J/ApJ/812/39ivo://CDS.VizieR/J/ApJ/812/39doi:10.26093/cds/vizier.18120039CDSStanghellini L.Magrini L.Casasola V.2018-02-01T11:50:43Z2016-02-22T13:33:05ZCDS support team

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

cds-question@unistra.frgalaxiesvisible-astronomyspectroscopyh-ii-regionsGas-phase abundances in HII regions of two spiral galaxies, NGC7793 and NGC4945, have been studied to determine their radial metallicity gradients. We used the strong-line method to derive oxygen abundances from spectra acquired with GMOS-S, the multi-object spectrograph on the 8m Gemini South telescope. We found that NGC7793 has a well-defined gas-phase radial oxygen gradient of -0.321+/-0.112dexR_25_^-1^ (or -0.054+/-0.019dex/kpc) in the galactocentric range 0.17<R_G_/R_25_<0.82, not dissimilar from gradients calculated with direct abundance methods in galaxies of similar mass and morphology. We also determined a shallow radial oxygen gradient in NGC 4945, -0.253+/-0.149dexR_25_^-1^ (or -0.019+/-0.011dex/kpc) for 0.04<R_G_/R_25_<0.51, where the larger relative uncertainty derives mostly from the larger inclination of this galaxy. NGC 7793 and NGC 4945 have been selected for this study because they are similar, in mass and morphology, to M33 and the Milky Way, respectively. Since at zeroth order we expect the radial metallicity gradients to depend on mass and galaxy type, we compared our galaxies in the framework of radial metallicity models best suited for M33 and the Galaxy. We found a good agreement between M33 and NGC7793, pointing toward similar evolution for the two galaxies. We notice instead differences between NGC 4945 and the radial metallicity gradient model that best fits the Milky Way. We found that these differences are likely related to the presence of an active galactic nucleus combined with a bar in the central regions of NGC 4945, and to its interacting environment.2015ApJ...812...39Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/812/39CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/567/A88 : Abundances in HII regions of M81 (Stanghellini+, 2014)J/AJ/147/131 : Abundances of nearby late-type galaxies. I. (Pilyugin+, 2014)J/A+A/559/A114 : Updated O3N2 and N2 abundance indicators (Marino+, 2013)J/ApJS/190/233 : Spectroscopy & abundances of SINGS galaxies (Moustakas+, 2010)J/A+A/512/A63 : Abundances of M33 HII regions (Magrini+, 2010)J/ApJ/706/553 : Fluxes in nearby star-forming galaxies (Boquien+, 2009)J/AJ/138/1037 : Star formation in Centaurus A Group dwarfs (Cote+ 2009)J/AJ/136/2782 : Star formation efficiency in nearby galaxies (Leroy+, 2008)J/A+A/440/783 : OB associations in NGC 7793 (Pietrzynski+, 2005)J/A+A/422/941 : Gas content in 1038 interacting galaxies (Casasola+, 2004)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/812/39https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/812/39http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/812/39https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/812/39https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/812/39http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/812/39GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/812/39/table3 (Positions and distances and H{beta} flux of HII regions in NGC 7793)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/812/39/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/812/39/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/812/39/table3?GETtext/xml+votable180.050000true359.502125-32.55558060.005555555555555556Cone search capability for table J/ApJ/812/39/table4 (Positions and distances and H{beta} flux of HII regions in NGC 4945)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/812/39/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/812/39/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/812/39/table4?GETtext/xml+votable180.050000true196.4304583-49.41111110.0055555555555555566/16441 43233https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/812/39?format=asciidefaultJ/ApJ/812/39/table5NGC 7793 fluxesIonIon designationphys.atmol.ionStagecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintReg[1/28] Region identifier (1)meta.id;obs.fieldintlambda[4861/6731] Wavelength in Angstroms0.1nmem.wlintFlux[4/3451]? Observed flux relative to H{beta} (1)phot.flux;arith.ratiofloatnullablee_Flux[0.02/130]? Error in Flux (1)stat.error;phot.fluxfloatnullableI[4/920]? Observed intensity relative to H{beta} (1)spect.line.intensity;arith.ratiofloatnullableJ/ApJ/812/39/table6NGC 4945 fluxesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintField[1/2]? Field identifier (only for table 6)meta.id;obs.fieldintnullableReg[1/28] Region identifier (1)meta.id;obs.fieldintIonIon designationphys.atmol.ionStagecharlambda[4861/6731] Wavelength in Angstroms0.1nmem.wlintFlux[4/3451]? Observed flux relative to H{beta} (1)phot.flux;arith.ratiofloatnullablee_Flux[0.02/130]? Error in Flux (1)stat.error;phot.fluxfloatnullableI[4/920]? Observed intensity relative to H{beta} (1)spect.line.intensity;arith.ratiofloatnullableJ/ApJ/812/39/table3Positions and distances and H{beta} flux of HII regions in NGC 7793f_RegFlag on Reg (1)meta.codecharRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintReg[1/28] Region numbermeta.id;meta.mainintprimaryDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainRg/R25[0.04/1] Isophotal radiusphys.size.radiusfloate_Rg/R25[0/0.07] Rg/R25 uncertaintystat.errorfloatRg[0.4/7.7] Galactocentric distancekpcpos.distance;pos.galactocentricfloate_Rg[0/1] Rg uncertaintykpcstat.errorfloatcbeta[0.09/3.5]? Extinction constant c{beta}phys.absorptionfloatnullablee_cbeta? cbeta uncertaintystat.errorfloatnullableFHb? H{beta} integrated flux (erg/cm^2^/s)0.001W.m**-2phot.flux;em.line.Hbetadoublenullablee_FHb? FHb uncertainty0.001W.m**-2stat.errordoublenullableNfDisplay the flux measurements for this regionmeta.ref.urlcharSpInteractive plot of spectrummeta.ref.urlcharJ/ApJ/812/39/table4Positions and distances and H{beta} flux of HII regions in NGC 4945f_RegFlag on Reg (1)meta.codechare_Rg[0/1] Rg uncertaintykpcstat.errorfloatSpInteractive plot of spectrummeta.ref.urlcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintField[1/2]? Field number (only for table 4)meta.id;obs.fieldintnullableReg[1/28] Region numbermeta.id;meta.mainintRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainRg/R25[0.04/1] Isophotal radiusphys.size.radiusfloate_Rg/R25[0/0.07] Rg/R25 uncertaintystat.errorfloatRg[0.4/7.7] Galactocentric distancekpcpos.distance;pos.galactocentricfloatcbeta[0.09/3.5]? Extinction constant c{beta}phys.absorptionfloatnullablee_cbeta? cbeta uncertaintystat.errorfloatnullableFHb? H{beta} integrated flux (erg/cm^2^/s)0.001W.m**-2phot.flux;em.line.Hbetadoublenullablee_FHb? FHb uncertainty0.001W.m**-2stat.errordoublenullableNfDisplay the flux measurements for this regionmeta.ref.urlchar