J/MNRAS/432/3047ivo://CDS.VizieR/J/MNRAS/432/3047doi:10.26093/cds/vizier.74323047CDSBernard E.J.Monelli M.Gallart C.Fiorentino G.Cassisi S.,Aparicio A.Cole A.A.Drozdovsky I.Hidalgo S.L.Skillman E.D.,Stetson P.B.Tolstoy E.2024-07-22T20:12:59Z2019-03-14T09:06:37ZCDS support team

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

cds-question@unistra.frgalaxiesvariable-starshst-photometryWe present the results of a new search for variable stars in the Local Group dwarf galaxy Leo A, based on deep photometry from the Advanced Camera for Surveys onboard the Hubble Space Telescope. We detected 166 bona fide variables in our field, of which about 60% are new discoveries and 33 candidate variables. Of the confirmed variables, we found 156 Cepheids, but only 10 RR Lyrae stars despite nearly 100percent completeness at the magnitude of the horizontal branch. The RR Lyrae stars include seven fundamental and three first-overtone pulsators, with mean periods of 0.636 and 0.366d, respectively. From their position on the period-luminosity (PL) diagram and light-curve morphology, we classify 91, 58 and 4 Cepheids as fundamental, first-overtone and second-overtone mode Classical Cepheids (CC), respectively, and two as Population II Cepheids. However, due to the low metallicity of Leo A, about 90percent of the detected Cepheids have periods shorter than 1.5d. Comparison with theoretical models indicate that some of the fainter stars classified as CC could be Anomalous Cepheids. We estimate the distance to Leo A using the tip of the red giant branch (TRGB) and various methods based on the photometric and pulsational properties of the Cepheids and RR Lyrae stars. The distances obtained with the TRGB and RR Lyrae stars agree well with each other while that from the Cepheid PL relations is somewhat larger, which may indicate a mild metallicity effect on the luminosity of the short-period Cepheids. Due to its very low metallicity, Leo A thus serves as a valuable calibrator of the metallicity dependences of the variable star luminosities.2013MNRAS.432.3047Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/432/3047CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/699/1742 : LCID project. I. Cetus and Tucana variables (Bernard+, 2009)J/ApJ/712/1259 : LCID project. II. Variables in IC1613 (Bernard+, 2010)J/AJ/123/3154 : RV light curves of variable stars in Leo A (Dolphin+, 2002)J/ApJS/214/19 : Suprime-Cam wide-field photometry of Leo A (Stonkute+, 2014)J/A+A/614/A144 : Photometry of stars in LeoA HST WFC3 field (Stonkute+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/432/3047https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/432/3047http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/432/3047https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/432/3047https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/432/3047http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/432/3047GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/432/3047/table3 (Pulsational properties of the variable stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/432/3047/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/432/3047/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/432/3047/table3?GETtext/xml+votable180.050000true149.815541730.74266670.005555555555555556Cone search capability for table J/MNRAS/432/3047/table4 (Properties of the candidate variable stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/432/3047/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/432/3047/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/432/3047/table4?GETtext/xml+votable180.050000true149.8162530.73711110.0055555555555555566/5287 52932.0401237512456292e-19 4.920466254354166e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/432/3047?format=asciidefaultJ/MNRAS/432/3047/table3Pulsational properties of the variable starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintLCShow the light curvesmeta.ref.urlcharVNameObject identification, VNNNmeta.id;meta.maincharVTypeVariable classification (1)meta.code;src.varcharRAJ2000Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainPerPerioddtime.periodfloatlogPerLogarithm of the Periodlog(d)time.periodfloatF475WIntensity-averaged F475W magnitudemagphot.mag;em.opt.BfloatAmp475The F475W amplitudemagsrc.var.amplitude;em.opt.BfloatF814WIntensity-averaged F814W magnitudemagphot.mag;em.opt.IfloatAmp814The F814W amplitudemagsrc.var.amplitudefloatF475W-F814WIntensity-averaged F475W-F814W colormagphot.color;em.opt;em.optfloatBmagIntensity-averaged B magnitudemagphot.mag;em.opt.BfloatAmpBThe B amplitudemagsrc.var.amplitudefloatVmagIntensity-averaged V magnitudemagphot.mag;em.opt.VfloatAmpVThe V amplitudemagsrc.var.amplitudefloatImagIntensity-averaged I magnitudemagphot.mag;em.opt.IfloatAmpIThe I amplitudemagsrc.var.amplitudefloatSimbadSimbad column added by the CDSmeta.ref.urlcharJ/MNRAS/432/3047/table4Properties of the candidate variable starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintLCShow the light curvesmeta.ref.urlcharVNameObject identification, VCNNmeta.id;meta.maincharVTypeVariable classification (1)meta.code;src.varcharRAJ2000Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainF475WIntensity-averaged F475W magnitudemagphot.mag;em.opt.BfloatF814WIntensity-averaged F814W magnitudemagphot.mag;em.opt.IfloatSimbadSimbad column added by the CDSmeta.ref.urlcharJ/MNRAS/432/3047/tablea1Cross-identification with previously known variables in Leo ArecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintVNameObject identification, VNNN or VCNNmeta.id;meta.maincharPer? Period, this paperdmeta.bibfloatnullableVTypeVariable classification, this paper (1)meta.code;src.varcharID02ID from Dolphin et al., 2002, Cat. J/AJ/123/3154meta.idcharPer02? Period from Dolphin et al., 2002, Cat. J/AJ/123/3154dtime.periodfloatnullablee_Per02? rms uncertainty on Per02dstat.errorfloatnullableVType02Variable classification from Dolphin et al., 2002, Cat. J/AJ/123/3154, [DSC2002] CN-VNN in Simbad (2)meta.code;src.varcharIDG07ID from Munich group (3)meta.idcharPerG07? Period from Munich group (3)dtime.periodfloatnullableIDH94ID from Hoessel et al., 1994AJ....108..645H [HSK94] VNN in Simbadmeta.idcharPerH94? Period from Hoessel et al., 1994AJ....108..645Hdtime.perioddoublenullableJ/MNRAS/432/3047/table2Photometry of the variable and candidate variable starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintVNameObject identification, VNNN or VCNNmeta.id;meta.maincharMHJD475Modified Heliocentric Julian Date for m475/B (1)dtime.epochdoubleF475WThe F475W magnitudemagphot.mag;em.opt.Bfloate_F475WError in F475Wmagstat.errorfloatBmagThe B magnitudemagphot.mag;em.opt.Bfloate_BmagError in Bmagmagstat.error;phot.mag;em.opt.BfloatMHJDVModified Heliocentric Julian Date for V (2)dtime.epochdoubleVmagThe V magnitudemagphot.mag;em.opt.Vfloate_VmagError in Vmagmagstat.error;phot.mag;em.opt.VfloatMHJD814Modified Heliocentric Julian Date for m814/I (1)dtime.epochdoubleF814WThe F814W magnitudemagphot.mag;em.opt.Ifloate_F814WError in F814Wmagstat.errorfloatImagThe I magnitudemagphot.mag;em.opt.Ifloate_ImagError in Imagmagstat.error;phot.mag;em.opt.Ifloat