1985ApJS...57...91E © 1985.TheAmericanAstronomicalSociety.Allrightsreserved.PrintedinU.S.A. The AstrophysicalJournalSupplementSeries,57:91-131,1985January 2 3 1 GuestInvestigator,MountWilson andLasCampanasObservatories,whichareoperatedbytheCarnegie InstitutionofWashington. GuestInvestigatorandVisitingResident Scientist,CerroTololoInter-AmericanObservatory. OperatedbytheAssociationofUniversities forResearchinAstronomy,Inc.,undercontractwiththe NationalScienceFoundation. Way. Thewidthofthespectraltypedistributionincreasesalongthissequencethreegalaxies.shiftsin luminous redsupergiantsintheLargeMagellanicCloud(LMC)ispresented.Newinfraredphotometryfor65 These excessesappearproportionaltothemeanmetallicitiesofthreesystems,suggestingthatmass-lossrates excess ishighestamongMilkyWayredsupergiantsandlowestintheSMC;LMCexcessesareintermediate. median valuesareattributedtoacombinationofthewell-knownshiftinHayashitrackasfunction candidates isgiven.ThesedataarecombinedwithexistingphotometricandspectroscopicMCobtainedby values for^are0.5and0.7magtheSMCLMC, respectively.ManystarsintheLMChaveA'm intrinsic colorsfortheredsupergiantsinthreegalaxies. heterogeneous natureofthespectraltypesheusedandbecausebiasesintroducedbyLee’sanalysisprocedure. from thatintheMilkyWay. for luminousMsupergiantsaresimilarinallthreegalaxies. different metallicitiesinthethreegalaxies. metallicity andtoprobablesmalldifferencesinTiObandstrengthsatagiveneffectivetemperatureforthe Humphreys. spectroscopic systemstoenablecomparisonwiththeMCdata. of theMCs.AspreviouslyshownbyEliasetal,brightest LMCsupergiantsare0.3-0.4magbrighterinM excess of1.0.Theseunderscoretheeffectthatreddeningcan haveonstudiesoftheyoungpopulationcomponent Our databaseisstillinadequatetodeterminewhetherornottheredsupergiantreddeninglawinMCsdiffers than thoseintheSMC. SMC and96LMCredsupergiantcandidatesisalsopresented.Spectroscopicconfirmationfor65ofthe v bol 1 luminosity andabundancedifferencesbetweenthethree galaxies. Differencesinspecificresultsbetweenthe luminosity andabundanceeffectsforthiscolor. present paperandthatofMcGregorHylandaredue to ourmuchlargerbodyofdataandthefactthat understood manner.Mostofthedifferencescanbe qualitatively understood,though,asarisingfrom law andtherevisedsetofspectraltypes. McGregor andHylanduseJ-Kcolorasapuretemperature indicator,whereasweshowthatthereare relation andinthedependenceofcoloronluminosity.Thesedifferencesareattributedtonewreddening The mainresultsofthisstudyredsupergiantcolorsandspectraltypesareasfollows: Available dataforMilkyWaysupergiantsarereexamined,andallputonuniformphotometric New BVRIphotometryfor116redsupergiantcandidatesintheSmallMagellanicCloud(SMC)and11 4. Withanewreddeninglawandhomogeneoussetofspectraltypesitispossibletoderive 2. Measurementsat3.5and10/amareusedtoinvestigatemass-lossrates.Itisfoundthatthetypicalj^m 3. AnewreddeninglawforgalacticMsupergiantsisderived.ItdiffersfromthatofLeebecausethe 5. Extinctionvaluesandbolometricmagnitudesarederived forindividualsupergiantsintheMCs.Median 1. ThemedianMKspectraltypeintheSMCisearlierthanMO.ItMlLMCandM2-3Milky © American Astronomical Society • Provided by theNASA Astrophysics Data System Cerro TololoInter-AmericanObservatory,NationalOpticalAstronomyObservatories,andCaliforniaInstituteofTechnology a) FortheMilkyWaysignificantdifferencesfrompreviousstudiesarefoundbothincolor-spectraltype b) Theintrinsiccolorsoftheredsupergiantsvaryamong thethreegalaxiesinacomplicatedandnotfully M SUPERGIANTSINTHEMILKYWAYANDMAGELLANICCLOUDS: 1 Cerro TololoInter-AmericanObservatory,NationalOpticalAstronomyObservatories COLORS, SPECTRALTYPES,ANDLUMINOSITIES Received 1984January16;acceptedJune1 3 Roberta M.Humphreys University ofMinnesota 2 Jay A.Frogel ABSTRACT J. H.Elias 91 AND 1985ApJS...57...91E literature, infraredobservations ofMagellanicCloudstars (1970). McGregor(1981)also observedTiObandstrengthsin mented withBVobservations oftheirownandfromthe properties ofMagellanicCloudsupergiants.Themostrecent, in whichthecolorsofMsupergiantsvarycanbestudied Glass (1979),andthestudy ofgalacticsupergiantsbyLee galactic, LMC,andSMC supergiants, whichtheysupple- made observationsat/,H,KandCOforanumber of Hyland (1981,1984;McGregor1981).and (§ VIII). extinctions towardtheindividualstars;theseareshownto be reddening lawhavebeenderivedwhichsupersedethoseob- but theinfraredphotometryandnearlyallofSMCdata photometry ofthelate-typesupergiantsinSMCand program ofspectralclassificationandinfraredvisual and themostcomprehensive,isworkofMcGregor and reanalyzed; newvaluesforintrinsiccolorsandthegalactic visible innearbygalaxies.TheLargeandSmallMagellanic typically almost1magatV(§VII). the MagellanicClouds(§V). to lowerdustabundances(duemetalabundances)in show stilllargerexcesses.Thiscanbeexplainedasbeingdue the LMCthaninSMC,andthatMilkyWaystars servations. Theseshowthatthe10/imexcessesarelargerin are new.ExistingdataforgalacticMsupergiantshavebeen LMC. Mostofthevisible-wavelengthLMCdatausedin proposed asstandardcandlesforextragalacticdistancede- lower metallicity.Theyarethusidealforstudyingtheeffects which thereisalargepopulationofKandMsupergiants. to anincreaseintheamountofavailabledata. tion ofanumberbiasespresentintheoriginalanalysisand tained byLee(1970).Theimprovementsareduetoelimina- analyses havebeenpreviouslypublished(Humphreys1979a), of differingmetallicityandgalacticenvironmentontheob- Both CloudsarelessmassivethantheMilkyWayandhave Clouds (theLMCandSMC)arethetwonearestgalaxiesin 92 ELIAS,FROGEL,ANDHUMPHREYS suitability forthisuse. served propertiesofMsupergiants.supergiantshavebeen their propertiesindifferentgalaxiesordertotest 1982; Humphreys1983),anditisthereforeusefultostudy terminations (seeEliasetal1981;SandageandTammann Also, theamplitudeofvariabilitystarsandway There havebeenanumberofotherinvestigationsthe The MKspectraltypesallowaccuratedeterminationsofthe The datapresentedhereincludeanumberof10/imob- In thispaperwereportthefinalresultsofacoordinated Late-type supergiantsareamongthemostluminousstars variable thanthoseintheSMC.Starsgenerallygetredder,withstrongerH0indices,astheybecomefainter.A and ofthewayinwhichstarcolorchangesastheyvary.Onaverage,supergiantsLMCaremore used, andhowthesampleofMilkyWayMsupergiantswasproduced. notable exceptiontothisruleisthattheLMCsupergiantsdevelopbluerB—Vcolorsastheybecomefainter. ( >0.4mag)H0indices.TherearenocounterpartstothesestarsintheLMCsample.Theymostlikely Subject headings:galaxies:MagellanicClouds—stellarcontentinfrared:generalstars:late-type asymptotic giantbranchstarsoflowmassratherthantruesupergiants. 2 2 6. MultipleIRandvisualobservationsofmanythestarsinMCspermitexaminationtheirvariability 7. TheSMCsampleofsupergiantshasasmallsubsetlarge(>0.5magatK)amplitudevariableswith 8. Inthreeappendicesdetailsaregivenonthecolortransformationsemployed,least-squarestechnique © American Astronomical Society • Provided by theNASA Astrophysics Data System I. INTRODUCTION in theMagellanicClouds,relativetoMilkyWay, at a right, theweakeningofbothCOandTiOabsorption(at a one another(§III).Assumingthesecorrectionstoberoughly corrections whencomparingstarsinthethreegalaxies with deficiency intheSMC,withrespecttoMilkyWay. factor of2to5deficiencyintheLMCanda310 given effectivetemperature. firmed. given effectivetemperature)intheMagellanicCloudsis con- dereddened J—Kcolorasatemperatureindicator.They list ofsuspectedMsupergiants intheSMCbySanduleak types arealsoaffectedbymetalabundance,theyrequire effects ofCNabsorption,andthedifferencestoin for theMagellanicCloudstars,McGregorandHylanduseda calculated modelatmospheres.Intheabsenceofspectraltypes CN abundance. Magellanic Cloudstars.Thedepressionisattributedtothe obtained fourmainresultsrelevanttothepresentinvestiga- and comparedtheseresultstheinfraredphotometrywith are weakerintheMagellanicCloudsthanMilkyWay; to theJandKmagnitudesatincreasedluminosity,that the red,didintermediateresolutionspectroscopyinblue, Magellanic Cloudscanbeaccountedforbylowermetal the depressionisgreaterinMilkyWaystarsthan tion. the MagellanicCloudsthantheyareinMilkyWay. the SMCstarsshowweakerCOthandoLMCstars. abundances intheMagellanicClouds;fromanalysisof probable metalabundancedependence(§VI),soitisnota (§ IV)ofbothgalacticandMagellanicCloudstarsshowsthat (J—K) asatemperatureindicator.Improveddereddening McGregor andHylandstemprimarilyfromtheuseof supergiant data,McGregor(1981)obtainsanestimateofa completely rehabletemperatureindicatorforMsupergiants. the /-colorhasadefiniteluminositydependenceand 0 The SMCstarsselectedforobservation weretakenfroma It alsoappearsthatV-K,R,andV—Ibecomebluer Since theeffectivetemperaturesinferredfromMKspectral 4. ThedifferencesseenbetweentheMilkyWayand 2. Atagiven(/-7f),bothCOandTiObandstrengths 1. TheyfindthattheHmagnitudesaredepressedrelative 3. The(V—K)colorsarebluerforagiven(J-in Differences betweentheresultsofthispaperand 0 0 a) NewVisualObservations II. OBSERVATIONS H O'!

