J/AJ/170/144ivo://CDS.VizieR/J/AJ/170/144CDSDawson A.Ginsburg A.Roman-Zuniga C.G.2026-06-29T09:05:23Z2026-06-29T09:00:47ZCDS support team

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

cds-question@unistra.fropen-star-clustersyoung-stellar-objectsinfrared-photometrystellar-massesastronomical-object-identificationWe present near-infrared JHKs and narrowband H_2_(1-0) photometric observations of the W51A region, obtained with GTC EMIR, aiming to characterize its young stellar population, and provide mass estimates for individual cluster members and the protoclusters. Our observations reveal over 3000 new sources, out of which 88 are located in the protoclusters, W51 IRS2 and W51 Main. The average extinction (A_V_), measured from the J-H color, of sources is 19A_V_ in W51 IRS2 and 14A_V_ in W51 Main. We document 17 new instances of H_2_ emission in the region by utilizing observations from the H_2_(1-0) narrowband filter. Despite limited completeness, we estimated masses for each cluster member and estimated the total cluster mass to be in the range of 900-4700M_{sun}_ for W51 IRS2 and 500-2700M_{sun}_ for W51 Main, using an assumed age range of 1-3Myr. We measured the initial mass function (IMF) in the proto-clusters assuming a range of ages from 1-3Myr and found that the IMF slopes for both protoclusters are consistent with the Salpeter IMF in the mass range M>=8M_{sun}_ within 1{sigma}-2{sigma}.2025AJ....170..144Dhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/AJ/170/144CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)II/316 : UKIDSS-DR6 Galactic Plane Survey (Lucas+ 2012)II/321 : IPHAS DR2 Source Catalogue (Barentsen+, 2014)I/350 : Gaia EDR3 (Gaia Collaboration, 2020)I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)J/MNRAS/353/1025 : JHK photometry of 4 W51 star clusters (Nanda+, 2004)J/A+A/466/137 : Westerlund 2 JHKs photometry (Ascenso+, 2007)J/ApJ/706/83 : Embedded YSO candidates in W51 (Kang+, 2009)J/ApJ/720/1055 : VBLA observations of W51 Main/South (Sato+, 2010)J/ApJ/746/154 : Improved kinematic plx for Sco-Cen members (Pecaut+, 2012)J/ApJS/208/9 : Intrinsic colors and temperatures of PMS stars (Pecaut+, 2013)J/ApJS/213/1 : The MSFRs Omnibus X-ray Catalog (MOXC) (Townsley+, 2014)J/A+A/595/A27 : JVLA images of W51A (Ginsburg+, 2016)J/ApJ/839/108 : YSOs in the star-forming regions W51 & W43 (Saral+, 2017)J/MNRAS/477/3369 : Young stellar objects in W49A and W51 (Eden+, 2018)J/A+A/624/A63 : W51 OB stars NIR spectroscopy (Bik+, 2019)J/AJ/162/153 : X-ray propert. of A,B-types, T-Tauri stars & YSOs (Nunez+, 2021)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/AJ/170/144https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/AJ/170/144http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/AJ/170/144https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/AJ/170/144https://vizier.iucaa.in/viz-bin/votable?-source=J/AJ/170/144http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/AJ/170/144GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/AJ/170/144/table3 (Gran Telescopio Canarias (GTC) catalog)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/170/144/table3?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/170/144/table3?