J/ApJS/166/567ivo://CDS.VizieR/J/ApJS/166/567doi:10.26093/cds/vizier.21660567CDSRagan S.E.Bergin E.A.Plume R.Gibson D.L.Wilner D.J.O'Brien S.,Hails E.2017-12-05T05:10:24Z2008-12-21T08:24:33ZCDS support team

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

cds-question@unistra.frh-ii-regionsmolecular-cloudsinfrared-sourcesWe have identified 41 infrared dark clouds from the 8um maps of the Midcourse Space Experiment (MSX), selected to be found within 1deg^2^ areas centered on known ultracompact HII regions. We have mapped these infrared dark clouds in N_2_H^+^ 1->0, CS 2->1, and C^18^O 1->0 emission using the Five College Radio Astronomy Observatory. The maps of the different species often show striking differences in morphologies, indicating differences in evolutionary state and/or the presence of undetected, deeply embedded protostars. We derive an average mass for these clouds using N_2_H^+^ column densities of >>2500M_{sun}_, a value comparable to that found in previous studies of high-mass star-forming cores using other mass tracers. The line widths of these clouds are typically 2.0-2.9km/s. Based on the fact that they are dark at 8um, compact, and massive, and have large velocity dispersions, we suggest that these clouds may be the precursor sites of intermediate- and high-mass star formation.2006ApJS..166..567Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/166/567CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/639/227 : MSX IR dark cloud candidates candidate catalog (Simon+, 2006)J/ApJ/641/389 : Properties of IR dark cloud candidates cores (Rathborne+ 2006)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/166/567https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/166/567http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/166/567https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/166/567https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/166/567http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/166/567GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/166/567/table1 (Basic properties of the target MSX pre-stellar cores)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/166/567/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/166/567/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/166/567/table1?GETtext/xml+votable180.050000true269.95625-24.01395830.0055555555555555565/7383 6/14359 14644 28912 28919 29090 29091 29096 29097 29100 29101 29103 29113 29115 29118 29508 29510 29511 30218 30219 30241 30262 30263 30268 30269 30312 30313 30315 30317 30318 30319 30417 30420 30616 30618 30619 30694 30695 30701 30717https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/166/567?format=asciiInfrareddefaultJ/ApJS/166/567/regionsList of HII regionsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHIIHII region identificationmeta.id;meta.maincharprimarySNameSimbad name of the HII regionmeta.idcharNsourcesNumber of associated sources in table1meta.numberintJ/ApJS/166/567/table2Molecular line observationsm_[RBP2006][ab] Multiplicity index on source namemeta.code.multipcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[RBP2006]Source namemeta.id;meta.maincharoRADifference in Right Ascension of Molecular Peak from Table 1 positionarcminpos.eq.ra;arith.difffloatoDEDifference in Declination of Molecular Peak from Table 1 positionarcminpos.eq.dec;arith.difffloatl_I(N2H+)Upper limit flag on I(N2H+)meta.code.errorcharI(N2H+)The N_2_H+ J=1-0 integrated intensityK.km/sphot.flux.density;em.radiofloate_I(N2H+)? Uncertainty in I(N2H+)K.km/sstat.errorfloatnullableW(N2H+)? The N_2_H+ J=1-0 line widthkm/sspect.line.widthfloatnullablee_W(N2H+)? Uncertainty in W(N2H+)km/sstat.errorfloatnullableV(N2H+)? The N_2_H+ J=1-0 LSR velocitykm/sspect.dopplerVelocfloatnullablee_V(N2H+)? Uncertainty in V(N2H+)km/sstat.errorfloatnullableI(C18O)? The C^18^O J=1-0 integrated intensityK.km/sphot.flux.density;em.radiofloatnullablee_I(C18O)? Uncertainty in I(C18O)K.km/sstat.errorfloatnullableW(C18O)? The C^18^O J=1-0 line widthkm/sspect.line.widthfloatnullablee_W(C18O)? Uncertainty in W(C18O)km/sstat.errorfloatnullableV(C18O)? The C^18^O J=1-0 LSR velocitykm/sspect.dopplerVelocfloatnullablee_V(C18O)? Uncertainty in V(C18O)km/sstat.errorfloatnullablel_I(CS)Upper limit flag on I(CS)meta.code.errorcharI(CS)The CS J=2-1 integrated intensityK.km/sphot.flux.density;em.radiofloate_I(CS)? Uncertainty in I(CS)K.km/sstat.errorfloatnullableW(CS)? The CS J=2-1 line widthkm/sspect.line.widthfloatnullablee_W(CS)? Uncertainty in W(CS)km/sstat.errorfloatnullablef_W(CS)[a] Weak CS line (1)meta.codecharV(CS)? The CS J=2-1 LSR velocitykm/sspect.dopplerVelocfloatnullablee_V(CS)? Uncertainty in V(CS)km/sstat.errorfloatnullableJ/ApJS/166/567/table1Basic properties of the target MSX pre-stellar coresrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHIIHII region identificationmeta.id;obs.fieldchar[RBP2006]Source namemeta.id;meta.maincharprimaryGLONGalactic Longitudedegpos.galactic.lonGLATGalactic Latitudedegpos.galactic.latfloatRAJ2000Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of Declination (J2000)pos.eq.dec;meta.mainMajAxisMajor axisarcminphys.angSizefloatMinAxisMinor axisarcminphys.angSizefloatBContBrightness contrastspect.line.intensity;arith.ratiofloatBWidthBandwidth observed (1)km/sinstr.bandwidthcharMSimbad column added by the CDSmeta.ref.urlchar