J/A+A/501/563ivo://CDS.VizieR/J/A+A/501/563doi:10.26093/cds/vizier.35010563CDSEspinoza P.Selman F.J.Melnick J.2017-06-22T14:28:35Z2009-08-13T22:32:14ZCDS support team

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

cds-question@unistra.fropen-star-clustersinfrared-photometrystellar-massesThe massive Arches cluster near the Galactic center should be an ideal laboratory for investigating massive star formation under extreme conditions. But it comes at a high price: the cluster is hidden behind several tens of magnitudes of visual extinction. Severe crowding requires space or AO-assisted instruments to resolve the stellar populations, and even with the best instruments interpreting the data is far from direct. Several investigations using NICMOS and the most advanced AO imagers on the ground revealed an overall top-heavy IMF for the cluster, with a very flat IMF near the center. There are several effects, however, that could potentially bias these results, in particular the strong differential extinction and the problem of transforming the observations into a standard photometric system in the presence of strong reddening. We present new observations obtained with the NAOS-Conica (NACO) AO-imager on the VLT. The problem of photometric transformation is avoided by working in the natural photometric system of NACO, and we use a Bayesian approach to determine masses and reddenings from the broad-band IR colors. A global value of Gamma=-1.1+/-0.2 for the high-mass end (M>10M_{sun}_) of the IMF is obtained, and we conclude that a power law of Salpeter slope cannot be discarded for the Arches cluster. The flattening of the IMF towards the center is confirmed, but is less severe than previously thought. We find Gamma=-0.88+/-0.20, which is incompatible with previous determinations. Within 0.4pc we derive a total mass of ~2.0(+/-0.6)x10^4^M_{sun}_ for the cluster and a central mass density rho=2(+/-0.4)x10^5^M_{sun}_/pc^3^ that confirms Arches as the densest known young massive cluster in the Milky Way.2009A&A...501..563Ehttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/A+A/501/563CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/581/258 : Infrared photometry in the Arches Cluster (Figer+, 2002)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/A+A/501/563https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/A+A/501/563http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/A+A/501/563https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/A+A/501/563https://vizier.iucaa.in/viz-bin/votable?-source=J/A+A/501/563http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/A+A/501/563GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/A+A/501/563/table2 (HKs photometry of stars in the Arches cluster)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/A+A/501/563/table2?https://vizier.iucaa.in/viz-bin/conesearch/J/A+A/501/563/table2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/A+A/501/563/table2?GETtext/xml+votable180.050000true266.461056928.82296810.0055555555555555566/32658https://cdsarc.cds.unistra.fr/viz-bin/moc/J/A+A/501/563?format=asciiInfrareddefaultJ/A+A/501/563/table2HKs photometry of stars in the Arches clusterrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintPSimbad column added by the CDSmeta.ref.urlcharSeqStar unique ID in this work (G1)meta.id;meta.mainintprimarydRARight Ascension offset (2)arcsecpos.eq.ra;arith.difffloatdDEDeclination offset (2)arcsecpos.eq.dec;arith.difffloatKsmagNACO Ks band magnitudemagphot.mag;em.IR.Kfloate_Ksmag1{sigma} uncertainty in Ksmagstat.error;phot.mag;em.IR.KfloatH-KsNACO (H-Ks) color indexmagphot.color;em.IR.H;em.IR.Kfloate_H-Ks1{sigma} uncertainty in (H-Ks)magstat.error;phot.color;em.IR.HfloatJ-H? NACO (J-H) color index (table3 only)magphot.color;em.IR.J;em.IR.Hfloatnullablee_J-H? 1{sigma} uncertainty in (J-H) (table3 only)magstat.error;phot.color;em.IR.Jfloatnullable_RAPosition, computed from center and {Delta} values (right ascension part)degpos.eq.ra;meta.main_DEPosition, computed from center and {Delta} values (declination part)degpos.eq.dec;meta.mainJ/A+A/501/563/table35JHKs photometry and physical parameters of stars in the Arches clusterrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeqStar unique ID in this work (G1)meta.id;meta.mainintdRARight Ascension offset (2)arcsecpos.eq.ra;arith.difffloatdDEDeclination offset (2)arcsecpos.eq.dec;arith.difffloatKsmagNACO Ks band magnitudemagphot.mag;em.IR.Kfloate_Ksmag1{sigma} uncertainty in Ksmagstat.error;phot.mag;em.IR.KfloatH-KsNACO (H-Ks) color indexmagphot.color;em.IR.H;em.IR.Kfloate_H-Ks1{sigma} uncertainty in (H-Ks)magstat.error;phot.color;em.IR.HfloatJ-H? NACO (J-H) color index (table3 only)magphot.color;em.IR.J;em.IR.Hfloatnullablee_J-H? 1{sigma} uncertainty in (J-H) (table3 only)magstat.error;phot.color;em.IR.JfloatnullableVMAGAbsolute V band magnitude (3)magphys.magAbs;em.opt.VfloatlogLLog of the luminosity (3)log(solLum)phys.luminosityfloatlogTeffLog of the effective temperature (3)log(K)phys.temperature.effectivefloatloggLog of the surface gravity (3)log(N.kg**-1)phys.gravityfloatE(H-Ks)Color excessmagphot.color.excessfloatMiniInitial mass (3)solMassphys.massfloatMactPresent day mass (3)solMassphys.massfloat