J/ApJ/812/131ivo://CDS.VizieR/J/ApJ/812/131doi:10.26093/cds/vizier.18120131CDSKuhn M.A.Feigelson E.D.Getman K.V.Sills A.Bate M.R.Borissova J.2017-10-16T07:45:38Z2017-10-09T14:06:58ZCDS support team

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

cds-question@unistra.frstellar-associationsopen-star-clustersh-ii-regionsWe analyze the physical properties of stellar clusters that are detected in massive star-forming regions in the MYStIX project - a comparative, multiwavelength study of young stellar clusters within 3.6 kpc that contain at least one O-type star. Tabulated properties of subclusters in these regions include physical sizes and shapes, intrinsic numbers of stars, absorptions by the molecular clouds, and median subcluster ages. Physical signs of dynamical evolution are present in the relations of these properties, including statistically significant correlations between subcluster size, central density, and age, which are likely the result of cluster expansion after gas removal. We argue that many of the subclusters identified in Paper I (Kuhn et al. 2014, J/ApJ/787/107) are gravitationally bound because their radii are significantly less than what would be expected from freely expanding clumps of stars with a typical initial stellar velocity dispersion of ~3 km/s for star-forming regions. We explore a model for cluster formation in which structurally simpler clusters are built up hierarchically through the mergers of subclusters - subcluster mergers are indicated by an inverse relation between the numbers of stars in a subcluster and their central densities (also seen as a density versus radius relation that is less steep than would be expected from pure expansion). We discuss implications of these effects for the dynamical relaxation of young stellar clusters.2015ApJ...812..131Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/812/131CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/138/227 : Stellar clusters in NGC 6334 complex (Feigelson+, 2009)J/ApJ/725/2485 : X-rays from the star-forming complex W40 (Kuhn+, 2010)J/ApJS/194/2 : Chandra Carina Complex Project (CCCP) catalog (Broos+, 2011)J/ApJS/194/9 : X-ray star clusters in the Carina complex (Feigelson+, 2011)J/AJ/144/192 : Spitzer survey of Orion A & B. I. YSO catalog (Megeath+, 2012)J/ApJ/787/107 : Spatial structure of young stellar clusters. I. (Kuhn+, 2014)J/ApJS/213/1 : The MSFRs Omnibus X-ray Catalog (MOXC) (Townsley+, 2014)J/ApJS/209/27 : MYStIX: the Chandra X-ray sources (Kuhn+, 2013)J/ApJS/209/28 : MYStIX Wide-Field NIR data: crowded fields (King+, 2013)J/ApJS/209/29 : MYStIX: Mid-IR observations and catalogs (Kuhn+, 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/802/60 : Structure of young stellar clusters. II. (Kuhn+, 2015)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/812/131https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/812/131http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/812/131https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/812/131https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/812/131http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/812/131GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/812/131/sources (MYStIX targets for subcluster analysis (from J/ApJ/787/107))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/812/131/sources?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/812/131/sources?