J/A+A/527/A148ivo://CDS.VizieR/J/A+A/527/A148doi:10.26093/cds/vizier.35270148CDSLind K.Charbonnel C.Decressin T.Primas F.Grundahl F.Asplund M.2017-12-18T07:57:08Z2011-02-14T08:53:36ZCDS support team

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

cds-question@unistra.frglobular-star-clusterschemical-abundancesline-intensitiesThe chemical compositions of globular clusters provide important information on the star formation that occurred at very early times in the Galaxy. In particular the abundance patterns of elements with atomic number z<=13 may shed light on the properties of stars that early on enriched parts of the star-forming gas with the rest-products of hydrogen-burning at high temperatures. We analyse and discuss the chemical compositions of a large number of elements in 21 red giant branch stars in the metal-poor globular cluster NGC6397. We compare the derived abundance patterns with theoretical predictions in the framework of the "wind of fast rotating massive star"-scenario. High-resolution spectra were obtained with the FLAMES/UVES spectrograph on the VLT. We determined non-LTE abundances of Na, and LTE abundances for the remaining 21 elements, including O (from the [OI] line at 630nm), Mg, Al, alpha, iron-peak, and neutron-capture elements, many of which had not been previously analysed for this cluster. We also considered the influence of possible He enrichment in the analysis of stellar spectra. We find that the Na abundances of evolved, as well as unevolved, stars in NGC6397 show a distinct bimodality, which is indicative of two stellar populations: one primordial stellar generation of composition similar to field stars, and a second generation that is polluted with material processed during hydrogen-burning, i.e., enriched in Na and Al and depleted in O and Mg. The red giant branch exhibits a similar bimodal distribution in the Stroemgren colour index c_y_=c_1_-(b-y), implying that there are also large differences in the N abundance. The two populations have the same composition for all analysed elements heavier than Al, within the measurement uncertainty of the analysis, with the possible exception of [Y/Fe]. Using two stars with almost identical stellar parameters, one from each generation, we estimate the difference in He content, Delta-Y=0.01+/-0.06, given the assumption that the mass fraction of iron is the same for the stars. NGC6397 hosts two stellar populations that have different chemical compositions of N, O, Na, Mg, and probably Al. The cluster is dominated (75%) by the second generation. We show that massive stars of the first generation can be held responsible for the abundance patterns observed in the second generation long-lived stars of NGC6397. We estimate that the initial mass of this globular cluster is at least ten times higher than its present-day value.2011A&A...527A.148Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/527/A148CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/503/545 : Equivalent widths of Li, Na, Fe, Ca in NGC 6397 (Lind+, 2009)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/527/A148https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/527/A148http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/527/A148https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/527/A148https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/527/A148http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/527/A148GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/527/A148/table2 (Equivalent widths and non-LTE abundances of Na)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/527/A148/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/527/A148/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/527/A148/table2?GETtext/xml+votable180.050000true265.0717917-53.69926940.0055555555555555566/42076https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/527/A148?format=asciiOpticaldefaultJ/A+A/527/A148/table2Equivalent widths and non-LTE abundances of Nae_W5688? Error on W5688pmstat.errorfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDIdentification number of target, <[LPC2009] NNNNNNN> in Simbadmeta.id;meta.mainintprimaryn_IDSimbad column added by the CDSmeta.ref.urlcharTeffEffective temperatureKphys.temperature.effectiveintloggSurface gravitylog(cm.s**-2)phys.gravityfloatVturbMicroturbulence velocitykm/sphys.veloc.microTurbfloatW5682? Equivalent width of NaI 568.2nm linepmspect.line.eqWidth;em.opt.Vfloatnullablee_W5682? Error on W5682pmstat.errorfloatnullableW5688? Equivalent width of NaI 568.8nm linepmspect.line.eqWidth;em.opt.VfloatnullableW8183? Equivalent width of NaI 818.3nm linepmspect.line.eqWidth;em.opt.Ifloatnullablee_W8183? Error on W8183pmstat.errorfloatnullablel_W8194[<] Limit flag on W8194 (indicates upper limit)meta.code.errorcharW8194? Equivalent width of NaI 819.4nm linepmspect.line.eqWidth;em.opt.Ifloatnullablee_W8194? Error on W8194pmstat.errorfloatnullablel_e(Na)[<] Limit flag on e(Na) (indicates upper limit)meta.code.errorchare(Na)? Non-LTE sodium abundance (G1)phys.abundfloatnullablee_e(Na)? Error on e(Na) (G1)stat.errorfloatnullablePapIDisplay the data of Paper I (Lind et al. 2009, Cat. J/A+A/503/545)meta.ref.urlchar_RAPosition from Lind et al., Cat. J/A+A/503/545 (right ascension part)degpos.eq.ra;meta.main_DEPosition from Lind et al., Cat. J/A+A/503/545 (declination part)degpos.eq.dec;meta.mainJ/A+A/527/A148/table1Equivalent widths and LTE line-by-line abundances for 19 elements of 21 red giantsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDIdentification number of target, <[LPC2009] NNNNNNN> in Simbadmeta.id;meta.mainintIonElement and ionisation stage of the linephys.atmol.element;spect.line;phys.atmol.ionizationcharlambdaApproximate central wavelength of line (2)nmem.wl.central;spect.linefloatEWEquivalent width of linepmspect.line.eqWidthfloate_EWrms uncertainty on EWpmstat.error;spect.line.eqWidthfloatepsLTE elemental abundance of Ion (G1)phys.abundfloate_epsrms uncertainty on epsstat.errorfloat