J/A+A/515/A42ivo://CDS.VizieR/J/A+A/515/A42doi:10.26093/cds/vizier.35150042CDSRygl K.L.J.Wyrowsky F.Schuller F.Menten K.M.2017-06-27T06:37:56Z2011-11-15T15:09:32ZCDS support team

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

cds-question@unistra.frmolecular-cloudsinterstellar-mediuminfrared-sourcesmillimeter-astronomysubmillimeter-astronomyradio-astronomyextinctionThe earliest phases of massive star formation are found in cold and dense infrared dark clouds (IRDCs). Since the detection method of IRDCs is very sensitive to the local properties of the background emission, we present here an alternative method to search for high column density in the Galactic plane by using infrared extinction maps. We find clouds between 1 and 5kpc, of which many were missed by previous surveys. By studying the physical conditions of a subsample of these clouds, we aim at a better understanding of the initial conditions of massive star formation. We made extinction maps of the Galactic plane based on the 3.6-4.5 microns color excess between the two shortest wavelength Spitzer IRAC bands, reaching to visual extinctions of ~100mag and column densities of 9x10^22^cm^-2^. From this we compiled a new sample of cold and compact high extinction clouds. We used the MAMBO array at the IRAM 30m telescope to study the morphology, masses, and densities of the clouds and the dense clumps within them. The latter were followed up by pointed ammonia observations with the 100m Effelsberg telescope to determine rotational temperatures and kinematic distances. Extinction maps of the Galactic plane trace large scale structures such as the spiral arms. The extinction method probes lower column densities, N(H_2)~4x10^22^cm^-2^, than the 1.2mm continuum, which reaches up to N(H_2)~3x10^23^cm^-2^ but is less sensitive to large scale structures. The 1.2mm emission maps reveal that the high extinction clouds contain extended cold dust emission, from filamentary structures to still diffuse clouds. Most of the clouds are dark in 24 microns, but several show already signs of star formation via maser emission or bright infrared sources, suggesting that the high extinction clouds contain a variety of evolutionary stages. The observations suggest an evolutionary scheme from dark, cold and diffuse clouds, to clouds with a stronger 1.2mm peak and to finally clouds with many strong 1.2mm peaks, which are also warmer, more turbulent, and already have some star formation signposts.2010A&A...515A..42Rhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/515/A42CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toV/112 : Catalog of Star-Forming Regions in the Galaxy (Avedisova, 2002)J/ApJS/95/457 : IRAS images of nearby dark clouds (Wood+ 1994)J/ApJ/639/227 : MSX IRDC candidate catalog (Simon+, 2006)J/ApJ/641/389 : Millimetric observations of IRDC cores (Rathborne+, 2006)J/ApJ/651/L125 : Water masers associated with IR dark cloud cores (Wang+, 2006J/ApJ/653/1325 : Galactic distribution of infrared dark clouds (Simon+, 2006)J/ApJS/166/567 : Radio Molecular lines in infrared dark clouds (Ragan+, 2006)J/ApJ/706/727 : Distance and mass of Infrared Dark Clouds (Marshall+, 2009)J/A+A/499/149 : 1.2mm maps of southern Infrared Dark Clouds (Vasyunina+, 2009)J/A+A/505/405 : A catalogue of Spitzer dark clouds (Peretto+, 2009)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/515/A42https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/515/A42http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/515/A42https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/515/A42https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/515/A42http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/515/A42GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/515/A42/table1 (Catalog of high extinction clouds (HECs) with the peak color excess, E<(3.6-4.5)>)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/515/A42/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/515/A42/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/515/A42/table1?GETtext/xml+votable180.050000true273.005-19.6019440.005555555555555556Cone search capability for table J/A+A/515/A42/clumps (Positions and fluxes of the clumps from the 1.2mm continuum data and their properties derived from NH_3_ and the 1.2mm continuum)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/515/A42/clumps?