J/A+A/581/A22ivo://CDS.VizieR/J/A+A/581/A22doi:10.26093/cds/vizier.35810022CDSAbate C.Pols O.R.Izzard R.G.Karakas A.I.2017-12-22T05:33:05Z2015-12-11T08:30:03ZCDS support team

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

cds-question@unistra.frmultiple-starschemically-peculiar-starsstellar-massesMany of the carbon-enhanced metal-poor (CEMP) stars that we observe in the Galactic halo are found in binary systems and show enhanced abundances of elements produced by the slow neutron-capture process (s-elements). The origin of the peculiar chemical abundances of these CEMP-s stars is believed to be accretion in the past of enriched material from a primary star in the asymptotic giant branch (AGB) phase of its evolution. We investigate the mechanism of mass transfer and the process of nucleosynthesis in low-metallicity AGB stars by modelling the binary systems in which the observed CEMP-s stars were formed. For this purpose we compare a sample of 67 CEMP-s stars with a grid of binary stars generated by our binary evolution and nucleosynthesis model. We classify our sample CEMP-s stars in three groups based on the observed abundance of europium. In CEMP-s/r stars the europium-to-iron ratio is more than ten times higher than in the Sun, whereas it is lower than this threshold in CEMP-s/nr stars. No measurement of europium is currently available for CEMP-s/ur stars. On average our models reproduce the abundances observed in CEMP-s/nr stars well, whereas in CEMP-s/r stars and CEMP-s/ur stars the abundances of the light-s elements (strontium, yttrium, zirconium) are systematically overpredicted by our models, and in CEMP-s/r stars the abundances of the heavy-s elements (barium, lanthanum) are underestimated. In all stars our modelled abundances of sodium overestimate the observations. This discrepancy is reduced only in models that underestimate the abundances of most of the s-elements. Furthermore, the abundance of lead is underpredicted in most of our model stars, independent of the metallicity. These results point to the limitations of our AGB nucleosynthesis model, particularly in the predictions of the element-to-element ratios. In our models CEMP-s stars are typically formed in wide systems with periods above 10000-days, while most of the observed CEMP-s stars are found in relatively close orbits with periods below 5000-days. This evidence suggests that either the sample of CEMP-s binary stars with known orbital parameters is biased towards short periods or that our wind mass-transfer model requires more efficient accretion in close orbits.2015A&A...581A..22Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/581/A22CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/574/A129 : The First CEMP star in the Sculptor dSph (Skuladottir+, 2015)J/A+A/579/A28 : Abundances of 3 CEMP stars (Bonifacio+, 2015)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/581/A22https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/581/A22http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/581/A22https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/581/A22https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/581/A22http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/581/A22GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/581/A22/table1 (Surface gravities, temperatures and chemical properties observed in the 67 CEMP-s stars of our sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/581/A22/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/581/A22/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/581/A22/table1?GETtext/xml+votable180.050000true311.5134167-20.98727780.0055555555555555566/524 5775 8197 10165 10209 10682 12880 13087 16365 16659 16679-16680 16880 17174 17221 17398 17623 17679 18606 18636-18637 18653 18663 18973 19923 19968 21221 22650 25551 25948 25950 26191 26644 26995 27030 27091 27322 30041 31136 31273 34046 34079 34504 35186 35588 35752 36228 36330 36410 36503 44671 44870 44939 44990 45427 45494 45676 46090 46704 46792 46848 47541 48555 48628 48722 