J/A+A/710/A148ivo://CDS.VizieR/J/A+A/710/A148CDSWang H.Li G.Fritzewski D.J.Van Reeth T.Aerts C.2026-06-09T09:45:17Z2026-06-09T10:44:06ZCDS support team

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

cds-question@unistra.fropen-star-clustersstellar-evolutionary-modelsphotometryspace-observatoriesobservational-astronomyvariable-starsIsochrone fitting is a classical method used to determine the ages of open clusters. However, the derived ages depend strongly on the chosen input physics of the stellar models used to deduce the isochrones. Additionally, it remains an open question whether the isochronal ages based on stellar surface parameters are consistent with the asteroseismic ages derived from stellar interior properties. Our aim was to investigate how isochrones based on different input physics and computed for a variety of initial conditions affect the age dating of the open cluster NGC6866. Using the four-year light curves of its members assembled by the Kepler mission, we further compared these results with asteroseismically derived ages. We extracted 180 cluster members by applying a clustering algorithm to Gaia DR3 data, and subsequently developed an isochrone-cloud fitting method that simultaneously accounts for the range of free parameters occurring in the input physics. Synthetic colour-magnitude diagrams (CMDs) with various initial rotation rates were generated and compared with the observations to determine the best-fitting rotation distribution. Variable stars were then identified among the cluster members. For the 19 gravity-mode (g-mode) pulsators, we performed modelling using a dedicated grid of rotating stellar models. This modelling was constrained by stellar surface parameters, the measured asymptotic gravity-mode (g-mode) period spacing Pi_0_, and the near-core rotation rate. Two approaches were considered: modelling the pulsators individually and under the assumption that they share a common age. Results-We found discrepant age estimates from PARSEC and MIST isochrones, which yielded 690^+140^_-30_Myr and 467^+70^_-50_Myr, respectively. The isochrone-cloud fitting indicates that NGC6866 has an initial rotation distribution peaking at v/v_crit_=0.6, which is a discrepancy with a factor of about two compared to the asteroseismic values. The asteroseismic modelling of the g-mode pulsators revealed agreement between seismic and isochronal masses, whereas the derived ages differ substantially due to the difference in internal mixing. When the g-mode pulsators were modelled under the assumption of one shared cluster age, we obtained a value of 759^+54^_-82_Myr, in agreement with the PARSEC-based isochronal age. We conclude that using different input physics and various initial conditions impacts the age-dating results of open clusters. Our findings point to the need for more carefully calibrated evolutionary models. The seismic content of NGC6866 makes it a suitable middle-aged cluster to achieve such calibrations.2026A&A...710A.148Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/710/A148CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/133 : Kepler Input Catalog (Kepler Mission Team, 2009)I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/710/A148https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/710/A148http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/710/A148https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/710/A148https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/710/A148http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/710/A148GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/710/A148/table1 (Variability identification of the cluster member stars within our region of interest)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/710/A148/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/710/A148/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/710/A148/table1?GETtext/xml+votable180.050000true300.325931039075743.92561606654030.0055555555555555566/14749 14751 14792 147941.9867573869263685e-19 3.916500758235022e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/710/A148?format=asciidefaultJ/A+A/710/A148/table1Variability identification of the cluster member stars within our region of interestrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintModindicates asteroseismic grid modelling resultsmeta.ref.urlcharGaiaDR3Gaia DR3 source idmeta.id;meta.mainSimbadSimbad column added by the CDSmeta.ref.urlchar_RA.icrsRight ascension (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.raindexed_DE.icrsDeclination (ICRS) at Epoch=J2000, proper motions taken into accountdegpos.eq.decindexedNameGaia designationmeta.idcharRA_ICRSRight ascension (ICRS) at Ep=2016.0 from Gaia DR3degpos.eq.ra;meta.mainDE_ICRSDeclination (ICRS) at Ep=2016.0 from Gaia DR3degpos.eq.dec;meta.mainplxParallax given by Gaia DR3maspos.parallax.trigdoublepmRAProper motion in RA from Gaia DR3maspos.pm;pos.eq.radoublepmDEProper motion in Dec from Gaia DR3maspos.pm;pos.eq.decdoubleGmagMean Gaia G magnitudemagphot.mag;em.optdoubleBP-RPColour index from Gaia bp minus RPmagphot.color;em.opt.B;em.opt.RdoubleMeanProbMean value of the cluster membership probability of this target from our perturbative clustering algorithmstat.probability;stat.meandoubleMedianProbMedian value of the cluster membership probability of this target from our perturbative clustering algorithmstat.probability;stat.mediandoubleStdDevProbStandard deviation value of the cluster membership probability of this target from our perturbative clustering algorithmstat.stdevdoubleKICKepler input catalog IDmeta.idintprimarySepSeparation from the KIC target to this Gaia target when crossmatchedarcsecpos.angDistancedoubleClassVariability class (1)meta.code.classcharJ/A+A/710/A148/sep-ageAsteroseismic grid modelling results using the separate age approachrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKICKepler input catalog IDmeta.id;meta.mainintlogAgeMedian fitted log10 agelog(yr)time.age;stat.mediandoublee_logAgeLower uncertainty range of logAgelog(yr)stat.error;time.agedoubleE_logAgeUpper uncertainty range of logAgelog(yr)stat.error;stat.maxdoubleMassMedian fitted stellar masssolMassphys.mass;stat.mediandoublee_MassLower uncertainty range of stellar masssolMassstat.error;phys.massdoubleE_MassUpper uncertainty range of stellar masssolMassstat.error;stat.maxdoublefovMedian fitted overshootstat.fit.paramdoublee_fovLower uncertainty range of fovstat.error;phys.angSize;instr.fovdoubleE_fovUpper uncertainty range of fovstat.error;stat.maxdoubleomegaiMedian initial rotation rate over critial ratestat.fit.paramdoublee_omegaiLower uncertainty range of omegaistat.errordoubleE_omegaiUpper uncertainty range of omegaistat.error;stat.maxdoubleMccMMedian convective core mass ratiophys.mass;arith.ratiodoublee_MccMLower uncertainty range of Mcc/Mstat.errordoubleE_MccMUpper uncertainty range of Mcc/Mstat.error;stat.maxdoubleJ/A+A/710/A148/shar-ageAsteroseismic grid modelling results using the shared age approachrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintKICKepler input catalog IDmeta.id;meta.mainintlogAgeMedian fitted log10 agelog(yr)time.age;stat.mediandoublee_logAgeLower uncertainty range of logAgelog(yr)stat.error;time.agedoubleE_logAgeUpper uncertainty range of logAgelog(yr)stat.error;stat.maxdoubleMassMedian fitted stellar masssolMassphys.mass;stat.mediandoublee_MassLower uncertainty range of stellar masssolMassstat.error;phys.massdoubleE_MassUpper uncertainty range of stellar masssolMassstat.error;stat.maxdoublefovMedian fitted overshootstat.fit.paramdoublee_fovLower uncertainty range of fovstat.error;phys.angSize;instr.fovdoubleE_fovUpper uncertainty range of fovstat.error;stat.maxdoubleomegaiMedian initial rotation rate over critial ratestat.fit.paramdoublee_omegaiLower uncertainty range of omegaistat.errordoubleE_omegaiUpper uncertainty range of omegaistat.error;stat.maxdoubleMccMMedian convective core mass ratiophys.mass;arith.ratiodoublee_MccMLower uncertainty range of Mcc/Mstat.errordoubleE_MccMUpper uncertainty range of Mcc/Mstat.error;stat.maxdouble