J/ApJ/921/176ivo://CDS.VizieR/J/ApJ/921/176doi:10.26093/cds/vizier.19210176CDSBalser D.S.Wenger T.V.Anderson L.D.Armentrout W.P.Bania T.M.,Dawson J.R.Dickey J.M.2023-08-25T09:42:38Z2023-04-04T13:53:56ZCDS support team

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

cds-question@unistra.frh-ii-regionsradio-continuum-emissioninterstellar-mediuminterferometryWe investigate the kinematic properties of Galactic HII regions using radio recombination line (RRL) emission detected by the Australia Telescope Compact Array at 4-10GHz and the Jansky Very Large Array at 8-10GHz. Our HII region sample consists of 425 independent observations of 374 nebulae that are relatively well isolated from other, potentially confusing sources and have a single RRL component with a high signal-to-noise ratio. We perform Gaussian fits to the RRL emission in position-position-velocity data cubes and discover velocity gradients in 178 (42%) of the nebulae with magnitudes between 5 and 200m/s/arcsec. About 15% of the sources also have an RRL width spatial distribution that peaks toward the center of the nebula. The velocity gradient position angles appear to be random on the sky with no favored orientation with respect to the Galactic plane. We craft HII region simulations that include bipolar outflows or solid body rotational motions to explain the observed velocity gradients. The simulations favor solid body rotation since, unlike the bipolar outflow kinematic models, they are able to produce both the large, >40m/s/arcsec, velocity gradients and also the RRL width structure that we observe in some sources. The bipolar outflow model, however, cannot be ruled out as a possible explanation for the observed velocity gradients for many sources in our sample. We nevertheless suggest that most HII region complexes are rotating and may have inherited angular momentum from their parent molecular clouds.2021ApJ...921..176Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/921/176CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJS/194/32 : The HII Region Discovery Survey (HRDS). II. (Anderson+, 2011)J/ApJ/752/148 : {kappa}-distributed electrons & OIII (Nicholls+, 2012)J/ApJS/212/1 : The WISE catalog of Galactic HII regions (Anderson+, 2014)J/ApJS/221/26 : Radio obs. of Galactic WISE HII regions (Anderson+, 2015)J/A+A/587/A135 : Halpha images of NGC 6334 and NGC 6357 (Russeil+, 2016)J/AJ/154/23 : Southern HII Region Discovery Survey: pilot (Brown+, 2017)J/ApJS/234/33 : A GBT survey of large Galactic HII regions (Anderson+, 2018)J/ApJ/887/114 : VLA ~8-10GHz obs. of WISE Galactic HII regions (Wenger+, 2019)J/ApJS/254/36 : Southern HII Region Discovery Survey. II. (Wenger+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/921/176https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/921/176http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/921/176https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/921/176https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/921/176http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/921/176GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/921/176/table2 (ATCA HII region (SHRDS; Wenger+ 2021, J/ApJS/254/36))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/921/176/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/921/176/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/921/176/table2?GETtext/xml+votable180.050000true273.56297-17.933060.005555555555555556Cone search capability for table J/ApJ/921/176/table3 (VLA HII region (Wenger+ 2019, J/ApJ/887/114))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/921/176/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/921/176/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/921/176/table3?GETtext/xml+votable180.050000true273.64893-16.752760.0055555555555555566/14622 14624 15473 21504 28808 28812 28814 28826 29101 29114 30245 30318-30319 30423 30694 37239 37335 37366 37369 37884 37886 37899-37900 37921 37923 38018 38024 38026 39250 39276 41599 41655 41657-41658 41660 41676 41681-41683 41685 41696 41759 41767 41769 41772 41776-41777 41779-41780 41782 41804-41805 41811 41815-41817 41820 41824 42159 42169-42170 42172-42174 42206-42207 42210 42212 42214-42216 42224-42226 42228-42230 42382 42387 42391 42393 42396-42398 42435-42436 42445 42447 42449 42451 42455-42457 42460 42497-42498 42500-42501 42516 43018-43021 43027https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/921/176?format=asciiRadiodefaultJ/ApJ/921/176/table2ATCA HII region (SHRDS; Wenger+ 2021, J/ApJS/254/36)_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.raindexed_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.decindexedrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDSource identifier (GLLL.lll+BB.bbb) (1)meta.id;meta.maincharFieldField identifiermeta.id;obs.fieldcharc0[-129.13/116.85] Velocity offsetkm/sphys.veloc;arith.difffloate_c0[0/0.51] Uncertainty in c0km/sstat.errorfloatGradient[1.8/668] Velocity gradient magnitudem.s**-1.arcsec**-1arith.grad;phys.velocfloate_Gradient[0.05/46] Uncertainty in Gradientm.s**-1.arcsec**-1stat.errorfloatPA[0.4/358] Position angledegpos.posAngfloate_PA[0.5/22.2] Uncertainty in PAdegstat.errorfloatQFQuality factor (A=highest); see textmeta.code.qualcharNbeam[1/11.2] Number of beamsmeta.numberfloatPkSNR[16/551] Peak Signal-to-Noisestat.snr;stat.maxfloatRMS[0.13/9.2] Root mean square errorkm/sstat.stdev;instr.det.noisefloatWCatDisplay data from the WISE cat. of Gal. HII regions (Anderson+, 2014, J/ApJS/212/1)meta.ref.urlchar_GlonPositions from names (longitude part)degpos.galactic.lon_GlatPositions from names (latitude part)degpos.galactic.latJ/ApJ/921/176/table3VLA HII region (Wenger+ 2019, J/ApJ/887/114)PkSNR[16/551] Peak Signal-to-Noisestat.snr;stat.maxfloatRMS[0.13/9.2] Root mean square errorkm/sstat.stdev;instr.det.noisefloat_GlonPositions from names (longitude part)degpos.galactic.lon_GlatPositions from names (latitude part)degpos.galactic.latIDSource identifier (GLLL.lll+BB.bbb) (1)meta.id;meta.maincharFieldField identifiermeta.id;obs.fieldcharQFQuality factor (A=highest); see textmeta.code.qualcharWCatDisplay data from the WISE cat. of Gal. HII regions (Anderson+, 2014, J/ApJS/212/1)meta.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.raindexed_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.decindexedrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintc0[-129.13/116.85] Velocity offsetkm/sphys.veloc;arith.difffloate_c0[0/0.51] Uncertainty in c0km/sstat.errorfloatGradient[1.8/668] Velocity gradient magnitudem.s**-1.arcsec**-1arith.grad;phys.velocfloate_Gradient[0.05/46] Uncertainty in Gradientm.s**-1.arcsec**-1stat.errorfloatPA[0.4/358] Position angledegpos.posAngfloate_PA[0.5/22.2] Uncertainty in PAdegstat.errorfloatNbeam[1/11.2] Number of beamsmeta.numberfloat