J/A+A/635/A2ivo://CDS.VizieR/J/A+A/635/A2doi:10.26093/cds/vizier.36350002CDSSadaghiani M.Sanchez-Monge A.Schilke P.Liu H.B.Clarke S.D.,Zhang Q.Girart J.M.Seifried D.Aghababaei A.Li H.Juarez C.,Tang K.S.2021-01-19T15:22:54Z2020-02-28T08:15:23ZCDS support team

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

cds-question@unistra.frinterstellar-mediumradio-astronomyWe aim to characterise certain physical properties of high-mass star-forming sites in the NGC6334 molecular cloud, such as the core mass function (CMF), spatial distribution of cores, and mass segregation. We used the Atacama Large Millimetre/sub-millimetre Array (ALMA) to image the embedded clusters NGC6334-I and NGC6334-I(N) in the continuum emission at 87.6GHz. We achieved a spatial resolution of 1300au, enough to resolve different compact cores and fragments, and to study the properties of the clusters. We detected 142 compact sources distributed over the whole surveyed area. The ALMA compact sources are clustered in different regions. We used different machine-learning algorithms to identify four main clusters: NGC6334-I, NGC6334-I(N), NGC6334-I(NW), and NGC6334-E. The typical separations between cluster members range from 4000au to 12000au. These separations, together with the core masses (0.1-100M_{sun}_), are in agreement with the fragmentation being controlled by turbulence at scales of 0.1pc. We find that the CMFs show an apparent excess of high-mass cores compared to the stellar Initial Mass Function. We evaluated the effects of temperature and unresolved multiplicity on the derived slope of the CMF. Based on this, we conclude that the excess of high-mass cores might be spurious and due to inaccurate temperature determinations and/or resolution limitations. We searched for evidence of mass segregation in the clusters and we find that clusters NGC6334-I and NGC6334-I(N) show hints of segregation with the most massive cores located in the centre of the clusters. We searched for correlations between the physical properties of the four embedded clusters and their evolutionary stage (based on the presence of Hii regions and infrared sources). NGC6334-E appears as the most evolved cluster, already harboring a well-developed Hii region. NGC6334-I is the second-most evolved cluster with an ultra-compact Hii region. NGC6334-I(N) contains the largest population of dust cores distributed in two filamentary structures and no dominant Hii region. Finally, NGC6334-I(NW) is a cluster of mainly low-mass dust cores with no clear signs of massive cores or Hii regions.We find a larger separation between cluster members in the more evolved clusters favoring the role of gas expulsion and stellar ejection with evolution. The mass segregation, seen in the NGC6334-I and NGC6334-I(N) clusters, suggests a primordial origin for NGC6334-I(N). In contrast, the segregation in NGC6334-I might be due to dynamical effects. Finally, the lack of massive cores in the most evolved cluster suggests that the gas reservoir is already exhausted, while the less evolved clusters still have a large gas reservoir along with the presence of massive cores. In general, the fragmentation process of NGC6334 at large scales (from filament to clump, i.e. at about 1pc) is likely governed by turbulent pressure, while at smaller scales (scale of cores and sub-fragments, i.e. a few hundred au) thermal pressure starts to be more significant.2020A&A...635A...2Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/635/A2CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/587/A135 : Halpha images of NGC 6334 and NGC 6357 (Russeil+, 2016)J/A+A/592/A54 : Combined ArTeMiS+SPIRE 350um image of NGC6334 (Andre+, 2016)J/A+A/593/A37 : Spectral cube toward NGC 6334 I and I(N) (van der Wiel+, 2016)J/A+A/632/A83 : NGC 6334 filament with ALMA (Shimajiri+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/635/A2https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/635/A2http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/635/A2https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/635/A2https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/635/A2http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/635/A2GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/635/A2/tablea1 (Properties of the ALMA continuum sources in NGC 6334)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/635/A2/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/635/A2/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/635/A2/tablea1?GETtext/xml+votable180.050000true260.1945-35.77120.005555555555555556Cone search capability for table J/A+A/635/A2/list (Information on fits images)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/635/A2/list?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/635/A2/list?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/635/A2/list?GETtext/xml+votable180.050000true260.22816-35.772270.005555555555555556Associated datahttps://cdsarc.cds.unistra.fr/assocdata/?obs_collection=J/A+A/635/A26/42456-424575.804436842484019e-23 5.804436842484019e-23https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/635/A2?format=asciiRadiodefaultJ/A+A/635/A2/tablea1Properties of the ALMA continuum sources in NGC 6334recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqALMA 87.6GHz compact source sequential numbermeta.recordintRAJ2000ALMA 87.6GHz Right ascension (J2000)pos.eq.ra;meta.mainDEJ2000ALMA 87.6GHz Declination (J2000)pos.eq.dec;meta.mainIALMA 87.6GHz peak intensitymJy/beamphot.flux;em.mm.50-100GHzfloatSALMA 87.6GHz flux densitymJyphot.flux.density;em.mm.50-100GHzfloate_Srms uncertainty on ALMA 87.6GHz flux densitymJystat.errorfloatamajALMA 87.6GHz major axisarcsecphys.angSizefloatbminALMA 87.6GHz minor axisarcsecphys.angSize;srcfloatPA? ALMA 87.6GHz position angledegpos.posAngintnullableFree-FreeRadio continuum contribution to the ALMA 87.6 GHz continuum flux (1)phot.flux.density;em.radiocharIRAssociation with infrared source (2)meta.codecharT? Assumed temperatureKphys.temperatureintnullableMg+d? Dust and gas masssolMassphys.massfloatnullablenH2? Volume density1e+08cm**-3phys.densityfloatnullableNH2? Column density1e+24cm**-2phys.columnDensityfloatnullableClusterCluster to which the source is associatedmeta.id.parentcharPmemb? Confidence level of membership in percentage%meta.code.memberintnullableONamesOther names for each source (3)meta.id;meta.maincharJ/A+A/635/A2/listInformation on fits imagesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right Ascension of center (J2000)degpos.eq.ra;meta.mainDEJ2000Declination of center (J2000)degpos.eq.dec;meta.mainNxNumber of pixels along X-axismeta.numberintNyNumber of pixels along Y-axismeta.numberintObs.dateObservation datestime.epoch;obsnullableFreqObserved frequencyGHzem.freqfloatsizeSize of FITS fileKibytephys.size;meta.fitsintFileNameName of FITS file, in subdirectory fitsmeta.id;meta.fitscharTitleTitle of the FITS filemeta.title;meta.fitscharAssocDataAssociated Data web pagemeta.ref.urlchar