J/A+A/588/A120ivo://CDS.VizieR/J/A+A/588/A120doi:10.26093/cds/vizier.35880120CDSCantat-Gaudin T.Donati P.Vallenari A.Sordo R.Bragaglia A.,Magrini L.2016-03-30T07:33:27Z2016-03-30T08:22:52ZCDS support team

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

cds-question@unistra.frmilky-way-galaxyopen-star-clustersline-intensitiesOpen clusters are distributed all across the disk and are convenient tracers of its properties. In particular, outer disk clusters bear a key role for the investigation of the chemical evolution of the Galactic disk. The goal of this study is to derive homogeneous elemental abundances for a sample of ten outer disk OCs, and investigate possible links with disk structures such as the Galactic Anticenter Stellar Structure. We analyse high-resolution spectra of red giants, obtained from the HIRES@Keck and UVES@VLT archives. We derive elemental abundances and stellar atmosphere parameters by means of the classical equivalent width method. We also performed orbit integrations using proper motions. The Fe abundances we derive trace a shallow negative radial metallicity gradient of slope -0.027+/-0.007dex/kpc in the outer 12kpc of the disk. The [alpha/Fe] gradient appears flat, with a slope of 0.006+/-0.007dex/kpc. The two outermost clusters (Be 29 and Sau 1) appear to follow elliptical orbits. Be 20 also exhibits a peculiar orbit with a large excursion above the plane. The irregular orbits of the three most metal-poor clusters (two of which are located at the edge of the Galactic disk), if confirmed by more robust astrometric measurements such as those of the Gaia mission, are compatible with an inside-out formation scenario for the Milky Way, in which extragalactic material is accreted onto the outer disk. We cannot determine if Be 20, Be 29, and Sau 1 are of extragalactic origin, as they may be old genuine Galactic clusters whose orbits were perturbed by accretion events or minor mergers in the past 5Gyr, or they may be representants of the thick disk population. The nature of these objects is intriguing and deserves further investigations in the near future.2016A&A...588A.120Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/588/A120CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+AS/108/151 : Open clusters CCD photometry. I. (Kaluzny, 1994)J/MNRAS/346/18 : VIc photometry in Saurer A, B and C (Carraro+, 2003)J/MNRAS/360/655 : BVI photometry of 3 open clusters (Carraro+, 2005)J/A+A/442/917 : BVI photometry in Berkeley 73, 75 and 25 (Carraro+, 2005)J/A+A/488/943 : Abundances of giants in 4 Galactic clusters (Sestito+, 2008)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/588/A120https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/588/A120http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/588/A120https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/588/A120https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/588/A120http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/588/A120GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/588/A120/table1 (Summary of main parameters for the ten clusters under study)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/588/A120/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/588/A120/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/588/A120/table1?GETtext/xml+votable180.050000true83.250.2170.005555555555555556Cone search capability for table J/A+A/588/A120/table2 (Summary of observations for 44 stars observed in ten clusters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/588/A120/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/588/A120/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/588/A120/table2?GETtext/xml+votable180.050000true83.1532250.184677780.0055555555555555566/3277 20763 20814 20957 20989 21372 22111 22885 22887 23612 238613.322582951404819e-19 3.852589004194616e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/588/A120?format=asciidefaultJ/A+A/588/A120/table1Summary of main parameters for the ten clusters under studyNMembNumber of membersmeta.numberintNtargNumber of targetsmeta.numberintAgeAgeGyrtime.agefloatr_AgeReference for Age (3)meta.ref;pos.framecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintClusterCluster namemeta.id.parentcharRAJ2000Right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainDsunHeliocentric distancekpcpos.distancefloatRGCGalactocentric distance (1)kpcpos.distance;pos.galactocentricfloatZHeigth above the planekpcpos.cartesian.z;pos.galacticfloat[Fe/H]Metallicity (2)phys.abund.Zfloate_[Fe/H]rms uncertainty on [Fe/H]stat.error;phys.abund.Fefloat[alpha/Fe]Abundance [alpha/Fe] (2)phys.abundfloate_[alpha/Fe]rms uncertainty on [alpha/Fe]stat.error;phys.abundfloatJ/A+A/588/A120/tableEquivalent widthsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintClusterCluster namemeta.id.parentcharStarIDStar ID within the cluster (this paper)meta.id;meta.mainintlambdaWavelength0.1nmem.wldoubleElElementphys.atmol.elementfloatEpExcitation potentialeVphys.atmol.excitationfloatloggfOscillator strengthphys.atmol.oscStrengthfloatEWEquivalent width0.1pmspect.line.eqWidthfloatJ/A+A/588/A120/table2Summary of observations for 44 stars observed in ten clustersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintEWShow the equivalent widthsmeta.ref.urlcharClusterCluster namemeta.id.parentcharStarStar name (1)meta.id;meta.maincharRAJ2000Star right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Star declination (J2000)pos.eq.dec;meta.mainVmagV magnitudemagphot.mag;em.opt.VfloatV-IV-I colour indexmagphot.color;em.opt.V;em.opt.IfloatObs.DateDate of observation (2)time.epochcharExpTimeExposure time(s) (in second unit)time.duration;obs.exposurecharS/NSignal-to-noise ratiostat.snrintRVRadial velocitykm/sphys.veloc;pos.heliocentricfloate_RVrms uncertainty on RVkm/sstat.errorfloatInstInstrumentmeta.id;instrcharStarIDStar ID within the cluster (this paper)meta.idint