J/ApJ/870/32ivo://CDS.VizieR/J/ApJ/870/32doi:10.26093/cds/vizier.18700032CDSKuhn M.A.Hillenbrand L.A.Sills A.Feigelson E.D.Getman K.V.2021-02-23T12:32:00Z2020-02-24T09:13:27ZCDS support team

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

cds-question@unistra.fropen-star-clustersstellar-associationsh-ii-regionsproper-motionsgalaxy-kinematicsradial-velocityvisible-astronomytrigonometric-parallaxThe Gaia mission has opened a new window into the internal kinematics of young star clusters at the sub-km/s level, with implications for our understanding of how star clusters form and evolve. We use a sample of 28 clusters and associations with ages from ~1-5Myr, where lists of members are available from previous X-ray, optical, and infrared studies. Proper motions from Gaia DR2 reveal that at least 75% of these systems are expanding; however, rotation is only detected in one system. Typical expansion velocities are on the order of ~0.5km/s, and in several systems, there is a positive radial gradient in expansion velocity. Systems that are still embedded in molecular clouds are less likely to be expanding than those that are partially or fully revealed. One-dimensional velocity dispersions, which range from {sigma}_1D_=1 to 3km/s, imply that most of the stellar systems in our sample are supervirial and that some are unbound. In star-forming regions that contain multiple clusters or subclusters, we find no evidence that these groups are coalescing, implying that hierarchical cluster assembly, if it occurs, must happen rapidly during the embedded stage.2019ApJ...870...32Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/870/32CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/ocl : Optically visible open clusters and Candidates (Dias+ 2002-2015)I/337 : Gaia DR1 (Gaia Collaboration, 2016)I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)I/345 : Gaia DR2 (Gaia Collaboration, 2018)VII/50 : CO Radial Velocities Toward Galactic H II Regions (Blitz+ 1982)J/A+A/171/261 : RRLs of Southern HII Regions (Caswell+ 1987)J/MNRAS/341/805 : UBVI CCD photometry of Cep OB3b (Pozzo+, 2003)J/PASJ/56/313 : 13CO survey of Mon & CMa molecular clouds (Kim+, 2004)J/A+A/437/467 : VLT-FLAMES survey of massive stars (Evans+, 2005)J/A+A/438/1163 : Catalogue of Open Cluster Data (COCD) (Kharchenko+, 2005)J/ApJ/648/1090 : Radial velocities of NGC 2264 stars (Furesz+, 2006)J/AJ/131/2114 : Radial velocities in Fornax dSph (Walker+, 2006)J/ApJ/676/1109 : Vel. of stars in the Orion Nebula Cluster (Furesz+, 2008)J/ApJ/697/1103 : Kinematics of Orion Nebula Cluster (Tobin+, 2009)J/ApJS/209/27 : the Chandra X-ray sources (Kuhn et al., 2013)J/ApJS/209/28 : Wide-Field near-IR data in crowded fields (King et al., 2013)J/ApJS/209/29 : Mid-IR observations and catalogs (Kuhn et al., 2013)J/ApJS/209/30 : MYStIX project: Bayesian matching (Naylor+, 2013)J/ApJS/209/31 : The MYStIX IR-Excess Source catalog (MIRES) (Povich+, 2013)J/ApJS/209/32 : Probable young stars in the MYStIX project (Broos+, 2013)J/ApJ/787/107 : Spatial structure of young stellar clusters. I. (Kuhn+, 2014)J/ApJ/787/108 : Ages for massive SFR stellar populations (Getman+, 2014)J/ApJ/807/27 : IN-SYNC. III. RVs of IC348 stars (Cottaar+, 2015)J/ApJ/799/136 : IN-SYNC. II. Cand. young stars in NGC 1333 (Foster+, 2015)J/ApJ/812/131 : Spatial structure of stellar clusters. III. (Kuhn+, 2015)J/ApJ/802/60 : Structure of young stellar clusters. II. (Kuhn+, 2015)J/A+A/596/A82 : X-ray study of the young cluster NGC6231 (Damiani+, 2016)J/ApJ/821/8 : Spectroscopic binary pop. of ONC and NGC2264 (Kounkel+, 2016)J/MNRAS/461/794 : Scorpius-Centaurus K-Type Stars (Pecaut+, 2016)J/MNRAS/460/2593 : Cygnus OB2 DANCe: Proper motion study (Wright+, 2016)J/ApJS/229/28 : SFiNCs: X-ray, IR and membership catalogs (Getman+, 2017)J/ApJ/834/142 : Gould's Belt Distances Survey. II. OMC (Kounkel+, 2017)J/AJ/154/87 : Stellar pop. of the young star cluster NGC 6231 (Kuhn+, 2017)J/A+A/616/A12 : Gaia DR2 sources in GC and dSph (Gaia Collaboration+, 2018)J/MNRAS/477/L50 : Structure of the Upper Scorpius association (Galli+, 2018)J/AJ/156/84 : APOGEE-2 survey of Orion Complex. II. (Kounkel+, 2018)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/870/32https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/870/32http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/870/32https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/870/32https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/870/32http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/870/32GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/870/32/table1 (Cluster/association sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/870/32/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/870/32/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/870/32/table1?GETtext/xml+votable180.050000true0.56212567.41877780.0055555555555555566/862 1231 1287 1539 3755 14029 15662 15683 21439 21458 22249 23637 28890 28913 29116 29463 38016 39907 42394 42441 42460 42462https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/870/32?format=asciiOpticaldefaultJ/ApJ/870/32/table1Cluster/association sampleSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintComplexLarge star-forming complex including several regionsobs.fieldcharRegRegion namemeta.id;meta.maincharprimaryRAJ2000System center hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000System center degree of declination (J2000)pos.eq.dec;meta.mainNs[29/1285] Number of stars used in the analysis for this systemmeta.numberintpmRA[-7/7.3] Proper motion of the system center in RAmas/yrpos.pm;pos.eq.rafloate_pmRA[0.07/0.3] pmRA uncertaintymas/yrstat.error;pos.pm;pos.eq.rafloatpmDE[-9.7/3] Proper motion of the system center in DEmas/yrpos.pm;pos.eq.decfloate_pmDE[0.07/0.5] pmDE uncertaintymas/yrstat.error;pos.pm;pos.eq.decfloatPlx[0.2/3.4] Parallax of the system centermaspos.parallaxfloate_Plx[0.04/0.06] Plx uncertaintymasstat.error;pos.parallaxfloatDist[296/3790] Distancepcpos.distance;pos.heliocentricinte_Dist[5/510] Negative error on Distpcstat.errorintE_Dist[5/700] Positive error on Distpcstat.error;stat.maxintSFiNCsDisplay the data from SFiNCs (Getman+, 2017, J/ApJS/229/28) for this regionmeta.ref.urlintnullablesigmaDisplay the velocity dispersion data for this region (link to Table 3)meta.ref.urlintnullableRVDisplay the radial velocity data for this region (link to Table 5)meta.ref.urlintnullableFig16Display the age and mass data for this region (link to fig16 table)meta.ref.urlintnullableJ/ApJ/870/32/table3Velocity dispersions in select clustersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRegSystem namemeta.id;pos.framecharNs[11/278] Number of stars used to calculate velocity dispersionsmeta.numberintSig1D[0.8/2.8] Characteristic one-dimensional velocity dispersionkm/sphys.veloc.dispersionfloate_Sig1D[0.1/0.5] Sig1D uncertaintykm/sstat.errorfloatSigpc1[0.9/3.4] Velocity dispersion in the first principal component for the two-dimensional velocity modelkm/sphys.veloc.dispersionfloate_Sigpc1[0.1/0.7] Sigpc1 uncertaintykm/sstat.errorfloatSigpc2[0.7/2.2] Velocity dispersion in the second principal component for the two-dimensional velocity modelkm/sphys.veloc.dispersionfloate_Sigpc2[0.1/0.7] Sigpc2 uncertaintykm/sstat.errorfloatSpc1/pc2[1/2] Ratio of velocity dispersions in the first and second velocity principal components (a measure of overall velocity anisotropy)phys.veloc.dispersion;arith.ratiofloate_Spc1/pc2[0.1/0.9] Spc1/pc2 uncertaintystat.errorfloatPA[5/179] Position angle (east from north) of the semimajor axis of the velocity dispersiondegphys.angSize.smajAxisintNout[9/23]? Fraction of stars belonging to the second component of the mixture model (1)%meta.numberintnullableu_NoutUncertainty flag on Noutmeta.code.errorchare_Nout[4/17]? Nout uncertainty%stat.errorintnullableSigout[2/13]? Velocity dispersion for the second component of the mixture model (1)km/sphys.veloc.dispersionfloatnullableDelBIC[-106/5.4]? Change in the Bayesian Information Criterion (BIC) when the second component was added (1)stat.fit.paramfloatnullableJ/ApJ/870/32/table5Radial velocities of clustersrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRegRegion namemeta.id;obs.fieldcharn_RegFlag on Reg (1)meta.notecharSet[0/12] Number of members with Gaia RV measurementsmeta.numberintRVgaia[-28.7/35.6]? Median RV (barycentric)km/sphys.veloc;pos.barycenter;stat.medianfloatnullableu_RVgaiaUncertainty flag on RVgaiameta.code.errorchare_RVgaia[0.9/10]? RVgaia uncertaintykm/sstat.errorfloatnullableRVlitRV measurements from the literature (barycentric) (2)km/sphys.veloc;pos.barycentercharJ/ApJ/870/32/fig16Data behind Figure 16recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRegDesignation of the stellar systemmeta.id;meta.maincharMass[2.1/4.2] Log of mass of the stellar systemlog(solMass)phys.massfloatAge[5.8/6.6] Log of median age of the stellar systemlog(Myr)time.age;stat.medianfloatRad[-0.5/0.6] Log of half-mass radius of the stellar systemlog(pc)phys.size.radiusfloatEmbFlag indicating whether a stellar system is embedded, partially embedded, or revealed (1)meta.codecharJ/ApJ/870/32/refsReferencesRefReference codemeta.notecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBibCodeBibcode of the referencemeta.bib.bibcodecharAutFirst author's name(s)meta.bib.authorcharCommVizieR catalog referencemeta.id;meta.datasetchar