Programmsterne: Beobachtungen erwuenscht.
Not Available
|
Programmsterne: Beobachtungen erwuenscht.
Not Available
|
35 Visual Minimum Times of 34 Eclipsing Binaries.
Not Available
|
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.
|
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
|
Beobachtungsergebnisse Bundesdeutsche Arbeitsgemeinschaft fur Veranderlichen Serne e.V.
Not Available
|
Envelope Ejection: An Alternative Evolutionary Process for Some Early Case B Binaries
We discuss the evolution of binaries with moderately high masses (~10-30Msolar) and with periods of ~3-300 days, corresponding mostlyto early case B. These are usually thought to evolve either byreasonably conservative Roche lobe overflow, if the initial mass ratiois fairly mild, or else by highly nonconservative common-envelopeevolution, with spiral-in to short periods (hours, typically), if theinitial mass ratio is rather extreme. We discuss here a handful ofbinaries from part of this period range (~50-250 days), which appear tohave followed a different path: we argue that they must have lost alarge proportion of initial mass (~70%-80%) but without shortening theirperiods at all. We suggest that their behavior may be due to the factthat stars of such masses, when evolved also to rather large radii, arenot far from the Humphreys-Davidson limit, where single stars lose theirenvelopes spontaneously in P Cygni winds, and so have envelopes that areonly lightly bound to the core. These envelopes therefore may berelatively easily dissipated by the perturbing effect of a companion. Inaddition, some or all of the stars considered here may have been closeto the Cepheid instability strip when they filled their Roche lobes. Oneor the other, or both, of high luminosity and Cepheid instability, incombination with an appropriately close binary companion, may beimplicated.
|
149 Bedeckungssterne der BAV-Programme. Eine Analyse der Beobachtungstatigkeit seit den Angangen.
Not Available
|
Einige interessante Bedeckungsveraenderliche.
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
|
Aktion Langperiodische Bedeckungsveranderliche.
Not Available
|
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.
|
Variations of the orbital periods in semi-detached binary stars with radiative outer layers
A detailed analysis of the period changes of sixteen semi-detachedbinaries which contain only stars with radiative outer layers(ET-systems) has been performed and their respective O-C diagrams arebrought and discussed. It was found that the course of the periodvariations is monotonic and in some systems the period is even constant.This detailed analysis of extensive sets of timings covering severaldecades brings a strong support to an earlier finding of te[Hall(1989)]{hal89} and develops it further. We show that all systems withthe orbital periods shorter than nine days display constant period orits increase, with the exception of an uncertain case of V 337 Aql. Thecourse of the period variations in TT Aur appears more complex but thecyclic term can be plausibly explained by the third body. A search forgeneral relations between the parameters of the systems and the periodchanges was undertaken. The mass ratio q appears to play a role in theperiod variations. Clear changes in systems with orbital periods shorterthan 9 days were detected only for q>0.4 while constant periods arecommon in systems with q<0.4 in this period range. The sense of thesecular changes in most systems is in accordance with the dominantconservative mass transfer in evolved binary and corresponds to the slowphase. The role of the evolutionary scenarios (case A versus B) and theinfluence of changes of the rotational angular momenta of the componentsare discussed.
|
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.
|
The interacting binary CX Draconis: new orbital elements and evidence for mass transfer.
New improved parameters for both components of the double-linedspectroscopic Be binary CX Dra are presented. CX Dra (P=6.69603 d)consists of a detached primary (B2.5V, 7.3Msun_,4Rsun_) and a secondary (F5III, 1.7Msun_) probablyfilling in its Roche lobe. The inclination angle i=50deg and dimensionsof both components do not allow the eclipses to occur. The equatorialrotational velocity of the primary 210km/s is highly asynchronous. CXDra can be therefore classified as a high-mass non-eclipsing Algol-typebinary. Emission lines of Hα and HeI 6678 were analysed. The V/Rratio of the double peaked emission in the original spectra of Hαsmoothly varies with the orbital phase. The difference profilesconstructed by subtracting the synthetic spectra of both components fromthe observed spectra enabled studying the non-photospheric emission(presumably originating in the circumstellar matter). Thenon-photospheric emission in Hα is interpreted in terms of twodistinct components. The broad part following the RV curve of theprimary belongs probably to the accretion disk while the other component(narrow peak) cannot be linked with any star. The velocity field of thenarrow peak offers a possibility that this feature is connected with themass stream. The broad double-peaked emission attributed to theaccretion disk around the hot primary is visible also in HeI 6678. Thetemperature of the disk must therefore correspond at least to11000-12000K and this disk is significantly hotter than in most otherAlgol-type systems. Conspicuous secular changes of the emission in HeI6678 were revealed. The analysis presented here led to the conclusionthat the Be phenomenon in CX Dra can be explained by the mass transferin the interacting binary.
