J/MNRAS/450/2025ivo://CDS.VizieR/J/MNRAS/450/2025doi:10.26093/cds/vizier.74502025CDSAlves M.I.R.Calabretta M.Davies R.D.Dickinson C.Staveley-Smith L.,Davis R.J.Chen T.Barr A.2024-08-14T20:21:42Z2016-01-29T16:35:44ZCDS support team

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

cds-question@unistra.frgalaxy-planesmilky-way-galaxyh-ii-regionsgalaxy-classification-systemsradio-astronomyWe present a Radio Recombination Line (RRL) survey of the Galactic plane from the Hi Parkes All-sky Survey and associated Zone of Avoidance survey, which mapped the region l=196{deg}-0{deg}-52{deg} and |b|<=5{deg} at 1.4GHz and 14.4-arcmin resolution. We combine three RRLs, H168{alpha}, H167{alpha}, and H166{alpha} to derive fully sampled maps of the diffuse ionized emission along the inner Galactic plane. The velocity information, at a resolution of 20km/s, allows us to study the spatial distribution of the ionized gas and compare it with that of the molecular gas, as traced by CO. The longitude-velocity diagram shows that the RRL emission is mostly associated with CO gas from the molecular ring and is concentrated within the inner 30{deg} of longitude. A map of the free-free emission in this region of the Galaxy is derived from the line-integrated RRL emission, assuming an electron temperature gradient with Galactocentric radius of 496+/-100K/kpc. Based on the thermal continuum map, we extracted a catalogue of 317 compact (<~15-arcmin) sources, with flux densities, sizes, and velocities. We report the first RRL observations of the southern ionized lobe in the Galactic Centre. The line profiles and velocities suggest that this degree-scale structure is in rotation. We also present new evidence of diffuse ionized gas in the 3-kpc arm. Helium and carbon RRLs are detected in this survey. The He line is mostly observed towards HII regions, whereas the C line is also detected further away from the source of ionization. These data represent the first observations of diffuse C RRLs in the Galactic plane at a frequency of 1.4GHz.2015MNRAS.450.2025Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/450/2025CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVIII/73 : HI Parkes All Sky Survey Catalogue (HIPASS) (Meyer+, 2004)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/450/2025https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/450/2025http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/450/2025https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/450/2025https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/450/2025http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/450/2025GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/450/2025/table2 (List of 317 HII regions in the range l=196{deg}-0{deg}-52{deg} and |b|<=5{deg}, extracted from the thermal continuum map of Fig. 7 using Sextractor)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/450/2025/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/450/2025/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/450/2025/table2?GETtext/xml+votable180.050000true267.0677-27.95630.0055555555555555565/9341 10453 10553 10556 6/20849 21646 22208 22249 22252 23645 28807-28809 28811-28813 28815 28824-28825 28831 28849 28890 28892 28896-28897 28900-28901 28912-28913 28915-28916 28918-28919 29088 29090-29091 29094-29095 29097 29100-29101 29112 29114-29115 29118-29119 29463 29467 29504-29505 29508 29510 29513 29515 29522 29529 29532 29535 30218-30219 30241 30244-30245 30258-30259 30262 30269 30271 30312-30313 30315 30317-30319 30329-30330 30341 30405 30417 30419-30420 30422-30423 30601 30604-30605 30618-30619 30622 30624 30644-30645 30691 30694-30695 30707 30712 30715 37333-37335 37339 37363 37371 37753 37842 37846 37850 37872 37884 37886 37895 37897 37899 37906 37921 37923 37925-37926 37928 37931 38017-38018 38024 39249 39259 39384 39386 39804 39922 41655 41657-41658 41663 41671 41675-41678 41681-41685 41689 41743 41756 41758-41759 41765 41767 41772-41773 41777-41782 41798 41803-41806 41811 41816-41817 41820 41824 41856 42159 42168 42170-42172 42174 42203 42206-42207 42210-42211 42216-42217 42228-42229 42376 42378-42379 42381-42382 42387 42390-42392 42395-42398 42417 42436 42438-42441 42444-42445 42447 42449 42454 42457 42460-42461 42481 42497-42498 42501-42503 42516 42561 43019 43024 43026 430409.276497240453405e-25 9.276497240453405e-25https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/450/2025?format=asciiOpticalRadiodefaultJ/MNRAS/450/2025/table2List of 317 HII regions in the range l=196{deg}-0{deg}-52{deg} and |b|<=5{deg}, extracted from the thermal continuum map of Fig. 7 using SextractorSeqSequential numbermeta.recordintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintGLONGalactic longitudedegpos.galactic.lonGLATGalactic latitudedegpos.galactic.latamaj? Semi-major axisarcminphys.angSizefloatnullablebmin? Semi-minor axisarcminphys.angSize.sminAxisfloatnullablePA[]? Position angle measured counterclockwise between the semimajor axis of the source and the longitude axisdegphys.angSize.smajAxisintnullableSpPeak flux at 1.4GHz (in Jy/beam)Jyphot.flux.density;em.radio.750-1500MHzfloate_SpError in peak flux (in Jy/beam)Jystat.error;src.spTypefloatSIntegrated flux at 1.4GHzJyphot.flux.density;em.radio.750-1500MHzfloate_SError in integrated fluxJystat.errorfloatV1RRL central velocity from a one- or two-component Gaussian fitkm/sphys.velocfloatV2? Second RRL central velocity from a two-component Gaussian fitkm/sphys.velocfloatnullableFlagFlag parameter (1)meta.code.errorintNotesGeneral remarks on the source (2)meta.notechar_RA.icrsRight ascension (ICRS) (computed by VizieR, not part of the original data)degpos.eq.ranullableindexed_DE.icrsDeclination (ICRS) (computed by VizieR, not part of the original data)degpos.eq.decnullableindexed