Photoelectric Minima of Some Eclipsing Binary Stars
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Contact Binaries with Additional Components. I. The Extant Data
We have attempted to establish observational evidence for the presenceof distant companions that may have acquired and/or absorbed angularmomentum during the evolution of multiple systems, thus facilitating orenabling the formation of contact binaries. In this preliminaryinvestigation we use several techniques (some of themdistance-independent) and mostly disregard the detection biases ofindividual techniques in an attempt to establish a lower limit to thefrequency of triple systems. While the whole sample of 151 contactbinary stars brighter than Vmax=10 mag gives a firm lowerlimit of 42%+/-5%, the corresponding number for the much better observednorthern-sky subsample is 59%+/-8%. These estimates indicate that mostcontact binary stars exist in multiple systems.
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Radial Velocity Studies of Close Binary Stars. X.
Radial velocity measurements and sine-curve fits to orbital velocityvariations are presented for the ninth set of 10 close binary systems:V395 And, HS Aqr, V449 Aur, FP Boo, SW Lac, KS Peg, IW Per, V592 Per, TUUMi, and FO Vir. The first three are very close, possibly detached,early-type binaries, and all three require further investigation.Particularly interesting is V395 And, whose spectral type is as early asB7/8 for a 0.685 day orbit binary. KS Peg and IW Per are single-linebinaries, with the former probably hosting a very low mass star. We havedetected a low-mass secondary in an important semidetached system, FOVir, at q=0.125+/-0.005. The contact binary FP Boo is also a very smallmass ratio system, q=0.106+/-0.005. The other contact binaries in thisgroup are V592 Per, TU UMi, and the well-known SW Lac. V592 Per and TUUMi have bright tertiary companions; for these binaries, and for V395And, we used a novel technique of arranging the broadening functionsinto a two-dimensional image in phase. The case of TU UMi turned out tobe intractable even using this approach, and we have not been able toderive a firm radial velocity orbit for this binary. Three systems ofthis group were observed spectroscopically before: HS Aqr, SW Lac, andKS Peg.Based on the data obtained at the David Dunlap Observatory, Universityof Toronto.
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Photometric Studies of the Near-Contact Binary AX Draconis
We have obtained CCD photometric observations of the near-contact binaryAX Dra during two observing seasons from 2001 March through May and from2003 April and May. From these measurements, the seasonal light curvesof AX Dra for 2001 and 2003 were compiled, and a total of 13 new timingsof minimum light were calculated. An analysis of the resulting O-Cdiagram reveals evidence for a periodic change with a semiamplitude of0.0061 days and a period of 56.1 yr, but this conclusion dependsentirely on the photographic plate estimates around 1960. Our lightcurves display the conventional O'Connell effect and small-scaleyear-to-year light variability. If these light variations are producedby a stellar spot, a cool-model spot on the secondary star satisfiesboth seasonal light curves quite well. The same representation appliesto the only other published photoelectric light curves.
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Spectral Classification of Stars in A Supplement to the Bright Star Catalogue
MK spectral types are given for about 584 stars in A Supplement to theBright Star Catalogue. These are compared with Hipparcos parallaxes tocheck the reliability of those classifications. The estimated errors are+/-1.2 subtypes, and 10% of the luminosity classes may be wrong.
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162-nd List of Minima Timings of Eclipsing Binaries by BBSAG Observers
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The 7.5 Magnitude Limit Sample of Bright Short-Period Binary Stars. I. How Many Contact Binaries Are There?
