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.
|
Astrometric orbits of SB^9 stars
Hipparcos Intermediate Astrometric Data (IAD) have been used to deriveastrometric orbital elements for spectroscopic binaries from the newlyreleased Ninth Catalogue of Spectroscopic Binary Orbits(SB^9). This endeavour is justified by the fact that (i) theastrometric orbital motion is often difficult to detect without theprior knowledge of the spectroscopic orbital elements, and (ii) suchknowledge was not available at the time of the construction of theHipparcos Catalogue for the spectroscopic binaries which were recentlyadded to the SB^9 catalogue. Among the 1374 binaries fromSB^9 which have an HIP entry (excluding binaries with visualcompanions, or DMSA/C in the Double and Multiple Stars Annex), 282 havedetectable orbital astrometric motion (at the 5% significance level).Among those, only 70 have astrometric orbital elements that are reliablydetermined (according to specific statistical tests), and for the firsttime for 20 systems. This represents a 8.5% increase of the number ofastrometric systems with known orbital elements (The Double and MultipleSystems Annex contains 235 of those DMSA/O systems). The detection ofthe astrometric orbital motion when the Hipparcos IAD are supplementedby the spectroscopic orbital elements is close to 100% for binaries withonly one visible component, provided that the period is in the 50-1000 drange and the parallax is >5 mas. This result is an interestingtestbed to guide the choice of algorithms and statistical tests to beused in the search for astrometric binaries during the forthcoming ESAGaia mission. Finally, orbital inclinations provided by the presentanalysis have been used to derive several astrophysical quantities. Forinstance, 29 among the 70 systems with reliable astrometric orbitalelements involve main sequence stars for which the companion mass couldbe derived. Some interesting conclusions may be drawn from this new setof stellar masses, like the enigmatic nature of the companion to theHyades F dwarf HIP 20935. This system has a mass ratio of 0.98 but thecompanion remains elusive.
|
163. List of Minima Timings of Eclipsing Binaries by BBSAG Observers
Not Available
|
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
|
162-nd List of Minima Timings of Eclipsing Binaries by BBSAG Observers
Not Available
|
CCD Minima for Selected Eclipsing Binaries in 2002
Not Available
|
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.
|
Beobachtungsergebnisse Bundesdeutsche Arbeitsgemeinschaft fur Veraenderliche Sterne e.V.
Not Available
|
Chemical composition of red horizontal branch stars in the thick disk of the Galaxy
High-resolution spectra of 13 core helium-burning stars in the thickdisk of the Galaxy have been obtained with the SOFIN spectrograph on theNordic Optical Telescope to investigate abundances of up to 22 chemicalelements. Abundances of carbon were studied using the C2 Swan(0, 1) band head at 5635.5 Å. The wavelength interval 7980-8130Å with strong CN features was analysed in order to determinenitrogen abundances and 12C/13C isotope ratios.The oxygen abundances were determined from the [O I] line at 6300Å. Abundances in the investigated stars suggest that carbon isdepleted by about 0.3 dex, nitrogen is enhanced by more than 0.4 dex andoxygen is unaltered. The 12C/13C ratios arelowered and lie between values 3 and 7 which is in agreement with ``coolbottom processing'' predictions (Boothroyd & Sackmann 1999). The C/Nratios in the investigated stars are lowered to values between 0.7 and1.2 which is less than present day theoretical predictions and call forfurther studies of stellar mixing processes. Abundance ratios of O, Mg,Eu and other heavy chemical elements to iron in the investigated starsshow a pattern characteristic of thick disk stars. The results provideevidence that the thick disk population has a distinct chemical historyfrom the thin disk. The onset of the bulk of SN Ia is suggested toappear at [Fe/H] ~ -0.6 dex. Based on observations obtained at theNordic Optical Telescope, La Palma. Table 1 is only available inelectronic at the 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/380/578
|
CCD Minima of Selected Eclipsing Binaries in 2000
This report presents minima timings of selected eclipsing binaries
|
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
|
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.
|
Is asynchronism in semidetached binary systems real?
We analyze statistical relationships between the parameters ofAlgol-type binaries with asynchronous rotation of the primary componentsand provide observational evidence for denser, more extended gaseousenvelopes in the eclipsing systems of this group. We conclude thatasynchronism of the primary components in such systems is not real. Thelines that are used to determine the rotational velocities of thesecomponents originate mostly in the part of the atmosphere which acquiresan additional angular momentum during the interaction with the gasstream and produces a transient accretion disk near the equatorialplane.
|
Photoelectric minima of 30 eclipsing binary systems
Not Available
|
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.
