J/A+A/712/A219ivo://CDS.VizieR/J/A+A/712/A219CDSSchiappacasse-Ulloa J.Lucatello S.Magrini L.Bragaglia A.Carretta E.2026-08-25T08:15:52Z2026-08-25T09:13:07ZCDS support team

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

cds-question@unistra.frglobular-star-clusterspopulation-ii-starsspectroscopymetallicityGlobular clusters host multiple stellar populations, likely composed of a subset of first-generation stars that enriched the intracluster medium and gave rise to second-generation (SG) stars, each characterised by distinctive chemical patterns. These patterns typically include enhancements in elements such as N, Na, and Al, coupled with depletions in C, O, and Mg in SG stars. Traditionally, heavier elements such as those in the iron peak were considered unaffected in most clusters. However, recent studies have reported significant internal spreads in these elements, suggesting a more complex picture of chemical enrichment within globular clusters. This study seeks to derive precise and homogeneous differential iron abundances in a large sample of globular clusters. By doing so, our aim is to investigate the presence of intrinsic iron spreads within them and to assess the existence of differences in Fe between their stellar populations. We used the Python-based tool Q2 to determine both differential stellar parameters and iron abundances for 92 sibling stars -- defined by the similarities in their stellar parameters -- across 13 Galactic globular clusters. This differential approach reduces the influence of non-local thermodynamic equilibrium effects, and minimises observational errors, and systematic biases linked to stellar parameters. We performed Monte Carlo simulations to evaluate the statistical significance of the measured spreads. Most of the globular clusters in our sample do not show evidence of statistically significant iron spreads. Only a few exceptions emerge, namely NGC1851, NGC3201, and NGC5634, which display a highly significant iron spread. In particular, NGC3201 shows a particularly pronounced spread in its first-generation population, reflecting a potential inhomogeneous iron abundance in its pristine material. Finally, through statistical tests, we conclude that our data do not support the presence of a widespread iron variation in globular clusters.2026A&A...712A.219Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/712/A219CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/712/A219https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/712/A219http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/712/A219https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/712/A219https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/712/A219http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/712/A219GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/712/A219/table1 (Position, stellar parameter, and differential iron abundance in 13 globular clusters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/712/A219/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/712/A219/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/712/A219/table1?GETtext/xml+votable180.050000true6.30535417-72.1306750.0055555555555555566/21017 25873 31019 31115 31416-31417 33321 34242 37294 37636 38465 42076 42955 47125 47168 47970-47971https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/712/A219?format=asciidefaultJ/A+A/712/A219/table1Position, stellar parameter, and differential iron abundance in 13 globular clustersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintClusterGlobular cluster namemeta.id.parentcharIDIdentification name of the starmeta.id;meta.maincharRAJ2000Right Ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Declination (J2000)degpos.eq.dec;meta.mainTeffEffective temperatureKphys.temperature.effectiveinte_TeffEffective temperature errorKstat.error;phys.temperature.effectiveintloggSurface gravitylog(cm.s**-2)phys.gravityfloate_loggSurface gravity errorlog(cm.s**-2)stat.errorfloat[Fe/H]Metallicity (dex)phys.abund.Zchare_[Fe/H]Metallicity error (dex)stat.error;phys.abund.Fefloatvtmicroturbulent velocitykm/sphys.velocfloate_vtmicroturbulent velocity errorkm/sstat.errorfloatDeltaFeDifferential Fe abundance (dex)phys.abund.Fe;arith.difffloate_DeltaFeDifferential Fe abundance error (dex)stat.errorfloatSimbadNameSimbad column added by the CDSmeta.idcharnullable