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Precise Times of Minimum Light of Neglected Eclipsing Binaries
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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.
| Spectroscopic and Photometric Analysis of the O-Type Binary V1182 Aquilae: A Close Eclipsing System with a Luminous Third Body
We obtained high-resolution spectroscopy and UBV photometry of theO-type eclipsing binary V1182 Aql. In the spectra lines of a thirdcomponent were found; the presence of third light is also supported bythe solution of the light curves. New masses for both components of thebinary were derived: M1=31.0 and M2=16.6Msolar. These values differ considerably from those given byBell et al., which were obtained by neglecting the presence of a thirdbody. With Teff~43,000 K the primary component is much hotterthan expected for the previously assumed spectral type O8. Itsclassification has to be revised to O5.5, which makes V1182 Aql probablythe earliest eclipsing binary in the Galaxy. The mass of the primary issmaller than suggested by evolutionary models, while the secondaryparameters agree with a position close to the zero-age main sequence(ZAMS). The third body, which manifests itself by strong lines in theoptical spectrum and by a third light contribution of ~17% as deducedfrom the light curve solution might be detectable by interferometricmeasurements.Based on observations collected at the European Southern Observatory, LaSilla, Chile, and at the German-Spanish Astronomical Centre, Calar Alto,operated by the Max-Planck-Institut für Astronomie, Heidelberg,jointly with the Spanish National Commission for Astronomy; also basedon spectral data retrieved from the ELODIE archive at Observatoire deHaute Provence (OHP).
| The massive binary CPD - 41° 7742. II. Optical light curve and X-ray observations
In the first paper of this series, we presented a detailedhigh-resolution spectroscopic study of CPD - 41°7742, deriving for the first time an orbital solution for bothcomponents of the system. In this second paper, we focus on the analysisof the optical light curve and on recent XMM-Newton X-ray observations.In the optical, the system presents two eclipses, yielding aninclination i77°. Combining the constraints from the photometrywith the results of our previous work, we derive the absolute parametersof the system. We confirm that the two components of CPD -41° 7742 are main sequence stars (O9 V + B1-1.5 V) withmasses (M_118 Mȯ and M_210 Mȯ)and respective radii (R_17.5 Rȯ and R_25.4Rȯ) close to the typical values expected for such stars.We also report an unprecedented set of X-ray observations that almostuniformly cover the 2.44-day orbital cycle. The X-ray emission fromCPD - 41° 7742 is well described by atwo-temperature thermal plasma model with energies close to 0.6 and 1.0keV, thus slightly harder than typical early-type emission. The X-raylight curve shows clear signs of variability. The emission level ishigher when the primary is in front of the secondary. During the highemission state, the system shows a drop of its X-ray emission thatalmost exactly matches the optical eclipse. We interpret the mainfeatures of the X-ray light curve as the signature of a wind-photosphereinteraction, in which the overwhelming primary O9 star wind crashes intothe secondary surface. Alternatively the light curve could result from awind-wind interaction zone located near the secondary star surface. As asupport to our interpretation, we provide a phenomenological geometricmodel that qualitatively reproduces the observed modulations of theX-ray emission.
| To see or not to see a bow shock. Identifying bow shocks with Hα allsky surveys
OB-stars have the highest luminosities and strongest stellar winds ofall stars, which enables them to interact strongly with theirsurrounding ISM, thus creating bow shocks. These offer us an idealopportunity to learn more about the ISM. They were first detected andanalysed around runaway OB-stars using the IRAS allsky survey by vanBuren et al. (1995, AJ, 110, 2614). Using the geometry of such bowshocks information concerning the ISM density and its fluctuations canbe gained from such infrared observations. As to help to improve the bowshock models, additional observations at other wavelengths, e.g.Hα, are most welcome. However due to their low velocity these bowshocks have a size of 1°, and could only be observed as awhole with great difficulties. In the light of the new Hα allskysurveys (SHASSA/VTSS) this is no problem any more. We developeddifferent methods to detect bow shocks, e.g. the improved determinationof their symmetry axis with radial distance profiles. Using twoHα-allsky surveys (SHASSA/VTSS), we searched for bow shocks andcompared the different methods. From our sample we conclude, that thecorrelation between the direction of both proper motion and the symmetryaxis determined with radial distance profile is the most promisingdetection method. We found eight bow shocks around HD17505, HD 24430, HD48099, HD 57061, HD92206, HD 135240, HD149757, and HD 158186 from 37 candidatestaken from van Buren et al. (1995, AJ, 110, 2614). Additionally to thetraditional determination of ISM parameters using the standoff distanceof the bow shock, another approach was chosen, using the thickness ofthe bow-shock layer. Both methods lead to the same results, yieldingdensities ( 1 cm-3) and the maximal temperatures (104 K), that fit well to the up-to-date picture of the WarmIonised Medium.
