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No Be binary component in the eclipsing binary DW Carinae
In a recent excellent study by Southworth and Clausen, refined orbitalelements and basic physical properties of DW Carinae were derived. Asuggestion was made that this binary is a Be-star system since a double,Hα emission line was observed. I argue that the observed Hαemission is nebular emission from the Carina nebula and that neither ofthe binary components of DW Carinae is a Be star.
| Programmsterne: Beobachtungen erwuenscht.
Not Available
| 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.
| Visual Minima Timings of Eclipsing Binaries Observed in the Years 1992 - 1996
The paper contains a list of 283 new times of minima and 77 revisedtimes of minima for 63 eclipsing binaries derived by the author fromhis visual observations.
| 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.
| 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.
| Infrared Photometry for Five Close Binary Systems
We present the JHKLM photometry for five close (W Ser) binary systemsobtained in the period 1996 2004. Positive phase shifts (with respect ofthe adopted ephemerides) have been found in the orbital infrared lightcurves for three binaries, RX Cas, KX And, and β Lyr; the rates ofincrease in their periods are 3.5 × 10-4, 1.6 ×10-3, and 1.4 × 10-4 days yr-1, respectively. We haveperformed the spectral classification of the components of the binariesunder study and estimated their parameters.
| Beobachtungsergebnisse Bundesdeutsche Arbeitsgemeinschaft fur Veranderlichen Serne e.V.
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| 162-nd List of Minima Timings of Eclipsing Binaries by BBSAG Observers
Not Available
| Evolution of Wolf-Rayet Stars in Binary Systems: An Analysis of the Mass and Orbital-Eccentricity Distributions
We have undertaken a statistical study of the component mass ratios andthe orbital eccentricities of WR + O close binary, detachedmain-sequence (DMS), contact early-type (CE), and semidetached (SD)systems. A comparison of the characteristics of WR + O systems and ofDMS, CE, and SD systems has enabled us to draw certain conclusions aboutthe evolutionary paths of WR + O binaries and to demonstrate that up to90% of all known WR + O binaries formed as a result of mass transfer inmassive close O + O binary systems. Since there is a clear correlationbetween the component masses in SD systems with subgiants, the absenceof an anticorrelation between the masses of the WR stars and O stars inWR + O binaries cannot be considered evidence against the formation ofWR + O binaries via mass transfer. The spectroscopic transitionalorbital period P tr sp corresponding to the transition from nearlycircular orbits (e sp<0.1) to elliptical orbits (e sp≥0.1) is14d for WR + O systems and 2d 3d for OB + OB systems. Theperiod range in which all WR + O orbits are circular &$(1mathop dlimits_. 6 ≤slant P ≤slant 14(d) ); is close to the range for SD systems with subgiants, &0mathop dlimits_. 7 ≤slant P ≤slant 15(d); . The large difference between the P tr sp values for WR + O and OB +OB systems suggests that a mechanism of orbit circularization additionalto that for OB + OB systems at the DMS stage (tidal dissipation of theorbital energy due to radiative damping of the dynamical tides) acts inWR + O binaries. It is natural to suggest mass transfer in the parent O+ O binaries as this supplementary orbit-circularization mechanism.Since the transitional period between circular and elliptical orbits forclose binaries with convective envelopes and ages of 5×109 yearsis &P_{tr} = 12mathop dlimits_. 4$; , the orbits of most known SD systems with subgiants had enough timeto circularize during the DMS stage, prior to the mass transfer. Thus,for most SD systems, mass transfer plays a secondary role incircularization of their orbits. In many cases, the initial orbitaleccentricities of the O + O binary progenitors of WR + O systems arepreserved, due to the low viscosity of the O-star envelopes and theshort timescale for their nuclear evolution until the primary O starfills its Roche lobe and the mass transfer begins. The mass transfer inthe parent O + O systems is short-lived, and the number of orbitalcycles during the early mass-transfer stage is relatively low (lowerthan for the progenitors of SD systems by three or four orders ofmagnitude). The continued transfer of mass from the less massive to themore massive star after the component masses have become equal leads tothe formation of a WR + O system, and the orbit's residual eccentricityincreases to the observed value. The increase of the orbitaleccentricity is also facilitated by variable radial mass loss via thewind from the WR star in the WR + O system during its motion in theelliptical orbit. The result is that WR + O binaries can haveconsiderable orbital eccentricities, despite their intense masstransfer. For this reason, the presence of appreciable eccentricitiesamong WR + O binaries with large orbital periods cannot be consideredfirm evidence against mass transfer in the parent O + O binary systems.Only for the WR + O binaries with the longest orbital periods (4 of 35known systems, or 11 %) can the evolution of the parent O + O binariesoccur without filling of the Roche lobe by the primary O star, beinggoverned by radial outflow in the form of the stellar wind and possiblyby the LBV phenomenon, as in the case of HD 5980.
| Zur qualitat der visuellen Beobachtung kurzperiodisch Veranderlicher.
Not Available
| Einige interessante Bedeckungsveraenderliche.
Not Available
| Das Brunner Punktesystem.
