J/ApJ/713/615ivo://CDS.VizieR/J/ApJ/713/615doi:10.26093/cds/vizier.17130615CDSMarconi M.Musella I.Fiorentino G.Clementini G.Aloisi A.,Annibali F.Contreras Ramos R.Saha A.Tosi M.van der Marel R.P.2012-06-04T20:43:43Z2012-05-14T13:33:02ZCDS support team

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

cds-question@unistra.frastronomical-modelsinfrared-photometryvisible-astronomyphotometryvariable-starsClassical Cepheids are primary distance indicators playing a fundamental role in the calibration of the extragalactic distance scale. The possible dependence of their characteristic period-luminosity (PL) relation on chemical composition is still debated in the literature, and the behavior of these pulsators at very low metallicity regimes is almost unexplored. In order to derive constraints on the application of the PL relation at low metal abundances, we investigate the properties of the few ultra-low metallicity (Z~0.0004) Cepheids recently discovered in the Blue Compact Dwarf galaxy IZw18. To this purpose, we have computed an updated and extended set of nonlinear convective models for Z=0.0004 and Y=0.24, spanning a wide range of stellar masses, and taking into account the evolutionary constraints for selected luminosity levels. As a result, we are able to predict the topology of the instability strip, the variations of all the relevant quantities along the pulsation cycle, including the morphology of the light curves, the theoretical period-luminosity-color, period-Wesenheit, and PL relations at such a low metallicity.2010ApJ...713..615Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/713/615CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/ApJ/679/71 : Mid-IR period-luminosity relations (Freedman+, 2008)J/A+A/476/73 : Calibration of Cepheid Period/Luminosity relation (Fouque+,J/AJ/134/594 : Araucaria project: Cepheids in WLM galaxy (Pietrzynski+, 2007)J/ApJ/652/1133 : BVI photometry of NGC 4258 Cepheids (Macri+, 2006)J/A+A/415/531 : Radial velocities of 10 Galactic Cepheids (Storm+, 2004)J/A+A/411/361 : VI photometry of extra-galactic Cepheids (Kanbur+, 2003)J/ApJ/452/238 : HST photometry of I Zw 18 massive stars (Hunter+ 1995)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/713/615https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/713/615http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/713/615https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/713/615https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/713/615http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/713/615GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapOpticalInfrareddefaultJ/ApJ/713/615/table3Intrinsic stellar parameters, periods and intensity-averaged mean magnitudes and colors for fundamental models with Z=0.0004, Y=0.24, and l/H_p_=1.5recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMass[4/13] MasssolMassphys.massfloatlogLLog of the luminositylog(solLum)phys.luminosityfloatTeff[4600/6200] Effective temperatureKphys.temperature.effectiveintlogPLog of the periodlog(d)time.periodfloatVMagIntensity-weighted mean absolute V band magnitudemagphys.magAbs;em.opt.V;stat.meanfloatB-VThe (B-V) color indexmagphot.color;em.opt.B;em.opt.VfloatV-RThe (V-R) color indexmagphot.color;em.opt.V;em.opt.RfloatV-IThe (V-I) color indexmagphot.color;em.opt.V;em.opt.IfloatV-JThe (V-J) color indexmagphot.color;em.opt.V;em.IR.JfloatV-KThe (V-K) color indexmagphot.color;em.opt.V;em.IR.Kfloat