| 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.
| Masses and other parameters of massive binaries
Binary stars provide us with the means to measure stellar mass. Here Ipresent several lists of known O-type stars with reliable mass estimatesthat are members of eclipsing, double-lined spectroscopic binaries. Themasses of young, unevolved stars in binaries are suitable for testingthe predictions of evolutionary codes, and there is good agreementbetween the observed and predicted masses (based upon temperature andluminosity) if the lower temperature scale from line-blanketed modelatmospheres is adopted. A final table lists masses for systems in awide variety of advanced evolutionary stages.
| Spectroscopy of four early-type eclipsing binaries
New spectroscopic data were obtained for the early-type binariesV337 Aql, V649 Cas, V382Cyg, and V431 Pup. Their radial velocitycurves are presented. These are the first such data for V337Aql and V431 Pup. In the case ofV382 Cyg, our data confirm previously obtainedresults. Especially for V649 Cas our radial velocitycurve yields important new implications for the component masses: thedetection of third body lines, which are blended with the lines of theprimary component, solves the problem of the unacceptably small massesformerly deduced for this binary; now we determine masses closer to thevalues expected for spectral type B 0. V431 Pup is animportant object, because it is a new member of the small group ofearly-type eclipsing binaries with an evolved component. A publishedlight curve of V337 Aql is solved by the MORO code, and systemparameters are derived. The period of V649 Cas isfound to be variable, and a more accurate period is calculated forV431 Pup. Based on observations collected at theEuropean Southern Observatory, La Silla, Chile, and at theGerman-Spanish Astronomical Center (DSAZ), Calar Alto, operated by theMax-Planck-Institut für Astronomie Heidelberg jointly with theSpanish National Commission for Astronomy.
| Classification and properties of UV extinction curves
The catalog of Savage et al. (\cite{ref27}) reporting colour excesses of1415 stars from ANS photometry offers the opportunity to deeplyinvestigate the characteristics of UV extinction curves which differfrom the standard extinction of the diffuse interstellar medium. To thisaim we have selected a sample of 252 curves, which have been comparedwith the relations derived by Cardelli et al. (\cite{ref4}; CCM in thefollowing) for a variety of R_V values in the range 2.4-5 and have beenclassified as normal if they fit at least one of the CCM curves oranomalous otherwise. We find that normal curves with small R_V are justas numerous as those with large R_V. The anomalous objects are arrangedinto two groups according to the strength of the bump at 0.217 mu . Fora given value of c_2 this increases along the sequence: type Aanomalous, normals and type B anomalous, suggesting that this sequenceshould correspond to an increase of the amount of small grains along thesightline. Considerations concerning the environmental characteristicsindicate that the anomalous behaviour is not necessarily tied to theexistence of dense gas clouds along the line of sight.
| New times of minima and ephemeris for several OB eclipsing binaries
New times of minimum light were measured for several early-typeeclipsing binaries: V337 Aql, V1182 Aql, V1331 Aql, IU Aur, QZ Car andV382 Cyg. The O-C diagram for these systems is discussed and newephemeris is given for AH Cep; observation of AQ Cir is added. It isshown that the scatter of times of minima is several times larger thanthe measuring errors for most of the binaries studied.
| 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.
| Detection of a third body in the spectrum of the early-type eclipsing binary V1182 Aql.
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| Bow Shocks Around Runaway Stars.III.The High Resolution Maps
In a recent survey for bow shock structures around OB runaway starsusing the ISSA/IRAS archival data and excess maps at 60 \mum, 58candidates were found. These objects are surrounded by extended infraredemission at 60 \mum, characteristic of warm dust heated by ultravioletphotons, a signature of wind bow shocks. High resolution IRAS (HiRes)images have been produced for these 58 objects and some of thosespatially resolved are presented in this study. The images were used todistinguish between multiple confused IR sources, possible artifacts andunambiguous bow shocks, as the sources of the extended 60 \mum emission.Six new bow shocks have been identified using this method, and threehave been rejected. Twenty two of the targets, however, remain spatiallyunresolved even at the nominal HiRes resolution of ~ 1arcmin . For thelarger and better defined bow shocks some internal substructure isdiscernible. The length of these features suggest that they arise as theresult of a subtle dynamical instability. It can not be ruled out,however, that some of the bow shock morphology could be imprinted by thesurrounding medium.
| The calculation of critical rotational periods in three typical close binary systems based on synchronization theory.
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| Measurement and study of rotation in close binary stars (III) Statistical analysis of synchronization.
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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.
| A possible mechanism for the formation of shoulders in eclipsing binaries.
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| Measurement and analysis of rotation in close binaries. II. Calculation of synchronism.