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/812/131/sources?GETtext/xml+votable180.050000true83.8220833-5.39111110.0055555555555555566/1287 14704 21439 22249 22855 23637 28890 28913 29116 29463 30341 37872 37884 38016 39907 42456 42461https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/812/131?format=asciidefaultJ/ApJ/812/131/sourcesMYStIX targets for subcluster analysis (from J/ApJ/787/107)Ns[246/2790] Total number of stars used in analysismeta.numberintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRegMassive star-forming region (MSFR) namemeta.id;meta.maincharDist[0.4/3.6] Distance to region used in MYStIX analysis (Feigelson et al. 2013ApJS..209...26F)kpcpos.distance;pos.heliocentricfloatlogFX[-6.8/-5.9] Apparent 0.5-8.0keV X-ray photon flux limit imposed for spatial uniformityph.s**-1.cm**-2phot.flux;em.X-rayfloatNsp[38/96] Percentage of all MPCMs%meta.numberintNx[174/2043] Number of X-ray starsmeta.numberintNir[49/815] Number of MYStIX InfraRed Excess (MIRES) starsmeta.numberintNob[1/134] Number of OB starsmeta.numberintMSFRMYStIX region name as in tables 1 and 6; column added by CDSmeta.id;obs.fieldcharN[1/20] Number of subcluster(s) in this regionmeta.numberintSimbadSimbad column added by the CDSmeta.ref.urlchar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/ApJ/812/131/table1Intrinsic Subcluster PropertiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMSFRMYStIX region namemeta.id;obs.fieldcharm_MSFRSubcluster designation as in Paper I (Kuhn+, 2014, J/ApJ/787/107) (G1)meta.code.multipcharClassMorphological classificationsrc.morphcharlogr4Log of fiducial subcluster radius (=4r_c_)log(pc)phys.size.radiusfloatl_logN4[>] Limit flag on logN4meta.code.errorcharlogN4? Log of number of stars within four core radiimeta.numberfloatnullableu_logN4[:] Uncertainty flag on logN4meta.code.errorcharn_logN4[+] Note on logN4 (1)meta.notecharl_logEps0[>] Limit flag on logEps0meta.code.errorcharlogEps0? Log of central surface density (stars/pc^2^)log(pc**-2)phot.flux.density.sbfloatnullableu_logEps0[:] Uncertainty flag on logEps0meta.code.errorcharn_logEps0[+] Note on logEps0meta.notecharl_logrho0[>] Limit flag on logrho0meta.code.errorcharlogrho0? Log of estimated central volumetric density (stars/pc^3^)log(pc**-3)phys.densityfloatnullableu_logrho0[:] Uncertainty flag on logrho0meta.code.errorcharn_logrho0[+] Note on logrho0meta.notecharEllSubcluster ellipticitysrc.ellipticityfloatJ-HJ-H NIR absorption indexmagphot.color;em.IR.J;em.IR.HfloatMEX-ray median energy absorption indicatorkeVphys.absorption;em.X-ray;stat.medianfloatlogAge? Log of median agelog(yr)time.age;stat.medianfloatnullablePapIDisplay data from Paper I (Kuhn+, 2014, J/ApJ/787/107) for this subclustermeta.ref.urlcharPapIIDisplay data from Paper II (Kuhn+, 2015, J/ApJ/802/60) for this subclustermeta.ref.urlcharJ/ApJ/812/131/table6Dynamical Subcluster PropertiesrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintMSFRMYStIX region namemeta.id;obs.fieldcharm_MSFRSubcluster designation as in Paper I (Kuhn+, 2014, J/ApJ/787/107) (G1)meta.code.multipcharlogtff? Log of free-fall time for the subcluster (stellar mass only)log(yr)time.epochfloatnullablelogsig? Log of mean velocity dispersion for stars within four core radii assuming that the subcluster is virializedlog(km.s**-1)phys.veloc.dispersionfloatnullablelogtcr1Log of subcluster crossing time assuming a velocity dispersion of 3.0 km/slog(yr)time.crossingfloatlogtcr2? Log of subcluster crossing time assuming a virial velocity dispersionlog(yr)time.crossingfloatnullablelogtrel1? Log of dynamical relaxation time assuming a velocity dispersion of 3.0 km/slog(yr)pos.parallax.dynfloatnullablelogtrel2? Log of dynamical relaxation time assuming a virial velocity dispersionlog(yr)pos.parallax.dynfloatnullablelogNrel1? Log of subcluster dynamical age in relaxation timelog(yr)time.age;pos.parallax.dynfloatnullablelogNrel2? Log of subcluster dynamical age in relaxation timelog(yr)time.age;pos.parallax.dynfloatnullablePapIDisplay data from Paper I (Kuhn+, 2014, J/ApJ/787/107) for this subclustermeta.ref.urlcharPapIIDisplay data from Paper II (Kuhn+, 2015, J/ApJ/802/60) for this subclustermeta.ref.urlchar