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© American Astronomical Society • Provided by the NASA Astrophysics Data System 1985ApJS...57...91E -1 provided bycomparingmultiplemeasurementsofstars (see best estimatesoftheuncertaintiesinphotometry are better thanonetemperature type, judgingbytheagreementof Table 19,AppendixB).The accuracyofthespectraltypesis well. ing totheyearwhenspectrumwasobtained.Thefirst half identified bySanduleakorHarvardvariablenumber.The (also see§III,below). the typesforthreestars observed inboth1978and1979 done withinaweekofoneanotherduringboththe1978 and colors suggestthatmostorallofthesemustbesupergiants as giants; thesecondhalfcontainsstarswithoutspectra; their of thetablecontainsstarsspectroscopicallyclassifiedassuper- phototube ontheCTIO1.5mtelescopeusinga10"di- 1979 observingruns,sotheyareeffectivelysimultaneous. The during both1978and1979. were selectedfromMorganandKeenan(1973).Sixty-five spectral typeisgiven,whereavailable,onthelinecorrespond- stars wereobtained;nearlyalloftheobserved (1973) andKunkelRydgren(1979).Observationsof116 preliminary resultsofthe1978observationsweregivenby tions intheSMCaresummarizedTable1.Thestars aphragm. ThephotoelectricstandardsusedwerefromLandolt BVRI photometrywasobtainedwithanRCA31034AGaAs Examples ofthespectraaregivenbyHumphreys(19796).The on theCTIO4mtelescope.Thedispersionwas48Amm, supergiant candidateswereconfirmedasKorMsupergiants. obtained withtheRCspectrographandCarnegieimagetube way asearlierobservationsintheLMC(Humphreys1979a); and thespectrawerewidened1.0mm.Classificationstandards Humphreys (1919b).Thestarswereclassifiedusingspectra and Gaposchkin1966)fromthefieldofSMC. (1984) plusseveralredHarvardvariables(Payne-Gaposchkin The spectralclassificationsandthevisualphotometrywere The resultsofthevisualphotometryandspectralclassifica- The visible-wavelengthobservationsweremadeinthesame © American Astronomical Society • Provided by theNASA Astrophysics Data System 46-44 .. 46-39a. 46-32 .. 46-2 ... 45-38 .. 46-39 .. 46-34 .. 46-30 .. 29-33 .. 53- 3... 52- 4... to Johnson(Lee1970)system.Seetext. Identification d c b a V —RandTcolorsonGaAssystem;additionaltermsrequiredtotransform SpectraltypesfromHumphreys1919a. IdentificationfromSanduleakandPhilip1977. All photometrydone1979Oct(JD2,444,162-4163). b STAR 21 Visual PhotometryofLMCMSupergiants 0 Spectral Ml lab Ml la Ml la Ml la Ml la M2 la MO la M2 lab M2 la M4 la MO la Type M SUPERGIANTS TABLE 2 11.92 12.42 12.03 11.64 12.55 12.01 12.31 12.67 13.35 12.33 11.74 Observed MagnitudesandColors in Eliasetal.(1982).Multipleobservationsweremadefor beam sizesusedrangedfrom5"to15".Contaminationby were obtainedwiththeCTIO4and1.5mtelescopes.The while theremainderofLMCdataandallSMC were madeonthe2.5mduPonttelescopeLasCampanas, LMC supergiantswasobtainedin1979October.Theresults (1979a), butsomeadditionalBVRIphotometryofbright luminous assupergiantsatmaximum light,theydonotappear well asthebrighteststars.Alternateidentificationsaregiven was madetoobservetheearhestandlatestspectraltypes as used fortheJHKL,H0,andCOmeasurements,while (Table 1hereandHumphreys1979a)wereobtainedinthe are giveninTable2. the LMCusedinthisstudyweretakenfromHumphreys cross-references tootherphotometry(bothvisualandIR) and (including theidentificationsusedbyHumphreys19796); many ofthestars. Ga:Ge bolometerwasusedforthe10jamobservations.Allof other starswascarefullyavoided.TheCTIOInSbsystem to betruesupergiantsandare discussedseparately(§VTII6). few additionalspectraltypesgleanedfromtheliterature. the dataareon“CIT”systemasdefinedbystandards 53 and31ofwhich,respectively,areconfirmedsupergiants stars observedintheIRareprimarily thebrightestsupergiants and Humphreys1980).Althoughthesestarsmaybe as tude variables.”ThesearetypifiedbyHV11417(Elias,Frogel, the spectraltypesfromTable1arerepeated,togetherwith a 1978-1982 observingseasons.The1978LMCmeasurements 2 The bulkofthevisualwavelengthobservationsstarsin The SMCinfrareddataarepresentedinTable3.Aneffort Infrared observationsof65SMCstarsand96LMCstars, Infrared datafortheLMCstars aregiveninTable4.The Five ofthestarsinTable3areidentifiedas“largeampli- B —V 2.03 2.09 2.00 2.05 2.08 1.75 1.93 1.99 1.92 1.98 1.99 a V-R 1.58 1.68 1.41 1.55 1.83 1.79 1.73 1.76 1.48 1.47 1.72 b) InfraredObservations a V —I 2.47 2.87 2.43 2.76 2.50 2.96 3.45 3.30 3.08 3.28 3.13 95 1985ApJS...57...91E e 6 HV 838 HV 832 HV 11295 HV 1475 BMB B-28 104-6 105-11 108- 2 107- 1 104-13 103- 5 Field Stars 106-9 107- 7 a 106- 7 105- 7 109- 6 108-6 108- 4 106-4 104- 5 108- 8 106-5 108-3 101-15 101-6 Identification (1) SMC 6 HV 11262Mlla SMC 5 SMC 22MOla SMC 14K5-M0I SMC 25K5-M0la SMC 21K5-M0I SMC 101M0la SMC 31 b © American Astronomical Society • Provided by theNASA Astrophysics Data System (2) Type MO Iab MO I M0 la MO lab M5(5) MO I M0 la-lab M0 lab M5-7(5) M4 (4) MOe I M0 lab K5e (4) M3 (3) M6 (1) K5-M0 I K0-K2 I K5 I K5-M0 lab Ml I K0-K5 la Spectral 4808 4237 4181 4238 4975 4240 4596 4808 4237 4956 4857 4957 4808 4982 4153 4808 4809 4238 4240 4809 4190 4190 4240 4982 4809 4181 4975 4956 4593 4977 4241 4808 4809 4809 4596 4153 4240 4153 4808 4238 4857 4543 4238 5154 4596 4237 4625 4957 4857 4240 4181 4808 2440000) (JD- Date 10.11 10.25 10. 13 10. 14 10.26 8.28 8. 34 8. 31 8.36 8.91 8.66 8.26 8.90 9. 55 8. 42 8.43 8. 34 9.44 9. 51 9.22 9.53(3) 8.99 9. 74(3) 9.62 8. 70 8. 31 8. 32 9.21 9.27(8) 9.62 9.48(3) 8.74 8. 53 8.58 7.87 9.28 8. 18 9.64 9. 65 7.85 7.96 8. 37 7.81 7. 98 8. 35 7.54 7.62 7.84 7.88 7.90 9.77 8.08 Infrared PhotometryofSMCMSupergiants 0.82(3) 0.87 0.78(3) 0.93 0.84(3) 0.76(3) 0.93 0.92 0.97 0.95 0. 79(3) 0. 66 0.81 0.92 0. 90 0.81 0.86 0.91 0.97 0.87 0.94 0.92 0.89 0. 90 0.90 0.85(3) 0.85 0.93 0.87 0.98 0.93(3) 0.95 0. 9 3 1.10(3) 0.92 0.93 0. 76 1. 04 1.04 1.16 1.21 1.19 1.19(8) 1.00 1.00 1. 15 1.20 1.11 1.27 1.07 1.08 1.01 Observed MagnitudesandColors 0.23 0. 15 0. 12 0. 16 0.23 0. 19 0.17 0. 19 0.22 0. 19 0. 19 0. 20 0. 12 0. 17 0.17 0.15 0. 14 0. 18 0.29 0.24 0. 19 0. 18 0.20 0. 18 0.20 0.25 0.17 0.17 0. 14 0. 17 0.17 0.43 0.46 0.25 0.27 0. 17 0. 18 0.22 0.21 0.21 0.22 0. 53 0. 33 0. 32 0.19 0.34 0. 34 0. 35 0. 52 0.25 0.23 0.17 TABLE 3 96 0.29 22 24(7) 17(6) 30 0.10 36(11) 0.13(4) 21(8) 39(6) 30(4) 0.03(3) 0. 42 0. 13 0. 12 0.03(3) 0.08(3) 0.09 0.08 0.05 0.03(3) 0.08 0.62(3) 0. 12 0. 11 0. 17 0. 11(4) 0.21 0.16(3) 0. 16 0.23 0.02(3) 0. 11 0.09(3) 0. 14 0. 14 0. 64 0.47(3) 0. 15 0.09 0.09(3) 0. 10 0. 10 0. 15 0.05(3) 0.16(3) 0. 71 0.62(3) 0. 60 0.62(3) 0.23 0. 12(4) 0. 78 0.23 0.07 0.09 0. 14 0.35(4) 0.16(3) 0. 63 0.89(3) 0.250 0.210 0.265 0.225 0.245 0.245 0.235 0.240 0.255 0.295 0.250 0.210 0. 175 0. 145 0. 175 0. 155 0.200 0.260 0.235(3) 0. 185 0.230 0.230 0.230 0. 175 0. 145 0.210 0.270 0.240 0.200 0.240 0. 105 0. 125 0.215 0.210 0.205 0.265 0.270 0.315 0.070 0.105(3) 0.220 0.240 0.115 0. 140 0. 130 0.240 0. 180 0.240 0.080 0. 150 0. 125 0.095 CO 8.21(85) [10] 88(27) 24(23) 0 Additional Photometry Visual IR 1 1 1,6 2,3,8 1 2 2, 3,8 SMC 2 3a limitat 10ym =7.2mag; Remarks 1985ApJS...57...91E e e 3 107-12 ...MOIab HV 11423 105-21 107-15 105-20 107-14 HV1652M0lab HV 11417...M5eI(2) HV 11329 HV 1719 116-2 111-26 HV11402MOla-lab 118-5 115-4 118-9a 115-6 114-3 112-13 110-13 112-7 118- 1 5 11 6-15 116- 13 115- 13 115-12 117- 15 Identification (1) LE-B74 SMC 72K5la R20 SMC 91 (2) © American Astronomical Society • Provided by theNASA Astrophysics Data System Spectral (JD- Type K5-M0 lab MO la MO I MO I K5-M0 1 MO lab M0 la MO lab MO la K5-M0 I K1-K3 lab M0 lab K5-M0 I MO I K2 I K5-M0 lab 2440000) 4238 4808 4809 4809 4809 4809 4809 4241 4808 4808 4956 4857 4625 4149 5154 4982 4976 4809 4749 4593 4485 4441 4149 4808 4596 4237 4543 4857 4625 4809 4625 4808 4808 4238 4976 4956 4594 4543 4147 4808 4809 4975 4857 4593 4543 4237 4240 4956 4808 4596 4240 4190 4181 4808 4982 3836 8. 77 8. 30 9.07 8.93 8.52(5) 8. 74 8. 79 7.87 9. 70 9. 01 8.83(8) 8.42(3) 9.17(4) 0.94(3)0.17 8. 70 8.69 7.84 9. 70 9. 68 9. 64 9. 52 9. 35 8.40 9.96 8.39 9.73 9.84 9.77 9. 65 9.20 9.94 9.94(8) 9.06 9. 70 9.79 9.78 9.71(8) 8.80 8. 95 9. 04 8.04 9.01 9. 37 8.86 7.85 7.88 7.90(3) 7.90 7. 93 7.89 7.83 10. 13 8. 69 8.42 8.95 8. 73 9.20 Observed MagnitudesandColors 0.88(3) 0.19 0.84(3) 0.18 0.88 0.19 0.85 0.81(3) 0.14 0.80(3) 0.15 0.93 0.18 0.88 0.86(3) 0.18 0.92 0.20 0.84 0.69 0.69 0. 75 0.90(3) 0.18 0.90 0.94 0. 9 3 0.96 0.21 0.84(3) 0.16 0.92 1.18(3) 0.57 0.83 0.88 1.20(5) 0.88 1.47 1.47 1.36 1.22 1.12(8) 1.47 1.48 1.49(3) 1. 18 1.12(4) 1.23 1.22 1.17 1.05 1.01 1.21 1.19 1.18 1.18 1.17 1.15(8) 0.92 1.06(8) 0.90 0.96 0.90 0.18 0.90(3) 0.19 0.87 0.93 TABLE 3—Continued 0. 17 0. 17 0. 37 0.24 0.26 0.25 0. 18 0.28 0.25 0. 17 0. 15 0. 16 0. 17 0.46 0. 35 0. 37 0.40 0.27 0. 19 0. 18 0.44 0. 18 0. 17 0.15 0. 17 0. 19 0. 18 0. 19 0.17 0.20 48(3) 41 48 67 54 73 74 74 51 74 72 97 82(4) 34(4) 87(4) 90(6) 52(7) 74(3) 55(3) 57(20) 77(6) 74(4) 18 28(4) 14(3) 0. 12 0. 13 0.09(3) 0.01(3) 0.03(3) 0.08(3) 0.08(3) 0. 13 0.30(4) 0.25 0.07 0. 11 0.81 0.58(4) 0.62(3) 0. 12 0.25 0.18(3) 0.24 0.21(3) 0.09(3) 0. 14 0.91 0.86 0. 12 0.60(4) 0.06 0.03(3) 0.04(3) 0.09 0.03(3) 0.75(3) 0.43(3) 0. 13 0.07 0.05 1.11 0.08 0. 11(4) 1.40(3) 0.22 1.41 1.41 1.39 1.32 1.25(4) 1.10(3) 0.07 1.33(3) 1.17 0.15(3) 0. 16 0.13(3) 0. 10 0. 15 0.11(3) 0. 195 0. 190 0.220 0. 160 0.220 0. 170 0.180 0.250 0. 185 0.200 0.215 0.250 0.195(3) 0. 170 0. 145 0. 125(3) 0.170 0.230 0.220 0.245 0.085 0. 185 0. 180 0. 190 0.200 0.220 0. 165 0.225* 0.240 0.045 0. 190 0. 180 0. 150 0.150 0. 165 0. 180(3) 0. 150 0. 195 0.215 0.135 0. 105 0. 155 0.210 0.225 0.205 0.235 0.255 0. 150 0. 195 0.260 0.255 0.260 0.255 0.250 0.255 0.240 [10] 28(30) Visual IR Additional Photometry 3,8 2,8 SMC 44 SMC 60 Remarks SMC 57 1985ApJS...57...91E 4 left outofTable4. Humphreys (1979«),showsitto be acarbonstar.Ithasthereforebeen lows. However,inordertocomparetheMCdatawith data of ourconclusionsdifferfromthoseotherinvestigators, itis for galacticsupergiantsandtounderstandfullywhyanumber Humphreys (1979u)aresufficientfortheanalysiswhich fol- in theLMCwithIRphotometrybutnospectraltypes than members ofvariousLMCclusters.Therearethusmore stars there areintheSMC. survey byElias(unpublished)forwhichphotometryorspec- from Humphreys(1979^),supergiantsdetectedina1.6/xm tral typesaregivenbyHumphreys(1979a),andthe red 98 4 InfraredphotometryofWd-bl, whichhasBVRIphotometryby For theLMCandSMCdatapresentedhereby (1) Blanco,McCarthy,andBlanco1980.