J/ApJ/763/101ivo://CDS.VizieR/J/ApJ/763/101doi:10.26093/cds/vizier.17630101CDSLamb J.B.Oey M.S.Graus A.S.Adams F.C.Segura-Cox D.M.2018-01-04T08:22:38Z2014-11-05T08:34:43ZCDS support team

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

cds-question@unistra.frvisible-astronomyWide-band photometrymagellanic-cloudsob-starsstellar-massesstellar-spectral-typesSome theories of star formation suggest massive stars may only form in clustered environments, which would create a deficit of massive stars in low-density environments. Observationally, Massey (2002, Cat. II/236) finds such a deficit in samples of the field population in the Small and Large Magellanic Clouds, with an initial mass function (IMF) slope of {Gamma}_IMF_~4. These IMF measurements represent some of the largest known deviations from the standard Salpeter IMF slope of {Gamma}_IMF_=1.35. Here, we carry out a comprehensive investigation of the mass function above 20M_{sun}_ for the entire field population of the Small Magellanic Cloud (SMC), based on data from the Runaways and Isolated O Type Star Spectroscopic Survey of the SMC (RIOTS4). This is a spatially complete census of the entire field OB star population of the SMC obtained with the IMACS multi-object spectrograph and MIKE echelle spectrograph on the Magellan telescopes. Based on Monte Carlo simulations of the evolved present-day mass function, we find the slope of the field IMF above 20M_{sun}_ is {Gamma}_IMF_=2.3+/-0.4. We extend our IMF measurement to lower masses using BV photometry from the OGLE II survey. We use a statistical approach to generate a probability distribution for the mass of each star from the OGLE photometry, and we again find {Gamma}_IMF_=2.3+/-0.6 for stellar masses from 7M_{sun}_ to 20M_{sun}_. The discovery and removal of ten runaways in our RIOTS4 sample steepens the field IMF slope to {Gamma}_IMF_=2.8+/-0.5. We discuss the possible effects of binarity and star formation history on our results, and conclude that the steep field massive star IMF is most likely a real effect.2013ApJ...763..101Lhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/763/101CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toII/236 : UBVR CCD survey of the Magellanic clouds (Massey+, 2002)III/195 : Atlas of Optical Spectral Classification OB Stars (Walborn+ 1990)J/A+A/562/A125 : OGLE-III SMC massive stars VI phot. (Kourniotis+, 2014)J/AJ/140/416 : IR photometry of massive stars in the SMC (Bonanos+, 2010)J/MNRAS/386/826 : Radial velocities of SMC massive stars (Evans+, 2008)J/A+A/466/277 : VLT-FLAMES survey of massive stars (Hunter+, 2007)J/A+A/452/179 : Ages of SMC young clusters and field stars (Chiosi+, 2006)J/AJ/127/1632 : UBVR(UIT) photometry of O and OB stars in SMC (Oey+, 2004)J/AJ/127/1531 : Star formation history of SMC (Harris+, 2004)J/MNRAS/353/601 : 2dF survey of the Small Magellanic Cloud (Evans+, 2004)J/AJ/123/855 : Magellanic Clouds Phot. Survey: the SMC (Zaritsky+, 2002)J/AJ/116/180 : Magellanic clouds ultraviolet observations (Parker+ 1998)J/AcA/48/147 : OGLE SMC BVI photometry (Udalski+ 1998)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/763/101https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/763/101http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/763/101https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/763/101https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/763/101http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/763/101GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/763/101/table1 (RIOTS4 spectral catalog (Runaways and Isolated O-Type Star Spectroscopic Survey of the SMC))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/763/101/table1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/763/101/table1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/763/101/table1?GETtext/xml+votable180.050000true10.5416667-73.23227780.0055555555555555566/33294 33295 33297 33298 33299 33304 33306 33307 33316 33317 333283.322582951404819e-19 4.920466254354166e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/763/101?format=asciiOpticaldefaultJ/ApJ/763/101/table1RIOTS4 spectral catalog (Runaways and Isolated O-Type Star Spectroscopic Survey of the SMC)SpTMK spectral typesrc.spTypecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[M2002][1600/83678] Identifier from Massey (II/236, <[M2002] SMC NNNNNN> in Simbad)meta.id;meta.mainintBmag[12.4/15.1] The B band magnitude (1)magphot.mag;em.opt.BfloatVmag[12.5/15.3] The V band magnitude (1)magphot.mag;em.opt.VfloatMbol[-14.4/-9.6] Bolometric absolute magnitudemagphys.magAbs.bolfloatQ[-1.2/-0.8] The reddening free parameter (2)magphot.color.reddFreefloatAv[0.05/2.1] The V band extinctionmagphys.absorption;em.opt.VfloatTeff[19000/47750] Effective temperatureKphys.temperature.effectiveintMass[20/75] Star masssolMassphys.massfloatE_MassUpper limit uncertainty in MasssolMassstat.error;stat.maxfloate_MassLower limit uncertainty in MasssolMassstat.error;phys.massfloatSimbadSimbad column added by the CDSmeta.ref.urlcharNEDSimbad column added by the CDSmeta.refchar_RAPositions from Massey et al. 2002, II/236 (right ascension part)degpos.eq.ra;meta.main_DEPositions from Massey et al. 2002, II/236 (declination part)degpos.eq.dec;meta.main