J/AJ/145/60ivo://CDS.VizieR/J/AJ/145/60doi:10.26093/cds/vizier.51450060CDSYang Y.-G.Qian S.-B.Dai H.-F.2017-10-13T15:41:04Z2014-03-27T12:09:31ZCDS support team

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

cds-question@unistra.freclipsing-binary-starsinfrared-photometryvisible-astronomybroad-band-photometryWe present new photometry for three short-period contact binaries, GN Boo, BL Leo, and V1918 Cyg, observed from 2008 December to 2012 April using several small telescopes in China. Photometric models were deduced from new observations using the updated Wilson-Devinney Code. The results show that GN Boo and BL Leo are W-type contact binaries, while V1918 Cyg is an A-type one. The mass ratios and fill-out factors are q=0.320(+/-0.002) and f=5.8(+/-0.1)% for GN Boo, q=0.476(+/-0.005) and f=21.3(+/-1.1)% for BL Leo, q=0.264(+/-0.002), and f=49.7(+/-0.7)% for V1918 Cyg, respectively. From the (O-C) curves, it is discovered that the orbital periods of three binaries have varied in a complicated way, i.e., cyclic oscillation for GN Boo, long-term period decrease for BL Leo, and both for V1918 Cyg. The cyclic variations for GN Boo and V1918 Cyg may probably be attributed to the magnetic activity of the primary component or light-time effect due to the third body. Meanwhile, the secular period decreases for BL Leo and V1918 Cyg may result from mass transfer from the primary to the secondary, accompanying the mass and angular momentum loss from the central system. Finally, GN Boo, BL Leo, and V1918 Cyg will evolve into deep contact binaries. Additionally, a statistical study of 37 contact binaries with decreasing periods is given. We obtained the relations of q-f and q-dlnP/dt, and preliminarily determined the mass loss rate of dln M/dt from the binary system.2013AJ....145...60Yhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/145/60CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-2014)B/gcvs : General Catalogue of Variable Stars (Samus+ 2007-2013)J/AJ/144/149 : Photometry of W UMa type TY Boo (Christopoulou+, 2012)J/other/NewA/17.347 : Eclipsing times of BE Cep (Dai+, 2012)J/other/RAA/11.181 : VR light curves of EI CVn (Yang, 2011)J/PASP/123/895 : EH Cnc RV light curves (Yang+, 2011)J/AJ/141/44 : V396 Mon BVRI light curves (Liu+, 2011)J/AJ/142/99 : BVRI observations of TZ Boo (Christopoulou+, 2011)J/AJ/137/236 : CC Com and BV Dra light curves (Yang+, 2009)J/AJ/136/594 : BS Cas BVR light curves (Yang+, 2008)J/A+A/446/785 : Catalogue of eclipsing variables (Malkov+, 2006)J/AcA/54/207 : Ephemerids of eclipsing binaries (Kreiner, 2004)J/other/IBVS/5296 : Extrema of pulsating stars (Agerer+, 2002)J/AJ/119/1901 : ROTSE all-sky surveys for variable stars (Akerlof+, 2000)J/A+A/311/523 : Photometry of W UMa (Maceroni+, 1996)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/145/60https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/145/60http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/145/60https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/145/60https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/145/60http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/145/60GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/145/60/variable (Information on the variable stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/145/60/variable?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/145/60/variable?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/145/60/variable?GETtext/xml+votable180.050000true222.53237529.64958330.0055555555555555566/9107 15179 28457https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/145/60?format=asciiOpticalInfrareddefaultJ/AJ/145/60/variableInformation on the variable starsPerPeriodmeta.notedoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharprimaryRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainVmagV-band magnitudemagphot.mag;em.opt.VfloatLCLight curvemeta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlcharJ/AJ/145/60/photometryBVR photometric observations of V1918 Cyg (table3), VR photometric observations of GN Boo (table2a), and VR photometric observations of BL Leo (table2b)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSimbad column added by the CDSmeta.id;meta.maincharHJD-B? Heliocentric Julian Date of B band (1)dtime.epochdoublenullableDBmag? Differential B band magnitude (1)magphot.mag;em.opt.B;arith.difffloatnullableHJD-V? Heliocentric Julian Date of V banddtime.epochdoublenullableDVmag? Differential V band magnitudemagphot.mag;em.opt.V;arith.difffloatnullableHJD-R? Heliocentric Julian Date of R banddtime.epochdoublenullableDRmag? Differential R band magnitudemagphot.mag;em.opt.R;arith.difffloatnullableJ/AJ/145/60/table4New eclipsing times of GN Boo, BL Leo, and V1918 CygrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar name (GN Boo, BL Leo, or V1918 Cyg)meta.id;meta.maincharHJDHeliocentric Julian Datedtime.epochdoublee_HJDError in HJDdstat.error;time.epochdoubleMinType of minimum (I or II)meta.codenullableFlt[BVRI] Filter (B, V, R , or I)meta.id;instr.filtercharTelTelescope (1.0m, 1.56m, 60cm, 80cm, or 85cm)meta.id;instr.telcharObsObservatory (SHAO, XLs, or YNAO) (1)meta.id;instr.obstycharJ/AJ/145/60/minimaAll available light minimum times of GN Boo (table5), photoelectric and CCD light minimum times of BL Leo (table6), and all compiled light minimum times of V1918 Cyg (table7)EpochEpochmeta.number;time.perioddoublerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameSimbad column added by the CDSmeta.id;meta.maincharHJDHeliocentric Julian Datedtime.epochdoubleMethObservational method (CCD, pe, pg, or vi) (1)meta.code;obscharMin[I II]Type of minimum (I or II)meta.codenullableO-C1Eclipse time residual (2)dstat.fit.residual;time.epochfloatO-C2? Eclipse time residual (3)dstat.fit.residual;time.epochfloatnullablef_O-C2[d] Discarded value due to a large residualmeta.codecharRefReference; in refs.dat filemeta.ref;pos.frameintJ/AJ/145/60/refsReferencesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRefReference numbermeta.id;meta.mainintprimaryBibCodeBibliographic codemeta.bib.bibcodecharAutAuthor's namemeta.bib.authorcharComCommentsmeta.notechar