J/A+A/571/A40ivo://CDS.VizieR/J/A+A/571/A40doi:10.26093/cds/vizier.35710040CDSSpite M.Spite F.Bonifacio P.Caffau E.Francois P.Sbordone L.2023-07-20T09:54:32Z2014-11-05T08:24:11ZCDS support team

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

cds-question@unistra.frcarbon-starsline-intensitieschemical-abundancesIt has been noted that, in classical extremely metal-poor (EMP) stars, the abundance ratio of two well-observed neutroncapture elements, Sr and Ba, is always higher than [Sr/Ba]=-0.5, which is the value of the solar r-only process; however, a handful of EMP stars have recently been found with a very low Sr/Ba ratio. We try to understand the origin of this anomaly by comparing the abundance pattern of the elements in these stars and in the classical EMP stars. For a rigorous comparison with previous data, four stars with very low Sr/Ba ratios were observed and analyzed in the same way as in the First Stars Program: analysis within LTE approximation through 1D (hydrostatic) model atmosphere, providing homogeneous abundances of nine neutron-capture elements.2014A&A...571A..40Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/571/A40CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/403/1105 : Extremely metal-poor giants EW (Francois+, 2003)J/AJ/128/2402 : Extremely metal-poor star candidates abundances (Lai+, 2004)J/ApJS/155/651 : Evolution of extremely metal-poor stars (Herwig+, 2004)J/AJ/132/137 : Extremely metal-poor carbon stars abundances (Cohen+, 2006)J/ApJ/658/367 : Abundances of carbon stars in Galactic halo (Komiya+, 2007)J/A+A/490/769 : Yields from extremely metal-poor stars (Campbell+, 2008)J/A+A/501/519 : Extremely metal-poor turnoff stars abund. (Bonifacio+, 2009)J/MNRAS/412/843 : SAGA extremely metal-poor stars (Suda+, 2011)J/MNRAS/434/1681 : Extremely metal-poor stars CaII triplet (Carrera+, 2013)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/571/A40https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/571/A40http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/571/A40https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/571/A40https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/571/A40http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/571/A40GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/A+A/571/A40/linelistLine list and abundancesn_EW2[s] s for syn (1)meta.notecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintlambda[3743/6457] Wavelength in Angstroms0.1nmem.wldoubleEPExcitation potential of the lower leveleVphys.atmol.excitation;phys.atmol.levelfloatloggf? Oscillator strengthphys.atmol.oscStrengthfloatnullableEW1? Equivalent width in CS29493-0900.1pmspect.line.eqWidthfloatnullablelogAb1? Log abundance in CS29493-090phys.abundfloatnullableEW2? Equivalent width in HE305-45200.1pmspect.line.eqWidthfloatnullablelogAb2? Log abundance in HE305-4520phys.abundfloatnullableIonSpecies identifierphys.atmol.ionStagecharn_loggf[hfs ] hfs means that the hyperfine structure was taken into accountmeta.notecharn_EW1[s] s for syn (1)meta.notecharl_logAb2Limit flag on logAb2meta.code.errorchar