J/MNRAS/497/1236ivo://CDS.VizieR/J/MNRAS/497/1236CDSMonty S.Venn K.A.Lane J.M.M.Lokhorst D.Yong D.2023-10-26T14:23:16Z2023-10-26T15:22:06ZCDS support team

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

cds-question@unistra.frhalo-starsmilky-way-galaxylocal-groupchemically-peculiar-starsvisible-astronomytrigonometric-parallaxproper-motionsradial-velocityThe low-metallicity, kinematically interesting dwarf stars studied by Stephens & Boesgaard (2002AJ....123.1647S, SB02) are re-examined using Gaia DR2 astrometry, and updated model atmospheres and atomic line data. New stellar parameters are determined based on the Gaia DR2 parallactic distances and Dartmouth Stellar Evolution Database isochrones. These are in excellent agreement with spectroscopically determined stellar parameters for stars with [Fe/H]>-2; however, large disagreements are found for stars with [Fe/H]=<-2, with offsets as large as {Delta}T_eff_~+500K and {Delta}logg~+1.0. A subset of six stars (test cases) are analysed ab initio using high-resolution spectra with Keck HIRES and Gemini GRACES. This sub-sample is found to include two {alpha}-challenged dwarf stars, suggestive of origins in a low-mass, accreted dwarf galaxy. The orbital parameters for the entire SB02 sample are re-determined using Gaia DR2 data. We find 11 stars that are dynamically coincident with the Gaia-Sausage accretion event and another 17 with the Gaia-Sequoia event in action space. Both associations include low-mass, metal-poor stars with isochrone ages older than 10Gyr. Two dynamical subsets are identified within Gaia-Sequoia. When these subsets are examined separately, a common knee in [{alpha}/Fe] is found for the Gaia-Sausage and low orbital energy Gaia-Sequoia stars. A lower metallicity knee is tentatively identified in the Gaia-Sequoia high orbital energy stars. If the metal-poor dwarf stars in these samples are true members of the Gaia-Sausage and Gaia-Sequoia events, then they present a unique opportunity to probe the earlier star formation histories of these systems.2020MNRAS.497.1236Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/497/1236CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/345 : Gaia DR2 (Gaia Collaboration, 2018)J/AJ/107/2240 : Proper motion stars survey. XII. (Carney+, 1994)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/497/1236https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/497/1236http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/497/1236https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/497/1236https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/497/1236http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/497/1236GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/497/1236/tablea5 (the updated abundances for the low metallicity ([Fe/H]<-2) stars in the SB02 sample, bins (iii) and (iv))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/497/1236/tablea5?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/497/1236/tablea5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/497/1236/tablea5?GETtext/xml+votable180.050000true182.73238890.39842560.005555555555555556Cone search capability for table J/MNRAS/497/1236/tableb1 (A the basic astrometric parameters from Gaia and radial velocities from this work and SB02)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/497/1236/tableb1?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/497/1236/tableb1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/497/1236/tableb1?GETtext/xml+votable180.050000true50.9133.970.0055555555555555566/118 208 893 1644 2736 3350 3494 4240 4776 4901 5638 6100 6159 8221 8917 9831 10359 11419 11920 12068 12468 13437 13826 13829 14214 15645 15773 15866 15954 16879 17369 18923 19083 19100 19129 19735 20680 22451 22754 22771 22837 23724 25891 26025 26284 28459 28664 31094 31447 32459 32582 40924https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/497/1236?format=asciiOpticaldefaultJ/MNRAS/497/1236/tablea5the updated abundances for the low metallicity ([Fe/H]<-2) stars in the SB02 sample, bins (iii) and (iv)SimbadNameSimbad column added by the CDSmeta.idcharnullableNameStar namemeta.id;meta.mainchar[Mg/Fe]Mg/Fe abundance ratio (G2)phys.abundfloate_[Mg/Fe]Error on [Mg/Fe] (G3)phys.abundfloato_[Mg/Fe]Number of lines used to determine [Mg/Fe]phys.abundint[Si/Fe]? Si/Fe abundance ratio (G2)phys.abundfloatnullablee_[Si/Fe]? Error on [Si/Fe] (G3)phys.abundfloatnullableo_[Si/Fe]Number of lines used to determine [Si/Fe]phys.abundint[Ca/Fe]Ca/Fe abundance ratio (G2)phys.abundfloate_[Ca/Fe]Error on [Ca/Fe] (G3)phys.abundfloato_[Ca/Fe]Number of lines used to determine [Ca/Fe]phys.abundint[TiI/Fe]TiI/Fe abundance ratio (G2)phys.abundfloate_[TiI/Fe]Error on [TiI/Fe] (G3)stat.error;phys.abundfloato_[TiI/Fe]Number of lines used to determine [TiI/Fe]meta.numberint[TiII/Fe]TiII/Fe abundance ratio (G2)phys.abundfloate_[TiII/Fe]Error on [TiII/Fe] (G3)stat.error;phys.abundfloato_[TiII/Fe]Number of lines used to determine [TiII/Fe]meta.numberint_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBinSubsample (G1)meta.idchar[Na/Fe]? Na/Fe abundance ratio (G2)phys.abundfloatnullablee_[Na/Fe]? Error on [Na/Fe] (G3)phys.abundfloatnullableo_[Na/Fe]Number of lines used to determine [Na/Fe]phys.abundintJ/MNRAS/497/1236/tablea6the updated abundances for the low metallicity ([Fe/H]<-2) stars in the SB02 sample, bins (iii) and (iv) continuedrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharBinSubsample (G1)meta.idchar[CrI/Fe]CrI/Fe abundance ratio (G2)phys.abundfloate_[CrI/Fe]Error on [CrI/Fe] (G3)stat.error;phys.abundfloato_[CrI/Fe]Number of lines used to determine [CrI/Fe]meta.numberint[CrII/Fe]? CrII/Fe abundance ratio (G2)phys.abundfloatnullablee_[CrII/Fe]? Error on [CrII/Fe] (G3)stat.error;phys.abundfloatnullableo_[CrII/Fe]Number of lines used to determine [CrII/Fe]meta.numberint[FeI/H]FeI/H abundance ratio (G2)phys.abund;arith.ratiofloate_[FeI/H]Error on [FeI/H] (G3)stat.error;phys.abundfloato_[FeI/H]Number of lines used to determine [FeI/H]meta.numberint[FeII/H]FeII/H abundance ratio (G2)phys.abund;arith.ratiofloate_[FeII/H]Error on [FeII/H] (G3)stat.error;phys.abundfloato_[FeII/H]Number of lines used to determine [FeII/H]meta.numberint[NiI/Fe]NiI/Fe abundance ratio (G2)phys.abundfloate_[NiI/Fe]Error on [NiI/Fe] (G3)stat.error;phys.abundfloato_[NiI/Fe]Number of lines used to determine [NiI/Fe]meta.numberint[YII/Fe]? YII/Fe abundance ratio (G2)phys.abundfloatnullablee_[YII/Fe]? Error on [YII/Fe] (G3)stat.error;phys.abundfloatnullableo_[YII/Fe]Number of lines used to determine [YII/Fe]meta.numberint[BaII/Fe]? BaII/Fe abundance ratio (G2)phys.abundfloatnullablee_[BaII/Fe]? Error on [BaII/Fe] (G3)stat.error;phys.abundfloatnullableo_[BaII/Fe]Number of lines used to determine [BaII/Fe]meta.numberintJ/MNRAS/497/1236/tableb1A the basic astrometric parameters from Gaia and radial velocities from this work and SB02SimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharRA_ICRSRight ascension (ICRS) at Ep=2015.5degpos.eq.ra;meta.maine_RA_ICRSError on RAdegdegstat.error;pos.eq.rafloatDE_ICRSDeclination (ICRS) at Ep=2015.5degpos.eq.dec;meta.maine_DE_ICRSError on DEdegdegstat.error;pos.eq.decfloatplxParallaxmaspos.parallax.trigfloate_plxError on plxmasstat.error;pos.parallaxfloatpmRAProper motion in right ascensionmas/yrpos.pm;pos.eq.rafloate_pmRAError on pmRAmas/yrstat.error;pos.pm;pos.eq.rafloatpmDEProper motion in declinationmas/yrpos.pm;pos.eq.decdoublee_pmDEError on pmDEmas/yrstat.error;pos.pm;pos.eq.decfloatRVRadial velocitykm/sphys.veloc;pos.heliocentricfloate_RVError on RVkm/sstat.errorfloatJ/MNRAS/497/1236/tableb2A the orbital properties for the SB02 starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharRperiPericentric radiuskpcpos.distance;src.orbitalfloate_RperiError on Rperikpcstat.errorfloatRapoApocentric radiuskpcpos.distance;src.orbitalfloate_RapoError on Rapokpcstat.errorfloatTradRadiation temperatureMyrphys.temperaturefloate_TradError on TradMyrstat.errorfloatUU component of space velocitykm/sphys.veloc;pos.cartesian.xfloate_UError on Ukm/sstat.error;pos.cartesian.xfloatVV component of space velocitykm/sphys.veloc;pos.cartesian.yfloate_VError on Vkm/sstat.error;pos.cartesian.yfloatWW component of space velocitykm/sphys.veloc;pos.cartesian.zfloate_WError on Wkm/sstat.error;pos.cartesian.zfloatJ/MNRAS/497/1236/tableb3A additional kinematic parameters used to classify the stars as being dynamically coincident with the Gaia-Sausage (Saug.) and Gaia-Sequoia (Seq. G1 and Seq. G2) eventsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar namemeta.id;meta.maincharSubgroupSubgroup (1)meta.idcharJphiOrbital azimuthal actionkpc.km/sarith.grad;phys.velocdoublee_JphiError on Jphikpc.km/sstat.errorfloatJrRadial actionkpc.km/sarith.grad;phys.velocfloate_JrError on Jrkpc.km/sstat.errorfloatJzVertical actionkpc.km/sarith.grad;phys.velocfloate_JzError on Jzkpc.km/sstat.errorfloateEccentricitysrc.orbital.eccentricityfloate_eError on estat.errorfloatZmaxMaximum height from the disckpcpos.cartesian.z;pos.galacticfloate_ZmaxError on Zmaxkpcstat.errorfloatEOrbital energykm**2.s**-2src.orbitaldoublee_EError on Ekm**2.s**-2stat.errorfloat