J/ApJ/559/864ivo://CDS.VizieR/J/ApJ/559/864doi:10.26093/cds/vizier.15590864CDSJohnson K.E.Kobulnicky H.A.Massey P.Conti P.S.2007-06-23T09:54:20Z2007-06-23T09:51:36ZCDS support team

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

cds-question@unistra.frh-ii-regionsradio-continuum-emissionWe report on the detection of optically thick free-free radio sources in the galaxies M33, NGC 253, and NGC 6946 using data in the literature. We interpret these sources as being young embedded star birth regions that are likely to be clusters of ultracompact H II regions. All 35 of the sources presented in this article have positive radio spectral indices ({alpha}>0 for S_{nu}_){prop.to}{nu}^{alpha}^), suggesting an optically thick thermal bremsstrahlung origin from the H II region surrounding the hot stars.2001ApJ...559..864Jhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/559/864CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/336/339 : VLA observations of ultracompact HII regions (Molinari+ 1998)J/A+AS/120/283 : Water maser features in UC HII regions (Hofner+ 1996)J/A+AS/133/29 : Molecular line survey towards UC HII (Hatchell+ 1998)J/ApJS/91/659 : Ultracompact HII regions radio images (Kurtz+ 1994)J/MNRAS/291/261 : Ultracompact HII regions studies. I. (Walsh+ 1997)J/MNRAS/301/640 : Ultracompact HII regions studies. II. (Walsh+, 1998)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/559/864https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/559/864http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/559/864https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/559/864https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/559/864http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/559/864GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/559/864/ngc6946 (Ultra-dense HII candidates in NGC 6946 (adopted distance: 5.1Mpc))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/559/864/ngc6946?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/559/864/ngc6946?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/559/864/ngc6946?GETtext/xml+votable180.050000true308.582458360.16846110.005555555555555556Cone search capability for table J/ApJ/559/864/m33 (Ultra-dense HII candidates in M33 (adopted distance: 840kpc))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/559/864/m33?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/559/864/m33?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/559/864/m33?GETtext/xml+votable180.050000true23.2630.7785830.005555555555555556Cone search capability for table J/ApJ/559/864/ngc0253 (Ultra-dense HII candidates in NGC 253 (adopted distance: 2.5Mpc))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/559/864/ngc0253?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/559/864/ngc0253?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/559/864/ngc0253?GETtext/xml+votable180.050000true11.8864583-25.289150.0055555555555555566/2155 2241 15592 15593 16655https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/559/864?format=asciiRadiodefaultJ/ApJ/559/864/ngc6946Ultra-dense HII candidates in NGC 6946 (adopted distance: 5.1Mpc)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[JKM2001]Source identification (NGC 6946 NN)meta.id;meta.mainintRAJ2000Right ascension (J2000) (1)pos.eq.ra;meta.mainDEJ2000Declination (J2000) (1)pos.eq.dec;meta.mainL6cm6cm luminosity1e+17W.Hz**-1phys.luminosity;em.radiofloate_L6cmrms uncertainty on L6cm1e+17W.Hz**-1stat.errorfloatn_L6cm[*] Note on L6cm (2)meta.notecharL20cm20cm luminosity1e+17W.Hz**-1phys.luminosity;em.radiofloate_L20cmrms uncertainty on L20cm1e+17W.Hz**-1stat.errorfloatn_L20cm[*] Note on L20cm (2)meta.notecharQLycProduction rate of Lyman continuum photon1e+49s**-1phot.count;em.UVfloate_QLycrms uncertainty on QLyc1e+49s**-1stat.errorfloatSISpectral index 20cm to 6cmspect.index;em.radio.750-1500MHzfloate_SIrms uncertainty on SIstat.errorfloatRR-band counterpart ?meta.notecharHalphaH{alpha} counterpart ?meta.notechar[LDG97]Lacey et al. (1997ApJS..109..417) numbermeta.idintJ/ApJ/559/864/m33Ultra-dense HII candidates in M33 (adopted distance: 840kpc)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[JKM2001]Source identification (M33 NN)meta.id;meta.mainintRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainL6cm6cm luminosity1e+16W.Hz**-1phys.luminosity;em.radiofloate_L6cmrms uncertainty on L6cm1e+16W.Hz**-1stat.errorfloatL20cm20cm luminosity1e+16W.Hz**-1phys.luminosity;em.radiofloate_L20cmrms uncertainty on L20cm1e+16W.Hz**-1stat.errorfloatQLycProduction rate of Lyman continuum photon1e+49s**-1phot.count;em.UVfloate_QLycrms uncertainty on QLyc1e+49s**-1stat.errorfloatSISpectral index 20cm to 6cmspect.index;em.radio.750-1500MHzfloate_SIrms uncertainty on SIstat.errorfloatBB-band counterpart ?meta.notecharHIIHII counterpart ? (1)meta.notechar[GDK99]Gordon et al. (1999, Cat. <J/ApJS/120/247> numbermeta.idintJ/ApJ/559/864/ngc0253Ultra-dense HII candidates in NGC 253 (adopted distance: 2.5Mpc)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[JKM2001]Source identification (NGC 253 N)meta.id;meta.mainintRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainL1.3cm1.3cm luminosity1e+17W.Hz**-1phys.luminosity;em.radiofloate_L1.3cmrms uncertainty on L1.3cm1e+17W.Hz**-1stat.errorfloatL2cm? 2cm luminosity1e+17W.Hz**-1phys.luminosity;em.radiofloatnullablee_L2cm? rms uncertainty on L2cm1e+17W.Hz**-1stat.errorfloatnullableL3.6cm3.6cm luminosity1e+17W.Hz**-1phys.luminosity;em.radiofloate_L3.6cmrms uncertainty on L3.6cm1e+17W.Hz**-1stat.errorfloatQLycProduction rate of Lyman continuum photon1e+49s**-1phot.count;em.UVinte_QLycrms uncertainty on QLyc1e+49s**-1stat.errorintSISpectral index 3.6cm to 1.3cmspect.index;em.radio.6-12GHzfloate_SIrms uncertainty on SIstat.errorfloatII-band counterpart ?meta.notecharHalphaH{alpha} counterpart ?meta.notechar[AU88]Ulvestad & Antonucci (1997ApJ...488..621U) numbermeta.idchar