(2)Elias,Frogel,Humphreys(3)LloydEvans1971.(4)1978.(5)Wood, Bessell,and Humphreys 1980.(5)Cohenetal.1981.(6)LloydEvans1971.(7)McGregorandHyland1984.(8)Wood,Bessell,Fox1983. Fox 1983. 3 NGC 330 e d c B42 B40 b a B10 HV 2232 HV 2084 Identification 120-8 120-7 116-19 120-14 120-6 118-22 116-20 118-18 c) InternalChecksontheDataandComparisonwith (1) (2) Large-amplitudevariableininfrared.Seetext. StarsfromSMCfield.Seetext. Photometry references:(1)Thispaper.Table1.SupersedesHumphreys19796.(2)Glass1979.(3)CatchpoleandFeast1981.(4)Elias,Frogel, and Spectral typesarefromthispaper,Table1,unlessanotherreferenceisindicatedbyanumberinparentheses.Additionalspectral arefrom Identificationsaregivenincols.(1)and(2).Theycodedasfollows,byletterprefix: NGC 330:Robertson1974 None: Sanduleak1984 SMC: Humphreys1979/?;seetext LE: Lloyd-Evans1978 R: Feast,Thackeray,andWesselink1960 BMB: Blanco,McCarthyandBlanco1980 HV: Harvardvariable,identifiedfromHodgeandWright1978 © American Astronomical Society • Provided by theNASA Astrophysics Data System LE-C12 M0-M1la4808 HV 11464M0la-lab3836 SMC 92K5-M0I4240 SMC 81K5-M0I4238 SMC 87K5-M0I4238 SMC 84K5-M0I4238 SMC 82K5-M0I4238 Spectral (JD- Type Other Observations M2 la4809 M2 la4808 2440000) K 4243 4243 4243 4190 4238 4190 11.04 10.09 8.66 9.26 8.73 8. 18 9.04 9.80(3) 9.40(3) 9.43 7.76 9.05 9. 33 9.44 9.91 ELIAS, FROGEL,ANDHUMPHREYS J-K H-K Observed MagnitudesandColors 0.77(3) 0.12 0.76(3) 0.12 0.84(3) 0.14 0.93 0.92 0.86 0.91 0.89 0.14 0.96 0.22 0.89(3) 0.19 0.84 0.16 0.92 0.89(3) 0.16 0.91 0.15 0.88 0.15 TABLE 3—Continued 0.23 0.25 0. 18 0. 16 0.15 measured atLasCampanas in 1978.ForthesestarstheLas infrared, withthepossible exception ofthe13LMCstars ferences aretabulatedinTable 6.Nonetshiftsareseeninthe check oninternalconsistency andtostudyvariability.Dif- observing seasons(Tables3 and4)canbeusedbothasa discussed inAppendixA. here andthe“Johnson”systemusedbyJohnsonMendoza frared colorandmagnitudetransformationsinTable5 are Glass (1979)andhisco-workers.Thederivationofthe in- (1968) andLee(1970),theAAOsystemusedbyMcGregor mations fortheinfrareddatabetween“CIT”system used and Hyland(1981,1982),theSAAOsystemused by necessary toplacealloftheobservationsbeusedona errors. common photometricsystemandtocheckforsystematic Infrared observationsofthesamestarsmadeindifferent Table 5(seealsoEliasetal1983)summarizesthetransfor- 30 0. 13 0.28(3) 0. 16 0.22 0. 12 0.06 0. 07 0. 10 0. 13 0.05 0.09 0.03 0.03 0.03 CO 0.205 0. 185 0. 185 0. 185 0.200 0.235 0.205 0.240 0. 180 0. 190 0. 190 0. 195 0. 175 0. 195 i) TheInfraredData [10] Additional Visual IR Photometry 7 7 7 Remarks SMC 100 1985ApJS...57...91E 4b-12 HV957 46-13 46-19 W0H289 46-17 W0H288 46-16 HV2532 Wd-b 3 Wd-b 21 40-10 HV894 40-4 HV5593 46-2 HV2k50 46-21 HDE269551 Star Identification 46-23 HV2544 37-24 HV2360 29-33 HV888 Field Stars 46-25 46-24 46-32 HV2561 46- 2 8 W0H312 45- 23HV5854 44- 24HV2555 (1) (2) American Astronomical Society •Provided bythe NASA Astrophysics Data System Spectral M3 I M2 la M2 la M4 la Type Ml la-lab4189 M0 lab M0 la 2440000) 4240 4238 4150 4237 4266 4237 4266 4267 4669 Date 4240 4150 4269 4150 4269 4149 4237 4596 4237 4189 4267 4237 4238 4149 4237 4150 4981 4189 4596 4189 4594 5033 3854 5034 50 34 3917 3917 5033 3854 3917 3854 4266 4189 4237 4240 4266 4237 4189 (JD- 5034 3854 3917 10. 86 8. 52 8. 54 8.61(3) 8.99 8.02 8. 15 6. 69 6. 78 8. 61 8.69(3) 8. 54 8.55(3) 9. 01 7. 50 6.99 7.71 7.26 7.71 7.68 7. 96 8.24 6. 96 6. 98 6.95 7.25 7. 22 7.22 7. 28 7. 94 7.92 7. 33 7.31 7. 31 6.84 9. 32 7.02 8.81 8. 71 8. 72 8.01 8.09 8.37 8.02 7.43 7.34 7. 13 Infrared PhotometryofLMCMSupergiants 0.90 0. 9 6 0.99 0.97(3) 0. 94 0.98 0.90 0.94 1. 10 1.02 1.01 1.11(3) 1.09 1.09 1.05 1.05 1.21 1.21 1.07 1.14 1.02 1.06 1.07 1.09 1. 13 1.06 1.09 1.10(3) 1.05 1.06 0.98 0.99(3) 1.05(3) 1.09 1.03 1.05 1.06 1.06 0.98 1.10(3) 1.00 1.01 1.00(3) 1.17 1.18(3) 1.04 1.02 Observed MagnitudesandColors 0.25 0.29 0.28 0.28 0.43 0. 37 0. 35 0.23 0.24 0. 30 0.29 0.29 0.23 0. 19 0.27 0.27 0.28 0.44 0.24 0.25 0.29 0. 24 0. 30 0.2 1 0.21 0.26 0.25 0. 19 0. 32 0.31 0. 30 0.24 0.26 0. 25 0.27 0. 36 0.28 0.22 0.22 0.27 0.29 0.26 0.26 0. 31 0.31 0.25 0.22 TABLE 4 0.47(5) 0. 36 0.44(5) 0.33(8) 0.67(4) 0.68(7) 0. 32(3) 0.32(5) 0.38(6) 0.40 0.49(4) 0.55(3) 0.52(4) 0. 56 0.45(3) K-L 0.50(3) 0.23 0. 16 0.16(4) 0. 12 0. 19 0.24 0. 31 0.35(4) 0.16(4) 0. 10(3) 0.41 0. 16 0.21(3) 0. 14 0. 15 0. 12(4) 0. 09 0. 15 0.15(3) 0. 17(4) 0. 17(3) 0.19(3) 0.23 0.22 0. 15 0.09(3) 0. 17(4) 0. 07 0. 10 0. 20 0. 11(4) 0. 19(3) 0.24(3) 0. 26 0.05(3) 0.22 0. 14(4) 0. 12(4) 0.10(3) 0.08 0.22(3) 0. 17 0.12(3) 0. 14 0.24 0.480 0. 300 0.230 0.270 405 270 270 275 035 035 280 260 265(3) 330 275 265 270 270 275 285 295 290 255 260 265 285 275(3) 350 270 265 300 175 225 245 250 260 225 275 265(3) 195 245 240 255 335 315 305 4.75(9) 5.08 6.02 5. [10] 36 (10) 10) 14) 0 Additional Visual IR Photometry 4 2 1,2 1,3 1 1,2,3 1,2 1 1 1,2,3 4.9 4 4,9 5.9 5,9 5,9 Remarks W0H 140 W0H 147 W0H 193 W0H 234 W0H 277 WOH 287 WOH 293 WOH 297 WOH 319 1985ApJS ... 57. 46-44 WOH341 Star Identification 46-43 WOH342 Wd-b72 Wd-b69 Wd-b68 46-39 WOH338 Wd-b42 Wd-b41 WOH 337HV2586 46-34a 46-39a WOH364g 46-30 HV2565 46-38 W0H336 46-31 HV2567 46-40 W0H335 47- 17HV5870 46- 36W0H330 46-33 W0H327 46-34 HV2566 (1) (2) © American Astronomical Society • Provided by theNASA Astrophysics Data System Spectral Type Ml la Ml la Ml lab M2 lab MO-Ml la4154 M2 lab M2 la 2440000) ■ 4154 (JD- 4596 4270 4237 5034 4154 3917 3854 4596 4240 4190 4596 4271 4237 4154 462 1 4267 4190 4 62,0 4621 4596 4978 4237 4190 4190 4590 42 70 5034 3917 4238 4238 4238 4190 3854 4267 4190 4596 4270 4190 4238 4267 4596 4237 4237 3854 4237 4190 4267 4189 3854 3917 3854 8.03 8.05(3) 6.83 7.02 7.99 9.24 8.30 8.05 6.88 7.01 7. 04 7.34 7.44 9.20(3) 9.18(3) 9. 73 9.55 8.10(3) 6.96 7.29 7. 32 7.41 9.63 8.07 8.09 8.55 0.97 8.50 1.050.26 8.47(3) 1.09(3)0.28 7.28 8.57(3) 1.03(3) 7.67 0.95 7.74 0.98 7.74 1.02 7.74 1.02 7.82 1.08 7.87(3) 1.09 7.64 7.59 7.69 7.64 7.90 8.00(3) 1.09(3) 8.11 8.11 7.92 7.89 7.95 1.03 7.96 1.11 8. 12 8. 14 0. 95 0. 94 0. 96 0. 98 J-K 0.96 0. 97 0. 99 0. 99 0.99(3) 0. 97 0. 93 0.81 0.84 0.85 1.01 0.90 1.05 0.99 1.00 1.01 0. 92 1.02 1.03 0.96 1.00 1.02 1.03 1.04 1.00 1.01 1.03 1.02 1.05 1.13 1.12 1.14(3) 1. 10 Observed MagnitudesandColors TABLE 4—Continued 0.25 0.26 0.25 0.25 0.26 0.24 0.20 0.26 0. 28 0. 25 0.27 0.24 0.26 0.27 0.29 0.28 0. 16 0.28 0.24 0.20 0.21 0. 19 0.22 0.17 0.21 0.26 0. 33 0.21 0.23 0.26 0.21 0.25 0. 31 0.24 0.23 0.23 0.26 0.20 0.25 0.25 0.27 0.24 0.27 0.26 0.28 0.28 0.30 0.27 100 0.33(8) 0.29(5) 36 46(5) 40 42(4) 35 26(4) 23(3) 40(7) 36(3) 23(3) 33(3) 35(4) 36 0.05 0.08(3) 0.09(4) 0.08(3) 0.08 0.08 0. 10 0.08 0.08(3) 0.26 0.28(3) 0.26(3) 0.28(4) 0.26(3) 0. 12 0.07 0.08 0. 12 0.06(3) 0.03 0. 07 0.07 0.26(3) 0.10(4) 0.08 0. 10 0.07 0.07(3) 0.06 0.07 0.06 0. 17 0. 12 0.22(3) 0.10(3) 0.09(3) 0.07 0.18(3) 0. 12 0. 17 0. 16 0.07(3) 0.08 0.06(3) 0. 14(4) 0.09 0.13(4) 0. 16 0.16(3) 0.15(3) 0. 190 0.245 0.265 0.270 0.275 0. 315 0. 300 0. 300 0. 300 0.270 0.265 0.255 0.260 0. 325 0. 300 0.290 0.230 0.290 0. 315 0. 305 0.280 0.255 0.220 0.295 0.230 0.200 0.325 0.230 0.245 0.250 0.210 0. 335 0.250 0.240 0.200 0.255 0.280 0.365 0. 325 0. 325 0.235 0.240 0.245 0.230 0.245 0.255 0.265 0.325 0.250 0.265 [10] 7 4(10) 4(22) (9) 0 Visual IRRemarks Additional Photometry 1,2,3 4 2 1.2.3 4 1 1 1 1 1,2 1 1 1.3 1,2 5,6,9WOH331 1 4 1,2 1,2,3 ...WOH322 1,2 1,2,3 5,9 from WOHTable WOH 323 WOH 321 1 985ApJS . . . 57 . . . ME f W46 W16 NGC 1984 MG 46 NGC 1818® HV 12620... D3 C12 B2 6 54- 53HV2798 53- 18WOH439 53-13 WOH433 54- 20 53- 8WOH412g 53- 6HV2677 52- 18HV5933 47- 20HV2604 54-12 HV2674 52-17 WOH399 46- 52 46-49 W0H346 53- 3 46-51 HV2602 45-38 HV2595 52- 4HV5914 Star Identification (1) HV 2556 46-25a (2) American Astronomical Society •Provided bythe NASA Astrophysics Data System Ml la M2 la Ml la M0 la Ml lab Spectral (JD- Type 2440000) Ml lab M0 lab M2Ia-Iab 3854 Ml la 4188 4189 4190 4238 4596 4187 4150 4242 4242 4596 4238 4625 4595 4669 4624 4190 4595 4596 4267 4242 4271 4238 4267 4237 4596 4237 5034 4596 4190 4190 4267 4271 4237 4267 4190 4596 4270 4237 4190 3854 4238 4237 4190 3854 4238 3917 5034 3917 3854 10. 68 10. 78 9. 13 9. 16 8. 32 8.02 0.930.21 8.02 0.950.23 9.67 8.30 8.37 8.08(3) 0.980.22 9.29 6. 77 8.36(3) 8.57 8.05(3) 7.83 6. 75 6.81 8.03(3) 8.39 7. 78 7.80(3) 7.90 7.79 8.40 8.48 7.97 7.95 7.77 7.76 7.76 7.77(3) 7.62 7.81 8.42 8.47(3) 7.73 8.80 8.86(3) 7.65 7.68 7.74(3) 7.56 7.58 7.44 7.73 7.63 0.90(3) 0.90 0. 91 0. 96 0. 9 9 0. 97 0.98 0.95 0. 96 0.99 1.12 0.27 1.16(3) 0.31 0.90 0.98 0.97 1.04 0.24 1.43 1.44 1.03(3) 0.25 0. 97 1.00 0.24 1.05(3) 0.28 1. 39 1.24 0.39 1.07 1. 13 1.14(3) 1.09 1.22 1.09 1.04 1.04 1.04 1.03 1.11 1.08 1.17 1.02 1.02 1.06 1.05 1.09 1. 10 1.01 0.23 1.03(2) 0.24 Observed MagnitudesandColors TABLE 4—Continued 0.23 0.22 0. 19 0.49 0. 16 0. 19 0.27 0. 34 0.45 0.49 0. 32 0. 34 0.24 0.23 0. 32 0. 36 0. 32 0. 24 0. 30 0.26 0.21 0.22 0.22 0.24 0.26 0.34 0.26 0.27 0. 32 0.26 0.27 0.28 0. 33 0.25 0. 28 0. 30 101 40(6) 0.10 52(6) 0.15 50(6) 0.24(3)0.140 38(7) 42(5) 0.17(3)0.255 28(3) 0.22(3)0.330 51(3) 0.250.165 61(6) 0.15(4)0.170 0.31(4) 0.320 0.29 0.310 0.09(3) 0.260 0.14 0.30 0.34 0.250 0.10 0.09(3) 0.185 0.06(3) 0.185 0.04(3) 0.205 0.07(3) 0.250 0.06 0.270 0.05 0.04 0.08(3) 0.315 0.31(3) 0.230 0.15 0.38 0.14(3) 0.170 0.11(3) 0.10(4) 0.04 0.09 0.07 0.185 0.04(3) 0.250 0.05 0.10 0. 