J/A+A/705/A31ivo://CDS.VizieR/J/A+A/705/A31CDSAnoardo S.Mucciarelli A.Palla M.Santarelli L.Lardo C.Romano D.2026-03-09T10:22:18Z2026-01-07T07:34:13ZCDS support team

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

cds-question@unistra.frmagellanic-cloudsgiant-starschemical-abundancesspectroscopyvisible-astronomyIn this study we investigate the chemical enrichment of the rapid neutron-capture process in the Small Magellanic Cloud (SMC). We measure [Eu/Fe] abundance ratios in 209 giant stars that are confirmed members of the SMC, providing the first extensive dataset of Eu abundances in this galaxy across its full metallicity range, spanning more than 1.5dex. We compare Eu abundances with those of Mg and Ba to evaluate the efficiency of the r-process relative to alpha-capture and s-process nucleosynthesis. The SMC shows enhanced [Eu/Fe] values at all metallicities (comparable with the values measured in the Milky Way), with a clear decline as [Fe/H] increases (from ~-1.75dex to ~-0.5dex), consistent with the onset of Type Ia supernovae. In contrast, [Eu/Mg] is enhanced by about +0.5dex at all [Fe/H], significantly above the values observed in Milky Way stars, where [Eu/Mg] remains close to solar, reflecting comparable production of r-process and alpha-capture elements. Moreover, [Ba/Eu] increases with metallicity, beginning at [Fe/H]~=-1.5dex, namely at a lower metallicity with respect to the Milky Way, where [Ba/Eu] starts to increase around [Fe/H]~=-1dex. Our findings suggest the SMC has a higher production of Eu (with respect to the alpha-elements) than the Milky Way but in line with what observed in other dwarf systems within the Local Group. We confirm that galaxies with star formation efficiencies lower than the Milky Way have high [Eu/alpha], probably indicating a stronger efficiency of the delayed sources of r-process at low metallicities.2026A&A...705A..31Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/705/A31CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)J/A+A/671/A124 : 206 SMC red giants chemical composition (Mucciarelli+, 2023)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/705/A31https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/705/A31http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/705/A31https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/705/A31https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/705/A31http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/705/A31GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/705/A31/table1 (Main information of the observed targets (corrected version, 09-Mar-2026))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/705/A31/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/705/A31/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/705/A31/table1?GETtext/xml+votable180.050000true6.7124313-71.57746140.0055555555555555566/33287 33293 33304 33306 33323 33326https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/705/A31?format=asciiOpticaldefaultJ/A+A/705/A31/table1Main information of the observed targets (corrected version, 09-Mar-2026)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaDR3Gaia DR3 identification numbermeta.id;meta.mainRAICRSRight ascension (ICRS at Ep=2016.0)degpos.eq.ra;meta.mainDEICRSDeclination (ICRS at Ep=2016.0)degpos.eq.dec;meta.mainGmagG magnitude (Gaia DR3)phot.mag;em.optfloatRVHeliocentric radial velocitykm/sspect.dopplerVeloc;pos.heliocentricfloate_RVUncertainty on radial velocitykm/sstat.errorfloatIDPapIStar name as in Paper I (FLD-NNN_NNNNNN), [MMB2023] FLD-NNN NNNNNN in Simbadmeta.idcharFieldTarget field of the star (FLD-NNN)meta.id;obs.fieldcharBinary[*] Possibility that the star is a binary (*)meta.codechargaiaDissplay the Gaia DR3 datameta.ref.urlcharSimbadNameSimbad column added by the CDSmeta.idcharnullableJ/A+A/705/A31/table2Stellar parameters and chemical abundances of the observed targetsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGaiaDR3Gaia DR3 identification numbermeta.id;meta.mainTeffEffective temperatureKphys.temperature.effectiveintloggSurface gravitylog(cm.s**-2)phys.gravityfloatvtMicroturbulent velocitykm/sphys.velocfloat[Fe/H]Abundance relative to the Sun for FeIphys.abundfloate_[Fe/H]Uncertainty on the abundance for FeIstat.error;phys.abund.Fefloatl_[Eu/Fe]Limit flag on [Eu/Fe]meta.code.error;phys.abundchar[Eu/Fe]Abundance relative to the Sun for EuIIphys.abundfloate_[Eu/Fe]? Uncertainty on the abundance for EuII (1)stat.error;phys.abundfloatnullable[Ba/Fe]Abundance relative to the Sun for BaIIphys.abundfloate_[Ba/Fe]Uncertainty on the abundance for BaIIstat.error;phys.abundfloat