J/A+A/606/A55ivo://CDS.VizieR/J/A+A/606/A55doi:10.26093/cds/vizier.36060055CDSMatrozis E.Stancliffe R.J.2019-05-08T15:14:26Z2017-10-09T11:19:39ZCDS support team

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

cds-question@unistra.frstellar-evolutionary-modelsmultiple-starschemical-abundancesCarbon-enhanced metal-poor (CEMP) stars with s-process enrichment (CEMP-s) are believed to be the products of mass transfer from an asymptotic giant branch (AGB) companion, which has long since become a white dwarf. The surface abundances of CEMP-s stars are thus commonly assumed to reflect the nucleosynthesis output of the first AGB stars. We have previously shown that, for this to be the case, some physical mechanism must counter atomic diffusion (gravitational settling and radiative levitation) in these nearly fully radiative stars, which otherwise leads to surface abundance anomalies clearly inconsistent with observations. Here we take into account angular momentum accretion by these stars. We compute in detail the evolution of typical CEMP-s stars from the zero-age main sequence, through the mass accretion, and up the red giant branch for a wide range of specific angular momentum ja of the accreted material, corresponding to surface rotation velocities, v_rot_, between about 0.3 and 300km/s. We find that only for j_a_>~10^17^cm^2^/s (v_rot_>20km/s, depending on mass accreted) angular momentum accretion directly causes chemical dilution of the accreted material. This could nevertheless be relevant to CEMP-s stars, which are observed to rotate more slowly, if they undergo continuous angular momentum loss akin to solar-like stars. In models with rotation velocities characteristic of CEMP-s stars, rotational mixing primarily serves to inhibit atomic diffusion, such that the maximal surface abundance variations (with respect to the composition of the accreted material) prior to first dredge-up remain within about 0.4dex without thermohaline mixing or about 0.5-1.5dex with thermohaline mixing. Even in models with the lowest rotation velocities (v_rot_<~1km/s), rotational mixing is able to severely inhibit atomic diffusion, compared to non-rotating models. We thus conclude that it offers a natural solution to the problem posed by atomic diffusion and cannot be neglected in models of CEMP-s stars.2017A&A...606A..55Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/606/A55CatalogResearchIsServedByTAP VizieR generic servicerelated-toJ/A+A/490/769 : Yields from extremely metal-poor stars (Campbell+, 2008)J/A+A/557/A106 : Evolution and CNO yields of Z=10^-5^ stars (Gil-Pons+, 2013)J/ApJ/833/20 : Carbon-enhanced metal-poor (CEMP) star abundances (Yoon+ 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/606/A55https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/606/A55http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/606/A55https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/606/A55https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/606/A55http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/606/A55GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapdefaultJ/A+A/606/A55/tablea1Summary of the models with both the default and non-standard rotational mixing parametersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintfcRotational mixing parameter f_c_ (0.010, 0.033, 0.100) (1)stat.paramfloatfmuRotational mixing parameter f_mu_ (0.00, 0.05, 1.00) (1)stat.paramfloatSet[1/3] Model set (2)meta.id;stat.fitintM1[0.9/1.5] Initial mass of the AGB donorsolMassphys.massfloatM2i[0.6/0.8] Initial mass of the accreting secondarysolMassphys.massfloatdM[0.001/0.3] Accreted masssolMassphys.massfloatM2f[0.8/0.95] Final mass of the secondarysolMassphys.massfloatja[1e+15/1e+18] Specific angular momentum of the accreted materialcm**2.s**-1phys.angMomentumfloatMthmixAmount of mass mixed by thermohaline mixing (3)solMassphys.massfloatAgeAge at MSTO (main-sequence turn-off)Gyrtime.agefloatTeffEffective temperature at MSTOKphys.temperature.effectiveintlogLLog of luminosity at MSTOlog(solLum)phys.luminosityfloatloggLog of gravity at MSTOlog(cm.s**-2)phys.gravityfloatMenvConvective envelope mass at MSTOsolMassphys.massdoublevrotSurface equatorial rotation velocity at MSTOkm/sphys.veloc.rotatfloatvcritCritical surface equatorial rotation velocity at MSTOkm/sphys.veloc.rotatfloatXs2Surface mass fraction of hydrogen after mass accretionphys.abund.Xfloat[C/H]2Abundance [C/H] after mass accretionphys.abundfloat[N/H]2Abundance [N/H] after mass accretionphys.abundfloat[O/H]2Abundance [O/H] after mass accretionphys.abundfloat[Fe/H]2Abundance [Fe/H] after mass accretionphys.abundfloat[C/Fe]2Abundance [C/Fe] after mass accretionphys.abundfloatXstm? Surface mass fraction of hydrogen after thermohaline mixing (3)phys.abund.Xfloatnullable[C/H]tm? Abundance [C/H] after thermohaline mixing (3)phys.abundfloatnullable[N/H]tm? Abundance [N/H] after thermohaline mixing (3)phys.abundfloatnullable[O/H]tm? Abundance [O/H] after thermohaline mixing (3)phys.abundfloatnullable[Fe/H]tm? Abundance [Fe/H] after thermohaline mixing (3)phys.abundfloatnullable[C/Fe]tm? Abundance [C/Fe] after thermohaline mixing (3)phys.abundfloatnullableXs4Surface mass fraction of hydrogen at MSTOphys.abund.Xfloat[C/H]4Abundance [C/H] at MSTOphys.abundfloat[N/H]4Abundance [N/H] at MSTOphys.abundfloat[O/H]4Abundance [O/H] at MSTOphys.abundfloat[Fe/H]4Abundance [Fe/H] at MSTOphys.abundfloat[C/Fe]4Abundance [C/Fe] at MSTOphys.abundfloatXs6? Surface mass fraction of hydrogen at the end of FDU (4)phys.abund.Xfloatnullable[C/H]6? Abundance [C/H] at the end of FDU (4)phys.abundfloatnullable[N/H]6? Abundance [N/H] at the end of FDU (4)phys.abundfloatnullable[O/H]6? Abundance [O/H] at the end of FDU (4)phys.abundfloatnullable[Fe/H]6? Abundance [Fe/H] at the end of FDU (4)phys.abundfloatnullable[C/Fe]6? Abundance [C/Fe] at the end of FDU (4)phys.abundfloatnullableXsf? Surface mass fraction of hydrogen near the tip of the RGB (4)phys.abund.Xfloatnullable[C/H]f? Abundance [C/H] near the tip of the RGB (4)phys.abundfloatnullable[N/H]f? Abundance [N/H] near the tip of the RGB (4)phys.abundfloatnullable[O/H]f? Abundance [O/H] near the tip of the RGB (4)phys.abundfloatnullable[Fe/H]f? Abundance [Fe/H] near the tip of the RGB (4)phys.abundfloatnullable[C/Fe]f? Abundance [C/Fe] near the tip of the RGB (4)phys.abundfloatnullable