J/ApJ/780/173ivo://CDS.VizieR/J/ApJ/780/173doi:10.26093/cds/vizier.17800173CDSBattisti A.J.Heyer M.H.2017-09-22T16:15:31Z2015-07-21T15:56:00ZCDS support team

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

cds-question@unistra.frmilky-way-galaxygalaxy-planesinterstellar-mediummolecular-cloudsgalaxy-kinematicsThe mass fraction of dense gas within giant molecular clouds (GMCs) of the Milky Way is investigated using ^13^CO data from the Five College Radio Astronomy Observatory Galactic Plane Surveys and the Bolocam Galactic Plane Survey (BGPS) of 1.1mm dust continuum emission. A sample of 860 compact dust sources are selected from the BGPS catalog and kinematically linked to 344 clouds of extended (>3') ^13^CO J=1-0 emission. Gas masses are tabulated for the full dust source and subregions within the dust sources with mass surface densities greater than 200M_{sun}_/pc^2^, which are assumed to be regions of enhanced volume density. Masses of the parent GMCs are calculated assuming optically thin ^13^CO J=1-0 emission and local thermodynamic equilibrium conditions. The mean fractional mass of dust sources to host GMC mass is 0.11^+0.12^_-0.06__. The high column density subregions comprise 0.07^+0.13^_-0.05_ of the mass of the cloud. Owing to our assumptions, these values are upper limits to the true mass fractions. The fractional mass of dense gas is independent of GMC mass and gas surface density. The low dense gas mass fraction suggests that the formation of dense structures within GMCs is the primary bottleneck for star formation. The distribution of velocity differences between the dense gas and the low density material along the line of sight is also examined. We find a strong, centrally peaked distribution centered on zero velocity displacement. This distribution of velocity differences is modeled with radially converging flows toward the dense gas position that are randomly oriented with respect to the observed line of sight. These models constrain the infall velocities to be 2-4km/s for various flow configurations.2014ApJ...780..173Bhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/780/173CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/799/29 : BGPS. XII. DR2 distance catalog (Ellsworth-Bowers+, 2015)J/ApJS/209/2 : The BGPS. X. Dense molecular gas (Shirley+, 2013)J/ApJ/770/39 : BGPS VIII. MIR kinematic distances (Ellsworth-Bowers+, 2013)J/MNRAS/431/1587 : GRS/BGPS sources in Galactic Plane (Eden+, 2013)J/MNRAS/422/3178 : Distances of 793 BGPS sources (Eden+, 2012)J/ApJ/741/110 : The BGPS. VII. Massive star-forming regions (Dunham+, 2011)J/ApJ/731/90 : Mid-IR content of BGPS sources (Dunham+, 2011)J/ApJS/195/14 : The Bolocam Galactic Plane Survey. V. (Schlingman+, 2011)J/ApJS/188/123 : The Bolocam Galactic Plane Survey. II. (Rosolowsky+, 2010)J/ApJ/723/492 : Physical properties of GRS clouds (Roman-Duval+, 2010)J/ApJ/721/137 : The Bolocam Galactic Plane Survey (BGPS) (Bally+, 2010)J/ApJ/699/1153 : Kinematic distances to GRS clouds (Roman-Duval+, 2009)J/ApJ/699/1092 : Giant molecular clouds (SRBY) (Heyer+, 2009)J/ApJS/182/131 : Molecular clouds and clumps in the GRS (Rathborne+, 2009)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/780/173https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/780/173http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/780/173https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/780/173https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/780/173http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/780/173GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/780/173/table1 (Giant Molecular Cloud (GMC) properties and dust masses)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/780/173/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/780/173/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/780/173/table1?GETtext/xml+votable180.050000true276.30887-12.751930.0055555555555555565/7383 7564 7578 7605 7651 7679 6/12970 12974 14353 14354 14356 14358 14359 14406 29505 29507 29508 29510 29511 29522 29528 29529 30218 30219 30222 30241 30244 30245 30260 30262 30263 30268 30269 30316 30318 30319 30330 30405 30416 30417 30594 30595 30601 30616 30618 30619 30622 30644 30645 30688 30691 30692 30694 30695 30701 30712https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/780/173?format=asciiOpticaldefaultJ/ApJ/780/173/table1Giant Molecular Cloud (GMC) properties and dust massesSimbadNameSimbad column added by the CDSmeta.idcharGLATGalactic latitudedegpos.galactic.latGLONGalactic longitudedegpos.galactic.lonSource[2430/6504] Sequence number of the primary source in the Bolocam Galactic Plane Survey (BGPS) catalog (1)meta.id;meta.mainintprimaryTthr[0.5/6.8] Threshold temperature to define the giant molecular cloudKphys.temperaturefloatVlsr[4/124] Local standard of rest velocity of the giant molecular cloudkm/sphys.veloc;pos.lsrfloatDkin[0.9/15] Kinematic distance to the giant molecular cloudkpcpos.distance;pos.heliocentricfloatRad[1/34] Radius of the giant molecular cloudpcphys.size.radiusfloate_Rad[0.01/15.1] Uncertainty in Radpcstat.errorfloatsigma[0.6/5] Velocity dispersion of the giant molecular cloudkm/sphys.veloc.dispersionfloate_sigma[0/2.48] Uncertainty in sigmakm/sstat.errorfloatMass[0.7/726] Mass of the giant molecular cloud (2)ksolMassphys.massfloate_Mass[0/463] Uncertainty in Mass (3)ksolMassstat.error;phys.massfloatMd1[0.2/100] Total dust mass derived from all primary and secondary sources in the Galactic Plane Survey (BGPS) within the cloud (4)ksolMassphys.massfloate_Md1[0.1/32] Uncertainty in Md1ksolMassstat.errorfloatMd2[0/71] Total dust mass of BGPS source pixels (5)ksolMassphys.massfloate_Md2[0/29] Uncertainty in Md2ksolMassstat.errorfloatNs[1/22] Total number of BGPS sources within the giant molecular cloud (6)meta.numberint_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