J/ApJS/265/18ivo://CDS.VizieR/J/ApJS/265/18doi:10.26093/cds/vizier.22650018CDSIshioka R.Chu Y.-H.Edmister A.Gruendl R.A.Zhang L.Zhu J.2023-10-17T11:35:17Z2023-06-16T10:23:38ZCDS support team

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

cds-question@unistra.frmagellanic-cloudsyoung-stellar-objectsinfrared-photometryvisible-astronomyspectroscopytwo-color-diagramsabsolute-magnitudeinterstellar-reddeningstellar-spectral-typeseffective-temperatureWe present low-resolution optical spectra and classifications of 92 blue objects with mid-infrared excesses in the Large Magellanic Cloud. The majority of these objects were selected with the criteria of U-B<0 and V<17 from the potential young stellar object (YSO) candidates in Gruendl & Chu (GC09; 2009, J/ApJS/184/172), which were identified based on Spitzer Infrared Array Camera and Multiband Imaging Photometer for Spitzer observations in conjunction with optical photometry from the Magellanic Clouds Photometric Survey. Many of the sample objects have ambiguous classifications. We examined the properties of these 92 objects using low-resolution optical spectra obtained with the SOAR 4.1m Telescope at Cerro Pachon and the Blanco 4m Telescope at Cerro Tololo Inter-American Observatory, supplemented by available photometric and imaging observations. We estimated the spectral types, temperatures, and luminosities of these objects from the optical to near-IR spectral energy distributions based on the photometric data, and further examined stellar absorption line features in the optical spectra to verify the spectral types. The interstellar/circumstellar environments, assessed from nebular line imaging observations and nebular lines detected in the stellar spectra, further helped constrain the nature of stars. Among these 92 objects, we confirm 42 stars as YSOs, and the remaining 50 objects as protoplanetary nebulae, post-AGB/RGB stars, blue evolved massive stars, stars with dust in vicinity, or uncertain classifications. Our results show that the photometric criteria in GC09 are generally effective in the initial selection of YSO candidates, and the low- resolution spectroscopy combined with environment assessment can be useful to better constrain the classifications and ameliorate most ambiguities.2023ApJS..265...18Ihttps://cdsarc.cds.unistra.fr/viz-bin/cat/J/ApJS/265/18CatalogResearchIsServedByTAP VizieR generic serviceIsServedByConesearch servicerelated-toB/mk : Catalogue of Stellar Spectral Classifications (Skiff, 2009- )III/147 : Studies of LMC stellar content (Rousseau+ 1978)III/92 : A Library of Stellar Spectra (Jacoby+ 1984)III/136 : Optical spectrophotometry of WR C and O Stars (Torres+ 1987)III/195 : Atlas of Optical Spectral Classification OB Stars (Walborn+ 1990)II/228 : DENIS Catalogue toward Magellanic Clouds (DCMC) (Cioni+ 2000)II/236 : UBVR CCD survey of the Magellanic clouds (Massey+, 2002)II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)II/288 : IRSF Magellanic Clouds Point Source Catalog (Kato+ 2007)II/351 : VISTA Magellanic Survey (VMC) catalog (Cioni+, 2011)I/345 : Gaia DR2 (Gaia Collaboration, 2018)VII/23 : Nebulae in the Magellanic Clouds (Davies+ 1976)J/AJ/103/1205 : Stellar Content of LH 9 and 10 in the LMC (Parker+ 1992)J/ApJS/91/659 : Ultracompact HII regions radio images (Kurtz+ 1994)J/A+A/299/755 : Stellar evolution. II. Post-AGB (Bloecker+, 1995)J/ApJ/452/210 : UBV photometry in LH 47/48 (Oey+ 