J/A+A/635/A161ivo://CDS.VizieR/J/A+A/635/A161doi:10.26093/cds/vizier.36350161CDSJain R.Prugniel P.Martins L.Lancon A.2022-11-21T14:54:57Z2020-03-27T06:26:46ZCDS support team

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

cds-question@unistra.frastronomical-modelsstellar-atmospheresglobular-star-clustersspectroscopyeffective-temperaturemetallicityRecent work has used spectra of ~5000 stars in NGC 6397 that were extracted from a MUSE mosaic to determine the atmospheric parameters for these stars by fitting the spectra against the Goettingen Spectral Library. A significant change in metallicity between the turn off and the red giant branch was found and was discussed as a possible manifestation of predicted effects of atomic diffusion. However, the small amplitude of the effect and inconsistency with earlier measurements call for more attention before this result is interpreted. Systematic effects due to the interpolation or to the synthetic spectra cannot be ruled out at this level of precision. We reanalyze the data with : the ELODIE and MILES reference libraries in order to assess the robustness of the result. These empirical libraries have a finer metallicity coverage down to approximately the cluster metallicity turn-off. Methods. We used the ULySS full-spectrum fitting package, together with the library interpolators to remeasure the three atmospheric parameters effective temperature, surface gravity, and [Fe/H] metallicity. We find a very low [Fe/H] dispersion along the isochrone (0.07dex), consistent with our error estimate (0.05dex). However, the [Fe/H] trend is not reproducible. This shows that the data have the potential to reveal patterns of the magnitude of the expected physical effects, but the analysis methods need to be refined to cull systematic effects that currently dominate the patterns.2020A&A...635A.161Jhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/635/A161CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/133/1658 : ACS survey of galactic globular clusters (Sarajedini+, 2007)J/A+A/588/A148 : NGC 6397 stars MUSE spectra (Husser+, 2016)https://archive.stsci.edu/prepds/acsggct : The ACS Globular Cluster Surveyhttp://muse-vlt.eu/science : MUSE science-verification data (extracted spectra)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/635/A161https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/635/A161http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/635/A161https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/635/A161https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/635/A161http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/635/A161GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/635/A161/table (Measured atmospheric parameters of NGC6397 stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/635/A161/table?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/635/A161/table?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/635/A161/table?GETtext/xml+votable180.050000true265.196228027-53.669540410.0055555555555555566/42076https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/635/A161?format=asciidefaultJ/A+A/635/A161/tableMeasured atmospheric parameters of NGC6397 starsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintspSpectrum from Husser et al., 2016, Cat. J/A+A/588/A148meta.ref.urlcharIDDesignation of the star from Husser et al. (2016, Cat. J/A+A/588/A148) (1)meta.id;meta.mainintRAJ2000Star right ascension (J2000)degpos.eq.ra;meta.mainDEJ2000Star declination (J2000)degpos.eq.dec;meta.mainloggphotSurface gravity of the star (determined photometrically)log(cm.s**-2)phot.sbfloatTeffEEffective temperature of the star predicted by ELODIE libraryKphys.temperature.effectiveinte_TeffEError in TeffEKstat.errorint[Fe/H]EMetallicity of the star predicted by ELODIE fitphys.abund.Z;meta.modelledfloate_[Fe/H]EError in [Fe/H]Estat.error;phys.abund.FefloatTeffMEffective temperature of the star predicted by MILES libraryKphys.temperature.effectiveinte_TeffMError in TeffMKstat.errorint[Fe/H]MMetallicity of the star predicted by MILES fitphys.abund.Z;meta.modelledfloate_[Fe/H]MError in [Fe/H]Mstat.error;phys.abund.FefloatTeffmeanMean of TeffE and TeffMKphys.temperature.effectivefloate_TeffmeanError on the TeffmeanKstat.errorfloatGaiaDR2GAIA star ID (2)meta.idcharSimbadSimbad column added by the CDSmeta.ref.urlchar