|
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.
|
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.
|
AQ Cassiopeiae: New five-color observations and photometric solutions, including corrections for stream emission
Complete five-color light curves are presented of the massive eclipsingbinary AQ Cassiopeiae. Stream extinction depresses light levels justbefore primary eclipse, complicating photometric solutions. Aphotometric solution excluding stream-depressed observations isdescribed. A stream capable of absorbing a detectable amount of light,moreover, also contributes extra light around first quadrature, when thestream is viewed against the sky. This excess light, is estimated usingthe stream model of Olson & Bell, is removed from affectedobservations, and a new and improved photometric solution is obtained.The radial velocity curve of the loser is extracted from spectroscopicobservations of the O I lambda7774 line, and absolute system parametersare estimated. The gainer is a rapid rotator, but this rotation haslittle effect on the photometric solutions of this totally eclipsingbinary. AQ Cas is not a double-contact system in which the hot gainerfills its limiting rotational lobe.
|
New six-color intermediate-band photometry and photometric solutions for U Cephei
We describe new six-color intermediate-band photometric observations ofU Cephei, obtained during an interval of consistently low mass-transferactivity. We use the new Wilson eclipsing binary computer program toobtain several photometric solutions, which incorporate the rapidrotation of the hot star. Residual trends for solutions using allobservations show the absorbing effect of the stream between phases 0.7and 0.96. A second set of solutions, omitting data in this phase range,leads to more satisfactory results. Our photometric mass ratio issomewhat smaller than the spectroscopic values found by both Batten(1974) and Tomkin (1981). Differences between our solutions and those ofRafert and Markworth (1991) are probably due to residual contaminationof light curves by circumstellar matter.
|
New rotational velocities for eclipsing binaries, and a comparison of spectroscopic and photometric rotations
Rotational velocities are determined spectroscopically for 38 eclipsingbinaries, including many long-period, nominally semidetached, systems.We note that spectroscopic rotations may differ from rotations derivedfrom light-curve modeling using the Wilson-Devinney program. In'direct-impact' mass-transferring systems, or in most systems withperiods smaller than about 7 days, observations suggest that the tworotations are usually about the same. In cases where the stream missesthe gainer and an accretion disk forms, however, photometric rotationestimates often exceed spectroscopic determinations. The possiblephysical significance of this situation is briefly discussed. Doubt iscast on the likelihood that the rotation of the hot component of U Sgehas changed detectably in the last 30 years.
|
Photometric Monitoring of the Longperiod Eclipsing Binaries at Yonsei-University Observatory
Not Available
|
Close binaries observed polarimetrically
Not Available
|
Non-LTE effects in streams, and mass-transfer rates in three eclipsing binaries
A mass-transferring stream in an eclipsing binary is seen in projectionagainst the hot star in roughly the quarter-period before primaryeclipse. At this time a small fraction of the light of the hot star isblocked by the stream, depressing light curves slightly. Five-colorobservations of such light curves in AQ Cas, RZ Sct, and U Sge arediscussed. Non-LTE and LTE predictions of stream-produced light losseswith these observations are compared, the validity of this mechanism isdiscussed, and mass-transfer rates are estimated.
|
Massive close binaries with early-type components, observed characteristics.
Not Available
|
The Farthest Known Eclipsing Binaries in Our Galaxy
Not Available
|
IRAS low-resolution spectra of cool carbon stars. II - Stars with thin circumstellar shells. III - Stars with thick circumstellar shells
IRAS low-resolution spectra and broad-band data and near-IR photometryare analyzed for 72 carbon stars with near-IR color temperatures over2000 K. Seven stars have an almost featureless spectrum without dustemission in the LRS wavelength region. The majority of the sample starshave the 11.5 micron SiC and an unidentified 8.6 micron emission featuresuperposed on the stellar continuum. The strength of the latter featurecorrelates with the strength of the 3 micron absorption band and isprobably of molecular origin. The broad-band data exhibit a 60 micronexcess which is ascribed to a cool dust shell. The IR spectral energydistributions of those stars with thick circumstellar shells areanalyzed. The slope of the far-IR flux can best be explained by theexistence of a well-defined outer boundary of the dust shell. Thetemperature at this outer boundary implies that the present high massloss rate started 100-1000 yr ago.
|
Five-color light curves of the beta Lyrae system AQ Cassiopeiae
The first modern (uvby I) photoelectric observations of the eclipsingsystem AQ Cas are given. The light is continuously variable at allwavelengths, and light curves are asymmetrical around primary eclipse,particularly in the UV. Analysis of the five colors of the light lost inprimary and secondary eclipses yield color excess E-sub-by = 0.64.Continuum stellar colors correspond to effective temperatures near28,000 K and 18,000 K for the two stars.
|