A sample of bright contact binary stars (W UMa type or EW, and related:with β Lyr light curves, EB, and ellipsoidal, ELL-in effect, allbut the detached, EA) to the limit of Vmax=7.5 mag is deemedto include all discoverable short-period (P<1 day) binaries withphotometric variation larger than about 0.05 mag. Of the 32 systems inthe final sample, 11 systems have been discovered by the Hipparcossatellite. The combined spatial density is evaluated at(1.02+/-0.24)×10-5 pc-3. The relativefrequency of occurrence (RFO), defined in relation to the main-sequencestars, depends on the luminosity. An assumption of RFO~=1/500 forMV>+1.5 is consistent with the data, although the numberstatistics is poor with the resulting uncertainty in the spatial densityand the RFO by a factor of about 2. The RFO rapidly decreases forbrighter binaries to a level of 1/5000 for MV<+1.5 and to1/30,000 for MV<+0.5. The high RFO of 1/130, previouslydetermined from the deep OGLE-I sample of disk population W UMa typesystems toward Baade's window, is inconsistent with and unconfirmed bythe new results. Possible reasons for the large discrepancy arediscussed. They include several observational effects but also apossibility of a genuine increase in the contact-binary density in thecentral parts of the Galaxy. Based on data from the Hipparcos satellitemission and from the David Dunlap Observatory, University of Toronto.
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The WARPS Survey. VI. Galaxy Cluster and Source Identifications from Phase I
We present in catalog form the optical identifications for objects fromthe first phase of the Wide Angle ROSAT Pointed Survey (WARPS). WARPS isa serendipitous survey of relatively deep, pointed ROSAT observationsfor clusters of galaxies. The X-ray source detection algorithm used byWARPS is Voronoi Tessellation and Percolation (VTP), a technique whichis equally sensitive to point sources and extended sources of lowsurface brightness. WARPS-I is based on the central regions of 86 ROSATPSPC fields, covering an area of 16.2 square degrees. We describe herethe X-ray source screening and optical identification process forWARPS-I, which yielded 34 clusters at 0.06
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UBV Photometric Study of the Eclipsing Binary DM Delphini
The near-contact system DM Del with an A2V primary and a G8 secondarywas observed in U, B and V wavelengths in July 1998. A new seasonallight curve is presented and a new observed time of minimum is given.The unperturbed part of the light curve was used to determine some basicparameters of the system with the Wilson-Devinney code, some of whichwere kept fixed for spot modelling of the light curves. A simple spotdistribution was determined, based on a model with two cool spots on thesurface of the secondary. Absolute elements were calculated and theevolutionary status was determined.
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CN Andromedae: A Broken-Contact Binary?
We solve new UBV light curves of the eclipsing binary CN Andromedaesimultaneously with radial velocities by the method of differentialcorrections. We find it semidetached with the more massive star fillingits limiting lobe and the less massive star very close to lobe-filling.Our solutions of earlier light curves have the same configuration.Within the uncertainties, the system may be in a broken or a marginalcontact stage as it undergoes thermal relaxation oscillations. The lightcurves are strongly affected by a large dark spot at high latitude onthe more massive star and by a bright substellar spot on the companion.Spot locations and temperatures do not differ significantly from epochto epoch. Based on single star evolutionary models, the primary's mass(1.299+/-0.045 Msolar) and radius (1.425+/-0.016Rsolar) are consistent with those of a star of age2.9×109 yr that will leave the main sequence in another2.0×109 yr. The orbital period has decreased during thepast 50 yr according to traditional eclipse timings and also accordingto our generalized light and velocity solutions that include a referenceepoch T0 and a rate of period change dP/dt. We finddP/dt=-0.01951+/-0.00054 s yr-1, which is consistent withmass transfer from the more to the less massive star of1.4×10-7 Msolar yr-1, assuming nomass is lost from the system. Reliable absolute dimensions aredetermined.
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KW Persei - a near-contact system?
