superposed on the secular period decreaseare found. The period changes of these systems, both the decreases andthe jumps, can be explained by secular mass and angular momentum lossvia magnetic braking.
| Possible Mass and Angular Momentum Loss in Algol-Type Binaries. III. TU Cancri, FZ Delphini, AY Geminorum, VZ Leonis, FH Orionis, IU Persei, XZ Persei, and BE Vulpeculae
Orbital period variations of eight Algol-type binaries, TU Cnc, FZ Del,AY Gem, VZ Leo, FH Ori, IU Per, XZ Per, and BE Vul, are studied based onthe analysis of the O-C observations. It is discovered that the periodsof three systems, TU Cnc, FH Ori, and IU Per, show secular decrease. ForAY Gem and XZ Per, the orbital periods can be described by a suddendecrease or by two sudden changes superposed on a secular decrease. Weakevidence also shows that the orbital periods of the other three systems,FZ Del, VZ Leo, and BE Vul, are decreasing. As in other systems proposedby Qian, the decrease in the orbital periods of these systems, combinedwith their semidetached configurations, suggests that they may beundergoing secular mass and angular momentum loss due to magneticbraking. The irregular period jumps superposed on the secular decrease(e.g., in AY Gem, FH Ori, XZ Per, and BE Vul) can be explained byvariable magnetic coupling and gravity coupling between the twocomponents. However, the present secular period decrease of thesesystems may be part of a long-period periodic change (as in TT Del),which needs further investigation.
| 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 Maxima of Pulsating Stars
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| Possible Mass and Angular Momentum Loss in Algol-Type Binaries. II. TT Delphini, BO Monocerotis, and Y Piscium
The period variations of three Algol-type binaries, TT Del, BO Mon, andY Psc, are studied based on the analysis of the O-C observations. Theorbital period of TT Del is discovered to be decreasing at a ratedP/dt=-2.20×10-6 days yr-1, while theorbital periods of BO Mon and Y Psc vary in some complex ways. For BOMon, three abrupt changes in its orbital period are found while itundergoes secular decrease at a rate dP/dt=-2.36×10-6days yr-1. For the remaining one, Y Psc, two jumps in theorbital period are found to superpose on a rapid period decrease(dP/dt=-4.90×10-6 days yr-1). As in the caseof TU Her (Paper I), the rapid decrease in the orbital periods of thesesystems, combined with their semidetached configurations, suggests thatthey may be undergoing rapid mass and angular momentum loss (AML) due tomagnetic braking. With the present decrease rate, after(7-9)×105 yr they will evolve into contact binaries.The abrupt changes that are superposed on the rapid period decrease maybe caused by the interplay between the variable AML and variablemagnetic coupling.
| 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.
| Rotation of Algol binaries - a line profile model applied to observations.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996MNRAS.283..613M&db_key=AST
| Evolutionary scenarios for double degenerate systems
We propose evolutionary scenarios in which double degenerate white dwarfsystems can be produced through one or two phases of stable masstransfer. We consider Algol-type evolution as well as evolutioninvolving first a stage of common-envelope (CE) evolution followed by aphase of stable mass transfer. We also show that the final orbitalperiod of double white dwarf systems depends on the period after thefirst phase of mass transfer, and that there is critical period (thebifurcation period) above which systems evolve to orbital periods of theorder of days and below which systems evolve towards very short orbitalperiods (a few hours). This probably corresponds to the observation thatdouble degenerate systems have periods either of hours or of days. Wealso find a limit on the stability of mass transfer for systems thatfirst go through a phase of CE evolution. We suggest that our newevolutionary scheme involving two stages of stable mass transfer and ourscheme involving first CE evolution followed by stable mass transfershould be included in population synthesis models.
| Vitesses radiales. Catalogue WEB: Wilson Evans Batten. Subtittle: Radial velocities: The Wilson-Evans-Batten catalogue.
We give a common version of the two catalogues of Mean Radial Velocitiesby Wilson (1963) and Evans (1978) to which we have added the catalogueof spectroscopic binary systems (Batten et al. 1989). For each star,when possible, we give: 1) an acronym to enter SIMBAD (Set ofIdentifications Measurements and Bibliography for Astronomical Data) ofthe CDS (Centre de Donnees Astronomiques de Strasbourg). 2) the numberHIC of the HIPPARCOS catalogue (Turon 1992). 3) the CCDM number(Catalogue des Composantes des etoiles Doubles et Multiples) byDommanget & Nys (1994). For the cluster stars, a precise study hasbeen done, on the identificator numbers. Numerous remarks point out theproblems we have had to deal with.
| Radio continuum emission from stars: a catalogue update.
