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Photoelectric Minima of Selected Eclipsing Binaries and Maxima of Pulsating Stars
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| New Minima Times of Selected Eclipsing Binaries
We present 169 CCD and photoelectric times of minima of selectedeclipsing binaries obtained from 2005 to 2007 at observatories inSlovakia
| Cross-Correlation in Four Dimensions: Application to the Quadruple-lined Spectroscopic System HD 110555
We develop a technique to measure radial velocities of stars fromspectra that present four sets of lines. The algorithm is an extensionof the two-dimensional cross-correlation method TODCOR to fourdimensions. It computes the correlation of the observed spectrum againsta combination of four templates with all possible shifts, and it alsoallows for the derivation of the light ratios of the components. Aftertesting the algorithm and demonstrating its ability to measure Dopplershifts accurately even under conditions of heavy line blending, we applyit to the case of the quadruple-lined system HD 110555. The primary andsecondary components of this previously known visual binary(ρ~0.4'') are each shown to be double-lined spectroscopicbinaries with periods of 57 days and 76 days, respectively, making thesystem a hierarchical quadruple. The secondary in the 76 day subsystemcontributes only 2.5% to the total light, illustrating the ability ofthe method to measure velocities of very faint components.
| Radial Velocity Studies of Close Binary Stars. XI.
Radial-velocity measurements and sine-curve fits to orbital radialvelocity variations are presented for 10 close binary systems: DU Boo,ET Boo, TX Cnc, V1073 Cyg, HL Dra, AK Her, VW LMi, V566 Oph, TV UMi, andAG Vir. With this contribution, the David Dunlap Observatory program hasreached the point of 100 published radial velocity orbits. The radialvelocities have been determined using an improved fitting technique thatuses rotational profiles to approximate individual peaks in broadeningfunctions. Three systems, ET Boo, VW LMi, and TV UMi, are found to bequadruple, while AG Vir appears to be a spectroscopic triple. ET Boo, amember of a close visual binary with Pvis=113 yr, waspreviously known to be a multiple system, but we show that the secondcomponent is actually a close, noneclipsing binary. The new observationshave enabled us to determine the spectroscopic orbits of the companion,noneclipsing pairs in ET Boo and VW LMi. A particularly interesting caseis VW LMi, for which the period of the mutual revolution of the twospectroscopic binaries is only 355 days. While most of the studiedeclipsing pairs are contact binaries, ET Boo is composed of twodouble-lined detached binaries, and HL Dra is a single-lined detached orsemidetached system. Five systems of this group have been observedspectroscopically before: TX Cnc, V1073 Cyg, AK Her (as a single-linedbinary), V566 Oph, and AG Vir, but our new data are of much higherquality than in the previous studies.Based on data obtained at the David Dunlap Observatory, University ofToronto, Canada.
| 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.
| New Times of Minima of Eclipsing Binary Systems and of Maximum of SXPHE Type Stars
We present 64 photoelectric minima observations of 31 eclipsingbinaries. We also report three new times of maxima of three SXPHE typepulsating stars.
| 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.
| New Minima of Selected Eclipsing Close Binaries
We present 180 CCD and photoelectric times of minima of selected closeeclipsing binaries.
| Some Photoelectric Minima of Eclipsing Binary Stars
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| The Geneva-Copenhagen survey of the Solar neighbourhood. Ages, metallicities, and kinematic properties of 14 000 F and G dwarfs
We present and discuss new determinations of metallicity, rotation, age,kinematics, and Galactic orbits for a complete, magnitude-limited, andkinematically unbiased sample of 16 682 nearby F and G dwarf stars. Our63 000 new, accurate radial-velocity observations for nearly 13 500stars allow identification of most of the binary stars in the sampleand, together with published uvbyβ photometry, Hipparcosparallaxes, Tycho-2 proper motions, and a few earlier radial velocities,complete the kinematic information for 14 139 stars. These high-qualityvelocity data are supplemented by effective temperatures andmetallicities newly derived from recent and/or revised calibrations. Theremaining stars either lack Hipparcos data or have fast rotation. Amajor effort has been devoted to the determination of new isochrone agesfor all stars for which this is possible. Particular attention has beengiven to a realistic treatment of statistical biases and errorestimates, as standard techniques tend to underestimate these effectsand introduce spurious features in the age distributions. Our ages agreewell with those by Edvardsson et al. (\cite{edv93}), despite severalastrophysical and computational improvements since then. We demonstrate,however, how strong observational and theoretical biases cause thedistribution of the observed ages to be very different from that of thetrue age distribution of the sample. Among the many basic relations ofthe Galactic disk that can be reinvestigated from the data presentedhere, we revisit the metallicity distribution of the G dwarfs and theage-metallicity, age-velocity, and metallicity-velocity relations of theSolar neighbourhood. Our first results confirm the lack of metal-poor Gdwarfs relative to closed-box model predictions (the ``G dwarfproblem''), the existence of radial metallicity gradients in the disk,the small change in mean metallicity of the thin disk since itsformation and the substantial scatter in metallicity at all ages, andthe continuing kinematic heating of the thin disk with an efficiencyconsistent with that expected for a combination of spiral arms and giantmolecular clouds. Distinct features in the distribution of the Vcomponent of the space motion are extended in age and metallicity,corresponding to the effects of stochastic spiral waves rather thanclassical moving groups, and may complicate the identification ofthick-disk stars from kinematic criteria. More advanced analyses of thisrich material will require careful simulations of the selection criteriafor the sample and the distribution of observational errors.Based on observations made with the Danish 1.5-m telescope at ESO, LaSilla, Chile, and with the Swiss 1-m telescope at Observatoire deHaute-Provence, France.Complete Tables 1 and 2 are only available in electronic form at the CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or viahttp://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/418/989
| Key parameters of W UMa-type contact binaries discovered by HIPPARCOS
A sample of W UMa-type binaries which were discovered by the HIPPARCOSsatellite was constructed with the aid of well defined selectioncriteria described in this work. The selection process showed up thatseveral systems of which the variability types have been assigned as EBin HIPPARCOS catalogue are genuine contact binaries of W UMa-type. Thelight curves of the 64 selected systems based on HIPPARCOS photometrywere analyzed with the aid of light curve synthesis method by Rucinskiand their geometric elements (namely mass ratio q, degree of contact f,and orbital inclination i) were determined. The solutions were obtainedfor the first time for many of the systems in the sample and would be agood source for their future light curve analyses based on more precisefollow-up observations.Based on observations made with the ESA HIPPARCOSastrometry satellite.
| VLA Radio Positions of Stars: 1978-1995
VLA astrometric positions of the radio emission from 52 stars arereported, from observations obtained between 1978 and 1995. Thepositions of these stars have been obtained and reduced in a uniformmanner. Based on our measurements, the offset of the optical (Hipparcos)frame from the radio reference frame is in agreement with the Hipparcosextragalactic link results, within their mean errors. Comparison of theVLA measurements with the Hipparcos optical positions confirms earlierestimates of the accuracy of these positions as 30 mas. Long-termmeasurements of UX Ari have improved its proper motion.
| First BVR Photometry of TV Ursae Minoris
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| The 74th Special Name-list of Variable Stars
We present the Name-list introducing GCVS names for 3153 variable starsdiscovered by the Hipparcos mission.
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