Photoelectric Minima of Some Eclipsing Binary Stars
We present 119 minima times of 47 eclipsing binaries.
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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.
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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.
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Contact Binaries with Additional Components. I. The Extant Data
We have attempted to establish observational evidence for the presenceof distant companions that may have acquired and/or absorbed angularmomentum during the evolution of multiple systems, thus facilitating orenabling the formation of contact binaries. In this preliminaryinvestigation we use several techniques (some of themdistance-independent) and mostly disregard the detection biases ofindividual techniques in an attempt to establish a lower limit to thefrequency of triple systems. While the whole sample of 151 contactbinary stars brighter than Vmax=10 mag gives a firm lowerlimit of 42%+/-5%, the corresponding number for the much better observednorthern-sky subsample is 59%+/-8%. These estimates indicate that mostcontact binary stars exist in multiple systems.
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New CCD Times of Minima of Eclipsing Binary Systems
We present a total of 208 CCD timings for 103 eclipsing binaries.
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BL Andromedae and GW Tauri: close binary stars in a key evolutionary stage
A photoelectric light curve of BL And is presented along with the firstCCD light curve of GW Tau. Both objects are short-period eclipsingbinaries and were observed in 2003 or 2004. Photometric elements werecomputed using the latest version of the Wilson-Van Hamme code. Theresults reveal that BL And is a semidetached system with the primarycomponent filling its Roche lobe and the secondary one almost fillingbut still detached, while GW Tau is a marginal-contact binary systemwith a small degree of contact (f= 10.9 per cent) and a largetemperature difference of about 3100K. All available eclipse times,including new ones, were analysed for each system. It was found that theorbital period of BL And is decreasing at the rate of dP/dt=-2.36× 10-8 (+/-0.09)dyr-1 while that of GW Taumay be decreasing or oscillating. We think period decrease is moreprobable. The derived configuration and secular period decrease for BLAnd combined with the asymmetry of the light curve indicate that thissystem may evolve from the present semidetached phase into a contactstage, with mass transfer from the primary component to the secondaryone through the L1 point, or that it might just undergo thebroken stage predicted by the theory of thermal relaxation oscillations.In contrast, GW Tau is a marginal-contact binary in poor thermal contactand may be at the beginning of the contact phase.
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V839 Oph - 60 Years after Its Discovery
The first part of this contribution contains a brief review ofobservational history and recent knowledge of the eclipsing binary V839Oph. The second part concerns changes in orbital period of this star. Inthe third part devoted to light curve peculiarities some visual lightcurves of V839 Oph are compared with a light curve of classic nova V1500Cyg.
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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.
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New Minima of Selected Eclipsing Close Binaries
We present 180 CCD and photoelectric times of minima of selected closeeclipsing binaries.
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Photoelectric Minima of Some Eclipsing Binary Stars
We present 70 minima times of 35 eclipsing binaries.
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CCD Times of Minima of Several Eclipsing Binaries
54 CCD minima timings of 28 eclipsing binaries made mainly by the authorare presented.
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Catalogue of the orbital elements, masses, and luminosities for short-periodic RS CVn-type eclipsing systems
New data on the orbital elements, masses, and luminosities werecollected for 31 pre-contact binary systems of short-periodic {RS}{CVn}-type. We treat the catalogued data statistically in order toaccurately define the properties and evolutionary status of each classsystem. The ages of pre-contact systems were estimated by the isochronemethod. Numerous comments and bibliographic references to the catalogueare also included.
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Photoelectric Minima of Eclipsing Binaries
Not Available
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Photoelectric Minima of Some Eclipsing Binary Stars
Not Available
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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/.
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Photoelectric Minima of Some Eclipsing Binary Stars
We present 48 minima times of 10 eclipsing binaries.
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Catalogue of the field contact binary stars
A catalogue of 361 galactic contact binaries is presented. Listedcontact binaries are divided into five groups according to the type andquality of the available observations and parameters. For all systemsthe ephemeris for the primary minimum, minimum and maximum visualbrightness and equatorial coordinates are given. If available,photometric elements, (m1+m2)sin3i,spectral type, parallax and magnitude of the O'Connell effect are alsogiven. Photometric data for several systems are augmented by newobservations. The quality of the available data is assessed and systemsrequiring modern light-curve solutions are selected. Selectedstatistical properties of the collected data are discussed.
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CCD Minima for Selected Eclipsing Binaries in 2002
Not Available
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The First Eclipsing Binary Observations at the Ulupinar Astrophysics Observatory
Not Available
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New Photoelectric and CCD Minima and Updated Ephemerides of Selected Eclipsing Binaries
This report presents minima times and updated ephemerides of selectedeclipsing binaries
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New Photoelectric Minima and Updated Ephemerides of Selected Eclipsing Binaries
This report presents minima times and updated ephemerides of selectedeclipsing binaries
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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
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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.
