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Photoelectric Minima of Some Eclipsing Binary Stars
We present 51 minima times of 19 eclipsing binaries.
| B.R.N.O. Contributions #34
Not Available
| Evolution of interacting binaries with a B type primary at birth
We revisited the analytical expression for the mass ratio distributionfor non-evolved binaries with a B type primary. Selection effectsgoverning the observations were taken into account in order to comparetheory with observations. Theory was optimized so as to fit best withthe observed q-distribution of SB1s and SB2s. The accuracy of thistheoretical mass ratio distribution function is severely hindered by theuncertainties on the observations. We present a library of evolutionarycomputations for binaries with a B type primary at birth. Some liberalcomputations including loss of mass and angular momentum during binaryevolution are added to an extensive grid of conservative calculations.Our computations are compared statistically to the observeddistributions of orbital periods and mass ratios of Algols. ConservativeRoche Lobe Over Flow (RLOF) reproduces the observed distribution oforbital periods but fails to explain the observed mass ratios in therange q in [0.4-1]. In order to obtain a better fit the binaries have tolose a significant amount of matter, without losing much angularmomentum.
| 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.
| Herbig Ae/Be Stars in nearby OB Associations
We have carried out a study of the early-type stars in nearby OBassociations spanning an age range of ~3-16 Myr, with the aim ofdetermining the fraction of stars that belong to the Herbig Ae/Be class.We studied the B, A, and F stars in the nearby (<=500 pc) OBassociations Upper Scorpius, Perseus OB2, Lacerta OB1, and Orion OB1,with membership determined from Hipparcos data. We also included in ourstudy the early-type stars in the Trumpler 37 cluster, part of the CepOB2 association. We obtained spectra for 440 Hipparcos stars in theseassociations, from which we determined accurate spectral types, visualextinctions, effective temperatures, luminosities and masses, usingHipparcos photometry. Using colors corrected for reddening, we find thatthe Herbig Ae/Be stars and the classical Be (CBe) stars occupy clearlydifferent regions in the JHK diagram. Thus, we use the location on theJHK diagram, as well as the presence of emission lines and of strong 12μm flux relative to the visual, to identify the Herbig Ae/Be stars inthe associations. We find that the Herbig Ae/Be stars constitute a smallfraction of the early-type stellar population even in the youngerassociations. Comparing the data from associations with different agesand assuming that the near-infrared excess in the Herbig Ae/Be starsarises from optically thick dusty inner disks, we determined theevolution of the inner disk frequency with age. We find that the innerdisk frequency in the age range 3-10 Myr in intermediate-mass stars islower than that in the low-mass stars (<1 Msolar) inparticular, it is a factor of ~10 lower at ~3 Myr. This indicates thatthe timescales for disk evolution are much shorter in theintermediate-mass stars, which could be a consequence of more efficientmechanisms of inner disk dispersal (viscous evolution, dust growth, andsettling toward the midplane).
| Photoelectric Minima of Some Eclipsing Binary Stars
We present 24 minima times of 18 eclipsing binaries.
| New Times of Minima of Eclipsing Binary Systems
We present 45 photoelectric minima observations of 20 eclipsingbinaries.
| 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
| Photoelectric Minimum Times of Some Eclipsing Binary Stars
We present 20 minima times of 8 eclipsing binaries.
| CCD Times of Minima of Some Eclipsing Binaries in 2002
We present CCD observations of minima of 11 eclipsing binaries.
| Beobachtungsegebnisse Bundesdeutsche Arbeitsgemainschaft fur Veranderliche Sterne e.V.
Not Available
| 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
| Beobachtungsergebnisse Bundesdeutsche Arbeitsgemeinschaft fur Veraenderliche Sterne e.V.
Not Available
| 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.
| CCD Times of Minima of Eclipsing Binary Systems
We present several CCD minima observations of 22 eclipsing binaries.
| Apsidal Motion in Double Stars. I. Catalog
A catalog of 128 double stars with measured periods of apsidal motion iscompiled. Besides the apsidal periods, the orbital elements of binariesand physical parameters of components (masses, radii, effectivetemperatures, surface gravities) are given. The agreement of the apsidalperiods found by various authors is discussed.