49078https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/581/A22?format=asciidefaultJ/A+A/581/A22/table8Confidence ranges of the input parameters of the modelled CEMP-s stars with chi^2^/nu<=3 and nu>=2 computed with model set A with WRLOF wind-accretion efficiency and spherically symmetric windrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintTypeType (G1)src.classcharNameStar namemeta.id;meta.maincharM1ib? Best Primary mass fitted parametersolMassphys.massfloatnullableM1im? Minimum primary mass fitted parametersolMassphys.massfloatnullableM1iM? Maximum primary mass fitted parametersolMassphys.massfloatnullableMPMZb? Best mass of the PMZ fitted parameterphys.massfloatnullableMPMZm? Minimum mass of the PMZ fitted parameterphys.massfloatnullableMPMZM? Maximum mass of the PMZ fitted parameterphys.massfloatnullableM2ib? Best secondary mass fitted parametersolMassphys.massfloatnullableM2im? Minimum secondary mass fitted parametersolMassphys.massfloatnullableM2iM? Maximum secondary mass fitted parametersolMassphys.massfloatnullablePib? Best orbital period fitted parameterdtime.perioddoublenullablePim? Minimum orbital period fitted parameterdtime.perioddoublenullablePiM? Maximum orbital period fitted parameterdtime.perioddoublenullableallDisplay data for all modelsmeta.ref.urlcharJ/A+A/581/A22/table1Surface gravities, temperatures and chemical properties observed in the 67 CEMP-s stars of our sampleSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSampleSample (G1)src.samplecharNameStar namemeta.id;meta.maincharloggSurface gravitylog(cm.s**-2)phys.gravityfloate_loggrms uncertainty on logglog(cm.s**-2)stat.errorfloatTeffEffective temperatureKphys.temperature.effectiveintl_PorbLimit flag on Probmeta.code.errorcharPorb? Orbital perioddtime.perioddoublenullableNNumber of observed elementsmeta.numberint[Fe/H]Metallicityphys.abund.Zfloat[C/Fe]Abundance [C/Fe]phys.abundfloat[s/Fe]Abundance [s/Fe] (1)phys.abundfloat[Eu/Fe]? Abundance [s/Fe]phys.abundfloatnullableallDisplay data for all modelsmeta.ref.urlchar_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.mainJ/A+A/581/A22/table2Physical parameters of the model CEMP-s stars with nu>=2 computed with model set A with WRLOF wind-accretion efficiency and spherically symmetric windrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSampleSample (G1)src.samplecharNameStar namemeta.id;meta.maincharM1iPrimary mass fitted parameter, M_1,i_solMassphys.massfloatMPMZMass of the PMZ fitted parameter, M_PMZ_dphys.massdoubleM2iSecondary mass fitted parameter, M_2,i_solMassphys.massfloatPiOrbital period fitted parameterdtime.perioddoubleDMaccMass accreted by the secondary star, {Delta}M_acc_solMassphys.massfloatPfOrbital period of the binary when the secondary star best reproduces the observed logg and surface abundancesdtime.perioddoublePfI? Final period determined in paper I (Abate et al., 2015A&A...576A.118A) (except in tables a4 and a7)dtime.perioddoublenullablechi2minMinimum chi^2^stat.fit.chi2floatnuNumber of degrees of freedom of the fitmeta.numberintchi2/nu? Reduced chi^2^R of the best fitmeta.notefloatnullableallDisplay data for all modelsmeta.ref.urlcharJ/A+A/581/A22/table3Physical parameters of the model CEMP-s stars with nu>=2 computed with model set B with WRLOF wind-accretion efficiency and spherically symmetric windrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSampleSample (G1)src.samplecharNameStar namemeta.id;meta.maincharM1iPrimary mass fitted parameter, M_1,i_solMassphys.massfloatMPMZMass of the PMZ fitted parameter, M_PMZ_dphys.massdoubleM2iSecondary mass fitted parameter, M_2,i_solMassphys.massfloatPiOrbital period fitted parameterdtime.perioddoubleDMaccMass accreted by the secondary star, {Delta}M_acc_solMassphys.massfloatPfOrbital period of the binary when the secondary star best reproduces the observed logg and surface abundancesdtime.perioddoublePfI? Final period determined in paper I (Abate et al., 2015A&A...576A.118A) (except in tables a4 and a7)dtime.perioddoublenullablechi2minMinimum chi^2^stat.fit.chi2floatnuNumber of degrees of freedom of the fitmeta.numberintchi2/nu? Reduced