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| OB-type binaries: Models versus observations
Recently published models on close binary evolution for massive stars (Mgreater than 5 solar mass) are compared to a set of detached andsemidetached OB binaries. For the majority of the detached systems, wefind good correspondence between theoretical and observedcharacteristics for stars with masses between 4.5 sola mass and 17 solarmass. We explore the origin of semidetached systems, and discussanomalies between models and observed characteristics. An initial massratio of around 0.6 seems to be preffered for this group. Finally, webriefly examine a number of massive (marginal) contact systems. Thelatter systems all seem to evolve according to case A of mass transfer.
| Measurement and Analysis of Rotation in Close Binary Stars - Part One - Observations and Results
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| The SVS Numbering Series Discontinued
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| A re-discussion of four early-type eclipsing binary systems
An analysis is made of the published photometric and spectroscopic datafor early-type eclipsing binaries using the Wilson-Devinney code withthe goal of providing a homogeneous set of data on the properties ofhigh-mass stars. Performing simultaneous multicolor light-curvesolutions is advocated, so as to keep the number of adjusted parametersat a minimum. The weighting scheme in such solutions should beconsidered carefully. The data for the double-lined systems V1182 Aql,CW Cep, AG Per and TT Aur are analyzed. Previous solutions for thesesystems are discussed, and likely sources of error are pointed out.
| Eclipsing binaries with eccentric orbits
Two groups of eclipsing binaries are dealt with: the first consists ofall binaries with enough data in the General Catalog of Variable Stars(GCVS; Cholopov et al, 1987), the other of those for which accurateparameters are known. In the first group, problems with classificationin GCVS are noticed and several examples of binaries with unexpectedparameters are named. For binaries of the second group, their fractionalradii, ages, and initial radii are used to discuss the relation of theirevolutionary status and orbital eccentricity. Dependence of eccentricityon spectral type and age is observed, and no peak in the initialeccentricity distribution at e = 0 seems to be present. It is suggestedthat binary origin by fragmentation followed by disruption of initialmultiple systems can explain all observed binaries, perhaps with theexception of contact systems in the main sequence. In several cases thecircularization must be due to mass transfer in the eccentric orbit.
| Rediscussion of eclipsing binaries. XVII - Spectroscopic orbits of OB systems with a cross-correlation procedure
An effort is made to apply the reduction techniques, including crosscorrelation, developed at Victoria by Hill et al. (1982) to photographicspectrograms of OB binaries in order to correct for the effects ofoverlapping profiles. According to the calibration using syntheticbinaries, the values of K derived by the cross correlation method arelarger than the true values by an average of 2.0 percent for the primarycomponents and 3.0 percent for the secondaries. The average luminosityratio is 0.7. The values of K obtained for the eclipsing binaries by theprocedure are, as expected, greater than the values obtained byoscilloscopic scanning of the same spectrograms. Although the values ofK and hence the masses and radii are probably more reliable than earlierresults, it is concluded that the elimination of systematic effects inthe velocities of double-line OB binaries is a difficult task that maynot have been accomplished completely.
| Close binaries observed polarimetrically
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| Investigation of statistical data for close binary stars.
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| Reexamination of the mass-radius relation of main sequence in binary systems
The mass-radius relation of the main sequence was reexamined using 171components of 88 double-lined detached binary systems with welldetermined absolute dimensions and masses. Empirical relations for theZAMS were obtained and compared with the theoretical models. Thepositions of the other 27 semidetached binaries in the log M - log Rdiagram are also discussed.
| An Updated List of Eclipsing Binaries Showing Apsidal Motion
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| Stellar masses and radii based on modern binary data
Accurate data on absolute dimensions of eclipsing binaries published inthe astronomical literature since 1980 are collected and analyzed.Simple approximation formulas relating the effective temperature withother basic physical parameters (mass, radius, bolometric magnitude) arederived. Mean and extreme values of these parameters for each spectraltype are also tabulated. The implication of improved data for theproblem of critical rotational periods and equatorial velocities ofearly-type stars is discussed.
| Angular momenta in binary systems
The correlations of angular momenta L to masses M are studied fordifferent types of spectroscopic binaries. Postulates about equivalentstates of angular momenta for different orbital parameters areintroduced. From comparisons with galaxies and single stars, it isevidenced that there is not a unique universal function L = AM exp b,when the finite structure of the relation is analyzed: each object hasits own coefficients A, b. It seems that there are an upper and a lowerlimit for all the possible functions.
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משמש של הקבוצה הבאה
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תצפית ומידע אסטרומטרי
| קבוצת-כוכבים: | נשר |
| התרוממות ימנית: | 18h55m23.12s |
| סירוב: | +09°20'48.1" |
| גודל גלוי: | 8.643 |
| מרחק: | 495.05 פארסק |
| תנועה נכונה: | -1.6 |
| תנועה נכונה: | -1.4 |
| B-T magnitude: | 9.219 |
| V-T magnitude: | 8.691 |
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