| A HIPPARCOS Census of the Nearby OB Associations
A comprehensive census of the stellar content of the OB associationswithin 1 kpc from the Sun is presented, based on Hipparcos positions,proper motions, and parallaxes. It is a key part of a long-term projectto study the formation, structure, and evolution of nearby young stellargroups and related star-forming regions. OB associations are unbound``moving groups,'' which can be detected kinematically because of theirsmall internal velocity dispersion. The nearby associations have a largeextent on the sky, which traditionally has limited astrometricmembership determination to bright stars (V<~6 mag), with spectraltypes earlier than ~B5. The Hipparcos measurements allow a majorimprovement in this situation. Moving groups are identified in theHipparcos Catalog by combining de Bruijne's refurbished convergent pointmethod with the ``Spaghetti method'' of Hoogerwerf & Aguilar.Astrometric members are listed for 12 young stellar groups, out to adistance of ~650 pc. These are the three subgroups Upper Scorpius, UpperCentaurus Lupus, and Lower Centaurus Crux of Sco OB2, as well as VelOB2, Tr 10, Col 121, Per OB2, alpha Persei (Per OB3), Cas-Tau, Lac OB1,Cep OB2, and a new group in Cepheus, designated as Cep OB6. Theselection procedure corrects the list of previously known astrometricand photometric B- and A-type members in these groups and identifiesmany new members, including a significant number of F stars, as well asevolved stars, e.g., the Wolf-Rayet stars gamma^2 Vel (WR 11) in Vel OB2and EZ CMa (WR 6) in Col 121, and the classical Cepheid delta Cep in CepOB6. Membership probabilities are given for all selected stars. MonteCarlo simulations are used to estimate the expected number of interloperfield stars. In the nearest associations, notably in Sco OB2, thelater-type members include T Tauri objects and other stars in the finalpre-main-sequence phase. This provides a firm link between the classicalhigh-mass stellar content and ongoing low-mass star formation. Detailedstudies of these 12 groups, and their relation to the surroundinginterstellar medium, will be presented elsewhere. Astrometric evidencefor moving groups in the fields of R CrA, CMa OB1, Mon OB1, Ori OB1, CamOB1, Cep OB3, Cep OB4, Cyg OB4, Cyg OB7, and Sct OB2, is inconclusive.OB associations do exist in many of these regions, but they are eitherat distances beyond ~500 pc where the Hipparcos parallaxes are oflimited use, or they have unfavorable kinematics, so that the groupproper motion does not distinguish it from the field stars in theGalactic disk. The mean distances of the well-established groups aresystematically smaller than the pre-Hipparcos photometric estimates.While part of this may be caused by the improved membership lists, arecalibration of the upper main sequence in the Hertzsprung-Russelldiagram may be called for. The mean motions display a systematicpattern, which is discussed in relation to the Gould Belt. Six of the 12detected moving groups do not appear in the classical list of nearby OBassociations. This is sometimes caused by the absence of O stars, but inother cases a previously known open cluster turns out to be (part of) anextended OB association. The number of unbound young stellar groups inthe solar neighborhood may be significantly larger than thoughtpreviously.
| New Light Synthesis and Spectrum Synthesis Constraints on a Model for beta Lyrae
A suite of programs that calculates both synthetic light curves andsynthetic spectra for a binary system with an optically thick accretiondisk has been applied for the first time to beta Lyrae A. Our resultsdemonstrate that the standard accretion disk model by Hubeny &Plavec shows significant residuals from observations, both photometricand spectroscopic, and that no changes in adjustable parameters are ableto remove the residuals. The basic problem is that the Hubeny &Plavec model requires a small visible segment of the hot star at thecenter of the accretion disk and this requirement conflicts with thephotometric evidence. As an alternative, we investigate standardaccretion disk models in which the central star is hidden from view. Wefind that no model of this type can satisfy either the observedphotometry or the IUE spectra. To resolve this impasse, we suggest thepresence of a light-scattering region above the accretion disk faces,which scatters light from the central star into the line of sight andprovides the high-T_eff radiation component required by both the lightcurves and the observed spectra. This source of radiation is very likelyrelated to the jets proposed by Harmanec et al. and Hoffman et al. Wecalculate the location of stream impact on the accretion disk rim.Observations show no detectable photometric signature of a rim brightspot. We suggest that the liberated kinetic energy is spread over aregion sufficiently large and at a sufficient optical depth to suppressappearance of a bright spot. A slight asymmetry of primary minimum mayindicate swelling of the accretion disk rim downstream from the streamimpact point, with an attendant slight increase in obscuration of thebackground light sources.
| Determination of empirical mass-luminosity and mass-radius relations for main-sequence stars that are the components of eclipsing binary systems
Based on a new catalog of photometric, geometrical, and absoluteelements for 112 eclipsing binary systems with both components on themain sequence and with known photometric and spectroscopic orbitalelements, we redetermined the mass-luminosity and mass-radius relations:M_bol = 4.46 - 9.52 lg M (lg M > -0.4), M_bol = 6.58 - 5.00 lg M (lgM <= -0.4), lg R = 0.096 + 0.652 lg M (lg M > 0.14), lg R = 0.049+ 0.993 lg M (lg M <= 0.14). For most systems, the masses and radiiof the components are determined with an accuracy of 2-3% and 2-4%,respectively. We estimated the parameters of these relations by theleast-squares method using the procedure for correcting the estimatesthus obtained for noise in the argument.