1995)J/A+AS/125/419 : Obscured AGB in Magellanic Clouds. I. (Loup+ 1997)J/AJ/117/238 : LMC extended catalog (Bica+, 1999)J/AJ/124/2039 : LMC Blue variable stars from MACHO (Keller+, 2002)J/AJ/128/1606 : Magellanic Clouds Phot. Survey (MCPS) (Zaritsky+, 2004)J/A+A/456/623 : VLT-FLAMES survey of massive stars (Evans+, 2006)J/AJ/132/2268 : SAGE calibration stars (Meixner+, 2006)J/ApJ/652/458 : BVRH{alpha} phot. of candid. Be stars (Wisniewski+, 2006)J/AJ/134/1963 : MACHO r,b light curves of MC EBs (Faccioli+, 2007)J/ApJS/178/56 : CO obs. of LMC Giant Molecular clouds (Fukui+, 2008)J/AJ/136/18 : LMC SAGE. New candidate YSOs (Whitney+, 2008)J/AJ/138/1003 : IR photometry of massive LMC stars (Bonanos+, 2009)J/ApJ/695/511 : Young massive stars in LHA 120-N 44 (Chen+, 2009)J/ApJS/184/172 : High- & intermediate-mass YSOs in the LMC (Gruendl+, 2009)J/ApJ/699/150 : Spectral classif. of Massive YSOs in LMC (Seale+, 2009)J/ApJ/707/1417 : HST view of YSOs in the LMC (Vaidya+, 2009)J/MNRAS/405/1349 : LMC PNe [OIII] 5007{AA} and H{beta} flux (Reid+, 2010)J/ApJ/721/357 : YSOs in the LMC star-forming region N206 (Romita+, 2010)J/AJ/142/103 : Cool evolved stars in SAGE-SMC and SAGE-LMC (Boyer+, 2011)J/A+A/530/A108 : VLT-FLAMES Tarantula Survey (Evans+, 2011)J/AcA/61/103 : VI light curves of LMC eclipsing binaries (Graczyk+, 2011)J/A+A/531/A157 : LMC planetary nebulae (VMC Survey II) (Miszalski+, 2011)J/A+A/530/A90 : Opt. bright post-AGB population of LMC (van Aarle+, 2011)J/MNRAS/411/1597 : LMC point source classif. in SAGE-Spec (Woods+, 2011)J/A+A/542/A66 : YSOs in 9 LMC star forming regions (Carlson+, 2012)J/MNRAS/425/355 : Hot stars in LMC UKST H{alpha} survey (Reid+, 2012)J/ApJ/789/139 : Three O-type binaries photometry in LMC (Morrell+, 2014)J/AJ/148/124 : Herschel key program Heritage (Seale+, 2014)J/A+A/564/A40 : VFTS. O-type stellar content of 30 Dor (Walborn+, 2014)J/A+A/574/A13 : VFTS. B-type stars classification and RV (Evans+, 2015)J/A+A/584/A5 : Massive LMC stars AAOmega spectroscopy (Evans+, 2015)J/MNRAS/454/1468 : LMC post-AGB, post-RGB star and YSOs (Kamath+, 2015)J/AcA/66/421 : EBs in the Magellanic System (Pawlak+, 2016)J/A+A/598/A84 : OB-type spectroscopic binaries (Almeida+, 2017)J/MNRAS/470/3250 : SAGE LMC point-sources classification (Jones+, 2017)J/AJ/154/199 : Survey of the MAgellanic Stellar History (Nidever+, 2017)J/other/NewA/56.28 : Be stars in MC star clusters NIR properties (Paul+, 2017)J/A+A/614/A147 : NGC 2070 point sources radial velocities (Castro+, 2018)J/A+A/636/A48 : VMC Survey. XXXVII. MC AGB stars (Groenewegen+, 2020)J/ApJ/898/85 : CII em-line stars in LMC with MagE spectra (Margon+, 2020)J/A+A/641/A142 : Post-AGB cand. in LMC & SMC SALT spectra (Szczerba+, 2020)J/MNRAS/494/458 : VMC XXXVI. Young stellar var. in LMC (Zivkov+, 2020)J/A+A/658/A36 : Transition disks around evolved stars (Kluska+, 2022)https://cds.unistra.fr/vizier-org/licences_vizier.htmlhttps://vizier.cds.unistra.fr/viz-bin/VizieR-2?-source=J/ApJS/265/18https://vizier.iucaa.in/viz-bin/VizieR-2?-source=J/ApJS/265/18http://vizieridia.saao.ac.za/viz-bin/VizieR-2?-source=J/ApJS/265/18https://vizier.cds.unistra.fr/viz-bin/votable?-source=J/ApJS/265/18https://vizier.iucaa.in/viz-bin/votable?-source=J/ApJS/265/18http://vizieridia.saao.ac.za/viz-bin/votable?