J/A+A/645/A110ivo://CDS.VizieR/J/A+A/645/A110doi:10.26093/cds/vizier.36450110CDSYang A.Y.Urquhart J.S.Thompson M.A.Menten K.M.Wyrowski F.,Brunthaler A.Tian W.W.Rugel M.Yang X.L.Yao S.Mutale M.2023-01-11T14:05:58Z2021-01-22T09:30:08ZCDS support team

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

cds-question@unistra.frinterstellar-mediumh-ii-regionsradio-continuum-emissionThe derived physical parameters for young HII regions are normally determined assuming the emission region to be optically-thin. However, this is unlikely to hold for young HII regions such as Hyper-compact HII(HCHII) and Ultra-compact HII(UCHII) regions and leads to the underestimation of their properties. This can be overcome by fitting the SEDs over a wide range of radio frequencies. Two primary goals are (1) determining physical properties from radio SEDs and finding potential HCHII regions; (2) using these physical properties to investigate their evolution. We used Karl G. Jansky Very Large Array (VLA) to make observations of X-band and K-band with angular-resolutions of ~1.7" and ~0.7", respectively, toward 114 HII regions with rising-spectra between 1-5GHz. We complement our observations with VLA archival data and construct SEDs between 1-26GHz and model them assuming an ionisation-bounded HII region with uniform density. The sample has a mean electron density of ne=1.6*10^4^cm^-3^, diameter diam=0.14pc, and emission measure EM=1.9*10^7^pc/cm^6^. We identify 16 HCHII region candidates and 8 intermediate objects between the classes of HCHII and UCHII regions. The ne, diam, and EM change as expected, however, the Lyman continuum flux is relatively constant over time. We find that about 67% of Lyman continuum photons are absorbed by dust within these HII regions and the dust absorption fraction tends to be more significant for more compact and younger HII regions. Young HII regions are commonly located in dusty clumps; HCHII regions and intermediate objects are often associated with various masers, outflows, broad radio recombination lines, and extended green objects, and the accretion at the two stages tends to be quickly reduced or halted.2021A&A...645A.110Yhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/645/A110CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/131/2525 : MAGPIS 20cm survey (Helfand+, 2006)J/MNRAS/435/400 : ATLASGAL compact HII regions (Urquhart+, 2013)J/MNRAS/473/1059 : Complete sample of Galactic clumps (Urquhart+, 2018)J/A+A/615/A103 : CORNISH project. III. UCHII region catalogueJ/A+A/579/A71 : Infrared emission of young HII regions (Cesaroni+, 2015)J/ApJS/235/3 : Massive outflows associated with ATLASGAL clumpshttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/645/A110https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/645/A110http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/645/A110https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/645/A110https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/645/A110http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/645/A110GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/645/A110/table1 (The 118 rising-spectra HII regions)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/645/A110/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/645/A110/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/645/A110/table1?GETtext/xml+votable180.050000true272.233639-20.0986360.005555555555555556Cone search capability for table J/A+A/645/A110/table3 (Observation results of 112 young HII regions at X-band (8-12GHz) and K-band (18-26GHz))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/645/A110/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/645/A110/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/645/A110/table3?GETtext/xml+votable180.050000true272.233639-20.0986360.005555555555555556Cone search capability for table J/A+A/645/A110/table5 (Derived physical properties of 116 young HII regions)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/645/A110/table5?