J/A+A/623/A128ivo://CDS.VizieR/J/A+A/623/A128doi:10.26093/cds/vizier.36230128CDSHansen C.J.Hansen T.T.Koch A.Beers T.C.Nordstroem B.Placco V.M.,Andersen J.2019-03-27T05:20:38Z2019-03-19T07:27:37ZCDS support team

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

cds-question@unistra.frmilky-way-galaxychemically-peculiar-starschemical-abundancesproper-motionsstellar-distanceCarbon-enhanced metal-poor (CEMP) stars span a wide range of stellar populations, from bona fide second-generation stars to later-forming stars that provide excellent probes of binary mass transfer and stellar evolution. Here we analyse 11 metal-poor stars (8 of which are new to the literature), and demonstrate that 10 are CEMP stars. Based on high signal-to-noise ratio (S/N) X-Shooter spectra, we derive abundances of 20 elements (C, N, O, Na, Mg, Ca, Sc, Ti, Cr, Mn, Fe, Ni, Sr, Y, Ba, La, Ce, Pr, Nd, and Eu). From the high-S/N spectra, we were able to trace the chemical contribution of the rare earth elements (REE) from various possible production sites, finding a preference for metal-poor low-mass asymptotic giant branch (AGB) stars of 1.5M_{sun}_ in CEMP-s stars, while CEMP-r/s stars may indicate a more massive AGB contribution (2-5M_{sun}_). A contribution from the r-process -- possibly from neutron star--neutron star mergers (NSM) -- is also detectable in the REE stellar abundances, especially in the CEMP-r/s sub-group rich in both slow(s)\ and rapid(r) neutron-capture elements. Combining spectroscopic data with Gaia DR2 astrometric data provides a powerful chemodynamical tool for placing CEMP stars in the various Galactic components, and classifying CEMP stars into the four major elemental-abundance sub-groups, which are dictated by their neutron-capture element content. The derived orbital parameters indicate that all but one star in our sample (and the majority of the selected literature stars) belong to the Galactic halo. These stars exhibit a median orbital eccentricity of 0.7, and are found on both prograde and retrograde orbits. We find that the orbital parameters of CEMP-no and CEMP-s stars are remarkably similar in the 98 stars we study. A special case is the CEMP-no star HE 0020-1741, with very low Sr and Ba content, which possesses the most eccentric orbit among the stars in our sample, passing close to the Galactic centre. Finally, we propose an improved scheme to sub-classify the CEMP stars, making use of the Sr/Ba ratio, which can also be used to separate very metal-poor stars from CEMP stars. We explore the use of [Sr/Ba] versus [Ba/Fe] in 93 stars in the metallicity range -4.2<~[Fe/H]<-2. We show that the Sr/Ba ratio can also be successfully used for distinguishing CEMP-s, CEMP-r/s, and CEMP-no stars. Additionally, the Sr/Ba ratio is found to be a powerful astro-nuclear indicator, since the metal-poor AGB stars exhibit very different Sr/Ba ratios compared to fast-rotating massive stars and NSM, and is also reasonably unbiased by NLTE and 3D corrections.2019A&A...623A.128Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/623/A128CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/375/366 : Carbon stars from the Hamburg/ESO survey (Christlieb+ 2001)J/AJ/139/1051 : Carbon-enhanced metal-poor stars in the Galaxy (Placco+, 2010)J/AJ/142/188 : Metal-poor stars from the HES using CH G-band (Placco+, 2011)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/623/A128https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/623/A128http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/623/A128https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/623/A128https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/623/A128http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/623/A128GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/623/A128/tablea2 (Kinematics of 98 stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/623/A128/tablea2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/623/A128/tablea2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/623/A128/tablea2?GETtext/xml+votable180.050000true3.2875417-34.09858330.0055555555555555566/2426 4098 8197 10430 16413 16588 16654 16659 16763 16795 16819 16854 17095 17256 17392 17432 17451 17730 17793 18098 18566 18683 18691 18708 18719 18964 19010 21016 21195 21221 22541 22625 22650 23180 24832 24914 25008 25357 25431 25534 25574 25733 25743 25785 25832 25879 25928 26052 26057 26232 26645 26658 26829 27048 27065 31303 31394 31595 33435 33498 33573 33751 34008-34009 34019 34589 34600 35408 35464 35543 35883 35992 36000 36196 36212 36503 36548 40404 40410 44016 44870 44965 45335 46195 46282-46283 46394 46426 46476 46479 46508 46688 48234 48415 48481 48577 48590 48613https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/623/A128?format=asciidefaultJ/A+A/623/A128/tablea1Atomic data for 19 elements (linelist)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintLineWavelength of absorption line in Angstroem0.1nmem.wl;spect.linedoubleZ.multElement with multiplicity (level of ionisation) and isotope (if hyperfine splitting is adopted)phys.atmol.elementfloatchiExcitation potentialeVphys.atmol.excitationfloatloggfOscillator strengthphys.atmol.oscStrengthfloatRefReference for atomic data listed (1)meta.refcharJ/A+A/623/A128/tablea2Kinematics of 98 starsSimbadNameSimbad column added by the CDSmeta.idcharStarStellar IDmeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintpmRA*Proper motion in right ascension (mu_{alpha}*cos{delta})mas/yrpos.pm;pos.eq.rafloatE_pmRA*Positive uncertainty in right ascension proper motionmas/yrstat.error;pos.pm;pos.eq.rafloate_pmRA*Negative uncertainty in right ascension proper motionmas/yrstat.error;pos.pm;pos.eq.rafloatpmDEProper motion in declination (mu_{delta})mas/yrpos.pm;pos.eq.decfloate_pmDESymmetric uncertainty in declination proper motionmas/yrstat.error;pos.pm;pos.eq.decfloatDDistance (if negative the star is below the plane)kpcpos.distancefloate_DUncertainty in distancekpcstat.error;pos.distancefloatRapoApocentric distancekpcpos.distancefloatRperiPericentric distancekpcpos.distance;src.orbitalfloatZmaxMaximum height above the planekpcpos.cartesian.z;pos.galactic;stat.maxfloateEccentricity of orbitsrc.orbital.eccentricityfloatClassCEMP subclassification, mp indicates C-normalsrc.classcharRefReference (1)meta.refint_RASimbad + paper (right ascension part)degpos.eq.ra;meta.main_DESimbad + paper (declination part)degpos.eq.dec;meta.main