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BAV-Results of observations - Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
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| Programmsterne: Beobachtungen erwuenscht.
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| A period study and light-curve synthesis for the Algol-type semidetached binary XXCephei
We obtained CCD photometric observations of the Algol-type semidetachedbinary XXCephei (XXCep) during 15 nights from 2002 September 17 to 2003February 2, and also on 2005 January 21. Except for those data taken onthe last night of the concentrated observing season, the 3881measurements were obtained over an interval of only 106 nights. Fromthese data, four new times of minimum light were calculated. The (O- C)diagram formed from all available timings, and thus the orbital periodof the system, can be partly represented as a beat effect between twocyclical variations with different periods (yr, yr) and amplitudes(K1=0.015d, K2=0.103d), respectively. Bothphysical and non-physical interpretations of these cycles wereinvestigated. The long-term sinusoidal variation is too long formagnetic cycling in solar-type single and close binary stars. Inaddition, we have studied the effect of a possible secular periodvariation. By analysing the residuals from our Wilson-Devinney (WD)binary model, we found small light variations with a period of 5.99dwith amplitudes growing toward longer wavelengths. We think that theseoscillations may be produced by instabilities at the systemicL1 point (also occupied by the point of the cool star) andthat these instabilities are, in turn, caused by non-uniform andsporadic convection. There is also a short-period oscillation of about45min in the WD light residuals that is attributed to accretion on tothe mass-gaining primary component from a feeble gas stream originatingon the cool donor star.
| Pulkovo compilation of radial velocities for 35495 stars in a common system.
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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.
| Beobachtungssergebnisse Bundesdeutsche Arbeitsgemeinschaft fuer Veraenderliche Sterne e.V.
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| 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.
| SB9: The ninth catalogue of spectroscopic binary orbits
The Ninth Catalogue of Spectroscopic Binary Orbits(http://sb9.astro.ulb.ac.be) continues the series of compilations ofspectroscopic orbits carried out over the past 35 years by Batten andcollaborators. As of 2004 May 1st, the new Catalogue holds orbits for2386 systems. Some essential differences between this catalogue and itspredecessors are outlined and three straightforward applications arepresented: (1) completeness assessment: period distribution of SB1s andSB2s; (2) shortest periods across the H-R diagram; (3)period-eccentricity relation.
| Up-to-Date Linear Elements of Eclipsing Binaries
About 1800 O-C diagrams of eclipsing binaries were analyzed and up-todate linear elements were computed. The regularly updated ephemerides(as a continuation of SAC) are available only in electronic form at theInternet address: http://www.as.ap.krakow.pl/ephem/.
| 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
| Search for A-F Spectral type pulsating components in Algol-type eclipsing binary systems
We present the results of a systematic search for pulsating componentsin Algol-type eclipsing binary systems. A total number of 14 eclipsingbinaries with A-F spectral type primary components were observed for 22nights. We confirmed small-amplitude oscillating features of a recentlydetected pulsator TW Dra, which has a pulsating period of 0.053 day anda semi-amplitude of about 5 mmag in B-passband. We discovered newpulsating components in two eclipsing binaries of RX Hya and AB Per. Theprimary component of RX Hya is pulsating with a dominant period of 0.052day and a semi-amplitude of about 7 mmag. AB Per has also a pulsatingcomponent with a period of 0.196 day and a semi-amplitude of about 10mmag in B-passband. We suggest that these two new pulsators are membersof the newly introduced group of mass-accreting pulsating stars insemi-detached Algol-type eclipsing binary systems.Table 4 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/405/231
| 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.
| 149 Bedeckungssterne der BAV-Programme. Eine Analyse der Beobachtungstatigkeit seit den Angangen.
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| Einige interessante Bedeckungsveraenderliche.
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| 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
| 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.
| 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.
| V907 Scorpii: A Remarkable Binary Star Whose Eclipses Turn On and Off and On and Off
V907 Scorpii, near the open cluster M7, and possibly a member, is uniqueamong all known eclipsing binary stars because its eclipses have turnedon and off twice within modern history. By using all availablephotometric and spectroscopic data, we have discovered that it is atleast a triple star and possibly a quadruple star system consisting of avisual binary with a very long orbital period, the brighter member ofwhich is itself the triple star. The triple star contains an eclipsingbinary star (B9.5 V) with an orbital period of 3.78 days and a faint,distant companion (late K, or perhaps a white dwarf) with an orbitalperiod of 99.3 days around the center of mass of the triple star system.Radial velocity measurements allow the masses to be estimated. Becausethe orbital planes of the eclipsing binary and its triple companion arenot coplanar, the orbital plane of the eclipsing binary shows nodalregression with a period of 68 yr. For about one-third of this time, theclose binary is eclipsing; the rest of the time the inclination is toosmall for eclipses to occur. The earliest observations of the system inthe year 1899 show eclipses; the eclipses stopped about 1918, startedagain about 1963, and stopped again in about 1986. We predict that theeclipses should start occurring once again in the year 2030+/-5.