11 0.17 0.15(4) 0.270 0.06(3) 0.09 0.09 0.29(4) 0.345 0. 31 0.08 0.05 0.21 0.335 0.28 0.330 0. 13 H0 9 0.290 0.215 0.210 0.305 0.310 0.175 0.185 0.280 0.330 0.295 0.280 0.260 0.310 0.250 0.230 0.235 0.310 0.290 0.285 0.255 0. 305 0.225 0.270 0.240 CO [10] 86(20) 91(10) 79(12) 0 Additional Visual IRRemarks Photometry 2 5,6,9WOH413 2 2 ...fromWOHTableII 1,3 1,2,3 4WOH381 1 1 1 4 1 1 1 4 1,2 1 1,2 9WOH354 1,3 4WOH349 5,9 WOH358 WOH 310 WOH 486 1985ApJS...57...91E ef & Star Identification MH23a Wd-a4 MH25 MH10 MG98 MH35 MG93 B2 3 C14 45-47 W7 46-29 NGC 1994 W31 NGC 2004’ MH8 MH7 Cl 45-41 D14 B31 C19 45-46 MH6 MH4 MH3 MH1 W69 Wa67 54-46a W57 W51 W34 W30 W44 W24 54-47a W12 D16 W5 D15 NGC 2100 30 Dor.(NGC2070) (1) e, f MG 95 MG94 MG 76 MG 91 MG 84 WOH 481 54-26 B4 C8 C32 (2) © American Astronomical Society • Provided by theNASA Astrophysics Data System Spectral (JD- Ml la-lab Ml lab Type 2440000) 4980 4669 4982 4668 4597 4980 4980 4668 4597 4668 4668 4668 4668 4240 4596 4240 4190 4240 4240 4240 4240 4977 4240 4238 4190 3915 . 4240 4596 3915 4240 3915 4265 4242 4265 4265 4242 4236 4236 4265 4236 4189 3916 3916 10. 10.20 9.46 8.91 8.89 8.22 8.24 8. 95 8.99 9.02 8.98 8. 8.44 8. 37 8. 9. 9. 9.41 9. 42 9. 17 .94 .58 .04 .61 .46 . 34 .81 .46 .47 .51(3) . 83 .82 . 73 . 72 .87 . 87 .85(3) 40 40 62(3) 70 77 77 0.99 0.97 1.17(3) 0.32 1.28 1.27 0.35 1.22 0.99 1.14 1.16 1.06 1.16 1.03 1.08 0. 9 9 1. 10 1.04 0.97 1.07 1.08(3) 1. 13 1.17 1.01 1.08 1.11 1.05 1. 13 1.01(3) 1. 19 1.24 1.25 0.97 0. 94 0.93 0.99 0. 98 0. 98 0.92 0.16 1.01 1.00 1.01 1.02(3) 0.23 1.03 0.25 Observed MagnitudesandColors TABLE 4—Continued 0.27 0.21 0.21 0.32 0.28 0.25 0.29 0. 35 0.21 0.23 0. 26 0.22 0. 24 0. 25 0.25 0.24 0.28 0. 30 0. 23 0.23 0.27 0.28 0.21 0.25 0.22 0. 38 0. 36 0. 30 0. 18 0.21 0.20 0.21 0.22 0.21 0.21 0.21 0.20 0.26 0.08 0.24 0.11 0.07 0.07 0.11(3) 0.270 0. 12 0.07 0.09 0.14 0.260 0. 38 0. 12 0.08(3) 0.255 0.06(3) 0. 12(3) 0. 10 0.09 0.09 0.06(3) 0.260(3) 0.07 0.07 0.09 0. 10 0. 12 0.12(3) 0. 11 0. 10 0.08(3) 0.190 0.06(3) 0.08(3) 0.240 0.10(3) 0.280(3) 0.09 0.255 0. 12 0. 09 0.04 0.07 0.11(3) 0.240 0.06 0.220 0.08 0.12(3) 0.315 0.08 0.315 0.330 0. 300 0. 195 0.250 0. 185 0.225 0.255 0.245 0.270 0.255 0. 230 0.270 0.270 0. 300 0. 230 0. 240 0.260 0. 250 0. 300 0.260 0.260 0. 155 0.270 0.270 0.270 0. 175 0.275 0.275 0.215 0.240 0. 185 [10] 1, 8 Visual IRRemarks Additional Photometry 1,8 1,8 1 1,8 1 1 1 8 W14 8 1,8 8Wl;WOH351 1,2 ...WOH318 ... W13 MH photometry MH23 istriple, WOH 452 MH photometry HV 2740;MG92; WOH 480 HV 6002;WOH478 C2 confused byMH35 confused. MG112 MH photometryis confused byMH8 WOH 446 1985ApJS...57...91E (6) CatchpoleandFeast1981.(7)McGregorHyland(8)1984.(9)Wood,Bessell,Fox1983. Star Identification measurements, whichmightberesponsibleforashift.Since chosen toleavetheCOindexvaluesunchanged.Noshiftsare of somethesamestarsbyMcGregorandHyland(1981, Campanas COindicesmaybesystematicallyhigh,by~0.038 tained morerecently(seealsoFrogel,Persson,andCohen seen incomparisonsofCTIOandLasCampanasdataob- the COdifferenceisonlymarginallysignificant,wehave 1983). there isnodifferenceintheH0index(0.005+0.023),and MH18 Wd-8 MH23b Wd-a3 MH24 Wd-a7 MG 104 + 0.013mag.Adifferentcontinuumfilterwasusedforthese 2 a c g e d b (1) Identificationaregivenincols.(1)and(2)theremarks.Theycodedasfollows,byletterprefix: Photometry references:(1)Humphreys1979<2.(2)Westerlund,Olander,andHedin1981.(3)Thispaper,Table4.(4)Glass1979.(5)Feast etal.1980. MH identificationsfromMcGregorandHyland1981.Seenote(a)forremainingidentificationcodes. IdentificationswithB,C,orDprefixfromRobertson1974. StarsinLMCfield.Seetext. Spectral typesaretakenfromHumphreys1979<2. Additional identificationcodesaregiveninthenotesforindividualclusters. identifications withWprefixfromWesterlund1961. Comparison ofthedatainTables3and4withobservations Wd: Westerlund1966 WOH: Westerlund,Olander,andHedin1981 None: SanduleakandPhilip1977 MG: MendozaandGómez1973 HV: Harvardvariable,identifiedfromHodgeandWright1967 (2) © American Astronomical Society • Provided by theNASA Astrophysics Data System Spectral (JD- Type 2440000)K J —K ho Kr it H —K co K —L r V —It v-Rj 2 r CIT c Color a References.—(1) Eliasetal.1983. (2)AppendixA. 4669 4621 4621 4597 4597 4982 4980 0.82 (0.912 +0.059) (0.954 +0.013) (0.922 +0.018) (0.931 +0.014) (0.897 +0.005) (0.92 ±0.03)CO (1.79 ±0.04)CO (2.6 ±0.3)HO ^Giass-0.008 ±0.007 (0.85 ±0.07) Kj +(0.047±0.009)J— ^aao-O-OH ±0.004 mh bfp 2bfp 10. 35 8.00 9. 12 9. 10 9.11(3) 7.96 7. 96 1.14 1.21 1.14(3) 0.30 1.24 1.22 1.22 1.20 0.29 Observed MagnitudesandColors Color Transformations M SUPERGIANTS TABLE 4—Continued — H-Kr tf-^AAQ-0.004 +0.003 H-K K-L F ToaAs V-ln n J-Kr 7-^aao+O-Wtó ±0.004 0. 32 0.27 0.34 0. 33 0.33 Transformation i TABLE 5 GaAs . -0.01+0.02 K-L 0. -0.009 +0.017 + 0.40 -0.036 +0.009 -0.009 +0.016 41(3) 0.20 between ourinfraredphotometricsystemandthoseofother zero-point shiftdeterminationisdominatedbytheGlass1974 scatter. Wearethuscertainthatanysystematicdifferences standards). Hereagainthereisneitheranetshiftnorexcessive observed incommonwithGlass(1979),Feastetal.(1980), differences andascatterconsistentwiththequoteduncertain- tudes canbeusedforanindependentcomparison(sincethe the colortransformations(AppendixA),soonlyKmagni- and CatchpoleFeast(1981)werealsousedindetermining ties andvariabilitybetweenthetimesofobservation.Thestars 1982) aftertransformationtotheCITsystemshowsnonet 0. 19 0.07 0.03 0.11(2) 0.270 0.05 0.170 0. 17 for V-Ij<2.20 0. 300 0.260 0.295 0.250 0. 305 [10] VisualIRRemarks 3 References Additional Photometry 1 7MG114 4,7 MG105;W0H357 103 1985ApJS...57...91E difference seenbetween1976 and 1977inthemeasurementsof but werenotwhollysuccessfulasisshownbytheSMCdata, photomultiplier sensitivityondeclinationwhichaffects the Westerlund, Olander,andHedin(1981;hereafterWOH)shows “confirmed” supergiantsisnot confirmedwhenallthestars where asmallshiftalsoexists.ToofewLMCstars were mount orinsidethetubeitself;theremaybesomeeffectsfrom by 0.2mag.Thisshiftisduetoavariabledependence of determining theshiftinLMC datafrom1977to1979. measured in1979todecidehow toshifttheSMCdataset,by cold boxesandeliminatethe“declinationeffect”weremade magnetic fieldsaswell.Effortstoimprovethephotomultiplier data between1976and1977(Table7).Comparisonwith Landolt 1983)andappearstobedueflexureinthe tube 31034A photomultipliers(e.g.,KunkelandRydgren1979; Clouds. IthasbeenseenbyotherusersoftheCTIORCA transfer fromtheequatorialstandardstoMagellanic that the1976dataareatfault:Vmagnitudestoofaint, shift intheVmagnitudezeropointisseenLMC Table 5. authors arewellaccountedforbythetransformationsin 104 ELIAS,FROGEL,ANDHUMPHREYSVol.57 The colordataareessentially uniform(Table7).TheV—R The situationwiththeBVRIdataisdifferent.Alarge CTIO —Glass—0.00±0.02...28 CTIO(l 980/81)—(1979/80)-0.01±0.02-0.03±0.01-0.01±0.01-0.00±0.0121 “Glass” referstophotometryfromGlass1979,Feastetal.1980,andCatchpole1981. CTIO-MH ±0.03±0.02-0.03±0.01-0.00±0.01...20 CTIO(1981/82) —(1980/81)-0.03±0.03+0.02±0.01-0.01±0.01-0.02±0.0111 CTIO(1979/80)-LC(1978) +0.02±0.04-0.00±0.02+0.00±0.01-0.0413 c b a Numberofstarsusedincomputingdifference. All photometryhasbeentransformedtothe“CIT”systemforcomparison. CTIO photometryisresultsofTables3and4combined.“MH”referstofromMcGregorHyland1981,1984. © American Astronomical Society • Provided by theNASA Astrophysics Data System 3c Difference KJ-KH-KH0CON d c d c 2 Westerlund, Olander,andHedin1981iscomparedwithphotometryfromHumphreys1979a. LMC (1979)-(1977)-0.06±0.16+0.03±0.03-0.02-0.05±0.1011 SMC (1979)-(1978)-0.09±0.02-0.02±0.01+0.01±0.01+0.02±0.0189 SMC (1979)-(1978)-0.11±0.02-0.02±0.01±0.00±0.01+0.02±0.0261 EMC (1977)-(1976)-0.14±0.04-0.01±0.01+0.08±0.0364 LMC (1977)—(1976)-0.22±0.05±0.00±0.01-0.04±0.01+0.01±0.0438 1977: WOH-RMH+0.02±0.03...0.000.01-0.1212 1976: WOH-RMH-0.20±0.03...-0.05±0.01-0.04±0.0312 d C b a LMC andSMCdifferencescomputedusingallstarswithphotometry. LMC andSMCdifferencescomputedusingonlysupergiantswithspectraltypesknown. Numberofstarsusedindifference. Photometry fortheLMCistakenfromHumphreys1979ßandTable4.WOHphotometryin ii) TheOpticalData 3h Difference VB-V—RV-IN Comparisons ofInfraredPhotometry Comparisons ofVisualPhotometry Mean DifferenceandUncertainty 13 TABLE 7 Mean DifferenceandUncertainty TABLEÓ marized inTable5. Johnson system,butwithconsiderablescatter.SincetheWOH Analysis oftwo-colorplots(similartothatinAppendix A) derive transformationsbetween themandtheJohnsonsystem colors fromTables1and2 fromHumphreys{1919a)and on theJohnsoitsystemandsomearenot,thusaccounting for combinations, itispossiblethatsomesubsetsoftheirdata are data weretakenusingseveraldifferentfilterandphototube {1919a) dataaresomewhattoored,comparedwithWOH. mag. means thattheuncertaintyinmeanV—Kisabout+ 0.05 remaining magnitudeshavebeenleftunchanged.Nocorrec- shows thattheWOHdataaremoreorlessonoriginal for theSMCcontributeroughlyequallytoanalyses,which net decreaseinbrightnessofthestarsatK-0.05mag. differences ismarginallysignificantandmaybeduetoareal the scatter.InAppendixA,we examinetheF—RandVI shows largedifferencesinthesensethatHumphreys LMC in1976havebeenmadebrighterby0.2mag,whilethe are takentogether.TheV—Idifferenceseeninthelarger tion wasappliedtotheSMCdata.Datafrom1978and1979 sample (confirmedplusprobablesupergiants)of1976-1977 V —RandIcolors.These transformationsaresum- Comparison oftheV-IdataforLMCwithWOH In theanalysisbelow,Vmagnitudesmeasuredin H O'! No. 1,1985 M SUPERGIANTS 105 rate to at least half a subtype. The LMC classifications should be of similar accuracy. A shift in median effective temperature is expected, since it is well known that the Hayashi track, the nearly vertical slope of the red giant band in the H-R diagram, depends on metallicity. The surface temperature increases with decreasing heavy element abundance because the opacity, due primarily to H_ ions, depends on the number of electrons from the heavy elements. The decrease in the number of contributing heavy elements with lower metallicity is offset by an increase in temperature. This effect is observed for the red giant branches of globular clusters. However, it is not possible to determine the actual shifts directly from the differences in median spectral type, since the relation between spectral type and effective temperature is metallicity dependent.

