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.
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Pulkovo compilation of radial velocities for 35495 stars in a common system.
Not Available
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Theoretical study of partial frequency redistribution function in irradiated, moving atmospheres of close binary components
We have studied the effects of partial frequency redistribution functionwith angle-averaged RII-A in irradiated and movingatmospheres of close binary components. We have considered theatmospheric extension of the primary component to be twice the radius ofthe primary component in a close binary system. We have considered twocases: (i) when the atmosphere is at rest and (ii) when the atmosphereis moving. In both the cases, we have computed the line profiles alongthe line of sight for a given optical depth. The irradiation from thesecondary component is assumed to be one, five and 10 times theself-radiation. The line fluxes in the line of sight are calculated byusing the total source functions due to self-radiation of the primarycomponent and due to the irradiation from the secondary component. Wehave noted double-peaked emission lines in the case of a static mediumand a reduction of emission peaks in the case of velocity field.
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Indirect imaging of an accretion disk rim in the long-period interacting binary W Crucis
Context: .Light curves of the long-period Algols are known for theircomplex shape (asymmetry in the eclipse, light variations outside theeclipse, changes from cycle-to-cycle), but their interpretation is notpossible in the standard model of binary stars. Aims: . Wedetermined that complex structures present in these active Algol systemscould be studied with the eclipse-mapping method that was successfullyapplied to the new 7-color photometric observations in the Geneva systemof W Cru, belonging to the isolated group of these active Algols.Methods: . Several cycles of this long-period (198.5 days) eclipsingbinary were covered by observations. We used a modified Rutten'sapproach to the eclipse-mapping. The optimization of the system'sparameters and the recovery of the disk intensity distribution areperformed using a genetic algorithm (GA). Results: .The finding ofa primary (hot) component is hidden in thick accretion disk confirmsprevious solutions. The mass of the primary component, M1 =8.2 Mȯ, indicates that it is a mid-B type star. Themass-losing component fills its critical lobe, which, for the system'sparameters, means it is a G-type supergiant with a mass M2 =1.6 Mȯ. The disk is very extended geometrically, and itsouter radius is about 80% of the primary's critical lobe. Areconstructed image reveals the rather clumpy and nonuniform brightnessdistribution of an accretion disk rim in this system that is seen almostedge-on. This clumpiness accounts for light curve distortions andasymmetries, as well as for secular changes.
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Analysis of Van Houten's Estimates of Variable Stars From Photographic Plates
Huge amount of observations from photogrphic plates made by C. J. vanHouten remained unprocessed and unpublished after his death. The datawere obtained during the first half of the 20th century. All of thestars are situated on the southern hemisphere a most of them areeclipsing binaries. These times of minima can do a great job for O-Canalysis of these objects. The aim of this paper is to introduce thisproject.
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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 Estimates of the Solar-Neighborhood Massive Star Birthrate and the Galactic Supernova Rate
The birthrate of stars of masses >=10 Msolar is estimatedfrom a sample of just over 400 O3-B2 dwarfs within 1.5 kpc of the Sunand the result extrapolated to estimate the Galactic supernova ratecontributed by such stars. The solar-neighborhood Galactic-plane massivestar birthrate is estimated at ~176 stars kpc-3Myr-1. On the basis of a model in which the Galactic stellardensity distribution comprises a ``disk+central hole'' like that of thedust infrared emission (as proposed by Drimmel and Spergel), theGalactic supernova rate is estimated at probably not less than ~1 normore than ~2 per century and the number of O3-B2 dwarfs within the solarcircle at ~200,000.
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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.
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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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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
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Catalog of Galactic OB Stars
An all-sky catalog of Galactic OB stars has been created by extendingthe Case-Hamburg Galactic plane luminous-stars surveys to include 5500additional objects drawn from the literature. This work brings the totalnumber of known or reasonably suspected OB stars to over 16,000.Companion databases of UBVβ photometry and MK classifications forthese objects include nearly 30,000 and 20,000 entries, respectively.
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Drei langperiodische Bedeckungsveranderliche: RZ Scuti, RZ Ophiuchi und EE Cephei.
Not Available
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Beobachtungstipp: das Minimum von RZ Oph im Mai 2002.
Not Available
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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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The use of the NextGen model atmospheres for cool giants in a light curve synthesis code
We have written a light curve synthesis code that makes direct use ofmodel atmosphere specific intensities, in particular the NextGen modelatmosphere grid for cool giants (Teff<= 6800 K and log(g)<= 3.5, Hauschildt et al. \cite{hauschildt99}). We point out thatthese models (computed using spherical geometry) predict a limbdarkening behaviour that deviates significantly from a simple linear ortwo-parameter law (there is less intensity at the limb of the star). Thepresence of a significantly nonlinear limb darkening law has two mainconsequences. First, the ellipsoidal light curve computed for a tidallydistorted giant using the NextGen intensities is in general differentfrom the light curve computed using the same geometry but with the blackbody approximation and a one- or two-parameter limb darkening law. Inmost cases the light curves computed with the NextGen intensities havedeeper minima than their black body counterparts. Thus the light curvesolutions for binaries with a giant component obtained with models withnear linear limb darkening (either black body or plane-parallel modelatmosphere intensities) are biased. Observations over a wide wavelengthrange (i.e. both the optical and infrared) are particularly useful indiscriminating between models with nearly linear limb darkening and theNextGen models. Second, we show that rotational broadening kernels forRoche lobe filling (or nearly filling) giants can be significantlydifferent from analytic kernels due to a combination of the nonsphericalshape of the star and the radical departure from a simple limb darkeninglaw. As a result, geometrical information inferred from Vrotsin i measurements of cool giants in binary systems are likewise biased.
