J/A+A/616/A107ivo://CDS.VizieR/J/A+A/616/A107doi:10.26093/cds/vizier.36160107CDSKim W.-J.Urquhart J.S.Wyrowski F.Menten K.M.Csengeri T.2020-05-04T10:58:47Z2018-08-28T09:20:49ZCDS support team

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

cds-question@unistra.frsurveysh-ii-regionsmillimeter-astronomysubmillimeter-astronomyinterstellar-mediumstar-forming-regionsPrevious radio recombination line (RRL) observations of dust clumps identified in the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) have led to the detection of a large number of RRLs in the 3mm range. Here, we aim to study their excitation with shorter wavelength (sub)millimeter radio recombination line (submm-RRL) observations. We made observations of submm-RRLs with low principal quantum numbers (n<=30) using the APEX 12m telescope, toward 104 HII regions associated with massive dust clumps from ATLASGAL. The observations covered the H25{alpha}, H28{alpha}, and H35{beta} transitions. Toward a small subsample the H26{alpha}, H27{alpha}, H29{alpha}, and H30{alpha} lines were observed to avoid contamination by molecular lines at adjacent frequencies. We have detected submm-RRLs (signal-to-noise >=3{sigma}) from compact HII regions embedded within 93 clumps. The submm-RRLs are approximately a factor of two brighter than the mm-RRLs and consistent with optically thin emission in local thermodynamic equilibrium (LTE). The average ratio (0.31) of the measured H35{beta}/H28{alpha} fluxes is close to the LTE value of 0.28. No indication of RRL maser emission has been found. The Lyman photon flux, bolometric, and submm-RRL luminosities toward the submm-RRL detected sources present significant correlations. The trends of dust temperature and the ratio of bolometric luminosity to clump mass, L_bol_/M_clump_, indicate that the HII regions are related to L_bol_/M_clump_, indicate that the HII regions are related to the most massive and luminous clumps. By estimating the production rate of ionizing photons, Q, from the submm-RRL flux, we find that the Q(H28{alpha}) measurements provide estimates of the Lyman continuum photon flux consistent with those determined from 5GHz radio continuum emission. Six RRL sources show line profiles that are a combination of a narrow and a broad Gaussian feature. The broad features are likely associated with high-velocity ionized flows. We have detected submm-RRLs toward 93 ATLASGAL clumps. Six RRL sources have high-velocity RRL components likely driven by high-velocity ionized flows. Their observed properties are consistent with thermal emission that correlates well with the Lyman continuum flux of the HII regions. The sample of HII regions with mm/submm-RRL detections probes, in our Galaxy, luminous clumps (L_bol_>10^4^L_{sun}_) with high L_bol_/M_clump_. We also provide suitable candidates for further studies of the morphology and kinematics of embedded, compact HII regions with the Atacama Large Millimeter/submillimeter Array (ALMA).2018A&A...616A.107Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/616/A107CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/MNRAS/473/1059 : Complete sample of Galactic clump propertiesJ/A+A/602/A37 : Millimeter RRL in ATLASGAL-selected massive clumpshttps://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/616/A107https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/616/A107http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/616/A107https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/616/A107https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/616/A107http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/616/A107GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/616/A107/table6 (Properties of clumps and embedded sources)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/616/A107/table6?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/616/A107/table6?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/616/A107/table6?GETtext/xml+votable180.050000true272.3383333-20.32555560.0055555555555555566/29090-29091 29094 29097 29101 29112 29114 29116 29118 29505 30256 30259 30262 30268-30269 30312-30313 30318-30319 30405 30420 30617-30618 30622 30644 30694 37923 37928 38024 41655 41681 41683 41772 41777 41780 41804-41805 41812 41817 41820 41824 42158-42159 42169-42170 42172 42215 42224-42225 42376 42391 42393 42396-42397 42436 42451 42455-42456 42462 42496 42498 43013 43019 43021https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/616/A107?format=asciiMillimeterdefaultJ/A+A/616/A107/table4Line parameters of all hydrogen RRLsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID[1/104] ID of ATLASGAL clumpmeta.idintNameATLASGAL clump name (AGALLLL.lll+BB.bbb)meta.id;meta.maincharTransRRL transitionsmeta.noteRRLVlsrLSR velocity of RRLskm/sphys.veloc;pos.lsrintdvRRL linewidthkm/sspect.line.widthinte_dvrms uncertainty on dvkm/sstat.errorintFintRRL velocity-integrated flux on Jy scaleJy.km/sphot.fluxfloate_Fintrms uncertainty on velocity-integrated fluxJy.km/sstat.errorfloatFpeakRRL peak intensity on Jy scaleJyphot.fluxfloatrmsrms noise per channelJystat.stdev;phot.flux.densityfloatJ/A+A/616/A107/table6Properties of clumps and embedded sourcesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintID[1/104] ID of ATLASGAL clumpmeta.idintNameATLASGAL clump name (AGALLLL.lll+BB.bbb)meta.id;meta.maincharsysVlsrLSR systemic velocity of clumpskm/sphys.veloc;pos.lsrfloatRRLVlsrLSR velocity of recombination linekm/sphys.recombination.coeff;pos.lsrfloatDist? Heliocentric distancekpcpos.distancefloatnullableTdust? Dust temperatureKphys.temperaturefloatnullablelogLbol? Log of bolometric luminositylog(solLum)phys.luminosityfloatnullablelogMclump? Log of the clump masslog(solMass)phys.massfloatnullablelogL/M? Log of ratio of Lbol and Mclumpphys.composition.massLightRatiofloatnullablelogLyman? Lyman photon flux of radio continuumlog(ph.s**-1)phot.flux.density;em.radio;spect.continuumfloatnullableFig2[2]? indicates an image of all spectrameta.codeintnullableH25a[*] indicates a h25alpha spectrummeta.codecharH26a[*] indicates a h26alpha spectrummeta.codecharH27a[*] indicates a h27alpha spectrummeta.codecharH28a[*] indicates a h28alpha spectrummeta.codecharH29a[*] indicates a h29alpha spectrummeta.codecharH30a[*] indicates a h30alpha spectrummeta.codecharH35b[*] indicates a h35beta spectrummeta.codecharH39a[*] indicates a h39alpha spectrummeta.codecharH40a[*] indicates a h40alpha spectrummeta.codecharH41a[*] indicates a h41alpha spectrummeta.codecharH42a[*] indicates a h42alpha spectrummeta.codecharSimbadSimbad column added by the CDSmeta.ref.urlchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.main