J/A+A/595/A27ivo://CDS.VizieR/J/A+A/595/A27doi:10.26093/cds/vizier.35950027CDSGinsburg A.Goss W.M.Goddi C.Galvan-Madrid R.Dale J.Bally J.,Battersby C.Youngblood A.Sankrit R.Smith R.Darling J.,Kruijssen J.M.D.Liu H.-Y.B.2017-07-03T14:25:43Z2016-10-25T09:20:35ZCDS support team

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

cds-question@unistra.frmolecular-cloudsh-ii-regionsradio-sourcesWe present new JVLA observations of the high-mass cluster-forming region W51A from 2 to 16GHz with resolution {theta}_fwhm_~~0.3-0.5". The data reveal a wealth of observational results: (1) Currently-forming, very massive (proto-O) stars are traced by o-H_2_CO 2_1,1_-2_1,2_ emission, suggesting that this line can be used efficiently as a massive protostar tracer. (2) There is a spatially distributed population of <~mJy continuum sources, including hypercompact HII regions and candidate colliding wind binaries, in and around the W51 proto-clusters. (3) There are two clearly detected protoclusters, W51e and W51 IRS2, that are gas-rich but may have most of their mass in stars within their inner <~0.05pc. The majority of the bolometric luminosity in W51 most likely comes from a third population of OB stars between these clusters. The presence of a substantial population of exposed O-stars coincident with a population of still-forming massive stars, along with a direct measurement of the low mass loss rate via ionized gas outflow from W51 IRS2, together imply that feedback is ineffective at halting star formation in massive protoclusters. Instead, feedback may shut off the large-scale accretion of diffuse gas onto the W51 protoclusters, implying that they are evolving towards a state of gas exhaustion rather than gas expulsion. Recent theoretical models predict gas exhaustion to be a necessary step in the formation of gravitationally bound stellar clusters, and our results provide an observational validation of this process.2016A&A...595A..27Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/595/A27CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/706/83 : Embedded YSO candidates in W51 (Kang+, 2009)J/ApJ/720/1055 : VBLA observations of W51 Main/South (Sato+, 2010)J/ApJS/191/232 : CO survey of W51 molecular cloud (Bieging+, 2010)J/MNRAS/424/1658 : Molecular clumps in W51 giant mol. cloud (Parsons+, 2013)J/A+A/582/A64 : W51/e2 and G34.3+0.2 IRAM spectra (Lykke+, 2015)J/A+A/589/A44 : W51 Main NH_3_ and CH_3_OH data cubes (Goddi+, 2016)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/595/A27https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/595/A27http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/595/A27https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/595/A27https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/595/A27http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/595/A27GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/595/A27/list (List of fits files)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/595/A27/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/595/A27/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/595/A27/list?GETtext/xml+votable180.050000true290.9234914.51060.0055555555555555566/30694https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/595/A27?format=asciiRadiodefaultJ/A+A/595/A27/listList of fits filesDEJ2000Declination of center (J2000)degpos.eq.dec;meta.mainrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension of center (J2000)degpos.eq.ra;meta.mainNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintNz? Number of slices, for the datacubemeta.numberintnullableObs.DateObservation date (YYYY-MM-DDThh:mm:ss.s)time.epoch;obscharFreqObserved frequencyGHzem.freqfloatbVel? Lower value of velocity interval, for the datacubekm/sphys.velocdoublenullableBVel? Upper value of velocity interval, for the datacubekm/sphys.velocfloatnullabledVel? Velocity resolution, for the datacubekm/sspect.resolutiondoublenullablesizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fitsJ/A+A/595/A27/photEVLA VLA point source photometryrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintAllDisplay data of this source for all frequenciesmeta.ref.urlcharNameObject name (SourceName)meta.id;meta.maincharLabelLabel for the frequency + epoch (FrequencyName)meta.id;obscharObs.dateDate of the observation (YYYY-MM-DDThh:mm:ss.ssssss) (ObservationDate)time.epochcharFreqObserved central frequency (Frequency)GHzem.freqfloatEp[1/3] Epoch ID of the observation (1, 2, or 3) (Epoch)meta.id;time.epoch;obsintBmajBeam major axis (BMAJ)arcsecphys.angSizedoubleBminBeam minor axis (BMIN)arcsecphys.angSize;srcdoubleFluxAp? Average intensity over an aperture (aperture_flux)Jy/beamphot.fluxdoublenullableFluxPk? Peak intensity of the source (peak_flux)Jy/beamphot.fluxdoublenullablerms? Noise estimated from a small area around the source (local_rms_noise)Jy/beamstat.snr;instr.det.noisedoublenullablecutfluxm? Lowest measured intensity in the source cutout (cutout_min_flux)Jy/beamphot.fluxdoublenullableGbckg? Fitted Gaussian background (gbackground)Jy/beaminstr.backgrounddoublenullableGamp? Fitted Gaussian amplitude (gamplitude)Jy/beamstat.fit.paramdoublenullableGRAdeg? Fitted Gaussian RA centroid (gracen)degpos.eq.radoublenullableGDEdeg? Fitted Gaussian Dec centroid (gdeccen)degpos.eq.decdoublenullableGXw? Fitted Gaussian x width (gxwidth)degstat.fit.paramdoublenullableGYw? Fitted Gaussian y width (gywidth)degstat.fit.paramdoublenullableGPA? Fitted position angle (gpositionangle)degpos.posAng;meta.modelleddoublenullableGchi2? Gaussian fit chi^2^ (gfit_chi2)stat.fit.chi2;stat.fit.param;meta.modelleddoublenullableGchi2r? Gaussian fit reduced chi^2^ (gfit_chi2_reduced)stat.fit.chi2;stat.fit.param;meta.modelleddoublenullable