J/A+A/599/A97ivo://CDS.VizieR/J/A+A/599/A97doi:10.26093/cds/vizier.35990097CDSHanke M.Koch A.Hansen C.J.McWilliam A.2017-03-20T14:51:57Z2017-03-06T07:47:02ZCDS support team

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

cds-question@unistra.frgalaxiesgiant-starschemically-peculiar-starschemical-abundancesline-intensitiesWe present our detailed spectroscopic analysis of the chemical composition of four red giant stars in the halo globular cluster NGC 6426. We obtained high-resolution spectra using the Magellan2/MIKE spectrograph, from which we derived equivalent widths and subsequently computed abundances of 24 species of 22 chemical elements. For the purpose of measuring equivalent widths, we developed a new semi-automated tool, called EWCODE. We report a mean Fe content of [Fe/H]=-2.34+/-0.05dex (stat.) in accordance with previous studies. At a mean {alpha}-abundance of [(Mg,Si,Ca)/3Fe]=0.39+/-0.03dex, NGC 6426 falls on the trend drawn by the Milky Way halo and other globular clusters at comparably low metallicities. The distribution of the lighter {alpha}-elements as well as the enhanced ratio [Zn/Fe]=0.39dex could originate from hypernova enrichment of the pre-cluster medium. We find tentative evidence for a spread in the elements Mg, Si, and Zn, indicating an enrichment scenario, where ejecta of evolved massive stars of a slightly older population polluted a newly born younger one. The heavy element abundances in this cluster fit well into the picture of metal-poor globular clusters, which in that respect appear to be remarkably homogeneous. The pattern of the neutron-capture elements heavier than Zn point towards an enrichment history governed by the r-process with only little - if any - sign of s-process contributions. This finding is supported by the striking similarity of our program stars to the metal-poor field star HD 108317.2017A&A...599A..97Hhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/599/A97CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/112/1054 : VI photometry of NGC 6426 (Zinn+ 1996)J/A+A/573/A13 : Metal abundances in 6 globular cluster (Dias+, 2015)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/599/A97https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/599/A97http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/599/A97https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/599/A97https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/599/A97http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/599/A97GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/599/A97/stars (List of studied red giants)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/599/A97/stars?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/599/A97/stars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/599/A97/stars?GETtext/xml+votable180.050000true266.236253.1609170.0055555555555555566/31095https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/599/A97?format=asciidefaultJ/A+A/599/A97/starsList of studied red giantsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarStar numbermeta.id;meta.mainintRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainName2MASS namemeta.idcharEWDisplay the equivalent widthsmeta.ref.urlcharJ/A+A/599/A97/table2Line list including equivalent widthsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintElElementphys.atmol.elementcharIonIonization stagephys.atmol.ionStagecharlambdaWavelength0.1nmem.wlfloatchiexExcitation potentialeVphys.atmol.excitationfloatloggfOscillator strengthphys.atmol.oscStrengthfloatEW14853? Equivalent width for star 148530.1pmspect.line.eqWidthintnullablee_EW14853? Equivalent width error for star 14853 (1)0.1pmstat.errorintnullableEW5659? Equivalent width for star 56590.1pmspect.line.eqWidthintnullablee_EW5659? Equivalent width error for star 5659 (1)0.1pmstat.errorintnullableEW736? Equivalent width for star 7360.1pmspect.line.eqWidthintnullablee_EW736? Equivalent width error for star 736 (1)0.1pmstat.errorintnullableEW2314? Equivalent width for star 23140.1pmspect.line.eqWidthintnullablee_EW2314? Equivalent width error for star 2314 (1)0.1pmstat.errorintnullable