J/A+A/710/A86ivo://CDS.VizieR/J/A+A/710/A86CDSCurjuric B.Drazdauskas A.Tautvaisiene G.Bragaglia A.,Alvarez-Baena N.D'Orazi V.Dal Ponte M.2026-06-03T11:03:05Z2026-06-03T12:02:30ZCDS support team

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

cds-question@unistra.fropen-star-clusterschemical-abundancesastronomical-modelsspectroscopystellar-agesOur main aim was to enlarge the pool of open clusters with determined carbon, nitrogen, and oxygen abundances in evolved giants to further advance chemical clocks in stellar age determinations. High-resolution spectra were analysed using a differential model atmosphere method. Carbon abundances were derived using spectral synthesis of the C2 band-heads at 5135 and 5635.5{AA}. The CN features at 6470-6490{AA} were analysed to determine the abundances of nitrogen. The oxygen abundances were determined from the [OI] line at 6300{AA}. We provide abundances of C, N, O for 88 giants in 28 open clusters and in two stars of the association Theia 1214. The results were compared with the theoretical predictions and used for the analysis of the [C/N] relations with age. The origin of the two Theia 1214 stars was investigated. Precise age dating requires separate age calibrations of [C/N] ratios for the first-ascent giants of the lower part of the red giant branch and for the red clump stars to account for the additional abundance alterations during the post-RGB luminosity bump evolution. In the first-ascent giant stars with larger turn-off masses, the observed C/N ratios are slightly higher than those predicted by standard models, and the obtained [C/N] versus age relation is flatter in the young age regime than in previous studies. We doubt that two stars investigated in the Theia 1214 association belong to the tail of NGC 752, most probably, they are field stars.2026A&A...710A..86Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/710/A86CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicehttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/710/A86https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/710/A86http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/710/A86https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/710/A86https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/710/A86http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/710/A86GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/710/A86/table4 (Chemical abundances and evolutionary stages of the stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/710/A86/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/710/A86/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/710/A86/table4?GETtext/xml+votable180.050000true13.314299749.53162720.0055555555555555566/1276 2311 2436 2448 2517 2859 2862 3254 3262 3304 3362 3603 3606 3680 3783 3795-3796 4298 4698-4699 12890-12891 12913 13286 14033 14129 14375 15396-15397 15430 15699 21523 21526 21532 21774-21775 24329 29152 29154 30438-30439 30444-30445 30456 31068 31070 32016 32198 40601https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/710/A86?format=asciidefaultJ/A+A/710/A86/table4Chemical abundances and evolutionary stages of the starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintStarStar identifier within the clustermeta.idcharGaiaDR3Gaia DR3 source identifiermeta.id;meta.main[C/H]Carbon abundance [C/H]phys.abundfloate_[C/H]Uncertainty in [C/H]stat.error;phys.abundfloato_[C/H]Number of carbon lines usedmeta.numberint[N/H]Nitrogen abundance [N/H]phys.abundfloate_[N/H]Uncertainty in [N/H]stat.error;phys.abundfloato_[N/H]Number of nitrogen lines usedmeta.numberint[O/H]Oxygen abundance [O/H]phys.abundfloate_[O/H]Uncertainty in [O/H]stat.error;phys.abundfloatEvolEvolutionary stage (1)meta.codecharSimbadSimbad column added by the CDSmeta.ref.urlchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.main