J/ApJ/964/164ivo://CDS.VizieR/J/ApJ/964/164doi:10.26093/cds/vizier/ba-y4-54CDSGautam A.K.Do T.Ghez A.M.Chu D.S.Hosek M.W.J.Sakai S.Naoz S.,Morris M.R.Ciurlo A.Haggard Z.Lu J.R.2026-07-02T12:01:15Z2025-06-04T09:51:29ZCDS support team

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

cds-question@unistra.frgalactic-centermultiple-starseclipsing-binary-starsinfrared-photometrystellar-agesstellar-spectral-typesradial-velocityWe present the first estimate of the intrinsic binary fraction of young stars across the central ~0.4pc surrounding the supermassive black hole (SMBH) at the Milky Way Galactic center (GC). This experiment searched for photometric variability in 102 spectroscopically confirmed young stars, using 119 nights of 10" wide adaptive optics imaging observations taken at W. M. Keck Observatory over 16yr in the K'-[2.1um] and H-[1.6um] bands. We photometrically detected three binary stars, all of which are situated more than 1" (0.04pc) from the SMBH and one of which, S2-36, is newly reported here with spectroscopic confirmation. All are contact binaries or have photometric variability originating from stellar irradiation. To convert the observed binary fraction into an estimate of the underlying binary fraction, we determined the experimental sensitivity through detailed light-curve simulations, incorporating photometric effects of eclipses, irradiation, and tidal distortion in binaries. The simulations assumed a population of young binaries, with stellar ages (4Myr) and masses matched to the most probable values measured for the GC young star population, and underlying binary system parameters (periods, mass ratios, and eccentricities) similar to those of local massive stars. As might be expected, our experimental sensitivity decreases for eclipses narrower in phase. The detections and simulations imply that the young, massive stars in the GC have a stellar binary fraction >=71% (68% confidence), or >=42% (95% confidence). This inferred GC young star binary fraction is consistent with that typically seen in young stellar populations in the solar neighborhood. Furthermore, our measured binary fraction is significantly higher than that recently reported by Chu et al. based on radial velocity measurements for stars >~1" of the SMBH. Constrained with these two studies, the probability that the same underlying young star binary fraction extends across the entire region is <1.4%. This tension provides support for a radial dependence of the binary star fraction, and therefore, for the dynamical predictions of binary merger and evaporation events close to the SMBH.2024ApJ...964..164Ghttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/964/164CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/523/248 : Variable stars in the Galactic center (Ott+, 1999)J/ApJ/597/323 : Cool stars at the Galactic Center (Blum+, 2003)J/ApJS/161/154 : Near-IR spectral atlas of OB stars (Hanson+, 2005)J/ApJ/643/1011 : Early-type stars in center of the Galaxy (Paumard+, 2006)J/ApJ/659/1241 : Stellar variability in Galactic Center (Rafelski+, 2007)J/ApJ/697/1741 : Warped disks of YSOs in Galactic center (Bartko+, 2009)J/A+A/499/483 : NIR observations of sources in the GC (Buchholz+, 2009)J/ApJ/703/1323 : Spectroscopy of stars:Galaxy's nuclear cluster (Do+ 2009)J/A+A/502/91 : Proper motions of stars near SgrA* (Schoedel+, 2009)J/A+A/511/A18 : NIR observations of stars near SgrA* (Schoedel+, 2010)J/A+A/537/A146 : Star models with rot. 0.8<M<120,Z=0.014 (Ekstrom+, 2012)J/other/Sci/337.444 : RV curves of Galactic massive O stars (Sana+, 2012)J/ApJ/764/154 : Stellar populations in the central 0.5pc. I. (Do+, 2013)J/ApJS/208/9 : Intrinsic colors & temp of PMS stars (Pecaut+, 2013)J/A+A/570/A2 : Spectra and RVs of nuclear stars (Feldmeier+, 2014)J/ApJ/783/131 : Kinematic of stars in Galactic center (Yelda+, 2014)J/A+A/584/A2 : KMOS view of Galactic centre.I. (Feldmeier-Krause+, 2015)J/ApJ/810/61 : Early-type EBs: intermediate orbit periods (Moe+, 2015)J/ApJ/808/106 : NIR spectroscopic obs. in the GC (Stostad+, 2015)J/ApJ/830/17 : GC secondary IR astrometric standards (Boehle+, 2016)J/ApJ/829/34 : Kepler heartbeat star radial velocities (Shporer+, 2016)J/ApJ/837/30 : 25yrs monitoring star orbits in the GC (Gillessen+, 2017)J/A+A/606/A92 : Gaia LMC EBs & multiple systems (Mowlavi+, 2017)J/A+A/610/A83 : GALACTICNUCLEUS: JHKs survey (Nogueras-Lara+, 2018)J/ApJ/871/103 : Catalog of 563 stars in the GC (Gautam+, 2019)J/ApJ/873/65 : Keck/NIRC2 obs. of the Galactic Center (Sakai+, 2019)J/AJ/168/166 : GC: high-PM stars magnitude analysis (Haggard+, 2024)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/964/164https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/964/164http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/964/164https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/964/164https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/964/164http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/964/164GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/964/164/table2 (Known young star sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/964/164/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/964/164/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/964/164/table2?GETtext/xml+votable180.050000true266.41714972-29.007671940.005555555555555556Cone search capability for table J/ApJ/964/164/table7 (Full stellar and injected binary recovery fraction (Appendix F))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/964/164/table7?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/964/164/table7?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/964/164/table7?GETtext/xml+votable180.050000true266.41714972-29.007671940.005555555555555556Cone search capability for table J/ApJ/964/164/table4 (Photometric calibrator star bandpass corrected reference fluxes)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/964/164/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/964/164/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/964/164/table4?GETtext/xml+votable180.050000true266.4168544-29.00745750.0055555555555555566/288308.679819833624978e-20 1.3390623994635458e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/964/164?format=asciiInfrareddefaultJ/ApJ/964/164/table2Known young star samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameName of starmeta.id;meta.maincharKpmag[10/17.2] Mean Vega magnitude of star in K' bandmagphot.mag;em.IR.K;stat.meanfloatHmag[12/19.2]? Mean Vega magnitude of star in H band (1)magphot.mag;em.IR.H;stat.meanfloatnullablen_Kpmag[33/100] Number of K' band observations of starmeta.number;obs;em.IR.Kintn_Hmag[0/19] Number of H band observations of star (1)meta.number;obs;em.IR.HintoRA[-4.4/5.6] Offset East from Sgr A* position (17:45:40.0359 -29:00:28.169)arcsecpos.eq.ra;arith.difffloatoDE[-6.4/3.7] Offset North from Sgr A* position (17:45:40.0359 -29:00:28.169)arcsecpos.eq.dec;arith.difffloatt0[2006.3/2012.1] Reference time for oRA, oDE in Julian yearsyrtime.epochdoubleG19Display data from Gautam+ 2019, J/ApJ/871/103 if anymeta.ref.urlintnullable_RAPosition, computed from Sgr A* position (17:45:40.0359-29:00:28.169) with oRA and oDE offsets (right ascension part)degpos.eq.ra;meta.main_DEPosition, computed from Sgr A* position (17:45:40.0359-29:00:28.169) with oRA and oDE offsets (declination part)degpos.eq.dec;meta.mainSimbadNameSimbad column added by the CDSmeta.idcharnullableJ/ApJ/964/164/table5OSIRIS spectroscopic observations and RV measurements of S2-36e_RVel[8.1/13.4] Uncertainty in radial velocitykm/sstat.error;spect.dopplerVelocfloatrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateUT Date'Y:M:D'time.epochnullablef_Date[T] Flag on UT Date (1)meta.code;time.epochcharMJDModified Julian Date of observationdtime.epochdoublelambdaMin[1.965] Wavelength range, minimumumem.wl;stat.minfloatlambdaMax[2.381] Wavelength range, maximumumem.wl;stat.maxfloatFiltFilter namemeta.id;instr.filtercharFrames[4/6] Framesmeta.number;obs.exposureintExpTime[900] Integration timestime;obs.exposureintScale[20/35] Scale, milliarcseconds/pixelmas/pixinstr.scaleintSNR[73/118] Signal-to-noisestat.snrintRVel[152/219] Radial velocitykm/sspect.dopplerVelocfloatJ/ApJ/964/164/table6RV measurements of