Not Available
| The Physical Basis of Luminosity Classification in the Late A-, F-, and Early G-Type Stars. I. Precise Spectral Types for 372 Stars
This is the first in a series of two papers that address the problem ofthe physical nature of luminosity classification in the late A-, F-, andearly G-type stars. In this paper, we present precise spectralclassifications of 372 stars on the MK system. For those stars in theset with Strömgren uvbyβ photometry, we derive reddenings andpresent a calibration of MK temperature types in terms of the intrinsicStrömgren (b-y)0 index. We also examine the relationshipbetween the luminosity class and the Strömgren c1 index,which measures the Balmer jump. The second paper will address thederivation of the physical parameters of these stars, and therelationships between these physical parameters and the luminosityclass. Stars classified in this paper include one new λ Bootisstar and 10 of the F- and G-type dwarfs with recently discoveredplanets.
| Accretion disk in the binary system V367 Cygni
New photoelectric observations of the interacting binary V367 Cyg weremade during two consecutive seasons, 1996 and 1997, using thetwo-channel photometer at Mt. Suhora Observatory. The BVRI light curvesare analyzed and system parameters are derived for two alternativemodels: with and without an accretion disk. A contact configuration isobtained for the no-disk model. The semidetached model, with a diskaround the invisible component gives a better fit and, in addition,explains most of the observed features of V367 Cyg. The disk in V367 Cyghas a radius of about R_d=23 Rsun, almost completely fillingthe secondary component's Roche lobe. Mass is transferred from the lessmassive (3.3 Msun) to the more massive (4.0 Msun)star at a high rate of 5-7 10-5 Msun/yr. Theoriginal observations are available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/368/932
| 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.
| Infrared Photometry for Variable Stars of Selected Types in 1978-1999
We present and discuss IR observations for 35 stars of differentvariability types averaged over many years. These include about twentysymbiotic stars, four W Ser stars and one Algol, six Miras, etc.
| 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.
| From OAO2 to HST. A quarter of a century of ultraviolet astronomy.
Not Available
| New spectral observations of the interacting eclipsing binary V367 Cygni
The results of high-dispersion CCD spectral observations of theinteracting eclipsing binary V367 Cyg near the HeI 6678 Angstrom, MgII4481 Angstrom, SiII 6347 Angstrom, and Hα lines are presented.Faint emission in the HeI 6678 Angstrom line was detected. The radialvelocity derived from this emission varies with a half-amplitude ofabout 180km/s, and is in antiphase with the variations of the MgII 4481A line, which is formed in the photosphere of the primary star. It isconcluded that the He I emission is formed in the accretion disc aroundthe invisible companion. A simultaneous solution for the orbitalradial-velocity variability curves (taking into account the inclinationangle of the orbit, determined previously from polarimetricobservations), results in estimates for the masses of the two componentsM_1 22 M_solar and M_2 11 M_solar. New orbital elements for the binaryare determined. Long-term variability in the radial velocity of thesystem's center of mass was also discovered. The variability of the HeI6678 Angstrom, SiII 6347 Angstrom, and Hα line profiles are usedto analyze the behavior of gas flows in the system. V367 Cyg appears tobe in an initial phase of rapid mass transfer, when matter flows fromthe more massive onto the less massive component.
| 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.
| On Light Curves Modeling of Low Inclination Binary Systems with Accretion Disks
Computer generated light curves of a low inclination, semidetachedbinary system containing an accretion disk, were analyzed with theWilson-Devinney code (which does not account for the disk effects), tosearch for the best solution. The following inclinations wereconsidered: 77 arcdeg 4, 75 arcdeg 0 and 60 arcdeg 0 as well as threedifferent disk contributions to the total light: 2%, 15% and 30%. Forthe disk contribution being small (2%), the resulting configurationagreed with the input one. For higher disk light detached geometry wasderived. The parameters obtained from modeling greatly differ from theinput ones and the fits are quite good.
| HD 187399 - A massive interacting binary system with an eccentric orbit and intense mass transfer: polarimetric observations.
Not Available
| The calculation of critical rotational periods in three typical close binary systems based on synchronization theory.
Not Available
| 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
| New polarimetric observations of V367 Cyg
Not Available
| The strongly constrained interacting binary BY Crucis.
We discuss spectroscopic and photometric observations (UV to IR) of BYCrucis, a new bright member of the interacting binaries of the WSerpentis class. The orbital period is 106.4days, and the mass functionamounts to 5.92Msun_. The primary is an early-F supergiantwhich fills its Roche lobe; the massive secondary is hidden inside athick accretion disk, which is probably the dominant light source in theultraviolet. The observed variations in the photometric lightcurves arecaused mainly by ellipsoidal variations. It is unlikely that an eclipseoccurs. A particularly interesting circumstance is that BY Cru is aprobable member of a visual multiple system which contains anotherevolved star. This circumstance enables us to estimate with someaccuracy the age of the interacting binary and the initial mass of theprimary. The history of this binary is then much more constrained thanfor the other W Serpentis stars. Also taking into account the fact thatthe binary has avoided Case C Roche lobe overflow, we determine upperand lower bounds for the initial and present masses of both components,and conclude that mass transfer has only been moderatelynon-conservative.
| Search for dust shells in W SER binaries and similar objects: KX Andromedae and V367 Cygni.
Not Available
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| Csillagkép: | Hattyú |
| Rektaszcenzió: | 20h47m59.58s |
| Deklináció: | +39°17'15.7" |
| Vizuális fényesség: | 7.074 |
| Távolság: | 1136.364 parszek |
| RA sajátmozgás: | -5.3 |
| Dec sajátmozgás: | -3.6 |
| B-T magnitude: | 7.869 |
| V-T magnitude: | 7.14 |
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