-source=J/ApJS/265/18GETtext/xml+votablehttps://tapvizier.cds.unistra.fr/TAPVizieR/tapCone search capability for table J/ApJS/265/18/blue (Blue stars with IR excesses (Table 1), estimates from photometric data (Table 3), environments & classification (Table 4) and classifications from literature (Table 5))https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/265/18/blue?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/265/18/blue?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/265/18/blue?GETtext/xml+votable180.050000true70.7581192-70.56812720.005555555555555556Cone search capability for table J/ApJS/265/18/tablea1 (List of 13 additional targets without U-B<0)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/265/18/tablea1?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/265/18/tablea1?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/265/18/tablea1?GETtext/xml+votable180.050000true73.0382042-66.9228750.005555555555555556Cone search capability for table J/ApJS/265/18/tablea2 (List of 19 targets which were not observed)https://vizier.cds.unistra.fr/viz-bin/conesearch/J/ApJS/265/18/tablea2?https://vizier.iucaa.in/viz-bin/conesearch/J/ApJS/265/18/tablea2?http://vizieridia.saao.ac.za/viz-bin/conesearch/J/ApJS/265/18/tablea2?GETtext/xml+votable180.050000true72.6664361-69.19973920.0055555555555555565/8274-8275 6/33051-33052 33054-33055 33073-33075 33077-33079 33090-33092 33094-33095 33105-33107 33113 33115-33116 33120-33121 33123 33126-33127 33792 375362.4016587514425055e-21 6.118840631666147e-19https://cdsarc.cds.unistra.fr/viz-bin/moc/J/ApJS/265/18?format=asciiOpticalInfrareddefaultJ/ApJS/265/18/blueBlue stars with IR excesses (Table 1), estimates from photometric data (Table 3), environments & classification (Table 4) and classifications from literature (Table 5)SimbadNameSimbad column added by the CDSmeta.idcharnullabler_Note? Reference for Note (see refs.dat file)meta.ref;pos.frameintnullablef_VmagFlag on Vmag (1)meta.codechar24mag[0.06/9.1]? Spitzer/MIPS 24um-band magnitude (3)magphot.flux.density;em.IR.15-30umfloatnullablee_24mag[0.01/0.3]? Uncertainty in 24mag (3)magstat.errorfloatnullableSpTSpectral type (6)src.spTypecharSEDmeta.ref.urlcharHaH{alpha} line features (9)meta.codecharHbH{beta} line features (9)meta.codecharrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNobsNumber of observations for this source (link to Table 2)meta.numberintnullableSeqSequential identifier used in this workmeta.idintprimarym_SeqComponent ID on Seqmeta.code.multipchar[GC2009]Position-based identifier, Gruendl & Chu (2009, J/ApJS/184/172)meta.id;meta.maincharf_UmagFlag on Umag (1)meta.codecharUmag[9.9/17.7]? U-band magnitude from MCPS unless flaggedmagphot.mag;em.opt.Ufloatnullablee_Umag[0.01/0.24]? Uncertainty in Umagmagstat.error;phot.magfloatnullablef_BmagFlag on Bmag (1)meta.codecharBmag[10.6/18] B-band magnitude from MCPS unless flaggedmagphot.mag;em.opt.Bfloate_Bmag[0.01/0.3]? Uncertainty in Bmagmagstat.error;phot.magfloatnullableVmag[10.5/18] V-band magnitude from MCPS unless flaggedmagphot.mag;em.opt.Vfloate_Vmag[0.01/0.21]? Uncertainty in Vmagmagstat.error;phot.magfloatnullablef_ImagFlag on Imag (1)meta.codecharImag[10.38/17.2]? I-band magnitude from MCPS unless flaggedmagphot.mag;em.opt.Ifloatnullablee_Imag[0.01/0.3]? Uncertainty in Imagmagstat.error;phot.magfloatnullableMCPSDisplay data from the MCPS (Zaritsky+, 2004, J/AJ/128/1606) within 1"meta.ref.urlintnullableJmag[10.67/16.6]? J-band magnitude (2)magphot.mag;em.IR.Jfloatnullablee_Jmag[0.02/0.2]? Uncertainty in Jmag (2)magstat.error;phot.magfloatnullableHmag[10.64/16.41]? H-band magnitude (2)magphot.mag;em.IR.Hfloatnullablee_Hmag[0.02/0.3]? Uncertainty in Hmag (2)magstat.error;phot.magfloatnullableKsmag[10/16]? Ks-band magnitude (2)magphot.mag;em.IR.Kfloatnullablee_Ksmag[0.02/0.3]? Uncertainty in Ksmag (2)magstat.error;phot.magfloatnullableNIRCatDisplay data from 2MASS (II/246) and IRSF (II/288) within 1"meta.ref.urlintnullable3.6mag[7.7/14.6]? Spitzer/IRAC 3.6um-band magnitude (3)magphot.mag;em.IR.3-4umfloatnullablee_3.6mag[0.05/0.12]? Uncertainty in 3.6mag (3)magstat.errorfloatnullable4.5mag[7.7/14]? Spitzer/IRAC 4.5um-band magnitude (3)magphot.mag;em.IR.4-8umfloatnullablee_4.5mag[0.03/0.11]? Uncertainty in 4.5mag (3)magstat.errorfloatnullable5.8mag[6.9/13.4]? Spitzer/IRAC 5.8um-band magnitude (3)magphot.flux.density;em.IR.4-8umfloatnullablee_5.8mag[0.03/0.3]? Uncertainty in 5.8mag (3)magstat.errorfloatnullable8.0mag[5.6/12]? Spitzer/IRAC 8.0um-band magnitude (3)magphot.flux.density;em.IR.8-15umfloatnullablee_8.0mag[0.05/0.3]? Uncertainty in 8.0mag (3)magstat.errorfloatnullable70mag[-3.2/2]? Spitzer/MIPS 70um-band magnitude (3)magphot.flux.density;em.IR.30-60umfloatnullablee_70mag[0.2/0.3]? Uncertainty in 70mag (3)magstat.errorfloatnullableB-V[-0.22/0.91]? B-V colormagphot.color;em.opt.B;em.opt.VfloatnullableU-B[-2.04/0.36]? U-B colormagphot.color;em.opt.U;em.opt.BfloatnullableB-V0[-0.33/0.1]? Dereddened B-V colormagphot.color;em.opt.B;em.opt.Vfloatnullablee_B-V0[0/0.04]? Uncertainty in B-V0 (4)magstat.error;phot.color;em.opt.BfloatnullableU-B0[-2.7/0.26]? Dereddened U-B colormagphot.color;em.opt.U;em.opt.Bfloatnullablee_U-B0[0/0.03]? Uncertainty in U-B0 (4)magstat.error;phot.color;em.opt.UfloatnullableAV[0.02/3.73] V-band reddeningmagphys.absorption;em.opt.Vfloate_AV[0/0.2]? Uncertainty in AV (4)magstat.errorfloatnullableVMag[-8.71/-2.3] Absolute dereddened V-band magnitudemagphys.magAbs;em.opt.Vfloate_VMag[0/0.2]? Uncertainty in VMag (4)magstat.error;phot.magfloatnullablef_TphFlag on Tph (5)meta.codecharTph[8500/50000] Photometrically-derived effective temperature (5)Kphys.temperature.effectiveinte_Tph[0/4500]? Uncertainty in Tph (5)Kstat.errorintnullablelogLph[3.2/6.4] Log of photometrically-derived luminositylog(solLum)phys.luminosityfloate_logLph[0/0.2]? Uncertainty in logLph (4)log(solLum)stat.errorfloatnullableLumLuminosity class (6)src.class.luminositycharSubsetSubset (7)meta.notecharHSTMultiplicity detected in HST archival images (8)meta.codecharHII[NY] Large scale environment, HII regionmeta.codecharGMC[NY] Large scale environment, GMCmeta.codecharDust[NY] Large scale environment, Dusty regionmeta.codecharl_ScHIILimit flag on ScHIImeta.code.errorcharu_ScHIIUncertainty flag on ScHIImeta.code.errorcharScHII[0.2/5]? Size of compact HII region or nebulaepcphys.angSize;obs.fieldfloatnullableNII/Ha[0.02/0.75]? Line ratio, [NII]/H{alpha}spect.line.intensity;arith.ratiofloatnullableOIII/Hb[0.05/7]? Line ratio, [OIII]/H{beta}spect.line.intensity;arith.ratiofloatnullableSII[0.4/2.32]? Line ratio, [SII], 6716/6731spect.line.intensity;arith.ratiofloatnullablefBGNDd=nebular emission from nebulosity of background environmentmeta.codecharTeff[7250/50000] Surface effective temperature (10)Kphys.temperature.effectiveintf_TeffFlag on Teff, P=measured from spectrameta.codecharlogL[3.2/6.4] Log of luminosity (10)log(solLum)phys.luminosityfloatAV2[0.02/3.4] V-band reddening (10)magphys.absorption;em.opt.VfloatSpT2Spectral