J/AJ/160/115ivo://CDS.VizieR/J/AJ/160/115doi:10.26093/cds/vizier.51600115CDSCaballero-Nieves S.M.Gies D.R.Baines E.K.Bouchez A.H.Dekany R.G.,Goodwin S.P.Rickman E.L.Roberts L.C.Taggart K.ten Brummelaar T.A.,Turner N.H.2021-02-19T07:30:26Z2020-11-06T09:21:00ZCDS support team

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

cds-question@unistra.frsurveysob-starsmultiple-starsinfrared-photometrystellar-spectral-typesWe present results of a high angular resolution survey of massive OB stars in the Cygnus OB2 association that we conducted with the Near-Infrared Imager camera and ALTAIR adaptive optics system of the Gemini North telescope. We observed 74 O- and early-B-type stars in Cyg OB2 in the JHK infrared bands in order to detect binary and multiple companions. The observations are sensitive to equal-brightness pairs at separations as small as 0.08", and progressively fainter companions are detectable out to {Delta}K=9mag at a separation of 2". This faint contrast limit due to read noise continues out to 10" near the edge of the detector. We assigned a simple probability of chance alignment to each companion based upon its separation and magnitude difference from the central target star and upon areal star counts for the general star field of Cyg OB2. Companion stars with a field membership probability of less than 1% are assumed to be physical companions. This assessment indicates that 47% of the targets have at least one resolved companion that is probably gravitationally bound. Including known spectroscopic binaries, our sample includes 27 binary, 12 triple, and 9 systems with 4 or more components. These results confirm studies of high-mass stars in other environments that find that massive stars are born with a high-multiplicity fraction. The results are important for the placement of the stars in the Hertzsprung-Russell diagram, the interpretation of their spectroscopic analyses, and for future mass determinations through measurement of orbital motion.2020AJ....160..115Chttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/160/115CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/wds : The Washington Visual Double Star Catalog (Mason+, 2001-2020)III/215 : 7th Catalog of Galactic Wolf-Rayet stars (van der Hucht, 2001)II/319 : UKIDSS-DR9 LAS, GCS and DXS Surveys (Lawrence+ 2012)II/314 : UKIDSS-DR8 LAS, GCS and DXS Surveys (Lawrence+ 2012)VII/233 : The 2MASS Extended sources (IPAC/UMass, 2003-2006)J/AJ/101/1408 : Massive stars in Cyg OB2. (Massey+ 1991)J/A+A/474/495 : X-ray flares Cygnus OB2 young stars (Albacete-Colombo+, 2007)J/ApJ/664/1102 : Radial velocity survey of Cyg OB2 association (Kiminki+,2007)J/MNRAS/374/372 : ZYJHK photometry in Upper Sco (Lodieu+, 2007)J/A+A/486/453 : NIR photometry of early-type stars in Cyg OB2 (Comeron+,2008)J/AJ/137/3358 : Speckle interferometry of massive stars (Mason+, 2009)J/ApJS/184/84 : X-ray sources in Cyg OB2 region (Wright+, 2009)J/A+A/518/A1 : Galactic massive stars with AstraLux (Maiz Apellaniz, 2010)J/ApJS/190/1 : A survey of stellar families (Raghavan+, 2010)J/A+A/538/A74 : Massive binaries in Cepheus OB2/3 region (Peter+, 2012)J/other/Sci/337.444 : RV curves of Galactic massive O stars (Sana+, 2012)J/A+A/550/A107 : RV catalogue of O stars in 30 Doradus (Sana+, 2013)J/ApJS/213/34 : Velocities of Cygnus OB2 massive binaries (Kobulnicky+, 2014)J/ApJ/785/47 : Sources around stars in Upper Scorpius (Lafreniere+, 2014)J/ApJS/215/15 : SMaSH+: observations and companion detection (Sana+, 2014)J/AJ/149/26 : Massive binary stars from an HST/FGS survey (Aldoretta+,2015)J/ApJ/811/85 : RVs & V-band LCs of probable mem. of Cyg OB2 (Kiminki+, 2015)J/MNRAS/449/741 : The massive star population of Cygnus OB2 (Wright+, 2015)J/ApJS/224/4 : GOSSS III. 142 addit. O-type systems (Maiz-Apellaniz+, 2016)J/A+A/601/A34 : Resolved astrometry of ten O-type binaries (Le Bouquin+,2017)J/A+A/626/A20 : MONOS. I. Spectral classifications (Maiz Apellaniz+, 2019)J/A+A/627/A2 : New V-band photometry of Cyg OB2 5 (V729 Cyg) (Rauw+, 2019)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/160/115https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/160/115http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/160/115https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/160/115https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/160/115http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/160/115GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/160/115/sample (Stars in Cygnus OB2 and multiplicity properties (paste of table1 and table5))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/160/115/sample?