IRS 16CCf_Date[T] T= observation conducted with TRICKmeta.code;time.epochcharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateUT Date'Y:M:D'time.epochnullableMJDModified Julian Date of observationdtime.epochdoubleSNR[165/182] Signal-to-noisestat.snrintRVel[175/180] Radial velocitykm/sspect.dopplerVelocfloate_RVel[2.8/3.7] Uncertainty in radial velocitykm/sstat.error;spect.dopplerVelocfloatJ/ApJ/964/164/table7Full stellar and injected binary recovery fraction (Appendix F)recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameName of starmeta.id;meta.maincharprimaryYSKnown young star (link to Table 2)meta.ref.urlintnullableKpmag[10.0/19.4] Mean Vega magnitude of star in K' bandmagphot.mag;em.IR.K;stat.meanfloatHmag[12.0/21.5]? Mean Vega magnitude of star in H band (1)magphot.mag;em.IR.H;stat.meanfloatnullableAgeSpectroscopically confirmed age of population (2)time.agecharn_Kpmag[30/100] Number of K' band observations of starmeta.number;obs;em.IR.Kintn_Hmag[0/19] Number of H band observations of star (1)meta.number;obs;em.IR.HintKprChi2[0.1/274] Reduced {chi}^2^ from no variability model in K' bandstat.fit.chi2;meta.modelled;em.IR.KfloatHrChi2[0.03/399]? Reduced {chi}^2^ from no variability model in H band (1)stat.fit.chi2;meta.modelled;em.IR.HfloatnullableKpVarVariable in K' band? Yes/Nometa.code;src.var;em.IR.KcharHVarVariable in H band? Yes/No (1)meta.code;src.var;em.IR.HcharFrac[0.0/0.2] Fraction of injected binaries recovered from stellar light curvestat;meta.modelledfloatoRA[-5.4/5.8] Offset East from Sgr A* position (17:45:40.0359 -29:00:28.169)arcsecpos.eq.ra;arith.difffloatoDE[-6.5/4.2] Offset North from Sgr A* position (17:45:40.0359 -29:00:28.169)arcsecpos.eq.dec;arith.difffloatt0Reference time for oRA, oDE in Julian yearsyrtime.epochdouble_RAPosition, computed from Sgr A* position (17:45:40.0359-29:00:28.169) with oRA and oDE offsets (right ascension part)degpos.eq.ra;meta.main_DEPosition, computed from Sgr A* position (17:45:40.0359-29:00:28.169) with oRA and oDE offsets (declination part)degpos.eq.dec;meta.mainSimbadNameSimbad column added by the CDSmeta.idcharnullableJ/ApJ/964/164/table1Observations used in this experimentNbright[185/490] Number of stars detected with mag_K'_<=16meta.number;src.sample;phot.magintNyoung[55/99] Number of known young stars detectedmeta.number;src.sample;time.ageintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintDateUT Date'Y:M:D'time.epochnullablef_Date[n] Flag on UT date (1)meta.code;time.epochcharMJDModified Julian Date of observationdtime.epochdoubleFiltBandpass (H or K')instr.bandpass;instr.filtercharNs[186/1038] Number of sample stars detectedmeta.number;src.sampleintMedErr[0.02/0.12] Median photometric uncertainty of bright starsmagstat.error;phot.mag;stat.medianfloatJ/ApJ/964/164/table4Photometric calibrator star bandpass corrected reference fluxes_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.mainNameName of starmeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSpTypeSpectral typesrc.spTypecharKsS10[10.1/15.0] Ks band Vega magnitude from S10 (1)magphot.mag;em.IR.Kfloate_KsS10[0.06/0.09] Uncertainty in Ks_S10_magstat.error;phot.mag;em.IR.KfloatdKmag[-0.07/-0.04] Magnitude difference, Ks_S10_-K'_NIRC2_magphot.mag;arith.diff;em.IR.Kfloate_dKmag[0.01]? Uncertainty in dKmagmagstat.error;phot.mag;arith.difffloatnullableKpNIRC2[10.1/15.1] K' band NIRC2 Vega magnitude, this articlemagphot.mag;em.IR.Kfloate_KpNIRC2[0.06/0.09] Uncertainty in K'_NIRC2_magstat.error;phot.mag;em.IR.KfloatHS10[12.0/16.9] H band Vega magnitude from S10 (1)magphot.mag;em.IR.Hfloate_HS10[0.06/0.09] Uncertainty in H_S10_magstat.error;phot.mag;em.IR.HfloatdHmag[-0.20/-0.13] Magnitude difference, H_S10_-H_NIRC2_magphot.mag;arith.diff;em.IR.Hfloate_dHmag[0.01]? Uncertainty in dHmagmagstat.error;phot.mag;arith.difffloatnullableHNIRC2[12.1/16.7] H band NIRC2 Vega magnitude, this articlemagphot.mag;em.IR.Hfloate_HNIRC2[0.07/0.10] Uncertainty in H_NIRC2_magstat.error;phot.mag;em.IR.HfloatS10Display data from Schoedel+ 2010, J/A+A/511/A18 within 0.08"meta.ref.urlintnullableSimbadNameSimbad column added by the CDSmeta.idcharnullable