J/ApJ/841/121ivo://CDS.VizieR/J/ApJ/841/121doi:10.26093/cds/vizier.18410121CDSArmentrout W.P.Anderson L.D.Balser D.S.Bania T.M.Dame T.M.,Wenger T.V.2025-05-22T20:11:18Z2023-09-25T07:08:47ZCDS support team

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

cds-question@unistra.frmilky-way-galaxyh-ii-regionsradio-astronomyinfrared-sourcesmolecular-physicsThe Outer Scutum-Centaurus (OSC) spiral arm is the most distant molecular spiral arm in the Milky Way, but until recently little was known about this structure. Discovered by Dame and Thaddeus, the OSC lies ~15kpc from the Galactic Center. Due to the Galactic warp, it rises to nearly 4{deg} above the Galactic Plane in the first Galactic quadrant, leaving it unsampled by most Galactic plane surveys. Here we observe HII region candidates spatially coincident with the OSC using the Very Large Array to image radio continuum emission from 65 targets and the Green Bank Telescope to search for ammonia and water maser emission from 75 targets. This sample, drawn from the Wide-field Infrared Survey Explorer Catalog of Galactic HII Regions, represents every HII region candidate near the longitude-latitude (l,b) locus of the OSC. Coupled with their characteristic mid-infrared morphologies, detection of radio continuum emission strongly suggests that a target is a bona fide HII region. Detections of associated ammonia or water maser emission allow us to derive a kinematic distance and determine if the velocity of the region is consistent with that of the OSC. Nearly 60% of the observed sources were detected in radio continuum, and more than 20% have ammonia or water maser detections. The velocities of these sources mainly place them beyond the Solar orbit. These very distant high-mass stars have stellar spectral types as early as O4. We associate high-mass star formation at 2 new locations with the OSC, increasing the total number of detected HII regions in the OSC to 12.2017ApJ...841..121Ahttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/841/121CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toVII/20 : Catalogue of HII Regions (Sharpless 1959)VIII/76 : Leiden/Argentine/Bonn (LAB) Survey of Galactic HI (Kalberla+ 2005)J/A+A/275/67 : Velocity Field of the outer Galaxy (Brand+ 1993)J/A+AS/103/541 : Arcetri Catalogue of H2O Maser Sources (Brand+ 1994)J/A+AS/115/81 : A CS(2-1) survey of UC HII regions (Bronfman+, 1996)J/PASJ/59/1185 : Water maser in galactic IRAS sources (Sunada+, 2007)J/AJ/140/1194 : FUV/HI relations in nearby galaxies (Bigiel+, 2010)J/ApJS/194/32 : The HII Region Discovery Survey (HRDS). II. (Anderson+, 2011)J/ApJ/738/27 : Galactic HII regions RRL and continuum data (Balser+, 2011)J/MNRAS/418/1689 : Red MSX water maser and ammonia emissions (Urquhart+, 2011)J/ApJ/754/62 : HRDS III. HII region kinematic distances (Anderson+, 2012)J/ApJS/208/11 : The Red MSX Source Survey: massive protostars (Lumsden+, 2013)J/ApJ/783/130 : Parallaxes of high mass star forming regions (Reid+, 2014)J/ApJS/212/1 : The WISE catalog of Galactic HII regions (Anderson+, 2014)J/ApJ/798/L27 : CO obs. of molecular clouds in the 2nd quadrant (Sun+, 2015)J/ApJ/806/199 : RRL and continuum data of 21 Gal. H II regions (Balser+, 2015)J/ApJS/221/26 : Radio obs. of Galactic WISE HII regions (Anderson+, 2015)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/841/121https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/841/121http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/841/121https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/841/121https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/841/121http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/841/121GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/841/121/table2 (VLA radio continuum parameters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/841/121/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/841/121/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/841/121/table2?GETtext/xml+votable180.050000true276.1052917-9.34405560.005555555555555556Cone search capability for table J/ApJ/841/121/table3 (Molecular line parameters)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/841/121/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/841/121/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/841/121/table3?GETtext/xml+votable180.050000true278.3775417-5.02144440.0055555555555555566/14336 14342 14344 14360 14363-14364 14366-14367 14389 14391 14435 14448 17856 23134 29530 30243 30252-30253 30266 30400 30404 30425 30429 30431 30592 30603 30606 30625-30626 30640 30643 30646-30649 30696-30697 30703 30712 30714 30718 32069 32081-32082 32084-32085 32092https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/841/121?format=asciiInfraredRadiodefaultJ/ApJ/841/121/table2VLA radio continuum parametersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintmolDisplay the GBT molecular line parameters for this source (link to Table 3)meta.ref.urlintnullableNameTarget name (GLLL.lll+bb.bbb) (G1)meta.id;meta.maincharprimaryRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainSint[0.6/601.2]? Integrated fluxmJyphot.flux.density;em.radio.6-12GHzfloatnullableSpk[0.09/48.7]? Peak flux, S_peak_mJy/beamphot.flux.density;em.radio.6-12GHzfloatnullablee_Spk[0.02/0.7] rms noise, {sigma}S_peak_mJy/beamstat.errorfloatArea[120/21830]? Area of each maskarcsec**2phys.areaintnullableA14Display data from Anderson+ 2014, J/ApJS/212/1meta.ref.urlintnullableJ/ApJ/841/121/table3Molecular line parametersA14Display data from Anderson+ 2014, J/ApJS/212/1meta.ref.urlintnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintVLADisplay the VLA parameters for this source (link to Table 2)meta.ref.urlintnullableNameTarget name (GLLL.lll+bb.bbb) (G1)meta.id;meta.maincharRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainTransTransition (1)meta.id;phys.atmol.transitionTL[15/14505] Line intensity (2)mKspect.line.intensityinte_TL[1/11]? TL uncertaintymKstat.errorintnullableDelVFWHM line width, {Delta}Vkm/sspect.line.widthchare_DelV[0.03/1.33]? DelV uncertainty (3)km/sstat.errorfloatnullableVLSR[-69.16/61.97] Local Standard of Rest peak velocitykm/sphys.veloc;pos.lsr;stat.maxfloate_VLSR[0.01/0.39]? VLSR uncertaintykm/sstat.error;phys.veloc;pos.lsrfloatnullablerms[7/40]? rms baseline noisemKstat.stdev;instr.det.noiseintnullableNoteNote(s) on previous detections (4)meta.notechar