J/ApJ/853/151ivo://CDS.VizieR/J/ApJ/853/151doi:10.26093/cds/vizier.18530151CDSMao Y.-W.Lin L.Kong Xu2018-12-11T12:57:17Z2018-12-05T15:23:47ZCDS support team

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

cds-question@unistra.frgalaxiesh-ii-regionschemical-abundancesvisible-astronomyspectroscopyinterstellar-mediumThis paper presents a spectroscopic investigation of 11 HII regions in the nearby galaxy NGC 2403. The HII regions are observed with a long-slit spectrograph mounted on the 2.16m telescope at XingLong station of National Astronomical Observatories of China. For each of the HII regions, spectra are extracted at different nebular radii along the slit-coverage. Oxygen abundances are empirically estimated from the strong-line indices R23, N2O2, O3N2, and N2 for each spectrophotometric unit, with both observation- and model-based calibrations adopted into the derivation. Radial profiles of these diversely estimated abundances are drawn for each nebula. In the results, the oxygen abundances separately estimated with the prescriptions on the basis of observations and models, albeit from the same spectral index, systematically deviate from each other; at the same time, the spectral indices R23 and N2O2 are distributed with flat profiles, whereas N2 and O3N2 exhibit apparent gradients with the nebular radius. Because our study naturally samples various ionization levels, which inherently decline at larger radii within individual HII regions, the radial distributions indicate not only the robustness of R23 and N2O2 against ionization variations but also the sensitivity of N2 and O3N2 to the ionization parameter. The results in this paper provide observational corroboration of the theoretical prediction about the deviation in the empirical abundance diagnostics. Our future work is planned to investigate metal-poor HII regions with measurable Te, in an attempt to recalibrate the strong-line indices and consequently disclose the cause of the discrepancies between the empirical oxygen abundances.2018ApJ...853..151Mhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/853/151CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/116/2805 : H II regions in spiral galaxies (Van Zee+, 1998)J/ApJ/510/104 : Ionizing Stars of Extragalactic H II Regions (Bresolin+ 1999)J/ApJ/513/168 : HST observations of carbon in spiral galaxies (Garnett+, 1999)J/ApJS/190/233 : Spectroscopy & abundances of SINGS galaxies (Moustakas+, 2010)J/AJ/139/1066 : X-ray view of NGC 2403 central region (Yukita+, 2010)J/ApJ/755/40 : HII reg. in Magellanic clouds from MCELS (Pellegrini+, 2012)J/ApJS/208/10 : {kappa}-distribution effects in HII regions (Dopita+, 2013)J/A+A/569/A68 : Green Bank Telescope observations of NGC 2403 (de Blok+, 2014)J/ApJ/789/76 : UV and IR properties for galaxies (Mao+, 2014)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/853/151https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/853/151http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/853/151https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/853/151https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/853/151http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/853/151GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/853/151/hiireg (Basic properties (table 1) and empirical oxygen abundances (12+log(O/H)) for the HII regions with integrated measurements (table 4) and for the centers of the HII regions (table5))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/853/151/hiireg?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/853/151/hiireg?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/853/151/hiireg?GETtext/xml+votable180.050000true114.08333365.6186110.0055555555555555566/7743https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/853/151?format=asciiOpticaldefaultJ/ApJ/853/151/table2Observed emission-line fluxes for the spectrophotometric unitsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRegHII region identifiermeta.id.parentcharIDSource identifier within Regmeta.id;meta.maincharHb[0.3/289.2] H{beta} line flux; in 1e-15erg/s/cm^2^ units1e-18W.m**-2phot.flux;em.line.Hbetafloate_Hb[0.1/2.2] Uncertainty in Hb1e-18W.m**-2stat.errorfloatOII-3727[1.2/21.1] The [OII]3727{AA} line flux (1)phot.fluxfloate_OII-3727[0.02/5.8] Uncertainty in OII-3727stat.errorfloatHg[0.3/1.4] The H{gamma} line flux (1)phot.flux;em.line.Hgamma;spect.linefloate_Hg[0/0.7]? Uncertainty in Hgstat.errorfloatnullableOIII-4959[0.2/1.5] The [OIII]4959{AA} line flux (1)phot.fluxfloate_OIII-4959[0/0.7] Uncertainty in OIII-4959stat.errorfloatOIII-5007[0.6/4.5] The [OIII]5007{AA} line flux (1)phot.fluxfloate_OIII-5007[0.01/1.1] Uncertainty