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/170/144/table3?GETtext/xml+votable180.050000true290.916458314.44329170.005555555555555556Cone search capability for table J/AJ/170/144/tablea1 (Catalog of cross-matched Gaia sources used to correct world coordinate system (WCS) offset)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/170/144/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/170/144/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/170/144/tablea1?GETtext/xml+votable180.050000true290.917291714.44340280.005555555555555556Cone search capability for table J/AJ/170/144/tableb1 (NACO Ks-band source catalog of W51 IRS2)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/AJ/170/144/tableb1?https://vizier.iucaa.in/viz-bin/conesearch/J/AJ/170/144/tableb1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/AJ/170/144/tableb1?GETtext/xml+votable180.050000true290.917583314.51536390.0055555555555555566/30694https://cdsarc.cds.unistra.fr/viz-bin/moc/J/AJ/170/144?format=asciiInfrareddefaultJ/AJ/170/144/table3Gran Telescopio Canarias (GTC) catalogrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintIDSource IDmeta.id;meta.maincharRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainindexedDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainJmag[8.3/26.7]? Apparent J-band magnitudemagphot.mag;em.IR.Jfloatnullablee_Jmag[1e-3/3443]? Uncertainty in Jmagmagstat.error;phot.mag;em.IR.JdoublenullableHmag[6.7/25.7]? Apparent H-band magnitudemagphot.mag;em.IR.Hfloatnullablee_Hmag[3e-4/91464]? Uncertainty in Hmagmagstat.error;phot.mag;em.IR.HdoublenullableKsmag[6.1/28.3]? Apparent Ks magnitudemagphot.mag;em.IR.Kfloatnullablee_Ksmag[5e-4/5672]? Uncertainty in Ksmagmagstat.error;phot.mag;em.IR.KdoublenullableAV[0.03/53.6]? Average extinctionmagphys.absorption;stat.meanfloatnullablee_AV[0.02/854796]? Uncertainty in AVmagstat.error;phys.absorptiondoublenullableAVmin[-35.1/45.2]? Minimum extinctionmagphys.absorption;stat.minfloatnullableAVmax[5.2/73.2]? Maximum extinctionmagphys.absorption;stat.minfloatnullableM1[0.09/275]? Mass estimate at 1 MyrsolMassphys.massfloatnullablee_M1[0/137.3]? Uncertainty in mass1solMassstat.error;phys.massfloatnullableM1min[0.09/275]? Minimum mass at 1 MyrsolMassphys.mass;stat.minfloatnullableM1max[0.09/275]? Maximum mass at 1 MyrsolMassphys.mass;stat.maxfloatnullableM2[0.09/93]? Mass estimate at 2 MyrsolMassphys.massfloatnullablee_M2[0/46.4]? Uncertainty in mass2solMassstat.error;phys.massfloatnullableM2min[0.09/93]? Minimum mass at 2 MyrsolMassphys.mass;stat.minfloatnullableM2max[0.09/93]? Maximum mass at 2 MyrsolMassphys.mass;stat.maxfloatnullableM3[0.09/55.3]? Mass estimate at 3 MyrsolMassphys.massfloatnullablee_M3[0.01/27.5]? Uncertainty in mass3solMassstat.error;phys.massfloatnullableM3min[0.09/55.3]? Minimum mass at 3 MyrsolMassphys.mass;stat.minfloatnullableM3max[0.09/55.2]? Maximum mass at 3 MyrsolMassphys.mass;stat.maxfloatnullableNotesAdditional notes (1)meta.notechar2MASSLink to 2MASS (II/246) data for sources within 1.5"meta.ref.urlintnullableUKIDSSLink to UKIDSS DR6 GPS (II/316) data for sources within 1.5"meta.ref.urlintnullableJ/AJ/170/144/tablea1Catalog of cross-matched Gaia sources used to correct world coordinate system (WCS) offsetrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainJmag[12.5/20.6]? Apparent J-band magnitudemagphot.mag;em.IR.JfloatnullableHmag[11.9/18.9]? Apparent H-band magnitudemagphot.mag;em.IR.HfloatnullableKsmag[11/17.2] Apparent Ks-band magnitudemagphot.mag;em.IR.KfloatOffset[0.01/1.3] Gaia offsetarcsecpos;arith.difffloatGaiaDR3Gaia DR3 (I/355) source IDmeta.id.assocJ/AJ/170/144/tableb1NACO Ks-band source catalog of W51 IRS2recnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintRAJ2000Hour of right ascension (J2000)pos.eq.ra;meta.mainDEJ2000Degree of declination (J2000)pos.eq.dec;meta.mainKsmag[9.4/18.5] Apparent Ks-band magnitudemagphot.mag;em.IR.Kfloate_Ksmag[0.01/3.3] Uncertainty in Ksmagmagstat.error;phot.magfloatOffset[0.02/4.5] GTC offsetarcsecpos;arith.difffloatMatchGTC matched? (Yes/No) (1)meta.codechar