An analysis of UBV photoelectric photometry for the eclipsing binary KWPer based on new observational data is presented. The light changes arenot only due to eclipses, but also to activity in the system. The U, Band V light curves are analyzed by the Binary Maker 2.0 andWilson-Devinney codes to derive the geometrical and physical parametersof the system. Since the O'Connell effect is present on the light curvesin the three colours, the unperturbed parts of the light curves areconsidered to represent the quiet stage of the system, in contrast tothe active stage which is represented by the perturbed parts of thelight curves. The discussion about the evolutionary status of the systemindicates that the secondary component of the binary system is anevolved star and the primary is a MS star. Table 4 is only available inelectronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr(130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/373/950
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A Photometric study of the near-contact system RU Ursae Minoris
The near-contact system RU UMi with an F0 primary and a K5 secondary wasobserved in U, B and V wavelengths in May and July 1998, as well as inMarch, May and July 1999. Six new observed times of minima are given anda new ephemeris is proposed. The basic parameters of the systemextracted by our observations were used for spot modelling of the lightcurves. A simple spot distribution was determined, based on a model withone relatively small cool spot on the surface of the secondary. Absoluteelements were calculated and the evolutionary status was determined. Ourdata favor a semi-detached configuration, with the secondary filling itsinner Roche lobe; the primary must also be near the limits of its lobe.Table 2 is only available in electronic form at the CDS via anonymousftp to cdsarc.u-strabg.fr(130.79.128.5)} or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qeat?/A+A/369/960
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Radial velocities. Measurements of 2800 B2-F5 stars for HIPPARCOS
Radial velocities have been determined for a sample of 2930 B2-F5 stars,95% observed by the Hipparcos satellite in the north hemisphere and 80%without reliable radial velocity up to now. Observations were obtainedat the Observatoire de Haute Provence with a dispersion of 80Ä,mm(-1) with the aim of studying stellar and galactic dynamics.Radial velocities have been measured by correlation with templates ofthe same spectral class. The mean obtained precision is 3.0 km s(-1)with three observations. A new MK spectral classification is estimatedfor all stars. Based on observations made at the Haute ProvenceObservatory, France and on data from The Hipparcos Catalogue, ESA.Tables 4, 5 and 6 are only available in electronic form at the CDS viaanonymous ftp to cdsarc.u-strasbg.fr or viahttp://cdsweb.u-strasbg.fr/Abstract.htm
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Near-Contact Binary Systems in the ROSAT All-Sky Survey
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1996ApJ...461..951S&db_key=AST
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On the nature of the AM phenomenon or on a stabilization and the tidal mixing in binaries. I. Orbital periods and rotation.
The paper casts a questioning eye on the unique role of the diffusiveparticle transport mechanism in explaining the Am phenomenon and arguesthat the so-called tidal effects might be of great importance incontrolling diffusion processes. A short period cutoff at =~1.2d as wellas a 180-800d gap were found in the orbital period distribution (OPD) ofAm binaries. The existence of the former can be ascribed to the state ofthe primaries with the almost-filled Roche lobes. The latter couldresult from the combined effects of the diffusion, tidal mixing andstabilization processes. Because the tidal mixing might surpassdiffusion in the binaries with the orbital periods P_orb_ less thanseveral hundred days and might thus sustain the He convection zone,which would otherwise disappear, no Am stars should lie below thisboundary. The fact that they are nevertheless seen there implies theexistence of some stabilization mechanism (as, e.g., that recentlyproposed by Tassoul & Tassoul 1992) for the binaries with orbitalperiods less than 180d. Further evidence is given to the fact that theOPD for the Am and the normal binaries with an A4-F1 primary arecomplementary to each other, from which it stems that Am stars are closeto the main sequence. There are, however, indications that they haveslightly larger radii (2.1-3 Rsun_) than expected for theirspectral type. The generally accepted rotational velocity cutoff at=~100km/s is shown to be of little value when applied on Am binaries ashere it is not a single quantity but, in fact, a function of P_orb_whose shape is strikingly similar to that of the curves of constantmetallicity as ascertained from observations. This also leads to thewell known overlap in rotational velocities of the normal and Am starsfor 402.5d.We have exploited this empirical cutoff function to calibrate thecorresponding turbulent diffusion coefficient associated with tidalmixing, having found out that the computed form of the lines of constantturbulence fits qualitatively the empirical shape of the curves ofconstant metallicity. As for larger orbital periods(20d55km/s found by Burkhart(1979) would then be nothing but a manifestation of insufficientlypopulated corresponding area of larger P_orb_.
