J/ApJ/675/1213ivo://CDS.VizieR/J/ApJ/675/1213doi:10.26093/cds/vizier.16751213CDSRosolowsky E.Simon J.D.2017-06-27T06:38:02Z2010-09-16T10:13:32ZCDS support team

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

cds-question@unistra.frgalaxiesh-ii-regionschemical-abundancesWe present a new determination of the metallicity gradient in M33, based on Keck LRIS measurements of oxygen abundances using the temperature-sensitive emission line [OIII] {lambda}4363 in 61 HII regions. These data approximately triple the sample of direct oxygen abundances in M33. We find a central abundance of 12+log(O/H)=8.36+/-0.04 and a slope of -0.027+/-0.012dex/kpc, in agreement with infrared measurements of the neon abundance gradient but much shallower than most previous oxygen gradient measurements. There is substantial intrinsic scatter of 0.11dex in the metallicity at any given radius in M33, which imposes a fundamental limit on the accuracy of gradient measurements that rely on small samples of objects. We also show that the ionization state of neon does not follow the ionization state of oxygen as is commonly assumed, suggesting that neon abundance measurements from optical emission lines require careful treatment of the ionization corrections.2008ApJ...675.1213Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/675/1213CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/131/2478 : M31 and M33 UBVRI photometry (Massey+, 2006)J/PASP/111/685 : HII regions of M33. II. (Hodge+, 1999)J/A+A/512/A63 : Abundances of M33 HII regions (Magrini+, 2010)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/675/1213https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/675/1213http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/675/1213https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/675/1213https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/675/1213http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/675/1213GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/675/1213/m33h2 (HII regions in M33: line fluxes, Balmer series line ratios and derived propertie)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/675/1213/m33h2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/675/1213/m33h2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/675/1213/m33h2?GETtext/xml+votable180.050000true23.45166730.660.0055555555555555566/2154 2155https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/675/1213?format=asciiOpticaldefaultJ/ApJ/675/1213/m33h2HII regions in M33: line fluxes, Balmer series line ratios and derived propertieOHgObserved H{gamma} relative to H{beta}meta.notefloatRAJ2000Right ascension (J2000.0) (1)pos.eq.ra;meta.mainrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[1/61] Sequential numbermeta.recordintn_Seq[d] Same object observed on multiple slit masksmeta.notecharDEJ2000Declination (J2000.0) (1)pos.eq.dec;meta.mainNameCross-identifications (2)meta.idcharRgalGalactocentric distancekpcpos.distance;pos.galactocentricfloatF[OII]Flux of [OII]{lambda}3727 line (3)spect.line.intensity;arith.ratiofloate_F[OII]rms uncertainty on F[OII]stat.errorfloatF[NeIII]Flux of [NeIII]{lambda}3869 line (3)spect.line.intensity;arith.ratiofloate_F[NeIII]rms uncertainty on F[NeIII]stat.errorfloatF[OIII]1Flux of [OIII]{lambda} 4363 (3)spect.line.intensity;arith.ratiodoublee_F[OIII]1rms uncertainty on F[OIII]stat.errorfloatF[OIII]2Flux of [OIII]{lambda} 4959 (3)spect.line.intensity;arith.ratiofloate_F[OIII]2rms uncertainty on F[OIII]stat.errorfloatF[OIII]3Flux of [OIII]{lambda} 5007 (3)spect.line.intensity;arith.ratiofloate_F[OIII]3rms uncertainty on F[OIII]stat.errorfloatTe([OIII])Electron temperature, from [OIII] linesKphys.temperature.electron;phys.electroninte_Te([OIII])rms uncertainty on Te([OIII])Kstat.errorinteps(O)Oxygen abundance{epsilson}(O)=12+log(O/H)phys.abundfloate_eps(O)rms uncertainty on oxygen abundancestat.errorfloatEWHb? H{beta} emission line equivalent width0.1nmspect.line.eqWidth;em.line.Hbetafloatnullablee_EWHb? Uncertainty in EWHb0.1nmstat.errorfloatnullablecHbH{beta} reddening correctionarith.factor;phot.fluxfloate_cHbUncertainty in cHbstat.errorfloatEW*Stellar absorption equivalent width0.1nmspect.line.eqWidthfloate_EW*Uncertainty in EW*0.1nmstat.error;spect.line.eqWidthfloatOHdObserved H{delta} relative to H{beta}meta.notefloatOH7Observed H7 relative to H{beta}meta.notefloatOH9Observed H9 relative to H{beta}meta.notedoubleHgcExtinction/Absorption corrected H{gamma}spect.line.intensity;arith.ratiofloatHdcExtinction/Absorption corrected H{delta}spect.line.intensity;arith.ratiofloatH7cExtinction/Absorption corrected H7spect.line.intensity;arith.ratiofloatH9cExtinction/Absorption corrected H9spect.line.intensity;arith.ratiofloatSimbadNameSimbad column added by the CDSmeta.idchar