|
Photoelectric Minima of Eclipsing Binaries
Not Available
|
Quantitative spectral types for 19 Algol secondaries
Time-resolved spectra of 19 short-period Algol-type binary star systemsobtained during total eclipse are used to derive the temperaturespectral class of the mass-losing secondary component. The spectralclassifications employed a quantitative comparison of the strengths ofabsorption features in stars of known spectral class with those of theprogram stars. The luminosity spectral class can not be determined fromthese data, so both main-sequence and giant stars were used for thecomparison. Our spectral types are compared with published types andfound to be generally in good agreement, unless the published types arederived from the light curves. The photometrically determined types aresystematically later than our directly determined types. This effect isshown also to exist in catalogs of Algol parameters.
|
The photometric search for earth-sized extrasolar planets by occultation in binary systems
The feasibility of the detection of small extrasolar planets by thepartial occultation they can cause on eclipsing binaries isinvestigated. This study is applied to the eight most luminous systems;the probability that an occultation can occur is estimated. It is foundthat the continuous observation of these eight objects would give a highprobability of detecting at least one planet if they all have planetarycompanions. The uncertainty that can be expected on the period ofrevolution of the planet from a single occultation observation isdiscussed.
|
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.
|
A Study of the DM and SD Type Eclipsing Variables by Means of the Cluster Analysis Technique
Not Available
|
Fourier analysis of the light changes of eclipsing variables in the frequency-domain
The method of Fourier analysis of the light changes in thefrequency-domain has been studied and discussed for 92 light curves ofdifferent types of eclipsing binary systems. Geometrical and physicalelements of the systems under analysis have been listed and discussed;accordingly the advantages and disadvantages of the method arepresented. The results show that the method is suitable for the analysisof detached and most of the semidetached systems, while for contactbinaries and Beta-Lyrae-type stars it has some difficulties. The lightcurve synthesis method is recommended.
|
A summary of the investigations of semi-detached close binaries (1986-1988)
Not Available
|
Statistical Study on the Semidetached and Near Contact Semidetached Binary Systems
Not Available
|
An Updated List of Eclipsing Binaries Showing Apsidal Motion
Not Available
|
Eclipsing binaries, Cygnus to Hydra, in 1972-1985
Photoelectric and visual observations of 40 known and suspectedeclipsing binaries are discussed. Revised light elements are derived forthree systems. The period of V450 Her should possibly be doubled fromabout 0.9d to about 1.8d. Secondary minimum has been detected in DI Hya.
|
Semidetached systems - Evolutionary viewpoints and observational constraints
The present knowledge on the evolution of semidetached systems isreviewed. Characteristics of observed systems are discussed and generalproperties tested by the behavior of theoretical models. New models ofmass accreting companion stars are computed. The accretion phase isdivided into a fast and slow phase with an accretion rate depending onthe initial mass of the mass losing star and on the initial mass ratio,asssuming the systems are undergoing a case B of mass transfer. Theresults are compared with observed systems with masses of the gainerslocated within the theoretical range. Up to now no computations existfor the evolution of medium mass close binaries including overshootingof the convective core. However some of the influences of extendedconvective mixing on the interaction of close binaries are investigated.A larger probability for the occurrence of case A of mass exchange and alarger remnant mass at the end of the process are the most importantresults. Finally the investigation into the origin of individual systems(in mass, mass ratio and period) is discussed, showing that progressboth in observations and in theoretical models result in a more detailedand more restricted determination of the initial parameters of theindividual systems.
|
A survey for transient accretion disks in short-period Algol systems. II
Time-resolved spectroscopy during primary eclipse was utilized in orderto search for emission lines from accretion disks surrounding theprimary component in short-period Algol systems. The results ofobservations of 46 systems surveyed during 80 eclipses are presented.For disks in long-period systems, the gas stream from the secondary starmoves around the trailing hemisphere of the primary and forms apermanent disk. However, in short-period systems the gas stream strikesthe primary star. Disks formed by this latter process are found to betransient and unstable. The discovery of two new transient disk systemsis reported: RW Mon and RR Dra. When the relative radius of the primarystar is plotted versus mass ratio, the systems with permanent disks,transient disks, and without disks segregate into three distinct regionsof the plot. This implies that the differences between systems withtransient disks and those without disks may be simply a matter of thelocation of the stream impact on the primary star.
|
Absolute parameters of stars in semidetached eclipsing binary systems
A number of questions concerning the absolute parameters of stars insemidetached binary systems are addressed. Consideration is given to:similarities between Algol-type binaries and unevolved detached binarieswith respect to the mass-luminosity law; and the single-line classicalAlgol candidates with known mass functions and photometric solutions formass ratio. It is shown that the validity of the mass luminosity-lawcannot be verified for individual Algol-type binaries though it doeshold well on average; and (2), the existence of a definite class ofsd-binaries not containing a proportion of significantly undersize typesis apparent. The conclusions are found to be in general agreement withthe observations of Hall and Neff (1979).
|