Type (10)src.spTypecharf_SpT2Flag on SpT, P=measured from spectrameta.codecharNotesRemarks (11)meta.notecharClassClassification, this worksrc.classcharClass-GC09Classification, GC09 (G1)src.classcharClass-LitClassification(s) from literaturesrc.classcharr_Class-LitReference(s) for Class-Lit (see refs.dat file)meta.ref;pos.framecharSpT-TWSpectral Type, this worksrc.spTypecharSpT-LitSpectral Type(s) from literaturesrc.spTypecharr_SpT-LitReference(s) for SpT-Lit (see refs.dat file)meta.ref;pos.framecharVarVariability (Period in parenthesis) from literaturemeta.code;src.varcharr_VarReference(s) for Var (see refs.dat file)meta.ref;pos.framecharONamesOther name(s)meta.idcharNoteNotemeta.notechar_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainf_ScHIIFlag on ScHII, d=measured from HST archival imagesmeta.codecharJ/ApJS/265/18/table2Journal of spectroscopic observationsTelTelescope (1)meta.id;instr.telcharSeq[1/111] Sequential identifier used in this workmeta.idintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintObs[2009/2020] Observation date, yeartime.epoch;obsExp[3/1200] Exposure timestime.duration;obs.exposureintN[1/3] Number of observationsmeta.numberintAirmass[1.2/2.1] Airmassobs.airMassfloatJ/ApJS/265/18/tablea1List of 13 additional targets without U-B<0SimbadNameSimbad column added by the CDSmeta.idcharnullablerecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintNobsNumber of observations for this source (link to Table 2)meta.numberintnullableSeq[3/88] Sequential identifier used in this workmeta.idintf_Seqd=Not observedmeta.codechar[GC2009]Position-based identifier, GC09 (Gruendl & Chu 2009, J/ApJS/184/172G)meta.id;meta.maincharVmag[9.8/18.3] MCPS V-band magnitudemagphot.mag;em.opt.VfloatU-B[-1.2/2]? MCPS U-B colormagphot.color;em.opt.U;em.opt.BfloatnullableU-B2[-0.93/-0.52]? U-B from other literature sourcesphot.color;em.opt.U;em.opt.BfloatnullableClass-GC09Classification, GC09 (G1)src.classcharComm-GC09Comment from GC09meta.notecharMCPSDisplay data from the MCPS (Zaritsky+, 2004, J/AJ/128/1606) within 1"meta.ref.urlintnullable_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.main_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/ApJS/265/18/tablea2List of 19 targets which were not observedSimbadNameSimbad column added by the CDSmeta.idcharnullableVmag[9.8/18.3] MCPS V-band magnitudemagphot.mag;em.opt.VfloatU-B[-1.2/2]? MCPS U-B colormagphot.color;em.opt.U;em.opt.BfloatnullableU-B2[-0.93/-0.52]? U-B from other literature sourcesphot.color;em.opt.U;em.opt.BfloatnullableClass-GC09Classification, GC09 (G1)src.classcharComm-GC09Comment from GC09meta.notecharMCPSDisplay data from the MCPS (Zaritsky+, 2004, J/AJ/128/1606) within 1"meta.ref.urlintnullable_RARight Ascension (J2000) from SIMBAD (not part of the original data)degpos.eq.ra;meta.mainrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintSeq[3/88] Sequential identifier used in this workmeta.idintf_Seqd=Not observedmeta.codechar[GC2009]Position-based identifier, GC09 (Gruendl & Chu 2009, J/ApJS/184/172G)meta.id;meta.mainchar_DEDeclination (J2000) from SIMBAD (not part of the original data)degpos.eq.dec;meta.mainJ/ApJS/265/18/refsReferencesRefReference codemeta.noteintrecnoRecord number assigned by the VizieR team. Should Not be used for identification.meta.recordintBibCodeBibcode of the referencemeta.bib.bibcodecharCommCorresponding VizieR catalogmeta.id;meta.datasetchar