J/MNRAS/449/741ivo://CDS.VizieR/J/MNRAS/449/741doi:10.26093/cds/vizier.74490741CDSWright N.J.Drew J.E.Mohr-Smith M.2024-08-14T20:21:30Z2015-03-24T08:07:24ZCDS support team

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

cds-question@unistra.frstellar-associationsob-starsstellar-agesstellar-massesWe have compiled a significantly updated and comprehensive census of massive stars in the nearby Cygnus OB2 association by gathering and homogenising data from across the literature. The census contains 169 primary OB stars, including 52 O-type stars and 3 Wolf-Rayet stars. Spectral types and photometry are used to place the stars in a Hertzprung-Russell diagram, which is compared to both non-rotating and rotating stellar evolution models, from which stellar masses and ages are calculated. The star formation history and mass function of the association are assessed, and both are found to be heavily influenced by the evolution of the most massive stars to their end states. We find that the mass function of the most massive stars is consistent with a "universal" power-law slope of {Gamma}=1.3. The age distribution inferred from stellar evolutionary models with rotation and the mass function suggest the majority of star formation occurred more or less continuously between 1 and 7Myr ago, in agreement with studies of low- and intermediate mass stars in the association. We identify a nearby young pulsar and runaway O-type star that may have originated in Cyg OB2 and suggest that the association has already seen its first supernova. Finally we use the census and mass function to calculate the total mass of the association of 16500^+3800^_-2800_M_{sun}, at the low end, but consistent with, previous estimates of the total mass of Cyg OB2. Despite this Cyg OB2 is still one of the most massive groups of young stars known in our Galaxy making it a prime target for studies of star formation on the largest scales.2015MNRAS.449..741Whttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/MNRAS/449/741CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/AJ/107/1433 : Cygnus OB2 polarimetry (Kobulnicky+, 1994)J/A+AS/111/407 : VI Cygni red + reddened stars (Parthasarathy+, 1995)J/MNRAS/298/753 : Variables in Cygnus OB2 (Pigulski+ 1998)J/ApJS/149/123 : WSRT survey of Cygnus OB2 (Setia Gunawan+, 2003)J/ApJ/643/238 : Chandra/2MASS sources in Cygnus OB2 (Butt+, 2006)J/A+A/464/211 : Chandra and near-IR obs. of Cyg OB2 (Albacete Colombo+, 2007)J/A+A/472/557 : Cygnus OB2 region 610MHz sources (Marti+, 2007)J/A+A/474/495 : Cygnus OB2 young stars X-ray flares (Albacete Colombo+, 2007)J/A+A/486/453 : NIR photometry of early-type stars in Cyg OB2 (Comeron+ 2008)J/ApJS/184/84 : X-ray sources in Cyg OB2 region (Wright+, 2009)J/ApJS/194/27 : Variable stars in Cygnus OB2 (Henderson+, 2011)J/ApJS/202/19 : riz photometry in Cyg OB2 (Guarcello+, 2012)J/A+A/543/A101 : OB stars in Cygnus OB2 association (Comeron+, 2012)J/ApJ/713/871 : Massive star-forming region Cygnus OB2. II. (Wright+, 2012)J/ApJ/751/4 : Radial velocities of massive stars in Cyg OB2 (Kiminki+ 2012)J/ApJ/773/135 : Disk-bearing stars in Cygnus OB2 (Guarcello+, 2013)J/ApJS/213/34 : Velocities of Cygnus OB2 massive binaries (Kobulnicky+, 2014)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/MNRAS/449/741https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/MNRAS/449/741http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/MNRAS/449/741https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/MNRAS/449/741https://vizier.iucaa.in/viz-bin/votable?-source=J/MNRAS/449/741http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/MNRAS/449/741GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/MNRAS/449/741/census (Stellar photometry, spectral types and derived quantities, with uncertainties)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/MNRAS/449/741/census?https://vizier.iucaa.in/viz-bin/conesearch/J/MNRAS/449/741/census?