| Photoelectric and CCD times of minima of several eclipsing binary systems
We present several photoelectric and CCD minima observations of severaleclipsing binaries. Most of them are apsidal motion stars (or at leastcandidate ones).
| Photoelectric and CCD times of minima of 19 eclipsing binary systems
We present several photoelectric and unfiltered CCD minima observationsof 19 eclipsing binaries. Most of them are apsidal motion stars (or atleast candidate ones).
| A Photometric and Spectrophotometric Study of MR Cygni
A self-consistent, physically accurate program suite has been used in anaccurate simulation of new spectroscopy and photometry of MR Cygni.Analysis of both the spectroscopic and photometric data used spectrumsynthesis techniques and a synthetic photometry augmentation of a lightsynthesis program package. The theoretical light curves closely fit theobservational data. The same self-consistent parameters from the lightsynthesis solution produced synthetic spectra precisely fitting theobserved spectra at all orbital phases. The IRAF-reduced spectroscopyhas produced an accurate double-lined radial velocity curve. The derivedmass ratio differs greatly from photometric mass ratios in theliterature. New UBV photometry closely replicates existing data andindicates photometric stability of the binary system. A syntheticspectrum fitted to IUE data established the primary component Teff. Thelight curve solution determined a single set of system parameters usedto calculate U, B, and V light curves. We conclude that MR Cygni is amember of the relatively rare class of hot Algol systems defined byPopper. It is likely that mass transfer still is in progress, but thereis no evidence, either from orbital period variation or from a brightspot on the mass gainer, for its existence. The lack of H alpha emissionin any of our spectra, including one at phase 0.063, suggests a smallcurrent rate of mass transfer. The fact that our computationallyself-consistent procedure has successfully represented both thephotometry and the spectroscopy for a binary system whose components areappreciably distorted demonstrates the overall power of the procedure.
| On the invisible components of some eclipsing binaries.
The aim of this paper is to search for evidences for the presence ofunseen companions in some eclipsing binary systems using their O-Cdiagrams. A total of 8507 times of minima (6890 visual and 1617photographic or photoelectric ones) of 18 systems have been collectedfrom the remarkable database of late Dieter Lichtenknecker(Lichtenknecker 1988) and from other more recent papers. Assuming thatlight-time effect (LITE) is responsible for the periodic components onthe O-C diagrams sets of orbital parameters were derived using Kopal's(1978, Dynamics of close binary systems. D. Reidel. Co.) method. In somecases (AB And, TV Cas, XX Cep, AK Her) the resulting orbital parametersand masses of the hypothetical third components are physicallyacceptable. Other systems show good evidence for multiplicity, but theavailable data sets are not suited to compute reliable solutions (W Del,U Peg, AT Peg, ST Per). For RT And, XZ And, OO Aql, Y Cam, RS CVn, CQCep, U CrB and MR Cyg) an unambigous identification of third componentsis not possible. In the cases of TW Cas and SW Lac we could not find anyLITE solution at all.
| Photoelectric minima of 30 eclipsing binary systems
Not Available
| EE Pegasi Revisited: A Spectrum Synthesis and New Light Synthesis Study
A self-consistent physical model, described in an earlier paper byLinnell & Hubeny, has permitted fits of synthetic spectra toobserved spectra of EE Pegasi. The synthetic spectra determineabundances for iron, calcium, and silicon. The same model has been thebasis of an optimized light synthesis solution of an accurate lightcurve by Ebbighausen. The solution, requiring use of a model atmospheresoption to represent the component star radiative properties, agrees withthe standard solution by Lacy & Popper. The derived componentparameters place them on an isochrone, determine a compositional Z, andare in accordance with evolution tracks by Schaller et al. The model isnot restricted to systems with small distortion.
| R Canis Majoris---Revisited
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996ApJ...458..371S&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.
| A search for possible unresolved components in eighteen eclipsing binaries.
Not Available
| The Effects of 100,000 Observation Data Sets on the Study of Eclipsing Binaries
Current technology permits acquisition of data sets consisting of100,000 or more high precision observations of individual eclipsingbinaries. This paper considers whether current light synthesis programscan easily process such data sets, and whether the underlying model forthe binary system has sufficient physical accuracy.
| Predicting the Secondary Minima Depths and Spectra of the Main Components for the Dm-Type Eclipsing Variable Stars
Not Available
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Miembro de los siguientes grupos:
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Datos observacionales y astrométricos
| Constelación: | Cisne |
| Ascensión Recta: | 21h58m56.59s |
| Declinación: | +47°59'00.0" |
| Magnitud Aparente: | 8.875 |
| Distancia: | 757.576 parsecs |
| Movimiento Propio en Ascensión Recta: | 0.4 |
| Movimiento Propio en Declinación: | -2.2 |
| B-T magnitude: | 8.875 |
| V-T magnitude: | 8.875 |
Catálogos y designaciones:
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