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An Optical Study of BG Geminorum: An Ellipsoidal Binary with an Unseen Primary Star
We describe optical photometric and spectroscopic observations of thebright variable BG Geminorum. Optical photometry shows a pronouncedellipsoidal variation of the K0 I secondary, with amplitudes of ~0.5 magat VRCIC and a period of 91.645 days.A deep primary eclipse is visible for λ<~4400 Å ashallower secondary eclipse is present at longer wavelengths. Eclipsetimings and the radial velocity curve of the K0 secondary star indicatean interacting binary where a lobe-filling secondary, M2~0.5Msolar, transfers material into a extended disk around amassive primary, M1~4.5 Msolar. The primary staris either an early B-type star or a black hole. If it did contain ablack hole, BG Gem would be the longest period black hole binary knownby a factor of 10, as well as the only eclipsing black hole binarysystem.
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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.
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UBV beta Database for Case-Hamburg Northern and Southern Luminous Stars
A database of photoelectric UBV beta photometry for stars listed in theCase-Hamburg northern and southern Milky Way luminous stars surveys hasbeen compiled from the original research literature. Consisting of over16,000 observations of some 7300 stars from over 500 sources, thisdatabase constitutes the most complete compilation of such photometryavailable for intrinsically luminous stars around the Galactic plane.Over 5000 stars listed in the Case-Hamburg surveys still lackfundamental photometric data.
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Catalogue of stars in the northern Milky Way having H-alpha in emission
Not Available
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W Crucis: an eclipsing binary system containing an accretion disk.
Recently published B and V light curves of W Cru have been analyzed bymeans of the light curve synthesis. A consistent model of the system canbe obtained if a thick accretion disk is introduced. The disk completelyobscures the more massive, mass accreting star, explaining the problemof its invisibility in the spectrum. In this model, the deeper minimumis the one caused by the eclipse of the mass losing star by the disk.Masses of the components were calculated to be M_1_=7.8Msun_,M_2_=1.25Msun_, the orbital separation A=299Rsun_,while the radius of the secondary R_2_=76Rsun_. The systemseems to be a product of the 'Case-C' mass transfer evolution.
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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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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
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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.
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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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Radio continuum emission from stars: a catalogue update.
An updated version of my catalogue of radio stars is presented. Somestatistics and availability are discussed.
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Rediscussion of photometric data and an accretion disk model for the 96-day binary UU CANCRI
Available photometric data of UU Cnc were reanalyzed in order to checkfor the presence of an accretion disk in the system. Light curvemodeling made with a code that simulates a light curve of a binarycontaining an accretion disk was performed. Results show that such amodel describes the observed B and V light curves very well. The systemwas found to consist of a more massive star completely hidden by anoptically thick accretion disk and of a 0.77Msun_ K4 IIIgiant with radius of about 37Rsun_. The system mass ratio wasderived to be about 0.56 and inclination close to 90 degrees. The diskseen edge-on contributes to the observed light curves very little. Itsmain effect in the light curve is due to its eclipse of the giant starobserved as the deeper minimum. Such a model could explain some cases ofthe β -Lyr paradox - invisibility in the spectrum of the moremassive star due to its obscuration by an optically thick accretiondisk, in systems with inclination close to 90 degrees.
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Astrophysics in 1993
After the astronomical excitements of 1991 and 1992, 1993 was frankly abit of a letdown. More papers by more people were submitted andpublished than ever before (and this review has twice as many authors asthe previous ones). Nevertheless, there seem to have been fewer large,definitive steps. As a result, we have focused on a handful of broadterrains for which the maps have improved, including stellar rotationand mass loss, dynamics of globular clusters, and quasar absorptionlines, but have also highlighted many more of the small steps by whichastonomy advances toward inventorying and and understanding theuniverse. As a consequence, the ordering of topics is less obviouslyfrom near to far than in 1991 and 1992. And the potential formisattributions and unjustifiable neglect is probably somewhat larger.
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Eclipses in Cataclysmic Variables with Stationary Accretion Disks. I. A New Approach to the Problem of Light Curve Analysis
Light curves of cataclysmic variables with stationary accretion disksare a superposition of a disk light curve and a hot spot light curve.The contribution from the spot complicates the analysis of the diskeclipse. As a new approach to this problem, it is proposed to performthe light curve analysis in three parts: (1) decomposition of theobserved light curve into the spot and disk light curves, (2) analysisof the disk light curve, and (3) analysis of the spot light curve, withparts (2) and (3) providing independent constraints on systemparameters. Simple models and methods, to be used in the analysis of thedisk and spot eclipse light curves, are then described. The model disklight curves include, in particular, the effects connected with thefinite geometrical thickness of the disk. A rediscussion of the M_V vs.dot M relation for stationary accretion disks shows that effects due tothe finite geometrical thickness of the disk can contributesignificantly to its luminosity.
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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.
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INHABITED SKY
