J/A+A/700/A213ivo://CDS.VizieR/J/A+A/700/A213doi:10.26093/cds/vizier/bc-nw/lcbdCDSVillanova S.Monaco L.Momany Y.Ordenes I.Harbeck D.Plotnikova A.2026-08-28T12:34:56Z2025-08-19T08:53:58ZCDS support team

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

cds-question@unistra.frglobular-star-clusterschemical-abundancesstellar-evolutionary-tracksGlobular clusters exhibit star-to-star chemical variations, traceable through both photometric and spectroscopic data. While UV photometry and light-element abundances (e.g., Na and O) are commonly used, the optical V vs. (V-I) color-magnitude diagram (CMD) is often assumed to be relatively unaffected by such inhomogeneities and is typically used to derive basic cluster parameters. On the other hand, C and N would be the best chemical tracers of these variations but are challenging to measure due to their spectral features lying in the blue/UV or IR regions. In this study, we investigate chemical variations in the globular cluster NGC104 (47Tucanae), aiming to trace multiple stellar populations across evolutionary phases and examine how the C/N anti-correlation evolves from the main sequence (MS) to the asymptotic giant branch (AGB). We also assess the impact of these populations on the interpretation of the V vs. V-I diagram. Using spectra spanning all evolutionary stages, we derive [C/Fe] and [N/Fe] abundances for a large stellar sample. These abundance measurements are inferred from the CN and the CH features, while atmospheric parameters are homogeneously derived from photometry. The inferred abundances allow us to disentangle multiple populations along the CMD and refine cluster parameters. We find that MS stars are more C- and N-rich than their red giant branch, horizontal branch, and AGB counterparts. The C/N anti-correlation shifts during the sub-giant branch phase, coinciding with the first dredge-up: C decreases by 0.15-0.20dex, N by ~0.1dex, while Fe remains unchanged. Interestingly, stars with different C and N abundances occupy distinct regions of the V vs V-I diagram--a pattern not attributable to differential reddening. Proper CMD fitting requires two isochrones with differing helium content, metallicity, and possibly age.2025A&A...700A.213Vhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/700/A213CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/125/197 : CN abundances of the 47 Tuc main sequence (Harbeck+, 2003)J/AJ/127/1588 : 47 Tuc main-sequence star abundances (Briley+, 2004)J/AJ/135/1551 : Abundances of stars in 47 Tuc (Koch+, 2008)J/A+A/537/A2 : 8.6um imaging of 47 Tuc (Momany+, 2012)J/A+A/549/A41 : Horizontal branch stars in 47 Tuc and M5 (Gratton+, 2013)J/A+A/550/A34 : Abundances of red giants in M4 and 47 Tuc (Carretta+, 2013)J/A+A/572/A108 : 47 Tuc red giants chemical composition (Thygesen+, 2014)J/ApJ/780/94 : Abundances of red giants in 47 Tuc (Cordero+, 2014)J/ApJ/797/124 : AGB and RGB stars in 47 Tuc (Lapenna+, 2014)J/MNRAS/459/610 : 47 Tuc sub-giant branch chemical abundances (Marino+, 2016)J/A+A/661/A35 : eROSITA study of 47 Tuc globular cluster (Saeedi+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/700/A213https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/700/A213http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/700/A213https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/700/A213https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/700/A213http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/700/A213GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/700/A213/table3 (Parameters and [C/Fe] and [N/Fe] abundances for our targets)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/700/A213/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/700/A213/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/700/A213/table3?GETtext/xml+votable180.050000true6.5515-71.969750.0055555555555555566/33321 333231.9821045660507152e-19 3.852589004194616e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/700/A213?format=asciidefaultJ/A+A/700/A213/table3Parameters and [C/Fe] and [N/Fe] abundances for our targetsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDIdentififiermeta.id;meta.maincharRAJ2000Right ascension (J2000.0)degpos.eq.ra;meta.mainDEJ2000Declination (J2000.0)degpos.eq.dec;meta.mainVmagJohnson V magnitudemagphot.mag;em.opt.VfloatImagJohnson I magnitudemagphot.mag;em.opt.IfloatpmRAProper motion along right ascensionmas/yrpos.pm;pos.eq.rafloatpmDEProper motion along declinationmas/yrpos.pm;pos.eq.decfloatTeffEffective temperatureKphys.temperature.effectiveintloggLogarithm of the surface gravitylog(cm.s**-2)phys.gravityfloatvtMicrotubulentekm/sphys.veloc.microTurbfloatPhaseEvolutionary phase (MS, SGB, RGB, HB or AGB)src.classcharGen[FG SG] Generation the target belongs to (1)meta.codechar[C/Fe]C abundancephys.abundfloat[N/Fe]N abundancephys.abundfloatSimbadNameSimbad column added by the CDSmeta.idcharnullable