b) Abundance Effects and Spectral Classification At the spectral resolution used for MK classification, there are no apparent effects of the differing metal abundances in the Milky Way, LMC, and SMC on the appearance of the spectra. Small effects can be seen in spectra at higher resolu- tion (McGregor 1981). The different metal abundances should, nevertheless, affect quantities inferred from MK spectral types, most notably temperatures and intrinsic colors. An attempt is made to derive intrinsic colors in § VI; the shifts in effective temperature are discussed below. It is necessary to assume Fig. 1.—Spectral type distributions and median types in the Milky relative abundances for the Milky Way, the LMC, and the Way, LMC, and SMC. Stars plotted are taken from Tables 20,11, and 13. SMC. Abundances derived for H n regions or supergiants are Only Milky Way stars with MK luminosity classes of la or lab are reviewed by Pagel and Edmunds (1981; see also Lequeux et al plotted; the hatched portion of the Milky Way diagram represents the distribution of the class la stars. Stars classified as intermediate between 1979; Foy 1981; McGregor 1981; Harris 1981a, 6, 1983). The two subclasses have been given half-weight in each of the two subclasses. discussions which follow are based on the M supergiants in the LMC being metal deficient by a factor of 2 with respect to the Milky Way, and the SMC deficient by a factor of 6.5 Supergiant spectral types later than K5 are based primarily HI. SPECTRAL TYPES on the appearance of the TiO bands at 4500 to 5000 A for MK temperature types, and on the depth of the 7120 A TiO a) Distributions band for the eight-color Wing (White and Wing 1978) types. The first major result of this paper is to confirm the The strength of the TiO bands, although predominantly de- substantial differences between mean spectral type in the pendent on temperature, must also depend on abundance. SMC, LMC, and the Milky Way reported by Humphreys Mould and McElroy (1978) and Mould and Bessell (1982) (19796). This is shown clearly in Figure 1, a histogram of the have found differences in the strength of the TiO bands at a spectral type distributions in the three galaxies. The stars given effective temperature between field giants and the M71 plotted are those used in the analyses (Tables 11, 13, and 20). and 47 Tue giant branches, which amount to - 0.13 mag in The galactic sample plot omits the low-luminosity lb super- the 7120 Á TiO band for early M stars (calculated using the giants. revised field relation of Mould and Siegel 1982). (Observations The two main features of the distributions are, first, the by Wing 1973 of

© American Astronomical Society • Provided by the NASA Astrophysics Data System 1985ApJS...57...91E 6 luminosity binsandfindingacommonslope12inter- (1970) arequiteheterogeneous. Arevisedsetofgalacticdata using anunbiasedleast-squaresmethod(Jefferys1980); fur- be deriveddirectly,asdiscussedbelow.)Thedatawerefitted cepts. (ThereddeninglawsfortheLMCandSMCcould not fainter, heavilyreddenedstars. ThespectraltypesusedbyLee classification betweenthebrighter,lessreddenedstarsand the colors ofMsupergiantsvarysubstantiallywithspectraltype, supergiant databygroupingtheinto12spectraltype and serious errorscanresultiftherearedifferencesinthespectral ther detailsaregiveninAppendixB.Becausetheintrinsic classifications ofWawrukiewicz(1971). Thesewerederivedusingatwo- filter photometricsystemtomeasure TiObanddepth.WhiteandWing These canbeusedtoexaminetheluminosityclassifications.In infrared photometryandMKluminositysubclassesgiven. (e.g., Lee1970).ItthereforeappearsthattheMagellanic good agreementwiththecalibrationofgalacticMKtypela reasonably unbiased.FordistancemodulifortheLMCand undoubtedly arebiasedtowardbrighterstarsbythemagni- Way supergiantsarecoolest. calibration. K =8.21andthelabmeanisAT8.81,withmoreoverlapin overlap inthedistributions.ThelameanSMCis Cloud MKluminosityclassificationsareaccurateandthat 7.59; forthoseclassifiedlabitis8.49,withremarkablylittle the LMCmeanKmagnitudeofstarsclassifiedlais remain differencesatthelevelof-100K,insensethat differences inspectraltype.Itseemslikely,though,thatthere effective temperatureamongthethreegalaxiesaresmaller there arenolargegalaxy-to-galaxyshiftsintheirabsolute to absoluteVmagnitudessomewhatbrighterthan-7,in type laare—11.0and—10.8,respectively.Thesecorrespond SMC of18.6and19.0,themeanabsoluteKmagnitudesfor tude limitsonthesamples,butlagroupsareprobably the distributionsthaninLMC.Thegroupsoflabstars the SMCsupergiantsarehottestonaverage,andMilky scale. effective temperaturesthanhighermetallicitystarswiththe metallicity starsofagivenTiObandstrengthwillhavecooler TiO shiftweretemperatureindependent.Therefore,low- (MO-2). ForM3-4thetemperatureshiftswouldbelessif than wouldbeinferredfromthesimplestinterpretationof are notgreatlydependentontheMsupergianttemperature for theSMCandlessthan100KLMC;thesevalues suggests theshiftrelativetoMilkyWaybenearly200K Examination ofeffectivetemperaturesgivenbyLee(1970) similar: starsintheSMCandLMCofagivenMKspectral same bandstrength.EffectsonMKclassificationshouldbe classified abouthalfasubtypeearlier,forearlyMsubtypes type willbecoolerthangalacticstarsofthesameMKtype. same effectivetemperature,andstarsintheLMCwouldbe 106 6 The reddeninglawwasdeterminedfromthegalacticM A1so, inadoptingspectraltypes, Leegave“highweight”tothe There are25LMCstarsand30SMCwithboth It appearsthatthedifferencesinaverageMsupergiant © American Astronomical Society • Provided by theNASA Astrophysics Data System c) LuminosityClassifications IV. THEREDDENINGLAW ELIAS, FROGEL,ANDHUMPHREYS As aresult,theWawrukiewiczclassifications ofdistant,luminousstars reddening dependenceoftheclassifications. seem systematicallytooearly(see Wing andYorka1979).Inaddition,the (1978) pointoutthatWawrukiewicz’s filtersarealsoaffectedbyCN absorption, andtheremaythusbe luminosityeffectsontheclassifications. two filtershavedifferenteffective wavelengths, whichmayleadtoasmall reddening lawtodifferfromthatforearly-typestars (see and lateMsupergiants.Analysesofsubsetsthedatado not ent, by0.075E_,whichcausesthenewintrinsicJ—K that theremightbedifferencesinthereddeninglawsforearly Lee (1970). colors (§Vic)tobegenerallybluerthanthoseobtained by Schultz andWiemer1975;Cohenetal.1981).Thissuggests the redderenergydistributionsofMsupergiantscause the (1971) spectraltypes.ThereddeninglawforJ—Kisdiffer- is notmuchdifferentfromthatgivenbyLee(1970).The below). Lee’s least-squaresprocedureandthebiastowardsteeper slopes introducedbytheSharpless(1966)andWawrukiewicz tematic effects:thebiastowardsmallerslopesintroducedby agreement isduetoapproximatecancellationoftwosys- MK typeswereusedindeterminingtheintrinsiccolors(§VI, The primaryreasonforthisisadearthofheavilyreddenedM photometric classificationsbyWhiteandWing(1978)rather supergiants withMKclassifications;thedifferencesbetween used inderivingthereddeninglawwasdoneonbasisof The resultsaregiveninTable8.groupingbyspectraltype tion areunlikelytobereddeningdependent.Notethatthe the WhiteandWing(1978)classificationsMKclassifica- was thereforeproduced(AppendixC),whichalsoincludes than thehomogenousMKclassificationsgiveninAppendixC. of thegalacticstars,andthenexcludingthosefewstarswith used toderiveintrinsiccolorsforgalacticsupergiantsin§VI. observations fromothersources.Thesereviseddataarealso anomalous colors;detailsaregiveninAppendicesBandC. bv The shiftsineffectivewavelengthoftheBVRIfiltersdue to For V-R,V-I,andV-K,thereddeninglawinTable8 The analysiswascarriedoutfirstbyfittingthedataforall d b d d e a son system. son system. A 3.55+0.2 J-K 0.605+0.35 “GaAs” system. CO -0.040+0.05 H0 0.060+.005 K-L 0.20+0.03 H-K 0.215+0.20 B-V 1.00 v V -K3.24+0.13 V-I 2.07+0.9 V -R1.26+0.05 2 M SupergiantReddeningLaw d c b a or Adopted value:seetext. On CITsystem;0.237onJohn- On CITsystem;0.655onJohn- On Johnsonsystem;2.52on C°l E/E_ colorbv TABLE 8 Vol. 57 1985ApJS...57...91E 7 Table 8andtheintrinsiccolorswerethereforeallderived No. 1,1985 intrinsic colorswillbeslightlyaffected. laws intheMagellanicCloudsdifferfromgalacticlaw, way ortheother.Thegalacticreddeninglawwastherefore between AandE_basedontheoreticalmodelsofgrain Neugebauer etal1978).Thesecondwastoassumearelation ways. Thefirstwastospliceapreviouslydeterminedinfrared using thesamereddeninglawforallspectralsubtypes. show anysignificantdifferences(i.e.,greaterthan~3times While theSMCsupergiantsshowonlymarginallysignificant used tocorrecttheMCdataforextinction.Ifreddening reddening lawlongwardoftheultraviolettobelikethatin Koomneef (1982)andMorganNandyshowthe extinction curveontothepresentresults,inthiscase E/_ andwhichwerethenmultipliedby less likelytohavestrongmassloss.However,examination of extinction lawforthegalacticcenter(Becklinetal.1978; E_/ andgiveninTable8.Finally,theextrapolation type stars(seeEliasetal1982)whichgivevaluesof 8 arederivedfrommeasurementsofheavilyreddenedearly- the uncertaintiesquotedinTable8).Thereddeninglaw or brightestsupergiants,thisdifferenceislikelyreal. galaxies werechoseninthesameway,fromamonglatest mag. Sincethestarsselectedformeasurementsin two (see Fig.2)withamedianK-[10]colorslightlylessthan 2.0 excess 10/imflux(thelargestAT—[10]colorforanSMC the MilkyWay.ForSMCthereisnodirectevidenceone because thereisonlyasmallrangeinAycoveredtheLMC to infinitewavelengthgiveA/E_wasdoneintwo LMC andSMCisthatthestarsinSMC,beingearlier, are supergiant is1.0for104-5),theLMCstarsallshowanexcess reddening lawwashighlydependentontheerrorsusedin The meanvalueisgiveninTable8;theerroranestimateof SMC havebeenmeasuredat10jam(seeTables3and4). B). FortheLMC,JHKobservationsofearly-typestarsby relations intheMagellanicCloudsfailedbecausederived computing shiftsineffectivewavelengthforthedifferingen- extinctions, A=1E_(WhittetandvanBreda1978). and SMC,comparedwiththescatterindata(Appendix analyses, andthusnotaccurateenoughtobeuseful.Thisis ergy distributions(seeCohenetal1981:AppendixA). Note, though,thatthedifferences ineffectivetemperaturebetweenthe the formaluncertaintiesgivenbyeitheroftwomethods. Both methodsgivevirtuallyidenticalvaluesanduncertainties. that derivedusingthereddeninglawforearly-typestarsand the trueuncertaintyinestimateandisslightlylargerthan excess andtemperature(e.g.,Humphreys, Strecker,andNey1972).A ferences inspectralclassification(see §III). SMC andLMCsupergiantsaresmaller thanthoseimpliedbythedif- theoretical lossrate(Reimers1975) isoftheform vK cohkH20HK HKBv VB VK 7 The coefficientsfortheCOandH0indicesgiveninTable Ten supergiantsintheLMCandfour Attempts tofindthereddeninglawbyfittingtwo-color The reddeninglawinTable8isalsofairagreementwith One possibleexplanationforthedifferencebetween GaIactic supergiantsshowaweakinversecorrelationbetween10jit m 2 V. 10MICRONMEASUREMENTSANDMASSLOSS © American Astronomical Society • Provided by theNASA Astrophysics Data System M SUPERGIANTS pected, onthebasisofFigure 2,toshow^-[10]colors K—L colorsasred0.4. 47-20, 52-18,54-12,54-20, and MH18).Allwouldbeex- 0.40 orlargerbutwithout 10 jamdata(Case40-10,46-21, presence ofhotdustemittingat3.5¡im(L)inthestars. This variable HV11417(Elias,Frogel,andHumphreys1980).TheK—L greater than1.0mag.There arenoSMCsupergiantswith K—L colorswillhavestrong10¡imemission.There are band 10/imexcessesare~0.5maggreaterthanin the in closeagreementwiththeobservations. uncertainties arenotplotted,buttypically±0.03-0.04mag. SMC supergiantsareshownasopencircles.Thesquareisthe Cloud stars.TheLMCsupergiantsareshownasfilledcircles,andthe colors, asshowninFigure2.Thisisprobablydueto the Examination ofthenarrow-band10/urndatainHumphreys, seven starsintheLMCwith mean K—LcolorsinTable3of suggests thatthosestarsinTables3and4withespecially red LMC—consistent withtheprediction. roughly thesame—then10jimexcessesinSMC dust formationefficienciesandmeanmass-lossratesare suggests thatforthemoreluminousgalacticstarsbroad- should belargerthantheLMCexcessesby-0.7mag. should be—3timesweaker(1.2magless)thanintheLMC, of dustisroughlyproportionaltometalabundance—thatis,if dance betweentheLMCandSMC.Excess10/xmemis- jttm, forwhichthemeanK—[10]colorisonly0.75mag.Also, has diK-[10]colorof1.9magandroughlythesameluminos- Strecker, andNey(1972)Humphreys(1974) star forsmallexcesses(i.e.,opticallythinshells).Iftheamount sion shouldbeproportionaltotheamountofdustarounda luminous starsmeasured;neitherhasanunusuallylatespec- with spectraltype.TheoneLMCM0starmeasured(46-32) ity asthethreeSMCM0supergiantsthatweredetectedat10 the LMCdatashowsnocorrelationofsizeexcess tral type. the twostrongestexcessesinLMCareforofless Fig. 2.—TenmicronexcessisplottedagainsK—LforMagellanic The 10jtimexcessesarestronglycorrelatedwiththeK— L A morelikelyexplanationisthedifferenceinmetalabun- If thisargumentiscorrect,thengalactic10jitmexcesses 107 1985ApJS...57...91E ity ofthesupergiantsininfraredissmall,so whose KmagnitudewasclosesttoGlass’svalue.Forall the cation. Theuncertaintiesintroduced bythelackofsimul- colors shouldbeclosetothose atthetimeofspectralclassifi- remaining SMCandLMCstarstheinfrareddatawereaver- remaining infraredcolorsweretakenfromtheentryinTable 4 were usedinformingthecolors.(Theindividualstars are be obtained.IntheSMC,someofstarswereobservedin was missing,thenthestarnotused.ForthreeSMC to havethesameintrinsicB - Vcolorsasgalacticstarsofthe (Appendix B,Table19). taneity areincludedinthe estimatesusedintheanalysis magnitudes wereusedinformingtheV—Kcolor,and the 29-33) thesameseasonasspectralclassification.Glass’s K obtained infrareddataforthreestars(Case46-40,37-24, and identified inTables11and12).IntheLMC,Glass(1979) analysis (seeAppendixB).Asshownin§Villa,thevariabil- aged andtheirV—Kcolorsweregivenlowerweightin the done; inthesecasestheinfrareddatafromthatseasononly stars withtwoclassificationsthe1979datawereused.Since paper. TheBVRIdatatakenthesameseasonasspectral the infraredsameseasonastheirspectralclassificationwas time ofclassification. obtained inthesameseasonasclassificationorifacolor classification wasdonewereused.IfBVRIdatanot references giveninAppendixC.ThecolorsfortheLMCand reddening lines(§IV)withanassumedunreddenedB—V ing Lee(1970),byfindingtheinterceptsoftwo-color the BVRIdatashouldaccuratelyrepresentcolorsat the spectraandphotometryweretakenonlyafewdaysapart, color. SMC analysesweretakenfromHumphreys(1979¿z)andthis has aKexcessaslarge0.1mag. hotter dustinthecircumstellarshells,whichwouldincrease extreme, anditisunlikelythatanyotherwell-observedstar smaller. ThediagnosticsofanexcessintheKfilterarethus most extremecasesof~0.04mag,andaweakeningthe no 10/immeasurementsalsoshowweakCO—especiallyCase an unusuallyredH—KcolorandaweakCOindex;byfar amount. Effectsatshorterwavelengthswillbeconsiderably CO indexbyasimilaramount.Thereislikelytobesome 52-18 (HV5933)and54-122674). 37-24 (HV2360).SomeofthestarswithredK—Lcolorsand dust shellaffectingtheCOindex.AnextremeexampleisCase of anadditionalweakbutredemissioncomponentfromthe dency towardweakCOindices,presumablyduetotheeffects the bestexampleisCase37-24.Nootherstarseemsso the KexcessanddecreaseCOindexbyanadditional to shorterwavelengthsimpliesexcessemissionatKforthe the pointsinFigure2aretypically700-800K.Extrapolation 108 For theinitialanalysis,Cloud supergiantswereassumed The intrinsiccolorsofMsupergiantswerederived,follow- For theinfrared,samedegreeofsimultaneitycouldnot For theMilkyWaystars,dataweretakenfrom The colortemperaturesfortheexcessemissionimpliedby The starswithstrongest10jitmexcessesalsoshowaten- © American Astronomical Society • Provided by theNASA Astrophysics Data System VI. INTRINSICCOLORS a) Derivation ELIAS, FROGEL,ANDHUMPHREYS consistency withtheMagellanicClouddata.Starswithout MK typeswerenotused. The MKspectraltypesforMilkyWaystarswereused for H —K,andK-LcolorsratherthanV-J,H, and luminosity effectswerefound tobepresent,thesizeof finding theintrinsiccolorsinordertoprovidemaximum frared colorsaresmallerwhentheydetermineddirectly. and V—Raregivenonthe Johnsonsystem(nottheGaAs from AppendixC.TheanalysesweredoneusingtheJ - K, {B —V)colorsobtainedfromthestarsinTable9,except dening linesfromplotsversusB-V(Table8)andthe (§ Vic).Wherenoeffectswere found,ameanwasdetermined effect wasdetermined;these effectsarediscussedbelow that thedereddenedgalacticH0andCOvaluesweretaken for allluminosityclasses. separated intotwoluminositygroups.Where,significant from Johnson(1966). oî B—Vwithspectraltypeissmooth.Variationsasafunc- racy oftheintrinsicB-Vcolorsis~0.07assumingrun spectral typesK5andearher,the(B—V)valuesweretaken M0-M4; scatterinthedereddenedcolorssuggestsaccu- erences therein;alsoFitzgerald1970)arebasedonevenfewer determining (2?—F)valuesisverysmall,thereseemstobe were used(Table9).Althoughthegroupofstarsin bandwidth effectsintheBandVfilters(e.g.,Cohenetal Wildey (1964).Twomodificationstothetechniqueweremade: no alternative.Previousdeterminations(Lee1970,andref- bers ofestimatedspectraltypeA0orearlier,andthecolor ing Msupergiantsinassociationsusingnearbyearly-typestars preliminary analysis.TherearenounreddenedgalacticM nosity effectsontheB—Vcolorswerealsoneglectedin tion ofspectraltypeappearsmall—lessthan—0.1mag.For stars. MKspectraltypes(AppendixC)covertherange excesses soderivedweremultipliedby0.85tocorrectfor close totheMsupergiantsderivereddening,following metal abundancewerederivedsubsequently(§Vic).Lumi- V—L, sincetheuncertaintiesinresultingintrinsic in- two starsinCarina(Humphreys,Strecker,andNey1972) 1981). AsetofeightstarsinhandxPer(Wildey1964) the starsusedfordereddeningwererestrictedtoclustermem- supergiants, socolorswerederivedextrinsicallybyderedden- same spectraltype.ChangesinintrinsicB—Vduetodifferent 0 2 0 0 These valuesaresummarized inTable10.ValuesofV—I The remainingintrinsiccolorsweredeterminedusingred- The broad-banddatawereanalyzedwiththegalacticstars YZ Per2M2lab1.57 T Per1M2lab1.85 BO Car1M4lb1.66 HD 905861M2lab1.64 HD 148263M2lab1.63 HD 145802M0lab1.66 RS Per2M4lab1.72 BUPer 3M4lb1.78 HD 136584Mllab1.63 HD 131361M2lab1.89 Star StarsType(£-K) 0 Extrinsic DereddeningofMSupergiants Comparison Spectral TABLE 9 Vol. 57 1985ApJS...57...91E well-represented subtypes(Ml lab-M3labintheMilkyWay, if thesearemaderedder(for example),alltheotherintrinsic estimate, giventhecomplexity oftheanalysis.Firstall, colors asafunctionofluminosityorparentgalaxyare the Because theanalysisinvolvedarelativelysmallnumber of colors willbecomeredderas well,inallthreegalaxies.For entire systemistiedtotheestimates ofintrinsicB—Vcolors; same forallMspectralsubtypes. Uncertaintiesaredifficultto stairs, somesmoothinghasbeenappliedtothecolors. and H-KaregivenontheCITsystem(Appendix A). system usedinTables1and2;seeAppendixA)J —K No. 1,1985 Specifically, itwasassumedthatanydifferencesinintrinsic © American Astronomical Society • Provided by theNASA Astrophysics Data System 0 (3) Thesestellartypeshaveintrinsiccolorsbasedpartlyonextrapolationofabundanceeffectsfromother,morecommon Errors inintrinsicB—Vcausecorrelatedshiftsothercolorsalong thetwo-colorreddeningUnes(seetext). types inthesamegalaxy(seetext). types haveintrinsiccolorsdeterminedbyapplyingmeanshiftsforallMsubtypestoluminosityclasslab(seetext). SMC LMC* Uncertainties* Reddening weight Milky Way e c b d a f Uncertaintiesforwell-representedspectraltypeswithfiveormore starsassumingtheB—Vcolorstobecorrect. Data aretoosparseinH0andCOindicestodetectluminosityeffects. Assumes BC^forSun=—0.08(Frogel,Persson,andCohen1981). Mean colorsfortypesla-lab.Luminosityeffectspresent7— and possiblyforAT-L(seetest). V- R,K-/allonJohnsonsystem;J-K,7/-allCITsystem. Notes.