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/160/115/sample?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/160/115/sample?GETtext/xml+votable180.050000true308.131412541.235616670.005555555555555556Cone search capability for table J/AJ/160/115/table4 (Stars detected in the sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/160/115/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/160/115/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/160/115/table4?GETtext/xml+votable180.050000true308.1314291741.235613890.0055555555555555565/3673 6/14670 146717.952274030004205e-20 3.852589004194616e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/160/115?format=asciiInfrareddefaultJ/AJ/160/115/sampleStars in Cygnus OB2 and multiplicity properties (paste of table1 and table5)SpTypeSpectral Classificationsrc.spTypecharSimbadNameSimbad column added by the CDSmeta.idcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStars designationmeta.id;meta.maincharprimaryf_NameFlag on Name (1)meta.codecharRAJ2000[20/20] Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[40/42] Degree of Declination (J2000)pos.eq.dec;meta.mainr_SpType[1/6] Reference code for SpType (2)meta.ref;pos.frameintVmag[8.99/13.61]? Apparent V magnitudemagphot.mag;em.opt.VfloatnullableJmag[4.667/10.427] Apparent J magnitudemagphot.mag;em.IR.JfloatHmag[3.512/10.15] Apparent H magnitudemagphot.mag;em.IR.HfloatKmag[2.704/9.993] Apparent K_s_ magnitudemagphot.mag;em.IR.KfloatEJKmag[0.57/1.4]? Color excess in J-Kmagphot.color;em.IR.J;em.IR.KfloatnullableEBVmag[1.28/3.44]? Color excess in B-Vmagphot.color;em.opt.B;em.opt.VfloatnullableEbymag[0.9/1.75]? Color excess in b-ymagphot.color.excessfloatnullableNobsNumber of observation for this star (link to table3)meta.numberintnullableNiri[2/47] Total number of stars found in target fieldmeta.numberintCand[0/4] Number of high probability companion stars from NIRImeta.numberintFGS[0/2]? Number of companions detected with FGSmeta.numberintnullableSB[0/2]? Spectroscopic binaries (3)meta.numberintnullableTotal[0/5]? Total number of unique companions from columns 3-5meta.numberintnullableNew[0/3]? New companions detected during this workmeta.numberintnullableMassMass of target star (4)phys.masscharJ/AJ/160/115/table3Observations of stars in Cyg OB2recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStar designationmeta.id;meta.maincharDate[3613/5019] Julian Date; JD-2450000dtime.epochdoublef_NameNotes on how the data was analyzed (1)meta.codecharFiltFilter usedinstr.setup;instr.filtercharStrehl[0.01/0.43] Strehl ratiostat.fit.paramfloatFWHM[74/159] Full Width at Half Maximummasspect.line.widthintNumber[17/130] Number of images combined for the analysismeta.numberintJ/AJ/160/115/table4Stars detected in the sampleONameOther Name (2)meta.id;meta.maincharNotesAdditional notesmeta.notecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameField Namemeta.id;obs.fieldcharSep[0.08/16.71]? Separationarcsecpos.angDistance;src.orbitalfloatnullablePA[0.1/360]? Position Angledegpos.posAngfloatnullableRAJ2000[20] Hour of Right Ascension (J2000)pos.eq.ra;meta.mainDEJ2000[40/42] Degree of Declination (J2000)pos.eq.dec;meta.mainJmag[-1.94/9.17]? Differential J magnitude (1)magphot.mag;em.IR.Jfloatnullablee_Jmag[0.01/1.82]? Error in J magnitudemagstat.error;phot.magfloatnullableHmag[0.04/9.17]? Differential H magnitude (1)magphot.mag;em.IR.Hfloatnullablee_Hmag[0.01/0.31]? Error in H magnitudemagstat.error;phot.magfloatnullableKmag[-1.07/9.37]? Differential K magnitude (1)magphot.mag;em.IR.Kfloatnullablee_Kmag[0.01/2.73]? Error in K magnitudemagstat.error;phot.magfloatnullableProb[0/0.832]? Probability of chance alignment with background field starinstr.background;obs.fieldfloatnullableUKIDSSUKIRT IR Deep Sky Survey identification numbermeta.id.crosschar