Synchronization and circularization in early-type binaries on main sequence
We showed in a preceding paper based on an analysis of the observedrates of apsidal motion that synchronization in early-type eclipsingbinaries continues on the main sequence, and the observedsynchronization times, tsyn, agree with the Zahn's theory andare inconsistent with the shorter time-scale proposed by Tassoul. Itfollows from this that circularization in early-type binaries must alsoproceed in accordance with the Zahn's theory because the circularizationtimes, tcirc, in both theories are rather tightly related totsyn via relation tcirc ~?tsyn,where ? is the orbital-to-axial momentum ratio.To further investigate this problem, we compile a catalogue of 101eclipsing binaries with early-type main-sequence components(M1,2 > 1.6Msolar). We determine the ages, t,and circularization time-scales, tcirc, for all these systemsin terms of the two competing theories by comparing observational datawith modern models of stellar evolution of Claret and atmospheric modelsof Kurucz. We compute tcirc with the allowance for theevolutionary variations of the physical parameters of the componentsand, for the first time in such studies, also take into account thevariations of the orbital parameters (P, a, e) in the process ofcircularization subject to the conservation of the total angularmomentum.The results of these computations show that the mechanism of orbitalcircularization in early-type close binary systems (CBSs) suggested byTassoul is, like in the case of synchronization, inconsistent withobservational data. At the same time, the Zahn's mechanism, which isbased on the dissipation of the energy of dynamic tides in the upperlayers of the envelopes of CBSs components due to non-adiabaticity ofthese layers, agrees satisfactorily with observations.
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Apsidal motion elements of three eccentric eclipsing binaries: V397 Cep, V493 Car and BW Aqr
The apsidal motion analysis of the eccentric eclipsing binaries: V397Cep, V493 Car and BW Aqr have been presented. The method described byLacy (1992) [Lacy, C.H S., 1992. AJ 104, 2213] has been used for theapsidal motion analysis. The apsidal motion periods have been found tobe 174.2 ± 1.4, 277.3 ± 21.3 and 7195 ± 174 yearsfor V397 Cep, V493 Car and BW Aqr, respectively.
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B.R.N.O. Contributions #36, Times of minima
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B.R.N.O. Contributions #34
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A new catalogue of eclipsing binary stars with eccentric orbits
A new catalogue of eclipsing binary stars with eccentric orbits ispresented. The catalogue lists the physical parameters (includingapsidal motion parameters) of 124 eclipsing binaries with eccentricorbits. In addition, the catalogue also contains a list of 150 candidatesystems, about which not much is known at present.Full version of the catalogue is available online (see the SupplementaryMaterial section at the end of this paper) and in electronic form at theCDS via http://cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/MNRAS/(vol)/ (page)E-mail: ibulut@comu.edu.tr
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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.
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Time Variation of SiO Masers in VX Sagittarii over an Optically Quiescent Phase
The time variation of SiO masers in a semi-regular variable, VX Sgr, wasinvestigated in the period between 1994 and 2004 when the optical lightcurve exhibited an ˜6-yr quiescent phase intercepting a regularlypulsating era. The quiescent period occurred with a delay of severalyears after a decrease in the SiO maser flux. VLBA observations of SiOmasers made during this period showed no drastic spatial variationexcept for emission features being shifted from south-west tonorth-east. The SiO maser flux decrease, and a succeeding opticalquiescent phase, may indicate that the stellar mass-loss rate diminishedover a few years around 1994. A SiO maser flare occurring in 1999 may bea reminiscence of a final gas blow, which resulted in the opticallyquiescent period.
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Photometric Study of the Binary System V397 Cephei
The first ground-based UBV observations (2001, Inf. Bull. VariableStars, 5129) of V397 Cep were analyzed by using the Wilson-Devinneymethod, and the results were compared with others in the literature. Aconsistent geometry with a photometric mass-ratio close to unity and aneccentric orbit of e ≃ 0.13 was found. The longitude of theperiastron (ω) was found significantly different for two differentlight curves, which is strongly suggestive of an apsidal motion with aperiod of about 300 yr. This makes V397 Cep an important candidate forstudies of apsidal motion.
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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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New Times of Minima of Eclipsing Binary Systems
We present several photoelectric minima observations of 7 eclipsingbinaries.
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The First Ground-based Photometric Observations of V397 Cephei
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Aus den IBVS.
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B Stars as a Diagnostic of Star Formation at Low and High Redshift
We have extended the evolutionary synthesis models by Leitherer et al.by including a new library of B stars generated from the IUEhigh-dispersion spectra archive. We present the library and show how thestellar spectral properties vary according to luminosity classes andspectral types. We have generated synthetic UV spectra for prototypicalyoung stellar populations varying the IMF and the star formation law.Clear signs of age effects are seen in all models. The contribution of Bstars in the UV line spectrum is clearly detected, in particular forgreater ages when O stars have evolved. With the addition of the newlibrary we are able to investigate the fraction of stellar andinterstellar contributions and the variation in the spectral shapes ofintense lines. We have used our models to date the spectrum of the localsuper-star cluster NGC 1705-1. Photospheric lines of C III λ1247,Si III λ1417, and S V λ1502 were used as diagnostics todate the burst of NGC 1705-1 at 10 Myr. Interstellar lines are clearlyseen in the NGC 1705-1 spectrum. Broadening and blueshifts of severalresonance lines are stronger in the galaxy spectrum than in our modelsand are confirmed to be intrinsic of the galaxy. Si II λ1261 andAl II λ1671 were found to be pure interstellar lines with anaverage blueshift of 78 km s-1 owing to a directed outflow ofthe interstellar medium. We have selected the star-forming galaxy1512-cB58 as a first application of the new models to high-z galaxies.This galaxy is at z=2.723, it is gravitationally lensed, and its highsignal-to-noise ratio Keck spectrum shows features typical of localstarburst galaxies, such as NGC 1705-1. Models with continuous starformation were found to be more adequate for 1512-cB58 since there arespectral features typical of a composite stellar population of O and Bstars. A model with Z=0.4 Zsolar and an IMF with α=2.8reproduces the stellar features of the 1512-cB58 spectrum.
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The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
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The HIPPARCOS Mission
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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.
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Miscellaneous spectroscopic notes
Results of slit-spectrograph observations are reported for approximately260 stars. The data presented range from recognition of many new Ap, Am,and other unusual stars to H-alpha observations of early-typesupergiants and Be stars. The material discussed was obtained over thepast 40 years at a number of U.S. observatories and at the DominionAstrophysical Observatory in Victoria, B.C.
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Spectral types for early-type stars observed by SKYLAB
MK spectral types are presented for 246 early-type stars observed withthe S-019 ultraviolet stellar astronomy experiment on Skylab. K-linetypes are also given where applicable, and various peculiar stars areidentified. The peculiar stars include five silicon stars, a shell star,a helium-rich star, a silicon-strontium star, a chromium-europium star,and two marginal metallic-line stars.
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