—(1) Thesestellartypeshavewell-definedcolors,typicallyderivedfromfiveormorestars.(2) Weight0.7fornonsimultaneousVandATmeasures. 2 MOIa Mila M21a M31a M4la K5lab K3Iab Mllab MOIab M2Iab M4lab M3Iab MOIb M2Ib Mllb M4Ib M3Ib K3I K5I MOI Mil M2I M2I Mil MOI M3I M4I Type c f 1.69 1.60 1.38 1.68 1.70 1.69 1.70 1.67 1.68 1.68 1.69 1.69 1.70 1.71 1.71 1.72 1.72 B-V V-RY-IV-KJ-KH-KK-LHOCOBC 1.42 1.64 1.75 1.74 1.75 1.72 1.73 1.74 1.73 2V 1,0 1.00.50.20 1.74 0.90 1.10 1.25 1.20 1.35 1.55 1.75 1.20 1.35 1.25 1.75 1.25 1.20 1.55 1.35 1.55 1.75 0.85 0.04 0.070.100.02 1.05 1.15 1.20 1.51 1.21 1.16 1.30 1.71 1.31 2.20 2.00 2.30 2.90 2.50 3.30 2.20 2.30 1.60 2.90 2.50 2.30 2.20 3.30 2.50 3.30 2.90 2.40 2.20 2.15 3.20 2.80 2.10 2.25 Adopted ColorsforK2-M4Supergiants 2.35 1.45 1.85 4.10 3.50 3.90 3.80 2.90 4.60 4.10 5.20 3.80 4.60 3.90 4.10 5.20 3.80 4.60 3.90 5.20 Intrinsic Colors* 2.70 4.45 3.30 3.75 3.65 3.60 5.05 3.90 3.70 3.90 M SUPERGIANTS 0.75 0.70 0.87 0.85 0.83 0.96 0.90 0.86 0.90 0.88 0.99 0.93 0.72 0.76 0.74 0.79 0.85 0.70 0.60 0.94 0.91 0.89 0.87 0.84 0.86 0.88 1.00 TABLE 10 0.14 0.17 0.11 0.21 0.19 0.25 0.23 0.17 0.21 0.19 0.25 0.23 0.17 0.21 0.19 0.25 0.23 0.19 0.21 0.25 0.23 0.27 0.14 0.11 0.17 0.19 0.21 large. best determinedsubtypes.However, errorsinthemeandif- particular type.Errorsinthe colorsforsparselyrepresented regarding shiftsbetweenluminosityclassesorgalaxies. This may sometimesbedatafor onlyoneortwostarsofa caution appliesespeciallytotheinfraredcolors,wherethere uncertainties intheintrinsiccolorsareprobably4%orless, as ferences betweenluminosity classes orgalaxiescannotbethis subtypes couldconceivablybe 2or3timeslargerthanforthe colors dependmuchmoreonthevalidityofassumptions summarized inthelastrowofTable10.Forothertypes, the MO-M2 intheLMC,andM0SMC)additional 0.18 0.15 0.22 0.20 0.24 0.28 0.26 0.12 0.16 0.20 0.18 0.14 0.27 0.31 0.29 0.35 0.33 0.29 0.31 0.35 0.33 0.37 0.10 0.05 0.17 0.19 0.21 0.09 0.04 0.07 0.10 0.10 0.09 0.25 0.10 0.10 0.30 0.09 0.10 0.10 0.25 0.30 0.25 0.30 0.09 0.10 0.25 0.10 0.30 0.07 0.04 0.09 0.10 0.20 0.22 0.17 0.30 0.29 0.27 0.34 0.32 0.27 0.30 0.29 0.34 0.32 0.27 0.30 0.29 0.11 0.34 0.32 0.16 0.27 0.29 0.21 0.30 0.32 0.23 0.34 0.24 1 -0.47 -0.88 -1.12 -1.20 -1.37 -1.25 -1.05 -0.64 -1.23 -2.42 -1.92 -1.50 -1.33 -1.48 -1.31 -1.54 -1.29 -2.40 -1.90 -2.46 -1.96 -1.37 -2.30 -1.80 -1.38 -1.21 -1.13 Boiometric Corrections* bc k +2.42 +2.46 +2.26 +2.23 +2.78 +2.60 +2.57 +2.55 +2.68 +2.50 + 2.48 + 2.62 + 2.59 +2.57 +2.53 +2.74 +2.56 +2.51 +2.80 +2.70 0.10 +2.64 +2.53 +2.65 +2.54 t2.75 +2.57 +2.52 Notes 109 1985ApJS...57...91E one directandtwoindirect. There arethreepiecesofevidencesupportingtheeffect,though, luminosity differencebetween laandlb(e.g.,Lee1970).Since less luminoussupergiants.ThisB—Vluminosityeffect is between typeslaandlb(excludinglabfromtheanaly- vary withluminosity.FixingV—Kleadstoadifference large scatterintherelationbetweenB—Vandothercolors. LMC (§VIII).Theshiftimplied bytheLMCvariabilityis different luminositiesagreebetterwhenR—Fisallowed to convincing wayfail,becauseerrorsinspectraltypeproduce a relatively small.Attemptstopresentthedatagraphically in a B —Vwithluminosityvariation inindividualstarsthe sis) of0.03maginB-Vwithanuncertaintyabout±0.02. J —K,andK-Larcluminositysensitive,withBV Table 3shows,onaverage,strongerCOby—0.03thanthe ference isconsistentwiththeuncertaintiesinphotometry, mean ofthethreeMcGregorandHylandvalues.Thisdif- used datafromGlass(1979)todeducealuminosityeffectin ing lawused. showing theneedforlargersample. for onlythreeSMCstars;thelargersampleofstarsin Fig. 7).McGregorandHylandwereabletoobtainCOindices luminosity (seebelow).Lee(1970),incontrast,findseffects the luminosityeffectbecomesthatseeninJ-K(seebelow, H —K;ifGlass’sdataarecorrectedforinternalreddeningin as notedpreviously,generallybetter.McGregorandHyland only inH—KandL. K —LbecomingredderandJ-bluerathigher deduced fromthedata.ThepresentworkshowsthatB—V, differences appeartoresultfromthedifferenceinredden- Table 10rangefrom0.83forM0labto0.96M4lab.These mag redderattypesM3andM4. important respects.Firstofall,Lee’sV—Kcolorsaresys- - 0.15permagnitude,orasmuch as0.3maginR—Fforthe the SMCandLMC,intrinsiccolorsaremadebluer nearly identicalbymakingtheintrinsicB—Vcolors-0.03 Table 10differfromthosegivenbyLee(1970)inseveral colors rangefrom0.90atM0to1.10M4,whereasthosein giants ofthesamespectraltype(Lee1970)andcouldbemade than thoseinLee(1970).OntheCITsystem,Lee’sJ—K tematically redderforthelaterspectraltypes,by-0.3magin 110 V —R.TheKcolorsinTable10areclosertothoseofM F —A'atM3andM4.Therearesmalleffectsin/ The secondpieceofevidence isthepositivecorrelationof The firstisthatthelongbaselinecolors(chieflyV-K) at The mostluminousstarsappearredderinB—Vthanthe A thirddifferenceisthenatureofluminosityeffects The agreementwithMcGregorandHyland(1981,1984)is, The intrinsiccolorsofgalacticsupergiantstabulatedin Second, theJ—KcolorsinTable10areconsiderablybluer © American Astronomical Society • Provided by theNASA Astrophysics Data System b) ComparisonwithPreviousWork c) LuminosityEffects ii) McGregorandHyland i) B-V i) Lee ELIAS, FROGEL,ANDHUMPHREYS J -Kor-0.8maginV-K.Thatis,moreluminous stars below. Thesamegeneraleffect canalsobeseenintheMagel- have eitherbluerJ—KcolorsorredderV (or colors inJ—KversusV isinanycasenearlyparallelto lanic Clouddata(seeFig.7). both). TheshiftisassumedtobeprimarilyinJ—K\justifica- similar tothatofthelband lab stars,andtherunofintrinsic The shiftbetweenlaandlbcorrespondsto+0.16mag in intercepts correspondingtothemediansofluminosityclasses ily demonstrated.Aplotof/-ATversusV-Kfor the presence ofaneffectatleastthatlarge.Wethereforefeel la andlb;thesolidlineismedianforluminosityclass lab. galactic MsupergiantswithMKclassificationsisshown in tions forthisandthepossiblecausesofeffectarediscussed Figure 3.Thethreelineshaveaslopeof0.202,calculatedfrom our useofaluminosity-dependentB-Vcolorisjustified. difference observedislow,theindirectevidencefor in R—Fbetweenlaandlboftheorder0.04-0.06mag. luminosity betweenclassesIIIandlbisroughly between giantsandsupergiants(Table10).Thedifferencein the reddeninglaw(Table8).Thedashedlinesare with twice thatbetweenlbandla,whichwouldsuggestadifference M starswouldshowlessR—Fvariation. can beconsideredasanupperlimit.Itisalsopossiblethatthe of astaratmaximumlight(equivalenttohighluminosity),it lines aremedianforluminosityclasseslaandlb. that ananalysissimilartoin§VIIIforlowerluminosity R —Fvariationsarelargeonlyatthehighestluminosities,so solid lineisthemedianvalueforstarsofluminosityclasslab.Thedashed data fromJohnsonandMendoza(1968)Lee(1970).Theslopesofthe the effectmaybeexaggeratedbyreducedsurfacegravity three linesaredefinedbythereddeninglaw(Table8);interceptof The distributioninspectral typeoftheclasslastarsis The luminosityeffectsinJ-Kand—Larcmoreread- Thus, whilethestatisticalaccuracyofsmallR—F The thirdfineofevidenceistheshiftinR—Fcolors Fig. 3.—PlotofJ—Kvs.V-forgalacticMsupergiants,using ii) JHKL Vol. 57 1985ApJS...57...91E 8 plausible, giventhestrengthof CNbands,anditisquitepossiblethat lengths (e.g.,CN),itseemsunlikely thatitcanbesolargeastodepress constant J—K.Thiswouldforcealltheotherbroad-bandcolorsinTable the BandVfluxesbyover0.5mag. Effectsof0.2magorlessaremore 10 tobecomeredder,including B —V,a.highlysuspiciousresult.Al- the V—KcolorsforMsupergiants dovarybyamountsofthissize. though thereisdoubtlessluminosity-dependent blanketingatallwave- is nearlyindependentofthereddeninglawadopted. (1981) interprettheluminosityshiftinJ-H,H-K high andmoderateluminositystars,thesizeofeffect also seenintheMCdata(Fig.8).McGregorandHyland small numbersofstarsinthelaandlbsamples.Theeffectis decreased by—0.1,aboutthreestandarddeviations.Inthe although thesizesofshiftsaredifferent,reflecting Way J—Kluminosityeffectbymakingtheextinction reddened thanthelabandlbstars,onecanreduceMilky coefficient smaller.Itcanberemovedonlyiftheis blanketing affectingthesecolorsisTiO,andsinceTiOband increased luminosity,basedontheirmodelcomputations. There aredifficultieswithmakingJ—Kluminosityindepen- SMC andLMCtheaveragereddeningisaboutsamefor account fortheeffect.Sincelastarsare,onaverage,more dent, namely,thatluminosityeffectsarerequiredmB — V, diagram asbeingduetoadepressionoftheHmagnitudeat the reddeninglinesodifferencesinspectraltypecannot strength isthedeterminantofspectraltype,thesecolorsought — 0.8mag'mVKbetweenluminosityclasslaandlbtocorrect to spectral type. to showrelativelysmallchangeswithluminosityatagiven No. 1,1985 V-K, V-I,andV-R.Sincethedominantsource of 8 Fig. 4.