An updated version of my catalogue of radio stars is presented. Somestatistics and availability are discussed.
| Speckle observations of visual and spectroscopic binaries. V.
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| Speckle observations of visual and spectroscopic binaries. IV
This is the fourth paper of this series giving results of speckleobservations for 22 visual and 161 spectroscopic binaries. Theobservation was carried out by using the 212 cm telescope of San PedroMartir Observatory in Mexico on 7 nights from July 20 to July 26, 1991.We obtained fringes in power spectra of 19 visual and 11 spectroscopicbinaries (6 newly resolved ones) with angular separation larger than0.06 arcsec. We introduced a new ICCD TV camera in this observation, andwere able to achieve the diffraction-limit resolution of the 212 cmtelescope.
| Speckle observations of visual and spectroscopic binaries. III
This is the third paper of this series giving results of speckleobservations carried out for seven visual and 119 spectroscopic binariesat seven nights from May 20 to May 27, 1989, and for 30 visual and 272spectroscopic binaries at 12 nights from June 11 to June 15, and fromAugust 28 to September 3, 1990, using the 212-cm telescope at San PedroMartir Observatory in Mexico. Fringes in the lower spectrum of 31 visualand spectroscopic binaries with angular separation larger than 21 arcsecare obtained. Additionally to two spectroscopic binaries, HD41116 andHD206901, named in the second paper of this series, six spectroscopicbinaries are found each of which has the third component starsurrounding two stars of spectroscopic binary having periodic variationof radial velocity.
| Eclipsing binaries, Pegasus to Sagittarius, in 1972-1987
Photoelectric and visual observations of 34 known and suspectedeclipsing binaries are discussed. Revised light elements are derived forDM Per and Beta Per. EL Sge is confirmed to vary with a period ofapproximately 0.333d. Large deviations from the published elements arereported for BG Peg, AB Per, LS Per, SU Psc, SZ Psc and TU Sge. Thecatalogue period of BQ Peg is probably incorrect.
| Speckle observations of spectroscopic binaries
Results from speckle observations of binary stars carried out between1987 and 1990 using a 212-cm telescope at the San Pedro MartirObservatory, Mexico, are presented. Fringe patterns for 21 of the 76reduced spectroscopic binaries in the Fourier domain were detected. Thespeckle observations and the astrometric observations are consistent forthe stars HD41116, HD202275, and HD206901.
| Rotation statistics of Algol-type binaries and results on RY Geminorum, RW Monocerotis, and RW Tauri
Rotation rates and other parameters are estimated from light curves ofthree Algol-type binaries, and rotation statistics based on bothspectral line broadening and light curves are collected for 36 Algolsystems. The statistics suggest that a subset of Algols have primarystars which rotate at the centrifugal limit and that many Algols havesufficient continual mass transfer to maintain nonsynchronous rotation.A formal procedure for estimating the critical rotation rate(centrifugal limit) is described. It is found that RY Gem rotates about14 times faster than synchronously, but not close to its centrifugallimit of about 24 times. For RW Mon, the rotation is about five timessynchronous. For RW Tau it was not possible to estimate the rotationfrom the light curves, but consistency with a published result from linebroadening is found.
| Statistical study of semi-detached and near-contact semi-detached binaries
A statistical study was made of 107 semidetached with combined lightcurve solutions. An empirical period-dependent mass-radius relation wasderived, thereby revealing the impossibility of having evolvedsemidetached systems with very short periods. Statistically, thenear-contact semidetached systems have the common properties of nearlyequal mass densities of the components, larger mass-ratios, shorterperiods and smaller specific angular momenta, and their A- F-typesecondaries generally have greater densities than the secondaries ofclassical Algol systems of the same spectral types. A detaileddiscussion is also made in this paper on the evolution of near-contactsemidetached binaries.
| Speckle observations of visual and spectroscopic binaries. II
Results are presented from speckle observations carried out for 54visual and 45 spectroscopic binaries by using the 212 cm telescope atSan Pedro Martir Observatory in Mexico on six nights from October 20 toOctober 25, 1988. Fringes in power spectrum of 41 visual andspectroscopic binaries (six newly resolved ones) with angular separationlarger than 0.15 arcsec are obtained. Two spectroscopic binaries, HD41116 and HD 206901, each of which has the third component staradditionally to two stars showing periodic variation of radial velocity,were found.
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