chi^2^R of the best fitmeta.notefloatnullableallDisplay data for all modelsmeta.ref.urlcharJ/A+A/581/A22/table4Physical parameters of the model CEMP-s stars with nu>=2 computed with model set C with WRLOF wind-accretion efficiency and spherically symmetric windrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSampleSample (G1)src.samplecharNameStar namemeta.id;meta.maincharM1iPrimary mass fitted parameter, M_1,i_solMassphys.massfloatMPMZMass of the PMZ fitted parameter, M_PMZ_dphys.massdoubleM2iSecondary mass fitted parameter, M_2,i_solMassphys.massfloatPiOrbital period fitted parameterdtime.perioddoubleDMaccMass accreted by the secondary star, {Delta}M_acc_solMassphys.massfloatPfOrbital period of the binary when the secondary star best reproduces the observed logg and surface abundancesdtime.perioddoublePfI? Final period determined in paper I (Abate et al., 2015A&A...576A.118A) (except in tables a4 and a7)dtime.perioddoublenullablechi2minMinimum chi^2^stat.fit.chi2floatnuNumber of degrees of freedom of the fitmeta.numberintchi2/nu? Reduced chi^2^R of the best fitmeta.notefloatnullableallDisplay data for all modelsmeta.ref.urlcharJ/A+A/581/A22/table5Physical parameters of the model CEMP-s stars with nu<=1 computed with model set ASampleSample (G1)src.samplecharNameStar namemeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintM1iPrimary mass fitted parameter, M_1,i_solMassphys.massfloatMPMZMass of the PMZ fitted parameter, M_PMZ_dphys.massdoubleM2iSecondary mass fitted parameter, M_2,i_solMassphys.massfloatPiOrbital period fitted parameterdtime.perioddoubleDMaccMass accreted by the secondary star, {Delta}M_acc_solMassphys.massfloatPfOrbital period of the binary when the secondary star best reproduces the observed logg and surface abundancesdtime.perioddoublePfI? Final period determined in paper I (Abate et al., 2015A&A...576A.118A) (except in tables a4 and a7)dtime.perioddoublenullablechi2minMinimum chi^2^stat.fit.chi2floatnuNumber of degrees of freedom of the fitmeta.numberintchi2/nu? Reduced chi^2^R of the best fitmeta.notefloatnullableallDisplay data for all modelsmeta.ref.urlcharJ/A+A/581/A22/table6Physical parameters of the model CEMP-s stars with nu<=1 computed with model set BNameStar namemeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSampleSample (G1)src.samplecharM1iPrimary mass fitted parameter, M_1,i_solMassphys.massfloatMPMZMass of the PMZ fitted parameter, M_PMZ_dphys.massdoubleM2iSecondary mass fitted parameter, M_2,i_solMassphys.massfloatPiOrbital period fitted parameterdtime.perioddoubleDMaccMass accreted by the secondary star, {Delta}M_acc_solMassphys.massfloatPfOrbital period of the binary when the secondary star best reproduces the observed logg and surface abundancesdtime.perioddoublePfI? Final period determined in paper I (Abate et al., 2015A&A...576A.118A) (except in tables a4 and a7)dtime.perioddoublenullablechi2minMinimum chi^2^stat.fit.chi2floatnuNumber of degrees of freedom of the fitmeta.numberintchi2/nu? Reduced chi^2^R of the best fitmeta.notefloatnullableallDisplay data for all modelsmeta.ref.urlcharJ/A+A/581/A22/table7Physical parameters of the model CEMP-s stars with nu<=1 computed with model set Cchi2minMinimum chi^2^stat.fit.chi2floatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSampleSample (G1)src.samplecharNameStar namemeta.id;meta.maincharM1iPrimary mass fitted parameter, M_1,i_solMassphys.massfloatMPMZMass of the PMZ fitted parameter, M_PMZ_dphys.massdoubleM2iSecondary mass fitted parameter, M_2,i_solMassphys.massfloatPiOrbital period fitted parameterdtime.perioddoubleDMaccMass accreted by the secondary star, {Delta}M_acc_solMassphys.massfloatPfOrbital period of the binary when the secondary star best reproduces the observed logg and surface abundancesdtime.perioddoublePfI? Final period determined in paper I (Abate et al., 2015A&A...576A.118A) (except in tables a4 and a7)dtime.perioddoublenullablenuNumber of degrees of freedom of the fitmeta.numberintchi2/nu? Reduced chi^2^R of the best fitmeta.notefloatnullableallDisplay data for all modelsmeta.ref.urlchar