J/ApJ/789/81ivo://CDS.VizieR/J/ApJ/789/81doi:10.26093/cds/vizier.17890081CDSFaesi C.M.Lada C.J.Forbrich J.Menten K.M.Bouy H.2017-06-12T08:25:14Z2016-08-29T08:12:39ZCDS support team

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

cds-question@unistra.frh-ii-regionsradio-astronomyvisible-astronomyh-alpha-photometryultraviolet-photometryinfrared-photometryextinctionmillimeter-astronomysubmillimeter-astronomyWe present the results of a galaxy-wide study of molecular gas and star formation in a sample of 76 H II regions in the nearby spiral galaxy NGC 300. We have measured the molecular gas at 250pc scales using pointed CO(J=2-1) observations with the Atacama Pathfinder Experiment telescope. We detect CO in 42 of our targets, deriving molecular gas masses ranging from our sensitivity limit of ~10^5^M_{sun}_ to 7x10^5^M_{sun}_. We find a clear decline in the CO detection rate with galactocentric distance, which we attribute primarily to the decreasing radial metallicity gradient in NGC 300. We combine Galaxy Evolution Explorer far-ultraviolet, Spitzer 24{mu}m, and H{alpha} narrowband imaging to measure the star formation activity in our sample. We have developed a new direct modeling approach for computing star formation rates (SFRs) that utilizes these data and population synthesis models to derive the masses and ages of the young stellar clusters associated with each of our H II region targets. We find a characteristic gas depletion time of 230Myr at 250pc scales in NGC 300, more similar to the results obtained for Milky Way giant molecular clouds than the longer (>2Gyr) global depletion times derived for entire galaxies and kiloparsec-sized regions within them. This difference is partially due to the fact that our study accounts for only the gas and stars within the youngest star-forming regions. We also note a large scatter in the NGC 300 SFR-molecular gas mass scaling relation that is furthermore consistent with the Milky Way cloud results. This scatter likely represents real differences in giant molecular cloud physical properties such as the dense gas fraction.2014ApJ...789...81Fhttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJ/789/81CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toJ/ApJ/821/125 : SMA obs. of giant molecular clouds in NGC 300 (Faesi+, 2016)J/ApJ/723/1019 : Galactic SFR and gas surface densities (Heiderman+, 2010)J/ApJ/723/492 : Physical data of GRS molecular clouds (Roman-Duval+, 20110)J/ApJ/706/599 : H{alpha} and UV SFR in the local volume (Lee+, 2009)J/ApJ/703/1672 : Far-IR and H{alpha} fluxes in galaxies (Kennicutt+, 2009)J/ApJ/699/1092 : Giant molecular clouds (SRBY) (Heyer+, 2009)J/AJ/136/2782 : Star formation efficiency in nearby galaxies (Leroy+, 2008)J/ApJS/173/293 : UV-Optical galaxy color-magnitude diagram I. (Wyder+, 2007)J/AJ/128/1167 : ARAUCARIA project : NGC 300 Cepheids. II (Gieren+, 2004)J/ApJS/100/125 : CO(J=2-1) Survey of the Milky Way (Sakamoto+, 1995)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJ/789/81https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJ/789/81http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJ/789/81https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJ/789/81https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJ/789/81http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJ/789/81GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJ/789/81/hiireg (APEX observations and photometry results of the HII region sample)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJ/789/81/hiireg?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJ/789/81/hiireg?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJ/789/81/hiireg?GETtext/xml+votable180.050000true13.61816611-37.696751110.0055555555555555566/35536 355386.772611666688002e-21 1.4134638842407062e-18https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJ/789/81?format=asciiOpticalUVInfraredRadiodefaultJ/ApJ/789/81/hiiregAPEX observations and photometry results of the HII region samplerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordint[DCL88]HII region catalog identifier (Deharveng et al. 1988A&AS...73..407D)meta.id;meta.maincharRAJ2000Right Ascension in decimal degrees (J2000)degpos.eq.ra;meta.mainDEJ2000Declination in decimal degrees (J2000)degpos.eq.dec;meta.mainTRMS[5/23] APEX RMS main beam temperaturemKstat.stdev;phys.temperature;meta.mainfloatvHI[78/197] H I velocitykm/sphys.veloc;pos.heliocentricfloatRGal[0/7] Deprojected galactocentric distancekpcpos.distance;pos.galactocentricfloatl_ICOLimit flag on ICOmeta.code.errorcharICO[48/1140] Spectrally-integrated CO intensitymK.km/sspect.line.intensityinte_ICO[37/113]? Uncertainty in ICOmK.km/sstat.errorintnullablef_ICO[a] a = Gaussian-derived ICOmeta.codecharW(CO)[2/21]? CO linewidthkm/sspect.line.widthfloatnullableTypeDetection type (G1)meta.codecharl_FHaLimit flag on FHameta.code.errorcharFHa[0.5/137]? ESO/WFI H{alpha} flux; in 1e-14erg/s/cm^2^1e-17W.m**-2phot.flux;em.line.Halphafloatnullablee_FHa[0.2/6]? Uncertainty in FHa1e-17W.m**-2stat.errorfloatnullablel_FFUVLimit flag on FFUVmeta.code.errorcharFFUV[8/5780] GALEX/FUV band flux densityuJyphot.flux;em.UVfloate_FFUV[2/290]? Uncertainty in FFUVuJystat.errorfloatnullablel_F24Limit flag on F24meta.code.errorcharF24[0.01/65] Spitzer/MIPS 24um flux densitymJyphot.flux.density;em.IR.15-30umfloate_F24[0.02/4.2]? Uncertainty in F24mJystat.errorfloatnullableAHa[0.01/0.7]? H{alpha} extinctionmagphys.absorptionfloatnullablee_AHa[0/0.2]? Uncertainty in AHamagstat.errorfloatnullableAFUV[0.01/1.6]? FUV extinctionmagphys.absorptionfloatnullablee_AFUV[0.01/0.5]? Uncertainty in AFUVmagstat.errorfloatnullablel_M(GMCC)Limit flag on M(GMCC)meta.code.errorcharM(GMCC)[0.4/7] Giant Molecular Cloud Complex mass100000solMassphys.massfloate_M(GMCC)[0.1/0.7]? Uncertainty in M(GMCC)100000solMassstat.errorfloatnullableM*[1/38]? Stellar mass1000solMassphys.massfloatnullablee_M*[0.2/7]? Uncertainty in M*1000solMassstat.errorfloatnullableAge[1.8/10]? AgeMyrtime.agefloatnullablee_Age[0.3/4]? Uncertainty in AgeMyrstat.error;time.agefloatnullableSFR[0.0002/0.01]? Star Formation RatesolMass/yrphys.SFRfloatnullableE_SFR[0.0001/0.003]? Upper uncertainty in SFRsolMass/yrstat.error;stat.maxfloatnullablee_SFR[0.0001/0.002]? Lower uncertainty in SFRsolMass/yrstat.error;phys.SFRfloatnullableF16Display data from Faesi+, 2016, J/ApJ/821/125, if anymeta.ref.urlintnullableSimbadSimbad column added by the CDSmeta.ref.urlcharNEDSimbad column added by the CDSmeta.ref.urlchar