J/A+A/303/137ivo://CDS.VizieR/J/A+A/303/137doi:10.26093/cds/vizier.33030137CDSBeaulieu J.P.Grison P.Tobin W.Pritchard J.D.Ferlet R.,Lepeintre F.Vidal-Madjar A.Maurice E.Prevot L.Gry C.,Guibert J.Moreau O.Tajhamady F.Aubourg E.Bareyre P.,Coutures C.Gros M.Laurent B.Lachieze-Rey M.Lesquoy E.,Magneville C.Milsztajn A.Moscoso L.Queinnec F.Renault C.,Rich J.Spiro M.Vigroux L.Zylberajch S.Ansari R.,Cavalier F.Moniez M.1999-08-24T21:42:31Z1999-08-24T21:40:51ZCDS support team

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

cds-question@unistra.frmagellanic-cloudsvariable-starsWe present CCD phase-binned light curves at 490nm for 97 Cepheid variable stars in the bar of the LMC. The photometry was obtained as part of the French EROS project and has excellent phase coverage, permitting accurate decomposition into Fourier components. We identify as `sinusoidal' or s-Cepheids those stars with periods less than 5.5d and small second-harmonic components. These stars comprise ~30% of our sample and most form a sequence ~1mag brighter than the LMC classical Cepheids in the period-luminosity diagram. They are also generally bluer and have lower-amplitude light curves. We infer that the s-Cepheids are first-overtone pulsators because, when their periods are converted to expected fundamental-mode values, they obey a common period-luminosity-colour relation with classical Cepheids. This also confirms the reality of the colour term in the Cepheid period-luminosity-colour relation. Further, the blue edge of the classical Cepheid instability strip agrees well with the theoretical calculations for the fundamental mode made by Chiosi et al. 1993 (=1993ApJS...86..541C) for the Hertzsprung-Russell and period-luminosity diagrams, but we find that our observed s-Cepheids are >0.2mag brighter and bluer than the Chiosi et al. predictions for the first-overtone. We identify a number of features in plots of our stars' Fourier-component amplitude ratios and phase differences. These features have been identified with resonances between different pulsation modes. In the LMC we find these features seem to occur at periods very similar to Galactic ones for classical Cepheids, but at different periods for s-Cepheids. We discover a double-mode Cepheid in the LMC, for which P(first overtone)/P(fundamental)=0.710+/-0.001, very similar to observed ratios for Galactic double-mode Cepheids.1995A&A...303..137Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/303/137CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/303/137https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/303/137http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/303/137https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/303/137https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/303/137http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/303/137GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/303/137/table1 (97 LMC bar Cepheids)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/303/137/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/303/137/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/303/137/table1?GETtext/xml+votable180.050000true79.462083-69.4752780.005555555555555556https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/303/137?format=asciiOpticaldefaultJ/A+A/303/137/table197 LMC bar CepheidsBEB_E_ magnitudemagphot.mag;em.opt.BfloatRER_E_ magnitudemagphot.mag;em.opt.RfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEROSEROS numbermeta.id;meta.mainintHV? HV number (Harvard Variable)meta.idintnullableRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainPPerioddtime.periodfloatTypeSee Note (1)meta.notecharR2/1Ratio of second harmonic; see note (2)stat.fit.paramfloatR3/1? Ratio of third harmonic; see note (2)stat.fit.paramfloatnullablePhi2/1? Phase difference; see note (3)time.phasefloatnullablePhi3/1? Phase difference; see note (3)time.phasefloatnullablee_BEError on BE magnitudemagstat.errorfloate_REError on RE magnitudemagstat.errorfloate_R2/1Error on R2/1 parameterstat.errorfloate_R3/1? Error on R3/1 parameterstat.errorfloatnullablee_Phi2/1Error on phase difference Phi2/1stat.errorfloate_Phi3/1? Error on phase difference Phi3/1stat.errorfloatnullableRemarksRemarksmeta.notechar