J/AJ/147/42ivo://CDS.VizieR/J/AJ/147/42doi:10.26093/cds/vizier.51470042CDSZhu L.Y.Qian S.B.Soonthornthum B.Liu L.He J.J.Liu N.P.,Zhao E.G.Zhang J.Wang J.J.2018-01-02T13:42:34Z2014-09-04T16:07:38ZCDS support team

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

cds-question@unistra.fropen-star-clusterseclipsing-binary-starsvisible-astronomyWide-band photometryccd-photometryNGC 188 is a good laboratory for studying the formation and evolution of W UMa type contact binaries due to its rich populations of them. We present a detailed photometric study of three short-period close binaries, EP Cep, ES Cep, and V369 Cep, in the old open cluster NGC 188 based on our two-set photometric observations. We discovered that both EP Cep and ES Cep are shallow-contact binaries with continuously decreasing periods. The difference is in their mass ratios. EP Cep has an extremely low-mass ratio, q=0.15, while ES Cep has a relatively high-mass ratio, q=0.69, indicating that they lie in different evolutionary stages. ES Cep is likely a newly formed contact binary via a Case A mass transfer, while EP Cep is an evolved system and may be on the oscillations caused by the combined effect of the thermal relaxation oscillation and the variable angular momentum loss. For another system, V369 Cep, we found that it is a primary-filling near-contact binary. Both the semidetached configuration and the continuous decrease in the orbital period indicate that it is undergoing a mass transfer from the primary component to the secondary one. This conclusion is in agreement with the excess luminosity seen in the light curves on the ingress of the secondary minimum produced by the impact of the mass transfer. All of the results suggest that V369 Cep is evolving into contact, and a shallow-contact high-mass ratio system similar to ES Cep will be formed. Then, it will evolve into a low-mass ratio contact binary just like EP Cep, and finally merge into a rapidly rotating single star.2014AJ....147...42Zhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/147/42CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/gcvs : General Catalogue of Variable Stars (Samus+ 2007-2012)B/vsx : AAVSO International Variable Star Index VSX (Watson+, 2006-2013)II/185 : NGC 188 photographic UBV photom. star catalog (Frolov, 1990)J/AJ/144/37 : BVRI photometry of the eclipsing binary BS Vul (Zhu+, 2012)J/AJ/137/5086 : NGC 188 V12 VI light curves (Meibom+, 2009)J/AJ/133/1409 : u'g'r'i'z' photometry in NGC 188 (Fornal+, 2007)J/AJ/131/1565 : UBVI photometry of Berkeley 17 and NGC 188 (Krusberg+, 2006)J/A+A/438/291 : X-ray sources in NGC 188 (Gondoin+, 2005)J/PASP/116/1012 : A star catalog for the open cluster NGC 188 (Stetson+, 2004)J/AJ/126/2922 : Astrometry and membership in NGC 188 (Platais+, 2003)J/A+A/390/961 : VI photometry in NGC 188 (Andreuzzi+, 2002)J/AJ/124/601 : Absolute positions & proper motions in NGC188 (Platais+ 2002)J/AJ/118/2894 : UBVRI CCD photometry in NGC 188 (Sarajedini+, 1999)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/147/42https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/147/42http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/147/42https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/147/42https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/147/42http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/147/42GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/147/42/stars (Positions and periods)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/147/42/stars?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/147/42/stars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/147/42/stars?GETtext/xml+votable180.050000true11.724916785.36208330.0055555555555555566/40783.322582951404819e-19 3.852589004194616e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/147/42?format=asciiOpticaldefaultJ/AJ/147/42/starsPositions and periodsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharprimaryRAJ2000Hour of Right Ascension (J2000) (1)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000) (1)pos.eq.dec;meta.mainPerPerioddtime.perioddoubleLCShow the light curvesmeta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlcharJ/AJ/147/42/table1V-band CCD observations of EP Cep, ES Cep, and V369 Cep in the old open cluster NGC 188recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar name (EP Cep, ES Cep, V369 Cep)meta.id;meta.maincharHJDHeliocentric Julian Datedtime.epochdoubleDVmagDifferential Johnson V band magnitudemagphot.mag;em.opt.V;arith.difffloat