J/AJ/110/2166ivo://CDS.VizieR/J/AJ/110/2166doi:10.26093/cds/vizier.51102166CDSMateo M.,Fischer P.,Krzeminski W.2023-04-06T16:50:18Z1997-12-09T20:30:32ZCDS support team

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

cds-question@unistra.frvariable-starsccd-photometryWe describe a survey for variable stars in the Sextans dwarf spheroidal (dSph) galaxy based on the analysis of 113 B and 48 V CCD images of four fields covering a total area of 18'x18'. We have identified 44 variables: 36 RR Lyr star, 6 anomalous Cepheids, one long-period red variable, all probable members of Sextans, and one foreground contact binary. We have used the pulsating stars to derive a true distance modulus of 19.67+/-0.15 for Sextans (or D=86+/-6kpc), where the error is primarily due to uncertainties in the luminosity-metallicity relation for RR Lyr stars. Based on our new data we conclude that [Fe/H]_Sex=-1.6+/-0.2, somewhat higher than the value from Suntzeff et al. (1993ApJ...418..208S) obtained from the analysis of fiber spectroscopy of the near-IR Calcium triplet. We present a new deep color-magnitude diagram for Sextans which reveals the presence of anomalous Cepheids in the galaxy. This young population may represent as much as 25% of the total stellar content of Sextans. We find a surprisingly strong correlation between the frequency of anomalous Cepheids in dSph galaxies and galaxian luminosity and speculate on the possible origin of this strange effect. The RR Lyr stars in Sextans do not exhibit the Oosterhoff dichotomy observed in globular clusters and in the Galactic halo field.1995AJ....110.2166Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/110/2166CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/110/2166https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/110/2166http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/110/2166https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/110/2166https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/110/2166http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/110/2166GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/110/2166/table10 (Photometry of non-variable stars in the deep Sextans images)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/110/2166/table10?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/110/2166/table10?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/110/2166/table10?GETtext/xml+votable180.050000true153.2040833-1.66236110.0055555555555555566/27207https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/110/2166?format=asciiOpticaldefaultJ/AJ/110/2166/table2Log of Sextans observationsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFrameFrame numbermeta.id;meta.mainintDateUT Date of observationtime.epochUTmidhTime of mid-exposurehtime.epochintUTmiTime of mid-exposuretime.epochExpExposure timestime.duration;obs.exposurefloatAirMassAir-mass at mid-exposureobs.airMassfloatHJD_midHJD of mid exposure, epoch 2448000time.epochdoubleSeeingSeeingarcsecinstr.obsty.seeingfloatFieldField, NE, NW, SE, SWobs.fieldcharFiltFilter, V or Bmeta.notecharJ/AJ/110/2166/table8B-band photometry of the Sextans variablesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarVariable star number, V1, V2, ... V46meta.id;meta.maincharHJDHeliocentric Julian Date of observationtime.epochdoubleBmagB magnitudemagphot.mag;em.opt.Bfloate_BmagB magnitude errormagstat.errorfloatPhase*[0/1[? Pulsation or orbital phasetime.phasefloatJ/AJ/110/2166/table9V-band photometry of the Sextans variablesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarVariable star number, V1, V2, ... V46meta.id;meta.maincharHJDHeliocentric Julian Date of observationtime.epochdoubleVmagV magnitudemagphot.mag;em.opt.Vfloate_VmagV magnitude errormagstat.errorfloatPhase*[0/1[? Pulsation or orbital phasetime.phasefloatJ/AJ/110/2166/table10Photometry of non-variable stars in the deep Sextans imagesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarStar numbermeta.id;meta.mainintXposX coordinatepixpos.cartesian.x;instr.detintYposY coordinatepixpos.cartesian.y;instr.detintFieldField, NE, NW, SE, SWobs.fieldcharRA2000Right ascension 2000pos.eq.ra;meta.mainDE2000Declination signpos.eq.dec;meta.mainnullableVmagV magnitudemagphot.mag;em.opt.Vfloate_VmagV magnitude errormagstat.errorfloatB-VB-V colormagphot.color;em.opt.B;em.opt.Vfloate_B-VB-V color errormagstat.errorfloat