J/ApJ/799/53ivo://CDS.VizieR/J/ApJ/799/53doi:10.26093/cds/vizier.17990053CDSKoepferl C.M.Robitaille T.P.Morales E.F.E.Johnston K.G.2015-07-25T13:22:14Z2015-07-01T13:49:26ZCDS support team

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

cds-question@unistra.frastronomical-modelsyoung-stellar-objectsinfrared-photometrygiant-starsIn contrast to most other galaxies, star formation rates in the Milky Way can be estimated directly from young stellar objects (YSOs). In the central molecular zone the star formation rate calculated from the number of YSOs with 24{mu}m emission is up to an order of magnitude higher than the value estimated from methods based on diffuse emission (such as free-free emission). Whether this effect is real or whether it indicates problems with either or both star formation rate measures is not currently known. In this paper, we investigate whether estimates based on YSOs could be heavily contaminated by more evolved objects such as main-sequence stars. We present radiative transfer models of YSOs and of main-sequence stars in a constant ambient medium which show that the main-sequence objects can indeed mimic YSOs at 24{mu}m. However, we show that in some cases the main-sequence models can be marginally resolved at 24{mu}m, whereas the YSO models are always unresolved. Based on the fraction of resolved MIPS 24{mu}m sources in the sample of YSOs previously used to compute the star formation rate, we estimate the fraction of misclassified "YSOs" to be at least 63%, which suggests that the star formation rate previously determined from YSOs is likely to be at least a factor of three too high.2015ApJ...799...53Khttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/799/53CatalogResearchIsServedByTAP VizieR generic servicerelated-toII/316 : UKIDSS-DR6 Galactic Plane Survey (Lucas+ 2012)II/295 : Spitzer IRAC survey of the galactic center (Ramirez+, 2008)J/ApJ/736/133 : Spitzer-IRS study of YSOs in galactic center (An+, 2011)J/ApJS/181/321 : Properties of Spitzer c2d dark clouds (Evans+, 2009)J/ApJS/181/227 : Catalog of 24um sources toward Galactic Center (Hinz+, 2009)J/ApJ/702/178 : YSOs in the central 400pc of the Galaxy (Yusef-Zadeh+, 2009)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/799/53https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/799/53http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/799/53https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/799/53https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/799/53http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/799/53GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tap6.772611666688002e-21 1.000830682546041e-20InfrareddefaultJ/ApJ/799/53/table3Parameters and measurements from our modelsrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintClassStellar classification (1)src.spTypecharInfall[0/0.0003] Infall ratesolMass/yrphys.mass.lossfloatStageYSO stage ("0/1" or "2+")src.classcharDenAmbient density (10^21^, 3x10^21^, or 10^-20^)g.cm**-3phys.densityfloatPAH[x-] PAH dust present: x=yesmeta.codecharKmag[4/178] UKIDSS K band (2.2 micron) magnitudemagphot.mag;meta.modelledfloat[8.0][-1.7/36.4] Spitzer/IRAC 8 micron band magnitudemagphot.mag;meta.modelledfloat[24][-5.5/19.7] Spitzer/MIPS 24 micron band magnitudemagphot.mag;meta.modelledfloatSB70[2.4/346049] Herschel/PACS 70 micron band maximum surface brightnessMJy/srphot.flux.density.sb;em.IR.60-100um;stat.maxdoubleHWHM[3/5.3] Half-Width at Half-Maximum of 24 micron imagearcsecphys.angSizefloat