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UBV Photometry of BX And
Not Available
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1998 UBV Observations of st Aquarii and Light Curve Analysis
1998 UBV photometry of short period eclipsing binary ST Aquarii havebeen presented. The photometric solution obtained from light curveanalysis by the method of differential corrections indicates that thesystem can be classified as a near contact binary. Derived value for theratio of radii left( {k = {left< {r_c } rightrangle }/{left< {r_hrightrangle }} \cong 0.67} right) shows that both components cannot beconsidered to be Main-Sequence, but they are probably evolved from M.S.
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Orbital period modulation and quadrupole moment changes in magnetically active close binaries
We discuss the main characteristics of the orbital period modulation inclose binaries with late-type components. We focus on the variousphysical scenarios proposed to explain this phenomenon and, inparticular, Hall's (1989) suggestion that it may be connected withmagnetic activity. Starting from the work of Applegate (1992) and Lanzaet al. (1998a), we develop an integral approach to evaluate thegravitational quadrupole moment of an active star and its variations,which we consider to be an important driver of the observed orbitalperiod changes. The method applies the tensor virial theorem afterChandrasekhar (1961) and directly relates the variation of thequadrupole moment with the changes of kinetic and magnetic energy of thestellar hydromagnetic dynamo. Particular effort has been applied inminimizing the number of free parameters entering the problem. A sampleof 46 close binaries with period changes of alternate signs has beenstudied by our method. The amplitude of the quadrupole moment changeappears to decrease with increasing angular velocity, implying that thetime-variable part of the kinetic energy of rotation varies as delta{cal T}/{cal T} ~ Omega ({-0.93+/-) 0.10}, with a correlationcoefficient of 0.83. The length of the cycle of the orbital periodmodulation seems to be correlated with the angular velocity asPmod ~ Omega ({-0.36+/-) 0.10}, but with a smallercorrelation coefficient of 0.62. These results support the suggestionthat a distributed non-linear dynamo is at work in the convectiveenvelopes of very active stars and that it strongly affects thedifferential rotation. We also discuss the energy budget of the processresponsible for the quadrupole moment variation and find that, onaverage, only ~ 10% of the energy required to maintain the differentialrotation may be lost by dissipation in the turbulent convective envelopeduring a cycle of the orbital period change. The problems of themagnetic field geometry and stability and the relationship between thelength of the activity cycle, as determined by the change of the area ofthe starspots and the orbital period modulation, respectively, are alsoaddressed.
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MK classification of four visual binary stars with variable components.
Not Available
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UBV photometry and period variations of V 839 Ophiuchi
A complete period variation analysis and new light curves of V~839 Ophtogether with new ephemeris data are presented. The period variation wasfound to be dP/dt=3.1x10^{-7} d/yr. The period increment indicates thatthe conservative mass transfer rate from the less massive component tothe more massive one is 6.5x10^{-7} M_{\sun}/yr. We fitted parabolic andwe discuss the possible detection of sinusoidal curves to the (O-C)diagram and sinusoidal oscillations with period of about 20 yr andsemi-amplitude of 0.0065 day. A simultaneous solution of the B and Vlight curves was computed using the Wilson-Devinney syntheticlight-curve code. The light curve solution indicates that the A-type WUMa-type system is in contact with a filling factor of ~39%. Table 2 andTable 5 only available in electronic form: see the Editorial in A&AS1994, Vol. 103, No. 1.
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MSC - a catalogue of physical multiple stars
The MSC catalogue contains data on 612 physical multiple stars ofmultiplicity 3 to 7 which are hierarchical with few exceptions. Orbitalperiods, angular separations and mass ratios are estimated for eachsub-system. Orbital elements are given when available. The catalogue canbe accessed through CDS (Strasbourg). Half of the systems are within 100pc from the Sun. The comparison of the periods of close and widesub-systems reveals that there is no preferred period ratio and allpossible combinations of periods are found. The distribution of thelogarithms of short periods is bimodal, probably due to observationalselection. In 82\% of triple stars the close sub-system is related tothe primary of a wide pair. However, the analysis of mass ratiodistribution gives some support to the idea that component masses areindependently selected from the Salpeter mass function. Orbits of wideand close sub-systems are not always coplanar, although thecorresponding orbital angular momentum vectors do show a weak tendencyof alignment. Some observational programs based on the MSC aresuggested. Tables 2 and 3 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
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Photovisual Magnitude Differences for 169 Double Stars
Photovisual magnitude differences determined from multi-exposurephotographic plates for 169 double stars are presented. The separationsrange from 1.5'' to 113\arcsec, and the photovisual magnitudedifferences vary from 0.03 to 6.14 magnitudes. The internal mean errorof a single magnitude difference estimate is +/-0.064 magnitude.
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INHABITED SKY