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/MNRAS/449/741/census?GETtext/xml+votable180.050000true308.012916741.25552780.0055555555555555566/14670 14692-146947.952274030004205e-20 6.118840631666147e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/MNRAS/449/741?format=asciidefaultJ/MNRAS/449/741/censusStellar photometry, spectral types and derived quantities, with uncertaintiesSimbadNameSimbad column added by the CDSmeta.idcharE_AV? Upper 1-{sigma} uncertainty on AVmagstat.error;stat.maxfloatnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Right ascension (J2000.0)pos.eq.ra;meta.mainDEJ2000Declination (J2000.0)pos.eq.dec;meta.mainSpTypeSpectral type of star and binary companionssrc.spTypecharr_SpTypeReferences for spectral types (comma separated, one reference for each star in the system), in refs.dat filemeta.ref;pos.framecharSchulteStar number in the Schulte system (1)meta.id;meta.mainchar[MT91]? Star number from Massey and Thompson (2)meta.idintnullableONamesOther star names and numbers (3)meta.idcharAV[2.1/10.2]? Extinction in the V bandmagphys.absorption;em.opt.Vfloatnullablee_AV? Lower 1-{sigma} uncertainty on AVmagstat.errorfloatnullablelogL[2.4/6.2]? Logarithm (base 10) of the bolometric luminositylog(solLum)phys.luminosityfloatnullableE_logL? Upper 1-{sigma} uncertainty on logLlog(solLum)stat.error;stat.maxfloatnullablee_logL? Lower 1-{sigma} uncertainty on logLlog(solLum)stat.errorfloatnullablelogT[4.1/5.1]? Logarithm (base 10) of the effective temperaturelog(K)phys.temperature.effectivefloatnullableE_logT? Upper 1-{sigma} uncertainty on logTlog(K)stat.error;stat.maxfloatnullablee_logT? Lower 1-{sigma} uncertainty on logTlog(K)stat.errorfloatnullablel_M1Limit flag on M1meta.code.errorcharM1[4.3/110]? Stellar mass derived from rotating stellar evolutionary models (recommended) (4)solMassphys.massfloatnullableE_M1? Upper 1-{sigma} uncertainty on M1solMassstat.error;stat.maxfloatnullablee_M1? Lower 1-{sigma} uncertainty on M1solMassstat.errorfloatnullableAge1[0/10]? Age derived from rotating stellar models (recommended) (4) (5)Myrtime.agefloatnullableE_Age1? Upper 1-{sigma} uncertainty on Age1Myrstat.error;stat.maxfloatnullablee_Age1? Lower 1-{sigma} uncertainty on Age1Myrstat.errorfloatnullableAge1M? Upper value of Age1 intervalMyrtime.ageintnullablel_M0Limit flag on M0meta.code.errorcharM0[4.4/112]? Stellar mass derived from non-rotating stellar evolutionary models (6)solMassphys.massfloatnullableE_M0? Upper 1-{sigma} uncertainty on M0solMassstat.error;stat.maxfloatnullablee_M0? Lower 1-{sigma} uncertainty on M0solMassstat.errorfloatnullableAge0[0/10]? Age derived from non-rotating stellar models (5) (6)Myrtime.agefloatnullableE_Age0? Upper 1-{sigma} uncertainty on Age0Myrstat.error;stat.maxfloatnullablee_Age0? Upper 1-{sigma} uncertainty on Age0Myrstat.errorfloatnullableAge0M? Upper value of Age_n intervalMyrtime.ageintnullableUmag? U band magnitudemagphot.mag;em.opt.UfloatnullableBmag? B band magnitudemagphot.mag;em.opt.BfloatnullableVmag? V band magnitudemagphot.mag;em.opt.Vfloatnullabler_Vmag[MU-] Flag indicating origin of the UBV photometry (7)meta.ref;pos.framecharJmag? J band magnitudemagphot.mag;em.IR.JfloatnullableHmag? H band magnitudemagphot.mag;em.IR.HfloatnullableKmag? K band magnitudemagphot.mag;em.IR.Kfloatnullabler_Kmag[2M U] Flag indicating origin of the JHK photometry (8)meta.ref;pos.framecharJ/MNRAS/449/741/refsReferencesRemRemarksmeta.notecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRefReference codemeta.notecharBibCodeBibcodemeta.bib.bibcodecharAutAuthor's namemeta.bib.authorchar