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/515/A42/clumps?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/515/A42/clumps?GETtext/xml+votable180.050000true273.922083-18.2122220.005555555555555556Cone search capability for table J/A+A/515/A42/table4 (Positions (J2000) and determined properties toward the positions without clumps)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/515/A42/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/515/A42/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/515/A42/table4?GETtext/xml+votable180.050000true273.88625-18.1708330.005555555555555556Cone search capability for table J/A+A/515/A42/fig1 (List of FITS files containing the 3.6-4.5um color excess maps for the inner part of the Galaxy)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/515/A42/fig1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/515/A42/fig1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/515/A42/fig1?GETtext/xml+votable180.050000true266.71504-28.489420.005555555555555556Cone search capability for table J/A+A/515/A42/fig5 (List of FITS files containing the 1.2mm dust continuum maps)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/515/A42/fig5?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/515/A42/fig5?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/515/A42/fig5?GETtext/xml+votable180.050000true273.9033333-18.18905560.005555555555555556Associated datahttps://cdsarc.cds.unistra.fr/assocdata/?obs_collection=J/A+A/515/A425/7278 7377 7579 10453 10543 10624 6/12970-12971 12974 14341 14352-14353 28808-28809 28812-28813 28826-28827 28830-28831 28874 28897 28900-28901 28913 28918-28919 29090 29094 29097 29100-29101 29103 29118-29119 29162 29461 29504-29506 29528-29529 29532-29533 29535 30218-30219 30241 30244-30245 30256 30258-30259 30262 30268-30269 30312 30315 30405 30416-30417 30420 30423 30594 30601 30604-30605 30618-30619 30644-30645 30688 30691 30694-30695 30712-30713 30716-30717 30719 41598-41599 41655 41658-41660 41671 41675-41678 41681-41684 41688 41696 41759 41766-41767 41769-41770 41772 41776-41778 41780 41782 41802-41805 41811 41816-41817 41820 41824 42159 42170-42171 42207 42210-42211 42213-42214 42216 42224-42226 42228-42229 42378-42379 42383 42387 42390 42392-42393 42396-42397 42439 42441 42444-42445 42450-42451 42456-42457 42460-42461 42500-42501 42512 43013 43015 430211.6553710550405622e-22 1.6553710550405622e-22https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/515/A42?format=asciiInfraredRadiodefaultJ/A+A/515/A42/table1Catalog of high extinction clouds (HECs) with the peak color excess, E<(3.6-4.5)>recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHECHigh extinction cloud name (GLLL.ll+BB.bb)meta.id;meta.maincharprimaryMSimbad column added by the CDSmeta.ref.urlintnullableRAJ2000Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Declination (J2000)pos.eq.dec;meta.mainE(ir)3.6-4.5{mu}m color excessmagphot.color.excessfloatJ/A+A/515/A42/table2Properties of the high extinction cloudsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHECHigh extinction cloud name (GLLL.ll+BB.bb)meta.id;meta.maincharMSimbad column added by the CDSmeta.ref.urlintnullablem_HEC[A-D] Subgrouping of cloud based on the kinematic distancemeta.code.multipcharRad? Radius of the cloud in arcsec (1)arcsecphys.angSize;srcintnullableRad2? Radius of the cloud in parsec (1)pcphys.size.radiusfloatnullable<Av>? Average visual extinction derived from the extinction mapsmagphys.absorptionintnullableNH2? Average hydrogen column density derived from the extinction maps1e+22cm**-2phys.columnDensity;stat.meanfloatnullableS1.2? Integrated 1.2mm fluxJyphot.flux.density;em.mm.200-400GHzfloatnullableMext? Cloud mass derived from the extinction mapssolMassphys.massintnullableM1.2? Cloud mass derived from the 1.2mmsolMassphys.massdoublenullableClump? Peak of the 1.2mm emission in the clump in units of mJy/beammJyphot.flux.density;em.mm.200-400GHzintnullableCloud? Mean 1.2mm emission of the cloud without the clumpsmJyphot.flux.density;em.mm.200-400GHzintnullableClassClass of HEC: diffuse, peaked or multiply p.src.classcharSimbadSimbad column added by the CDSmeta.ref.urlcharJ/A+A/515/A42/clumpsPositions and fluxes of the clumps from the 1.2mm continuum data and their properties