J/ApJ/808/106ivo://CDS.VizieR/J/ApJ/808/106doi:10.26093/cds/vizier.18080106CDSStostad M.Do T.Murray N.Lu J.R.Yelda S.Ghez A.2017-07-06T06:25:33Z2015-12-18T09:41:06ZCDS support team

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

cds-question@unistra.frinfrared-photometryline-intensitiesextinctionWe present new near-infrared spectroscopic observations of the outer edges of the young stellar cluster around the supermassive black hole at the Galactic center. The observations show a break in the surface density profile of young stars at ~13" (0.52pc). These observations spectroscopically confirm previous suggestions of a break based on photometry. Using Gemini North's Near-Infrared Integral Field Spectrometer, we are able to detect and separate early- and late-type stars with a 75% completeness at K_s_=15.5. We sample a region with radii between 7" and 23" (0.28-0.92pc) from Sgr A* and present new spectral classifications of 144 stars brighter than K_s_=15.5, where 140 stars are late-type (>1Gyr) and only four stars are early-type (young, 4-6Myr). A broken power-law fit of the early-type surface density matches well with our data and previously published values. The projected surface density of late-type stars is also measured and found to be consistent with previous results. We find that the observed early-type surface-density profile is inconsistent with the theory of young stars originating from a tightly bound infalling cluster, as no significant trail of young stars is found at radii above 13". We also note that either a simple disk instability criterion or a cloud-cloud collision could explain the location of the outer edge, though we lack information to make conclusive remarks on either alternative. If this break in surface density represents an edge to the young stellar cluster, it would set an important scale for the most recent episode of star formation at the Galactic center.2015ApJ...808..106Shttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/808/106CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/A+A/584/A2 : KMOS view of the Galactic centre. I. (Feldmeier-Krause+, 2015)J/ApJ/779/L6 : 3D kinematic obs. of stars in Galactic Centre (Do+, 2013)J/ApJ/764/154 : Stellar populations in the central 0.5pc. I. (Do+, 2013)J/A+A/549/A57 : Young, massive star candidates in Sgr A* (Nishiyama+, 2013)J/A+A/511/A18 : NIR obs. of stars near SgrA* (Schoedel+, 2010)J/ApJ/703/1323 : Star spectroscopy in the Galaxy's nuclear cluster (Do+ 2009)J/ApJ/697/1741 : Warped disks of YSOs in Galactic center (Bartko+, 2009)J/A+A/499/483 : NIR obs. of sources in galactic center (Buchholz+, 2009)J/ApJ/670/1115 : IRS spectra at 38 positions in Gal. Center (Simpson+, 2007)J/ApJ/643/1011 : Early-type stars in the center of the Galaxy (Paumard+, 2006)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/808/106https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/808/106http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/808/106https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/808/106https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/808/106http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/808/106GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/808/106/stars (NIFS observations of early- and late-type stars)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/808/106/stars?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/808/106/stars?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/808/106/stars?GETtext/xml+votable180.050000true266.41802167-29.005824440.005555555555555556Cone search capability for table J/ApJ/808/106/table4 (NIFS observations of stars without spectral identification)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/808/106/table4?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/808/106/table4?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/808/106/table4?GETtext/xml+votable180.050000true266.41746583-29.005727220.0055555555555555566/288307.952274030004205e-20 1.0188844282367877e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/808/106?format=asciiInfrareddefaultJ/ApJ/808/106/starsNIFS observations of early- and late-type starsDateDate of the observationtime.epochnullableNameStellar identifiermeta.id;meta.maincharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSpTSimbad column added by the CDSsrc.classcharKsmag[10.7/18.7] The K_S_ band magnitudemagphot.mag;em.IR.Kfloatf_Ksmag[b] Flag on Ksmag (G1)meta.codecharoRARight Ascension offset (G2)arcsecpos.eq.ra;arith.difffloatoDEDeclination offset (G2)arcsecpos.eq.dec;arith.difffloatRad[7.7/22.8] Projected radius from Sgr A*arcsecpos.angDistancefloatl_SNRLimit flag on SNRmeta.code.errorcharSNR[3/141] Signal-to-Noisestat.snrintEW2.29[0/17.4]? Equivalent width of CO 2.2935 micron feature (1)0.1nmspect.line.eqWidthfloatnullablee_EW2.29[0.1/3]? Uncertainty in EW2.2935 (1)0.1nmstat.errorfloatnullableEW2.32[0.7/30]? Equivalent width of CO 2.3227 micron feature (1)0.1nmspect.line.eqWidthfloatnullablee_EW2.32[0.1/2]? Uncertainty in EW2.3227 (1)0.1nmstat.errorfloatnullableEWNaI[-0.3/10.8]? Equivalent width of Na I line (only for table 3) (1)0.1nmspect.line.eqWidthfloatnullablee_EWNaI[0.1/2]? Uncertainty in EWNaI (1)0.1nmstat.errorfloatnullableEWBrg[0.7/2.5]? Equivalent width of Br{gamma} line (only for table 2) (2)0.1nmspect.line.eqWidthfloatnullablee_EWBrg[0.3/2]? Uncertainty in EWBrg (2)0.1nmstat.errorfloatnullableAKs[2.3/3] The K_S_ band extinctionmagphys.absorptionfloatC?Contamination? Y/Nmeta.codecharFigFigure number in the online set images; column added by CDSmeta.idcharS10Sources within 0.17" in Schoedel+, 2010, J/A+A/511/A18meta.ref.urlintnullable_RASimbad column added by the CDSdegpos.eq.ra;meta.main_DESimbad column added by the CDSdegpos.eq.dec;meta.mainJ/ApJ/808/106/table4NIFS observations of stars without spectral identificationrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNameStellar identifiermeta.id;meta.maincharDateDate of the observationtime.epochnullableKsmag[14.7/20.6]? The K_S_ band magnitudemagphot.mag;em.IR.Kfloatnullablef_Ksmag[bc] Flag on Ksmag (G1)meta.codecharoRARight Ascension offset (G2)arcsecpos.eq.ra;arith.difffloatoDEDeclination offset (G2)arcsecpos.eq.dec;arith.difffloatRad[7.7/22.1] Projected radius from Sgr A*arcsecpos.angDistancefloatl_SNRLimit flag on SNRmeta.code.errorcharSNR[0/40] Signal-to-Noisestat.snrintAKs[2.3/3] The K_S_ band extinctionmagphys.absorptionfloatFigFigure number in the online set images; column added by CDSmeta.idcharS10Sources within 0.17" in Schoedel+, 2010, J/A+A/511/A18meta.ref.urlintnullable_RASimbad column added by the CDSdegpos.eq.ra;meta.main_DESimbad column added by the CDSdegpos.eq.dec;meta.main