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A Study of the Binary GR Tauri from Optical and Infrared Observations
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1995AJ....110.1796L&db_key=AST
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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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Near-contact binaries
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Conference report : evolutionary links in the zooofinteracting binaries.
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A Study of the Near-Contact Binary FO Virginis with the IUE
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Gravitational radiation and spiralling time of close binary systems. IV
Binary systems with their primary and secondary component masses lessthan 2 solar masses have been investigated to evaluate the rate ofemission of gravitational energy (PB) and spiralling time (tau exp 0)for them. In all, 22 binary systems have been considered. It is foundthat in spite of the same mass range, these systems form two distinctgroups. New relations have been given between PB and tau exp 0 for eachgroup. For a few eccentric orbit systems the rate of decay of orbitalperiods due to the loss of energy from the system via giavitationalradiation emission has also been given and compared with a short-periodbinary pulsar.
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Statistical study of semi-detached and near-contact semi-detached binaries
A statistical study was made of 107 semidetached with combined lightcurve solutions. An empirical period-dependent mass-radius relation wasderived, thereby revealing the impossibility of having evolvedsemidetached systems with very short periods. Statistically, thenear-contact semidetached systems have the common properties of nearlyequal mass densities of the components, larger mass-ratios, shorterperiods and smaller specific angular momenta, and their A- F-typesecondaries generally have greater densities than the secondaries ofclassical Algol systems of the same spectral types. A detaileddiscussion is also made in this paper on the evolution of near-contactsemidetached binaries.
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New Photoelectric Observations of the Eclipsing Binary FO Vir
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A summary of the investigations of semi-detached close binaries (1986-1988)
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The early F-type stars - Refined classification, confrontation with Stromgren photometry, and the effects of rotation
The classification for early F-type stars in the MK spectralclassification system presented by Gray and Garrison (1987) is refined.The effect of rotation on spectral classification and ubvy-betaphotometry of early F-type stars is examined. It is found that theclassical luminosity criterion, the 4417 A/4481 A ratio givesinconsistent results. It is shown that most of the stars in the DeltaDelphini class of metallic-line stars are either normal or areindistinguishable from proto-Am stars. It is suggested that thedesignation Delta Delphini should be dropped. The classifications arecompared with Stromgren photometry. The effects of rotation on thedelta-c1 index in the early-F field dwarfs is demonstrated.
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Statistical Study on the Semidetached and Near Contact Semidetached Binary Systems
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The evolutionary state of contact and near-contact binary stars
A compilation is presented of the masses, radii, and luminosities of thecomponents of 31 F-K type binary systems which have been found to be incontact or near-contact states. Comparisons of these data with thoseexpected for single stars demonstrates that: (1) the primary componentsof the shallow-contact W-type WUMa systems are unevolved main-sequencestars, while those of the deeper-contact A-type systems are near to theterminal-age main sequence; (2) the secondary components of the W-typesystems have radii of the order of 1.5 times larger than expected fortheir ZAMS masses, while those of the A-type systems have radii of theorder of three times larger; (3) the nine systems in the sample which donot display EW-type light curves can be divided into three marginalcontact systems, five semidetached systems, and one detached system. Theimplications of these findings for the types of evolution into contactare addressed.
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Spectroscopic binaries - 15th complementary catalog
Published observational data on the orbital characteristics of 436spectroscopic binaries, covering the period 1982-1986, are compiled intables. The data sources and the organization of the catalog are brieflydiscussed, and notes are provided for each item.
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Information on the Photoelectric Observations of Variable Stars Deposited at Odessa Astronomical Observatory
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INHABITED SKY
