J/MNRAS/327/918ivo://CDS.VizieR/J/MNRAS/327/918doi:10.26093/cds/vizier.73270918CDSTolstoy E.Irwin M.J.Cole A.A.Pasquini L.Gilmozzi R.Gallagher J.S.2024-06-27T20:17:44Z2006-04-06T09:16:02ZCDS support team

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

cds-question@unistra.frgalaxiesgiant-starsradial-velocitychemical-abundancesSpectroscopic abundance determinations for stars spanning a Hubble time in age are necessary in order to determine unambiguously the evolutionary histories of galaxies. Using FORS1 in multi-object spectroscopy mode on ANTU (UT1) at the ESO VLT on Paranal, we have obtained near-infrared spectra from which we have measured the equivalent widths of the two strongest Ca II triplet lines to determine metal abundances for a sample of red giant branch stars, selected from ESO NTT optical (I, V-I) photometry of three nearby Local Group galaxies: the Sculptor dwarf spheroidal, the Fornax dwarf spheroidal and the dwarf irregular NGC 6822. The summed equivalent width of the two strongest lines in the Ca II triplet absorption-line feature, centred at 8500{AA}, can be readily converted into an [Fe/H] abundance using the previously established calibrations by Armandroff & Da Costa (1991AJ....101.1329A) and Rutledge, Hesser & Stetson (1997, Cat. <J/PASP/109/883>). We have measured metallicities for 37 stars in Sculptor, 32 stars in Fornax and 23 stars in NGC 6822, yielding more precise estimates of the metallicity distribution functions for these galaxies than it is possible to obtain photometrically. In the case of NGC 6822, this is the first direct measurement of the abundances of the intermediate-age and old stellar populations. We find metallicity spreads in each galaxy which are broadly consistent with the photometric width of the red giant branch, although the abundances of individual stars do not always appear to correspond to their colour. This is almost certainly predominantly due to a highly variable star formation rate with time in these galaxies, which results in a non-uniform, non-globular-cluster-like evolution of the Ca/Fe ratio.2001MNRAS.327..918Thttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/327/918CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toI/185 : Giant branch of the Fornax dwarf spheroidal galaxy (Sagar+, 1990)J/AJ/116/1922 : CaII H and K filter photometry. III. (Anthony-Twarog+, 1998)J/PASP/109/883 : Globular metallicity scale. I. (Rutledge+ 1997)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/327/918https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/327/918http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/327/918https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/327/918https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/327/918http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/327/918GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/327/918/sculptor (Sculptor positions and results)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/327/918/sculptor?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/327/918/sculptor?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/327/918/sculptor?GETtext/xml+votable180.050000true15.005417-33.7544440.005555555555555556Cone search capability for table J/MNRAS/327/918/fornax (Fornax positions and results)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/327/918/fornax?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/327/918/fornax?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/327/918/fornax?GETtext/xml+votable180.050000true39.96375-34.4994440.005555555555555556Cone search capability for table J/MNRAS/327/918/ngc6822 (NGC 6822 positions and results)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/327/918/ngc6822?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/327/918/ngc6822?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/327/918/ngc6822?GETtext/xml+votable180.050000true296.197917-14.7833330.0055555555555555566/29718 35549 35720 35969https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/327/918?format=asciiOpticaldefaultJ/MNRAS/327/918/sculptorSculptor positions and resultsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar designation (G1)meta.id;meta.maincharn_Name[*$p+|] Note (1)meta.notecharImagI magnitudemagphot.mag;em.opt.IfloatV-IV-I colour indexmagphot.color;em.opt.V;em.opt.IfloatEWCaIISummed equivalent width of the two strongest lines in the Ca II triplet absorption-line feature, 8542{AA}+8662{AA}0.1nmspect.line.eqWidthfloate_EWCaIIrms uncertainty on EWCaII0.1nmstat.errorfloat[Fe/H]? MetallicitySunphys.abund.Zfloatnullablee_[Fe/H]? rms uncertainty on [Fe/H]Sunstat.error;phys.abund.FefloatnullableRVMeasured radial velocitykm/sphys.veloc;pos.heliocentricfloate_RVrms uncertainty on RVkm/sstat.error;spect.dopplerVelocfloatOffsetOffset of the star position in a through-slit image to correct the radial velocitykm/sphys.veloc;arith.diffintRVcCorrected radial velocity (RV + Offset)km/sphys.veloc;pos.heliocentricfloatRAJ2000Right ascension (J2000.0)pos.eq.ra;meta.mainDEJ2000Declination (J2000.0)pos.eq.dec;meta.mainJ/MNRAS/327/918/fornaxFornax positions and resultsNameStar designation (G1)meta.id;meta.maincharImagI magnitudemagphot.mag;em.opt.IfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintn_Name[*$p+|] Note (1)meta.notecharV-IV-I colour indexmagphot.color;em.opt.V;em.opt.IfloatEWCaIISummed equivalent width of the two strongest lines in the Ca II triplet absorption-line feature, 8542{AA}+8662{AA}0.1nmspect.line.eqWidthfloate_EWCaIIrms uncertainty on EWCaII0.1nmstat.errorfloat[Fe/H]? MetallicitySunphys.abund.Zfloatnullablee_[Fe/H]? rms uncertainty on [Fe/H]Sunstat.error;phys.abund.FefloatnullableRVMeasured radial velocitykm/sphys.veloc;pos.heliocentricfloate_RVrms uncertainty on RVkm/sstat.error;spect.dopplerVelocfloatOffsetOffset of the star position in a through-slit image to correct the radial velocitykm/sphys.veloc;arith.diffintRVcCorrected radial velocity (RV + Offset)km/sphys.veloc;pos.heliocentricfloatRAJ2000Right ascension (J2000.0)pos.eq.ra;meta.mainDEJ2000Declination (J2000.0)pos.eq.dec;meta.mainJ/MNRAS/327/918/ngc6822NGC 6822 positions and resultsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar designation (G1)meta.id;meta.maincharn_Name[*$p+|] Note (1)meta.notecharImagI magnitudemagphot.mag;em.opt.IfloatV-IV-I colour indexmagphot.color;em.opt.V;em.opt.IfloatEWCaIISummed equivalent width of the two strongest lines in the Ca II triplet absorption-line feature, 8542{AA}+8662{AA}0.1nmspect.line.eqWidthfloate_EWCaIIrms uncertainty on EWCaII0.1nmstat.errorfloat[Fe/H]? MetallicitySunphys.abund.Zfloatnullablee_[Fe/H]? rms uncertainty on [Fe/H]Sunstat.error;phys.abund.FefloatnullableRVMeasured radial velocitykm/sphys.veloc;pos.heliocentricfloate_RVrms uncertainty on RVkm/sstat.error;spect.dopplerVelocfloatOffsetOffset of the star position in a through-slit image to correct the radial velocitykm/sphys.veloc;arith.diffintRVcCorrected radial velocity (RV + Offset)km/sphys.veloc;pos.heliocentricfloatRAJ2000Right ascension (J2000.0)pos.eq.ra;meta.mainDEJ2000Declination (J2000.0)pos.eq.dec;meta.main