derived from NH_3_ and the 1.2mm continuumrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHECHigh extinction cloud name (GLLL.ll+BB.bb)meta.id.parentcharm_HEC[A-D] Subgrouping of cloud based on the kinematic distancemeta.code.multipcharmmMillimeter clump numbermeta.code.multipcharF1.21.2mm peak flux in mJy/beammJyphot.flux.density;em.mm.200-400GHzinte_F1.2F1.2 uncertainty in mJy/beammJystat.errorintS1.2Integrated 1.2mm fluxmJyphot.flux.density;em.mm.200-400GHzintS1.2dIntegrated 1.2mm flux within 0.25pc diametermJyphot.flux.density;em.mm.200-400GHzdoubleaClump major axisarcsecphys.angSizefloatbClump minor axisarcsecphys.angSize;srcfloatPA[-90/+90] Position angledegpos.posAngfloatH2O[-/+] Water maser detection (+: detection, -: non-detection and empty: not observed)meta.codechardkinKinematic distancekpcpos.distance;pos.heliocentricfloatAvVisual extinction based on N_H2_ from the 1.2mm emissionmagphys.absorption;em.opt.VintFWHMSize at FWHMpcphys.angSizefloatNH2Hydrogen column density1e+22cm**-2phys.columnDensityfloatnH2Hydrogen volume density100000cm**-3phys.densityfloatM1.2Cloud mass derived from the 1.2mmsolMassphys.massintM1.2dMass within 0.25pc diametersolMassphys.massintMvir? Virial masssolMassphys.massintnullableTrot? NH_3_ rotational temperatureKphys.temperaturefloatnullablee_Trot? Trot uncertaintyKstat.errorfloatnullablenNH3? NH_3_ column density1e+15cm**-2phys.columnDensityfloatnullablee_nNH3? NNH3 uncertainty1e+15cm**-2stat.errorfloatnullableSimbadSimbad column added by the CDSmeta.refcharRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainJ/A+A/515/A42/table4Positions (J2000) and determined properties toward the positions without clumpsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHECHigh extinction cloud name (GLLL.ll+BB.bb)meta.id.parentcharm_HEC[A-D] Subgrouping of cloud based on the kinematic distancemeta.code.multipcharmmMillimeter clump numbermeta.code.multipcharRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.maindkin? Kinematic distancekpcpos.distance;pos.heliocentricfloatnullableS1.2d? Integrated 1.2mm flux within 0.25pc diametermJyphot.flux.density;em.mm.200-400GHzintnullableMass? Mass within 0.25pc diametersolMassphys.massintnullableTrot? NH_3_ rotational temperatureKphys.temperaturefloatnullablee_Trot? Trot uncertaintyKstat.errorfloatnullableJ/A+A/515/A42/table5Observed ammonia parameters with uncertainties from hyperfine and Gaussian fits with CLASSe_TmbTmb uncertaintyKstat.errorfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintHECHigh extinction cloud name (GLLL.ll+BB.bb)meta.id.parentcharm_HEC[A-D] Subgrouping of cloud based on the kinematic distancemeta.code.multipcharmmMillimeter clump numbermeta.code.multipcharVlsrNH_3_(1,1) velocity in the local standard of rest (LSR)km/sphys.veloc;pos.lsrfloate_VlsrVlsr uncertaintykm/sstat.error;phys.veloc;pos.lsrfloatTmbNH_3_(1,1) main beam temperatureKphys.temperaturefloatdVNH_3_(1,1) line widthkm/sspect.line.widthfloate_dVdV uncertaintykm/sstat.errorfloattauNH_3_(1,1) main group optical depthphys.absorption.opticalDepth;meta.mainfloate_tautau uncertaintystat.errorfloatTmb2? NH_3_(2,2) main beam temperatureKphys.temperaturefloatnullablee_Tmb2? Tmb2 uncertaintyKstat.errorfloatnullabledV2? NH_3_(2,2) line widthkm/sspect.line.widthfloatnullablee_dV2? dv2 uncertaintykm/sstat.errorfloatnullableTmb3? NH_3_(3,3) main beam temperatureKphys.temperaturefloatnullablee_Tmb3? Tmb3 uncertaintyKstat.errorfloatnullabledV3? NH_3_(3,3) line widthkm/sspect.line.widthfloatnullablee_dV3? dV3 uncertaintykm/sstat.errorfloatnullableJ/A+A/515/A42/fig1List of FITS files containing the 3.6-4.5um color excess maps for the inner part of the GalaxyrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFileNameName of the FITS file in subdirectory "ce"meta.id;meta.fitscharGLONGalactic longitude, image centerdegpos.galactic.lonGLAT[0] Galactic latitude, image centerdegpos.galactic.lat_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.decnullableindexedJ/A+A/515/A42/fig5List of FITS files containing the 1.2mm dust continuum mapsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintFileNameName of FITS file (GLLll), in the "mambo" subdirectory, with 1.2mm mapmeta.id;meta.maincharRAJ2000Right ascension (J2000), image centerpos.eq.ra;meta.mainDEJ2000Declination (J2000), image centerpos.eq.dec;meta.main