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/645/A110/table5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/645/A110/table5?GETtext/xml+votable180.050000true272.233639-20.0986360.0055555555555555565/7578 6/14358-14359 29091 29094 29097 29100-29101 29112 29114-29115 29461 29504-29505 29507-29508 29510-29511 29522 29532-29533 30218-30219 30240 30244-30245 30256 30258-30259 30262 30268-30269 30318-30319 30405 30416 30420 30423 30594 30605 30616 30618 30622 30644 30691 30694 30701 30714 30718-307199.276497240453405e-25 1.5902566968739225e-23https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/645/A110?format=asciiRadiodefaultJ/A+A/645/A110/table1The 118 rising-spectra HII regionsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSimbadSimbad column added by the CDSmeta.ref.urlchar_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.decnullableindexedNameGalactic name (GLLL.llll+BB.bbbb)meta.id;meta.maincharn_Name[+*] Note on Name (1)meta.notecharS1.4GHz? Integrated flux density at 1.4GHzmJyphot.flux.density;em.radio.750-1500MHzfloatnullableS5GHzIntegrated flux density at 5GHzmJyphot.flux.density;em.radio.3-6GHzdoubleDist? Heliocentric distancekpcpos.distancefloatnullablelogLb? Log bolometric luminositylog(solLum)phys.luminosityfloatnullabler_logLbReferences for luminosity and distance (2)meta.ref;pos.frameint_GlonRight Ascension (J2000) from SIMBAD (not part of the original data)degpos.galactic.lon_GlatDeclination (J2000) from SIMBAD (not part of the original data)degpos.galactic.latJ/A+A/645/A110/table3Observation results of 112 young HII regions at X-band (8-12GHz) and K-band (18-26GHz)S20GHz? Integrated flux density at 20 GHzmJyphot.flux.density;em.radio.12-30GHzfloatnullableS22GHz? Integrated flux density at 22 GHzmJyphot.flux.density;em.radio.12-30GHzfloatnullableS24GHz? Integrated flux density at 24 GHzmJyphot.flux.density;em.radio.12-30GHzfloatnullablethetaKa? Deconvolved angular size at K band (major axis)arcsecphys.angSizefloatnullable_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.decnullableindexedrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameGalactic name (GLLL.llll+BB.bbbb)meta.id;meta.maincharn_Name[o+] Note on Name (1)meta.notecharSpeakX? Peak flux density at the central frequency (10GHz) of X-bandmJy/beamphot.flux.density;em.radio.6-12GHzfloatnullablesigmaXrms of the the central frequency (10GHz) of X-bandmJyinstr.det.noisefloatS9GHzIntegrated flux density at 9 GHzmJyphot.flux.density;em.radio.6-12GHzfloatS10GHzIntegrated flux density at 10 GHzmJyphot.flux.density;em.radio.6-12GHzfloatS11GHzIntegrated flux density at 11 GHzmJyphot.flux.density;em.radio.6-12GHzfloatthetaXaDeconvolved angular size (major axis) at X bandarcsecphys.angSize;instr.detfloatthetaXbDeconvolved angular size (minor axis) at X bandarcsecphys.angSize;instr.detfloatSpeakKPeak flux density at the central frequency (22GHz) of K-bandmJy/beamphot.flux.density;em.radio.12-30GHzfloatsigmaKrms of the the central frequency (22GHz) of K-bandmJyinstr.det.noisefloatthetaKb? Deconvolved angular size at K band (minor axis)arcsecphys.angSizefloatnullable_GlonRight Ascension (J2000) from SIMBAD (not part of the original data)degpos.galactic.lon_GlatDeclination (J2000) from SIMBAD (not part of the original data)degpos.galactic.latJ/A+A/645/A110/table5Derived physical properties of 116 young HII regionsNameGalactic name (GLLL.llll+BB.bbbb)meta.id;meta.maincharnutTurnover frequencyGHzem.freqfloatlogNLyLyman continuum photonslog(s**-1)phot.count;em.X-rayfloatSptypeSpectral type derived from Lyman continuum fluxsrc.spTypecharfd? fraction of ionizing photons absorbed by dust within HII regions (1)meta.numberfloatnullableCbandName of the C-band image in subdirectory imagesmeta.notecharKbandName of the K-band image in subdirectory imagesmeta.notecharXbandName of the X-band image in subdirectory imagespos.cartesian.x;obs.imagecharFitName of the fitting image in subdirectory imagesmeta.id;meta.filechar_GlonRight Ascension (J2000) from SIMBAD (not part of the original data)degpos.galactic.lon_GlatDeclination (J2000) from SIMBAD (not part of the original data)degpos.galactic.lat_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data. The format may include more digits than the original data because of internal accuracy requirements in VizieR and across other CDS services)degpos.eq.decnullableindexedrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintneElectron number densitycm**-3meta.idfloatDiamphysical linear diameterpcpos.distancefloatEMEmission measurepc.cm**-6phys.emissMeasurefloat