J/ApJ/510/104ivo://CDS.VizieR/J/ApJ/510/104doi:10.26093/cds/vizier.15100104CDSBresolin F.Kennicutt R. C.Garnett D. R.2017-10-13T15:41:58Z2005-11-15T15:42:19ZCDS support team

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

cds-question@unistra.frgalaxiesvisible-astronomyh-ii-regionsspectroscopyMedium-resolution spectra from 3650 to 10000 {AA} are presented for 96 giant H II regions distributed in 20 spiral galaxies. In order to interpret the data, we have calculated two separate grids of photoionization models, adopting single-star atmospheres (Kurucz) and star clusters synthesized with different initial mass functions (IMFs) as ionizing sources. Additional models were computed with more recent non-LTE stellar atmospheres, in order to check the effects of different stellar ionizing fluxes. We use the radiation softness parameter {eta}'=([O II]/[O III])/([S II]/[S III]) of Vilchez & Pagel (1988MNRAS.231..257V) to test for a metallicity dependence of the effective temperatures of the ionizing stars. Our results are consistent with a significant decrease in mean stellar temperatures of the ionizing stars with increasing metallicity. The magnitude of the effect, combined with the behavior of the He I {lambda}5876/H{beta} ratio, suggest a smaller upper mass limit for star formation at abundances higher than solar, even when considering the effects of metallicity on stellar evolution and atmospheric line blanketing. However, the exact magnitudes of the stellar temperature and IMF variations are dependent on the choice of stellar atmosphere and evolution models used, as well as on uncertainties in the nebular abundance scale at high metallicities. Our results also constrain the systematic behavior of the ionization parameter and the N/O ratio in extragalactic H II regions. The observed spectral sequences are inconsistent with current stellar evolution models, which predict a luminous, hot W-R stellar population in evolved H II regions older than 2-3 Myr. This suggests either that the hardness of the emitted Lyman continuum spectrum has been overestimated in the models or that some mechanism disrupts the H II regions before the W-R phases become important.1999ApJ...510..104Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/510/104CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+AS/112/35 : Emission lines from giant HII regions (Garcia Vargas+, 1995)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/510/104https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/510/104http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/510/104https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/510/104https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/510/104http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/510/104GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/510/104/table3 (Reddening-corrected line fluxes of HII regions)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/510/104/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/510/104/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/510/104/table3?GETtext/xml+votable180.050000true10.6410140.368170.0055555555555555566/2154 2155 2622 2623 2708 2709 3389 6034 7241 7606 7743 8320 10769 10856 10979 11027 13522 18398 27030 27512 27514 28173 31880 31881 43881https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/510/104?format=asciiOpticaldefaultJ/ApJ/510/104/table3Reddening-corrected line fluxes of HII regionsSeqGalaxy sequence numberinte_OIIUncertainty in OIIintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameGalaxy namecharRAoffRight ascension offset from the galaxy nucleusarcsecintDEoffDeclination offset from the galaxy nucleusarcsecintOIIOII (3727{AA}) flux (1)intOIIIOIII (5007+4959{AA}) flux (1)inte_OIIIUncertainty in OIIIintHeIHeI (5876{AA}) flux (1)inte_HeIUncertainty in HeIintNIINII (6548+6583{AA}) flux (1)inte_NIIUncertainty in NIIintSIISII (6716+6731{AA}) flux (1)inte_SIIUncertainty in SIIintSIII(9069+9532{AA}) flux (1)inte_SIIIUncertainty in SIIIintHIINameHII region names (2)charSimbadSimbad column added by the CDSchar_RAPosition, computed from the galaxy center as given by Simbad, and RA/Dec offsets (right ascension part)degpos.eq.ra;meta.main_DEPosition, computed from the galaxy center as given by Simbad, and RA/Dec offsets (declination part)degpos.eq.dec;meta.main