J/A+A/465/943ivo://CDS.VizieR/J/A+A/465/943doi:10.26093/cds/vizier.34650943CDSSzalai T.Kiss L.L.Meszaros Sz.Vinko J.Csizmadia Sz.2007-04-24T15:59:05Z2007-04-24T15:56:25ZCDS support team

CDS, Observatoire de Strasbourg, 11 rue de l'Universite, F-67000 Strasbourg, France

cds-question@unistra.freclipsing-binary-starsvariable-starsWe detected tertiary components of close binaries from spectroscopy and light curve modelling, investigated the light-travel time effect and the possibility of magnetic activity cycles, measured mass ratios for unstudied systems, and derived absolute parameters. We carried out new photometric and spectroscopic observations of five bright close eclipsing binaries, predominantly in the southern skies. We obtained full Johnson BV light curves, which were modelled with the Wilson-Devinney code. Radial velocities were measured with the cross-correlation method using IAU radial velocity standards as spectral templates. Period changes were studied with the O-C method, utilising published epochs of minimum light (XY Leo) and ASAS photometry (VZ Lib). For three objects (DX Tuc, QY Hya, V870 Ara), absolute parameters have been determined for the first time. We spectroscopically detected the tertiary components in XY Leo and VZ Lib and discovered one in QY Hya. For XY Leo we updated the light-time effect parameters and detected a secondary periodicity of about 5100d in the O-C diagram that may hint at the existence of short-period magnetic cycles. A combination of recent photometric data shows that the orbital period of the tertiary star in VZ Lib is likely to be over 1500d. QY Hya is a semi-detached X-ray active binary in a triple system with K and M-type components, while V870 Ara is a contact binary with the third smallest spectroscopic mass ratio for a W UMa star to date. Being close to the theoretical minimum for contact binaries, this small mass ratio suggests that V870 Ara has the potential of constraining evolutionary scenarios of binary mergers. The inferred distances to these systems are compatible with the Hipparcos parallaxes.2007A&A...465..943Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/465/943CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/119 : Catalogue of field contact binary stars (Pribulla+, 2003)J/A+A/446/785 : Catalogue of eclipsing variables (Malkov+, 2006)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/465/943https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/465/943http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/465/943https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/465/943https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/465/943http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/465/943GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/465/943/stars (Variables list)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/465/943/stars?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/465/943/stars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/465/943/stars?GETtext/xml+votable180.050000true359.339583-64.2433330.0055555555555555566/4427 24687 44514 46084 47243https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/465/943?format=asciiOpticaldefaultJ/A+A/465/943/starsVariables listrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameVariable namemeta.id;meta.maincharRAJ2000Simbad right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Simbad declination (J2000)pos.eq.dec;meta.mainPorbOrbital perioddtime.perioddoubleBFileName of the file with HJD/Bmag light curves in photjd subdirectorymeta.id;phot.mag;meta.filecharVFileName of the file with HJD/Vmag light curves in photjd subdirectorymeta.id;phot.mag;meta.filecharIFileName of the file with HJD/Imag light curves in photjd subdirectorymeta.id;phot.mag;meta.filecharBPFileName of the file with Phase/Bmag light curves in photph subdirectorymeta.id;phot.mag;meta.filecharVPFileName of the file with Phase/Vmag light curves in photph subdirectorymeta.id;phot.mag;meta.filecharIPFileName of the file with Phase/Imag light curves in photph subdirectorymeta.id;phot.mag;meta.filecharRVFileName of the file with Phase/RV curves in photph subdirectorymeta.id;meta.filechar