| Catalogue of H-alpha emission stars in the Northern Milky Way
The ``Catalogue of Stars in the Northern Milky Way Having H-alpha inEmission" appears in Abhandlungen aus der Hamburger Sternwarte, Band XIin the year 1997. It contains 4174 stars, range {32degr <= l() II< 214degr , -10degr < b() II < +10degr } having the Hαline in emission. HBH stars and stars of further 99 lists taken from theliterature till the end of 1994 were included in the catalogue. We givethe cross-identification of stars from all lists used. The catalogue isalso available in the Centre de Données, Strasbourg ftp130.79.128.5 or http://cdsweb.u-strasbg.fr and at the HamburgObservatory via internet.
| Magnetic activity and evolution of Algol-type stars - II
We examine the possibility of probing dynamo action in mass-losingstars, components of Algol-type binaries. Our analysis is based on thecalculation of non-conservative evolution of these systems. We model thesystems USge and betaPer where the more massive companion fills itsRoche lobe at the main sequence (case AB) and where it has a smallhelium core (early case B) respectively. We show that to maintainevolution of these systems at the late stages which are presumablydriven by stellar `magnetic braking', an efficient mechanism forproducing large-scale surface magnetic fields in the donor star isneeded. We discuss the relevance of dynamo operation in the donor starto the accelerated mass transfer during the late stages of evolution ofAlgol-type binaries. We suggest that the observed X-ray activity inAlgol-type systems may be a good indicator of their evolutionary statusand internal structure of the mass-losing stellar components.
| TRY Geminorum - Revised Elements
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1997AJ....114..800S&db_key=AST
| 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.
| Catalogue of stars in the northern Milky Way having H-alpha in emission
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| 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
| 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.
| DN Orionis: A Long-Period Mass-Transferring "Slightly Detached" Algol Binary
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....110.1809E&db_key=AST
| The Henry Draper Extension Charts: A catalogue of accurate positions, proper motions, magnitudes and spectral types of 86933 stars
The Henry Draper Extension Charts (HDEC), published in the form offinding charts, provide spectral classification for some 87000 starsmostly between 10th and 11th magnitude. This data, being highlyvaluable, as yet was practically unusable for modern computer-basedastronomy. An earlier pilot project (Roeser et al. 1991) demonstrated apossibility to convert this into a star catalogue, using measurements ofcartesian coordinates of stars on the charts and positions of theAstrographic Catalogue (AC) for subsequent identification. We presenthere a final HDEC catalogue comprising accurate positions, propermotions, magnitudes and spectral classes for 86933 stars of the HenryDraper Extension Charts.
| Rapid H-alpha emission variations in accretion disks in long-period ALGOLS
We demonstrate the continuous presence of large variations indouble-peaked H-alpha long period Algol-type binaries, using recentlyobtained CCD spectra. Most fluctuations occur on a time scale less thanor = an orbital period and a steady state in H-alpha emission ia neverreached. In AD Her (P = 10 d), H-alpha emission dropped in strength morethan a factor of five in one seven-day interval. Contemporay O I lambdaobservations showed no significant changes in oxygen absorption strengthor radial velocity during this time. We tentatively suggest that H-alphavariations arise from an inner-disk instability, possibly triggered bysmall modulations in the mass-transfer rate. This behavior isreminiscent of some cataclysmic variables.
| O I lamba 7774 absorption as a tracer of streams and disks in nondegenerate binary stars
We propose a new spectroscopic approach for observing circumstellarmatter in binary stars, based on the neutral oxygen lambda 7774absorption lines. We present oxygen equivalent widths and radialvelocities in 20 nondegenerate eclipsing binaries. We note limitationsand advantages of using this line to trace circumstellar matter inbinary systems, and confirm the presence of streams and rotatingaccretion disks in a number of short- long-period Algol systems. Wediscuss evidence for geometrically thick disks, and describe a smallradial infall superimposed on disk rotation in most long-period systems.We speculate that infall may be related to viscous dissipation in disks.We emphasize the great sensitivity of lambda 7774 in studying thekinematics of circumstellar matter in many nondegenerate binary stars.
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