in OIII-5007stat.errorfloatHa[1.7/4.3] H{alpha} line flux (1)phot.flux;em.line.Halpha;spect.linefloate_Ha[0.01/1.1] Uncertainty in Hastat.errorfloatNII-6583[0.09/0.9]? The [NII]6583{AA} line flux (1)phot.fluxfloatnullablee_NII-6583[0/1.6]? Uncertainty in NII-6583stat.errorfloatnullableJ/ApJ/853/151/table3Attenuation-corrected emission-line fluxes for the spectrophotometric unitsIDSource identifier within Regmeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRegHII region identifiermeta.id.parentcharHb[0.4/347.3] H{beta} line flux; in 1e-15erg/s/cm^2^ units1e-18W.m**-2phot.flux;em.line.Hbetafloate_Hb[0.1/9.7] Uncertainty in Hb1e-18W.m**-2stat.errorfloatOII-3727[1.2/21.7] The [OII]3727{AA} line flux (1)phot.fluxfloate_OII-3727[0.03/29.7] Uncertainty in OII-3727stat.errorfloatHg[0.3/1.4] The H{gamma} line flux (1)phot.flux;em.line.Hgamma;spect.linefloate_Hg[0.01/1.3]? Uncertainty in Hgstat.errorfloatnullableOIII-4959[0.2/1.5] The [OIII]4959{AA} line flux (1)phot.fluxfloate_OIII-4959[0.01/0.7] Uncertainty in OIII-4959stat.errorfloatOIII-5007[0.6/4.5] The [OIII]5007{AA} line flux (1)phot.fluxfloate_OIII-5007[0.01/2] Uncertainty in OIII-5007stat.errorfloatHa[1.7/2.9] H{alpha} line flux (1)phot.flux;em.line.Halpha;spect.linefloate_Ha[0.02/3] Uncertainty in Hastat.errorfloatNII-6583[0.08/0.8]? The [NII]6583{AA} line flux (1)phot.fluxfloatnullablee_NII-6583[0/1.7]? Uncertainty in NII-6583stat.errorfloatnullableJ/ApJ/853/151/hiiregBasic properties (table 1) and empirical oxygen abundances (12+log(O/H)) for the HII regions with integrated measurements (table 4) and for the centers of the HII regions (table5)SimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFluxesDisplay the emission-line fluxes (not corrected (table2) and corrected (table3))meta.ref.urlcharRegHII region identifier (1)meta.id;meta.maincharprimaryRAJ2000Hour of right ascension (J2000) (2)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000) (2)pos.eq.dec;meta.mainFHa[0.3/30.1] H{alpha} flux in 10^-13^erg/s/cm^2^ units (1)1e-16W.m**-2phot.flux;em.line.Halphafloatf_FHa[a] Flag on FHa for HII region no. 351 (3)meta.codecharDateObservation date (UT)time.epoch;obsnullableExpExposure timestime.duration;obs.exposureintNexpNumber of exposuremeta.numberintStdStandard star selected from the IRS catalog (Corbin & Warren 1991, I/172)meta.idcharSlit[-78/63] Rotation angle of the spectrographic slit (4)degobs.paramfloatAirmass[1.1/1.2] Airmass at each slit positionobs.airMassfloatR23K99i[8.4/8.9] R23 calibration addressed in Kobulnicky+ (1999ApJ...514..544K); integrated measurementsphys.abundfloate_R23K99i[0.008/0.08] R23K99i uncertaintystat.errorfloatN2O2K02i[8.2/8.9]? N2O2 calibration addressed in Kewley & Dopita (2002ApJS..142...35K); integrated measurementsphys.abundfloatnullablee_N2O2K02i[0.006/0.07]? N2O2K02i uncertaintystat.errorfloatnullableR23P05i[7.9/8.6] R23 calibration addressed in Pilyugin & Thuan (2005ApJ...631..231P); integrated measurementsphys.abundfloate_R23P05i[0.009/0.09] R23P05i uncertaintystat.errorfloatN2O2B07i[7.9/8.5]? N2O2 calibration addressed in Bresolin (2007ApJ...656..186B); integrated measurementsphys.abundfloatnullablee_N2O2B07i[0.006/0.06]? N2O2B07i uncertaintystat.errorfloatnullableO3N2P04i[8/8.5]? O3N2 calibration addressed in Pettini & Pagel (2004MNRAS.348L..59P); integrated measurementsphys.abundfloatnullablee_O3N2P04i[0.003/0.03]? O3N2P04i uncertaintystat.errorfloatnullableN2P04i[8/8.4]? N2 calibration addressed in Pettini & Pagel (2004MNRAS.348L..59P); integrated measurementsphys.abundfloatnullablee_N2P04i[0.004/0.03]? N2P04i uncertaintystat.errorfloatnullableR23K99[8.5/8.9] R23 calibration addressed in Kobulnicky+ (1999ApJ...514..544K); HII centerphys.abundfloate_R23K99[0.004/0.08] R23K99 uncertaintystat.errorfloatN2O2K02[8.2/9]? N2O2 calibration addressed in Kewley & Dopita (2002ApJS..142...35K); HII centerphys.abundfloatnullablee_N2O2K02[0.005/0.07]? N2O2K02 uncertaintystat.errorfloatnullableR23P05[8.1/8.7] R23 calibration addressed in Pilyugin & Thuan (2005ApJ...631..231P); HII centerphys.abundfloate_R23P05[0.004/0.09] R23P05 uncertaintystat.errorfloatN2O2B07[7.9/8.5]? N2O2 calibration addressed in Bresolin (2007ApJ...656..186B); HII centerphys.abundfloatnullablee_N2O2B07[0.004/0.07]? N2O2B07 uncertaintystat.errorfloatnullableO3N2P04[8/8.5]? O3N2 calibration addressed in Pettini & Pagel (2004MNRAS.348L..59P); HII centerphys.abundfloatnullablee_O3N2P04[0.002/0.03]? O3N2P04 uncertaintystat.errorfloatnullableN2P04[8/8.4]? N2 calibration addressed in Pettini & Pagel (2004MNRAS.348L..59P); HII centerphys.abundfloatnullablee_N2P04[0.003/0.04]? N2P04 uncertaintystat.errorfloatnullable