J/ApJ/756/108ivo://CDS.VizieR/J/ApJ/756/108doi:10.26093/cds/vizier.17560108CDSClementini G.Cignoni M.Contreras Ramos R.Federici L.Ripepi V.,Marconi M.Tosi M.Musella I.2017-12-05T05:09:47Z2014-05-05T12:18:46ZCDS support team

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

cds-question@unistra.frvariable-starshst-photometrygalaxiesWe present results from the first combined study of variable stars and star formation history (SFH) of the Milky Way "ultra-faint" dwarf (UFD) galaxy Leo T, based on F606W and F814W multi-epoch archive observations obtained with the Wide Field Planetary Camera 2 on board the Hubble Space Telescope. We have detected 14 variable stars in the galaxy. They include one fundamental-mode RR Lyrae star and 11 Anomalous Cepheids with periods shorter than 1 day, thus suggesting the occurrence of multiple star formation episodes in this UFD, of which one about 10 Gyr ago produced the RR Lyrae star. A new estimate of the distance to Leo T of 409^+29^_-27_kpc (distance modulus of 23.06+/-0.15mag) was derived from the galaxy's RR Lyrae star. Our V, V-I color-magnitude diagram (CMD) of Leo T reaches V~29mag and shows features typical of a galaxy in transition between dwarf irregular and dwarf spheroidal types. A quantitative analysis of the SFH, based on the comparison of the observed V, V-I CMD with the expected distribution of stars for different evolutionary scenarios, confirms that Leo T has a complex SFH dominated by two enhanced periods about 1.5 and 9 Gyr ago, respectively. The distribution of stars and gas shows that the galaxy has a fairly asymmetric structure.2012ApJ...756..108Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/756/108CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/hst : HST Archived Exposures Catalog (STScI, 2007)II/294 : The SDSS Photometric Catalog, Release 7 (Adelman-McCarthy+, 2009)J/A+A/562/A134 : A lower bound on the Milky Way mass (Bratek+, 2014)J/AJ/144/4 : Dwarf galaxies in the Local Group (McConnachie+, 2012)J/ApJS/178/247 : H{alpha} and [NII] survey in local 11 Mpc (Kennicutt+, 2008)http://www.sdss.org/ : SDSS home pagehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/756/108https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/756/108http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/756/108https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/756/108https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/756/108http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/756/108GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/756/108/table2 (Identification and properties of the Leo T variable stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/756/108/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/756/108/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/756/108/table2?GETtext/xml+votable180.050000true143.722166717.05172220.0055555555555555566/4410https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/756/108?format=asciiOpticaldefaultJ/ApJ/756/108/table2Identification and properties of the Leo T variable starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameVariable star identifier (<[CCC2012] VNN> in Simbad)meta.id;meta.maincharprimaryObjID[6438/7235]? SDSS last four numbers (1)meta.idintnullableRAJ2000[9] SDSS hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000[17] SDSS degree of declination (J2000)pos.eq.dec;meta.mainfp[c] position read from HLA (2)meta.codecharTypeVariable star type (G1)meta.code;src.varcharPer[0.3/0.9] Perioddtime.periodfloatHJDEpoch (max); JD-2454000dtime.epochdoubleLCShow the light curvesmeta.ref.urlchar<Vmag>[22.4/23.6] Mean HST/WFPC2 V-band magnitudemagphot.mag;em.opt.Rfloatu_<Vmag>Uncertainty flag on <Vmag>meta.code.error;pos.cartesian.ychar<Imag>[21.9/23.2] Mean HST/WFPC2 I-band magnitudemagphot.mag;em.opt.Ifloatu_<Imag>Uncertainty flag on <Imag>meta.code.errorcharAv[0.1/1.1] V-band extinctionmagphys.absorption;em.opt.Vfloatu_AvUncertainty flag on Avmeta.code.errorcharAi[0.1/0.7] I-band extinctionmagphys.absorption;em.opt.Ifloatu_AiUncertainty flag on Aimeta.code.errorcharNpNumber of photometric observations for this star in table 3meta.numberintnullableSloanDisplay the online SDSS data for this starmeta.ref.urlcharSimbadSimbad column added by the CDSmeta.ref.urlcharJ/ApJ/756/108/table3Johnson-Cousins V, I photometry of the variable starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFiltFilter used in the observation (V or I)instr.setup;obscharNameVariable star identifier (VNN)meta.id;meta.maincharTypeVaribale star type (G1)meta.code;src.varcharHJDHeliocentric Julian Date; (HJD-2400000)dtime.epochdoublemag[21.7/24] Observed magnitude in Filtmagphot.magfloate_mag[0.01/0.1] Uncertainty in magmagstat.error;phot.magfloat