J/A+A/630/A116ivo://CDS.VizieR/J/A+A/630/A116doi:10.26093/cds/vizier.36300116CDSSavino A.Tolstoy E.Salaris M.Monelli M.de Boer T.J.L.2019-10-01T07:58:14Z2019-10-01T08:49:55ZCDS support team

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

cds-question@unistra.frgalaxiesstellar-ageshst-photometryhertzsprung-russell-diagramWe report a new star formation history for the Tucana dwarf spheroidal galaxy, obtained from a new look at a deep HST/ACS colour-magnitude diagram. We combined information from the main sequence turn-off and the horizontal branch to resolve the ancient star formation rates on a finer temporal scale than previously possible. We show that Tucana experienced three major phases of star formation, two very close together at ancient times and the last one ending between 6 and 8 Gyr ago. We show that the three discrete clumps of stars on the horizontal branch are linked to the distinct episodes of star formation in Tucana. The spatial distribution of the clumps reveals that each generation of stars presents a higher concentration than the previous one. The simultaneous modelling of the horizontal branch and the main sequence turn-off also allows us to measure the amount of mass lost by red giant branch stars in Tucana with unprecedented precision, confirming dwarf spheroidals to be excellent laboratories to study the advanced evolution of low-mass stars.2019A&A...630A.116Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/630/A116CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/315/40 : Photometry of the Tuc dwarf galaxy (Saviane, 1996)J/ApJ/699/1742 : LCID project. I. Cetus and Tucana variables (Bernard+, 2009)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/630/A116https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/630/A116http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/630/A116https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/630/A116https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/630/A116http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/630/A116GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tap2.0401237512456292e-19 4.9761815603361e-19defaultJ/A+A/630/A116/table1Star formation historyrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[alpha/Fe]Mean alpha enhancement of the binphys.abundfloat[Fe/H]Mean [Fe/H] of the binphys.abund.Fe;stat.meanfloatAgeMean look back time of the binGyrtime.agefloatSFRStar formation rate in the binsolMass/yrphys.SFRdoublee_SFRUncertainty on the star formation ratesolMass/yrstat.error;phys.SFRdoubleJ/A+A/630/A116/photHST/ACS photometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintF475WMagnitude in the F475W bandmagphot.mag;em.opt.Bfloate_F475W? Error on the F475W magnitude (1)magstat.errorfloatnullableF814WMagnitude in the F814W bandmagphot.mag;em.opt.Ifloate_F814W? Error on the F814W magnitude (1)magstat.errordoublenullable