J/MNRAS/476/5216ivo://CDS.VizieR/J/MNRAS/476/5216doi:10.26093/cds/vizier.74765216CDSDuong L.Freeman K.C.Asplund M.Casagrande L.Buder S.Lind K.,Ness M.Bland-Hawthorn J.De Silva G.M.D'orazi V.Kos J.Lewis G.F.,Lin J.Martell S.L.Schlesinger K.Sharma S.Simpson J.D.Zucker D.B.,Zwitter T.Anguiano B.Da Costa G.S.Hyde E.Horner J.Kafle P.R.,Nataf D.M.Reid W.Stello D.Ting Y.-S.Wyse R.F.G.2024-08-18T20:18:46Z2021-05-31T16:47:43ZCDS support team

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

cds-question@unistra.frmilky-way-galaxyvisible-astronomyUsing data from the GALAH pilot survey, we determine properties of the Galactic thin and thick discs near the solar neighbourhood. The data cover a small range of Galactocentric radius (7.9<~R_GC_<~9.5kpc), but extend up to 4kpc in height from the Galactic plane, and several kpc in the direction of Galactic anti-rotation (at longitude 260{deg}<=l<=280{deg}). This allows us to reliably measure the vertical density and abundance profiles of the chemically and kinematically defined 'thick' and 'thin' discs of the Galaxy. The thin disc (low-{alpha} population) exhibits a steep negative vertical metallicity gradient, at d[M/H]/dz=-0.18+/-0.01dex/kpc, which is broadly consistent with previous studies. In contrast, its vertical {alpha}-abundance profile is almost flat, with a gradient of d[{alpha}/M]/dz=0.008+/-0.002dex/kpc. The steep vertical metallicity gradient of the low-{alpha} population is in agreement with models where radial migration has a major role in the evolution of the thin disc. The thick disc (high-{alpha} population) has a weaker vertical metallicity gradient d[M/H]/dz=-0.058+/-0.003dex/kpc. The {alpha}-abundance of the thick disc is nearly constant with height, d[{alpha}/M]/dz=0.007+/-0.002dex/kpc. The negative gradient in metallicity and the small gradient in [{alpha}/M] indicate that the high-{alpha} population experienced a settling phase, but also formed prior to the onset of major Type Ia supernova enrichment. We explore the implications of the distinct {alpha}-enrichments and narrow [{alpha}/M] range of the sub-populations in the context of thick disc formation.2018MNRAS.476.5216Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/476/5216CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/322 : UCAC4 Catalogue (Zacharias+, 2012)J/MNRAS/478/4513 : GALAH Survey DR2 (Buder+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/476/5216https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/476/5216http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/476/5216https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/476/5216https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/476/5216http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/476/5216GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/476/5216/tablea1 (Stars analysed in this work)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/476/5216/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/476/5216/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/476/5216/tablea1?GETtext/xml+votable180.050000true115.5245-58.90950.0055555555555555565/8307 8310-8311 8457 8460 8482-8483 8486-8487 9359 9383 9385 9398 9403-9404 9406 9731 9733 9735 9742 9745 9748 9760 9762 9769-9770 6/33095 33101 33106-33107 33112 33171 33177 33179-33180 33218-33219 33222-33225 33227 33234-33235 33238-33239 33249 33252 33264-33265 33267-33269 33802-33803 33806-33807 33818-33819 33822-33825 33827 33844-33846 33866 33888 33922-33923 33926-33927 33952-33953 33956 33992 37435 37519 37521 37526-37527 37566-37567 37583 37605 37607 38915 38918 38921-38923 38944-38945 38947-38948 38950 38953 38955-38958 38962-38964 38972 38974 38976 38978 38984 38988-38989 39000 39044 39046 39052 39054-39055 39057-39060 39064-39066 39073-39075 39084https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/476/5216?format=asciiOpticaldefaultJ/MNRAS/476/5216/tablea1Stars analysed in this workSimbadSimbad column added by the CDSmeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGALAHUnique identifier for each GALAH observation of an object (1)meta.id;meta.mainUCAC4Identifer in the UCAC4 cataloguemeta.idcharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainDistDistancepcpos.distancedoublePr(thick)[0/1] Normalised thick disk membership probability (2)stat.probabilityfloat