J/ApJ/852/50ivo://CDS.VizieR/J/ApJ/852/50doi:10.26093/cds/vizier.18520050CDSFernandez-Alvar E.Carigi L.Schuster W.J.Hayes C.R.Avila-Vergara N.,Majewski S.R.Allende Prieto C.Beers T.C.Sanchez S.F.Zamora O.,Garcia-Hernandez D.A.Tang B.Fernandez-Trincado J.G.Tissera P.,Geisler D.Villanova S.2018-11-28T08:32:02Z2018-10-24T07:54:16ZCDS support team

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

cds-question@unistra.frchemical-abundancesinfrared-astronomyspectroscopyhalo-starsradial-velocityThe formation processes that led to the current Galactic stellar halo are still under debate. Previous studies have provided evidence for different stellar populations in terms of elemental abundances and kinematics, pointing to different chemical and star formation histories (SFHs). In the present work, we explore, over a broader range in metallicity (-2.2<[Fe/H]<+0.5), the two stellar populations detected in the first paper of this series from metal-poor stars in DR13 of the Apache Point Observatory Galactic Evolution Experiment (APOGEE). We aim to infer signatures of the initial mass function (IMF) and the SFH from the two {alpha}-to-iron versus iron abundance chemical trends for the most APOGEE-reliable {alpha}-elements (O, Mg, Si, and Ca). Using simple chemical-evolution models, we infer the upper mass limit (Mup) for the IMF and the star formation rate, and its duration for each population. Compared with the low-{alpha} population, we obtain a more intense and longer-lived SFH, and a top-heavier IMF for the high-{alpha} population.2018ApJ...852...50Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/852/50CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/147 : The SDSS Photometric Catalogue, Release 12 (Alam+, 2015)J/A+A/326/751 : Chemical composition of halo and disk stars (Nissen+, 1997)J/ApJ/703/2177 : Metal-poor MS turnoff stars summary (Schlaufman+, 2009)J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009)J/ApJ/714/663 : Stellar density map of the Milky Way (de Jong+, 2010)J/A+A/511/L10 : Abundances and space velocities of 94 stars (Nissen+, 2010)J/A+A/530/A15 : Abundances of 94 stars (Nissen+, 2011)J/ApJ/757/164 : Oxygen abundances of dwarf stars (Ramirez+, 2012)J/ApJ/749/77 : MW halo. III. Statistical abundances (Schlaufman+, 2012)J/ApJ/771/67 : Abundances for 97 metal-poor stars. II. (Ishigaki+, 2013)J/A+A/566/A118 : A comprehensive view of Virgo stellar stream (Duffau+, 2014)J/A+A/577/A81 : Deep SDSS Optical Spectroscopy. II. (Fernandez-Alvar+, 2015)J/AJ/149/153 : Red giant abundances in 10 GCs (Meszaros+, 2015)J/AJ/151/144 : ASPCAP weights for APOGEE chemical elements (Garcia+, 2016)J/A+A/593/A28 : Halo metal-poor stars chemical data (Fernandez-Alvar+, 2016)J/ApJ/819/103 : Abundances of two very metal-poor stars (Afsar+, 2016)J/MNRAS/456/3655 : Masses and ages of red giants (Martig+, 2016)J/MNRAS/460/3179 : APOGEE stars distance and extinction (Wang+, 2016)J/A+A/604/A108 : UniDAM results (Mints+, 2017)J/MNRAS/476/2117 : Outliers and similarity in APOGEE (Reis+, 2018)J/ApJ/852/49 : Properties of metal-poor stars in APOGEE DR13 (Hayes+, 2018)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/852/50https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/852/50http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/852/50https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/852/50https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/852/50http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/852/50GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/852/50/table1 (Halo stars selected within the DR13 APOGEE database, with the stellar atmospheric parameters and chemical abundances determined by ASPCAP (Garcia Perez+ 2016, J/AJ/151/144) and used in this work)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/852/50/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/852/50/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/852/50/table1?GETtext/xml+votable180.050000true209.76141671.31566670.0055555555555555566/2705 2971 3598 4073 4111 4133 4298 4675 5338 5538 5916 5979 6151 8087 8335 8446 8966 8972 8991 9015 9087 9154 9172 9256 9257 9258 9436 9437 9493 9495 9536 9598 9599 9665 9667 9687 9692 9707 9769 9857 9860 9883 9908 9999 10086 10089 10204 10211 10212 10488 10674 10677 11124 11125 11203 11275 11298 11432 11433 11986 12274 12405 12900 12951 13981 14356 14498 14504 14715 14794 14828 14961 14967 15057 15106 15111 15132 15139 15158 15377 17799 18091 19094 19100 19230 19698 19980 20750 20812 22254 23751 25356 25387 25403 25491 25617 25880 26014 26099 26115 26118 26121 26169 26182 26249 26267 26275 26281 26596 26653 26699 26706 26708 26721 26722 26921 26972 26987 26996 27007 27035 27072 27127 27228 27668 27677 27861 27916 28245 28291 28296 28326 28551 28560 28859 29565 29888 29922 30225 30231 30236 30247 30353 30358 30373 30381 30387 30681 30774 30777 31396 31405 31416 31578 31604 31605 31758 32472 32699 40748 40820 44731https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/852/50?format=asciiInfrareddefaultJ/ApJ/852/50/table1Halo stars selected within the DR13 APOGEE database, with the stellar atmospheric parameters and chemical abundances determined by ASPCAP (Garcia Perez+ 2016, J/AJ/151/144) and used in this workrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint2MASS2MASS identifier (HHMMSSss+DDMMSSs; J2000)meta.id;meta.maincharPopPopulation (1)src.classcharTeff[4001/4494] Effective temperatureKphys.temperature.effectiveintlog(g)[0.4/2.4] log surface gravitylog(cm.s**-2)phys.gravityfloatRV[-462.4/382.1] Radial velocitykm/sphys.veloc;pos.heliocentricdouble[Fe/H][-2.4/0.3] Metallicitylog(Sun)phys.abund.Zfloat[O/Fe][-0.4/0.8]? The O/Fe abundancelog(Sun)phys.abunddoublenullable[Mg/Fe][-0.06/0.5] The Mg/Fe abundancelog(Sun)phys.abundfloat[Si/Fe][-0.2/0.7]? The Si/Fe abundancelog(Sun)phys.abunddoublenullable[Ca/Fe][-0.3/0.7] The Ca/Fe abundancelog(Sun)phys.abundfloatPapIDisplay data from Paper I (Hayes+, 2018, J/ApJ/852/49)meta.ref.urlintnullableSloanDisplay the online SDSS-DR12 data for the nearest objectmeta.ref.urlchar_RAPosition from 2MASS name (right ascension part)degpos.eq.ra;meta.main_DEPosition from 2MASS name (declination part)degpos.eq.dec;meta.main