—PlotsoîJ-Hvs.KforgalacticandMsupergiants,asin3,exceptthatsupergiantsareincludedshown astriangles Fig. 5.—PlotoîK-Lvs.Hforgalacticsupergiants;symbolsandlinesdefinedasin3 IfthedominantluminosityeffectisinF—A",oneneedsashift of The sameeffectisseenïna.J—H,HKdiagram(Fig.4), 0.0 0.2040.6 © American Astronomical Society • Provided by theNASA Astrophysics Data System H ^CIT Fig. 45 M SUPERGIANTS bluer intheLMCthan MilkyWay.Thedifferencesin bluer intheSMCthan the MilkyWay,and~0.2mag The MCstarswithspectraltypesaresimilarinluminosity to LMC starswithphotometryonlywouldprobablybeclassified same intrinsicB—Vcolorsas luminosityclassla-labstarsin as lb.IfoneassumesthattheLMCandSMCstarshave the Cloud starstendtohaveBVRIcolorssomewhatbluer than reduced insizeifitisassumedthatmoreluminousstarsare the MilkyWay,resulting V—Kcolorsare0.2-0.3mag the MilkyWaylaandlabstars(§IIIc);someoffaintest redder inV-K,V-/,andR. effect inV—RorI.TheJKluminositycanbe redder ‘mB—VandKLbluerinJthanlaborlb this claimandshowthattheeffectextendstoV—Kas well. their galacticcounterparts.TheresultsinTable10support creased emissionbydustathigherluminosity(§V). mag. TheK—Lcoloreffectsareprobablyrelatedtoin- more luminousstarshavingredderK—Lcolors.Thiseffect luminosity classesla,lab,andlbareshownasinFigure3; small, inwhichcasethereisnoevidenceforanyluminosity supergiants. ThisassumesthatluminosityeffectsinV—Kaie (if assumedduetoK—Ldifferencesonly)isessentiallythe same asthatfoundbyLee(1970;hisFig.2).Thesizeis~0.1 same effect.)Theslopeandinterceptsofthemedianlinesfor there isagainaseparationbetweenluminosityclasses,with shown inFigure5.(AplotoîK—LagainstVshowsthe V —Iareabouttwo-thirdsas large.TheV—Rdifferencesare Humphreys (1979a,b)pointedoutthattheMagellanic To summarize,then,theluminosityclasslasupergiantsare The K—LversusHplotforgalacticMsupergiantsis d) ColorDifferencesbetweenGalaxies 111 1985ApJS...57...91E was donesoastohaveroughlyequal numbersineachgroup;thepointofdivisionisapproximatelyM =-10.5forboththeSMCandLMC;thisalso corresponds roughly tothedivisionbetweenluminosity subtypeslaandlab. and labsupergiants(Fig.4)areshown (transformed)asdashedandsolidlines,respectively.Thedotted Unesareofthesameslopewhoseinterceptis the medianvalueforallstarsin sample;thedot-dashedlinesaremedianUnesforbrighterstars (at K)only.Thedivisionintobrightandfaintstars line, respectively.StarsaredistinguishedbyapparentKmagratherthan giants. ThereddeninglinesderivedforMilkyWayluminosityclasslaand MK luminosityclass. lab supergiants(Fig.5)areshown(transformed)asadashedandsolid K Fig. 7.—PlotsoîJ-Kvs.V forSMC(top)andLMC{bottom)Msupergiants.Thereddening linesderivedforMilkyWayluminosityclassla Fig. 6.—PlotofK-Lvs.H-KforMagellanicCloudMsuper- © American Astronomical Society • Provided by theNASA Astrophysics Data System 4 5 6 ELIAS, FROGEL,ANDHUMPHREYS V-K present intheMagellanicClouds. ity effectseenintheMilkyWaycannotbeshownto ( ~0.04maginthemeanK—Lcolors).Veryfewof correct sense,butprobablylessthan10%oftheK-Lcolor below it.Thiscouldbebecauseextremelyluminousstars fainter MCstarsweremeasuredatL,sothe—Lluminos- sponses tabulatedbyJohnson(1965)suggestashiftinthe measured byLee(1970)requireatransformation.There- measured atL,orbecausethe“Johnson”K-Lcolors dominate theLMCsample,sinceonlybrighteststarswere least 20%ofthestarswithnegativereddeningvalues.Itis Milky Waylaline(fromFig.5),whiletheSMCstarshewell shown inFigure6.HeretheLMCstarsheonorabove ors, asdiscussedin§Vic,below. redder B—VcolorsandbluerR,I,Kcol- most likelythatreducedmetalabundancesintheMagellanicI 0.10 magfortheSMC.SuchashiftinSMCwouldleaveat would belargelyremovediftheintrinsicB—Vcolorsfor Clouds producedecreasedlineblanketing,leadingtoslightly supergiants, by-0.05-0.09magfortheLMC,andatleast about halfthesizeofV—Kdifferences.Thesedifferences SMC andLMCsupergiantswereredderthanthoseofgalactic A plotofK-LversusH-KforMCsupergiantsis Vol. 57 1985ApJS...57...91E 9 in /—ATthanthemedianlinesforfullsamples. Way. TheSMCCOindicesare—0.05magweakerthan the between theMagellanicCloudsandMilkyWayin the The luminosityeffectin/-ATseengalacticstarsappears discrepancy isprobablyafairindicatoroftheuncertaintyin LMC COindicesatthesamespectraltype.However, the evidence foradifferencebetweentheLMCandMilky H0 index.IntheCOindexthereisnocompellingdirect giants arequitesparse.Thereisnoevidenceforadifference MC V—Kcolors,wouldmakethe/differenceslarger. colors redder,inordertomatchgalacticV-Kwith values asredthe LMC(seeFig.3). would havetobe35%smaller shift theMilkyWaylaJ-Kcolorsto the medianlinesforbrighterstarsHe0.02-0.03magbluer to bepresentintheLMCandSMCaswell(Figs.7,8).Here the shifts.NotethatmakingMagellanicCloud(B—V) shift fortheLMC,incontrasttoFigure7.Thesizeofthis the MC.TheshiftforSMCinFigure8islargerthan shifts observedinFigure7areindeedduetobluerV—K although thedisplacementisless,implyingthatpartsof 8) alsoshowtheMCstarstoheabovegalacticlaline, supergiants givecolorscloseto those predictedbyLee(1970)after the directionofLMCmade atthesametimeasthoseof transformation (Frogeletal1978). ThereddeningcoefficientîovJ—K uncertainties inthereddeninglaworcolortransforma- mag mV—K(Fig.6),farlargerthancanbeaccountedforby line forluminosityclassla;theSMCstarshesomewhatbelow Fox 1983). except thatfaintestLMCstarsareplottedascrosses.Theanomalousfaint 4. TheLMCandSMCsupergiantshefarabovethegalactic star isHV12620,whichprobablynotasupergiant(Wood,Bessell,and supergiants. ReddeninglinesforMilkyWayluminosityclasslaandlab supergiants areshown(transformed)asinFig.7.Symbols7, Milky Waylastarsisroughly+0.21magin/—or—1.1 2 tion. the LMCstars.Thedifferencebetweenand 0 against V—K,withtransformedreddeninglinesfromFigure No. 1,1985 9 Measurements(Elias,unpublished) offoregroundKandMgiantsin For theH0andCOindicesdataforgalacticsuper- The J—H,HKdiagramsfortheLMCandSMC(Fig. Fig. 8.—PlotsoíJ-Hvs.H-KforLMC(left)andSMC(right) 2 LMC andSMCJ—KcolorsareshowninFigure7plotted © American Astronomical Society • Provided by theNASA Astrophysics Data System M SUPERGIANTS 10 recent determinations (Ridgwayetal1980). increased because theeffectivetemperaturesthatthey usedarelessthan mag fortheSMC. bluer andtomakeB—Vredder(alsoUB,whichis not blanketing istomaketheV-R,V-I,andV-Kcolors interpreted asduetodecreasedlineblanketingatVrelative weak dependenceofJ—K on CNblanketing(eitherdueto redder thangalacticstarsby0.02magintheLMCand 0.04 0.04-0.05 mag.TheMagellanicCloudintrinsiccolors were Tsuji 1978).Itappearsthatthegeneraleffectofdecreasing later (seeCollinsandFaÿ1974).Rodriguez(1969) has SMC V—Kcolorsarebluer,thiscolordifferenceis type correspondtoashiftredderV-Kby0.2mag.The of -0.2inV—KcorrespondstoanincreaseA- F of discussed here).Aroughestimateisthatablanketingdecrease estimated theamountofTiOblanketinginstarstypeM0 or The coolertrueeffectivetemperaturesoftheSMCsupergiants predicted bytheshiftsineffectivetemperaturealone(§III6). estimated totalblanketingforafewluminousMstars(see also AT. Humphreys(1974)andSmak(1966)haveempirically relative totheMilkyWaysupergiantsofsamespectral The shiftsinthebroad-band(K-A,V-I,andV-K) possible tosortoutthevariouseffectsinanapproximateway. where thestarsobservedbelongmainlytoluminosityclassla. therefore estimatedbyadopting(B—V)colorswhich are colors UstedinTable10areoppositesensetothose paper showthatthesituationismorecomplex,because(J— interpret physically.McGregorandHyland(1981,1984),using of luminosityclasseslaborlb,andtheMagellanicClouds, relative totheMilkyWay,wereduechangesineffective metal abundance.TheyalsoarguedthattheweakerCOin- They usedthe(/—AT)colorsasmeasurementsofeffective show luminosityeffectswhichcomphcatecomparisonsbe- dent) temperatureindicator,andbecauseJ—KCOboth AT) doesnotseemtobearehable(i.e.,abundanceindepen- dices intheSMCrelativetoLMC,andLMC because theycomparestarsofthesameeffectivetemperature luminosity thantheLMCstars(seesummaryinAppendixC). H —KwereduetochangesinCNblanketingwithdiffering only aHmitedquantityofinfrareddata,attemptedtodiscuss rather thanthesameMKspectraltype. LMC withoutpostulatinganadditionalluminosityeffect, tween theMilkyWay,wheremoststarswithinfrareddataare the differencesbetweenSMC,LMC,andMilkyWay. supergiants intheMilkyWaycouldbe~0.05maggreater Both examinationofthedatasummarizedinAppendixCand temperature andmetalabundance.Thedatapresentedinthis temperature andsuggestedthatdifferencesinJ-H similar butsmallerdifferencebetweentheMilkyWayand Gallagher 1983)suggeststhatthemeanCOindicesforla supergiants (Baldwin,Frogel,andPersson1973;Kenyon the correlationofCOwithluminositybetweengiantsand galactic starsusedinfindingtheCOindex,areoflower than theLMCvalues.McGregorandHyland(1984)finda 0 0 0 10 TheHumphreysandSmakempirical TiOblanketingvaluesmustbe With largersetofphotometricandspectroscopicdataitis The modelsofMcGregorand Hyland(1981)predictonlya The complexbehavioroftheintrinsiccolorsisdifficultto e) Discussion 113 1985ApJS...57...91E derived forindividualstars. Random scatterintheindividual pected tobeblueratlowerluminositiesandmetal colors willhaveasmalleffect; judgingbythescatterin colors atagivenspectraltype. Ifthisisnotthecase,itwillbe whereas thatofHissmall.ThemodelsforMsupergiant luminosity dependenceoftheJ—Kcolorisquitesubstantial, with increasedluminosityateffectivetemperaturescorre- a sourceoferrorinthereddening andbolometriccorrections and metalabundancefortheintrinsiccolorsadopted. It is Usted inTable10.Thevaluesarewithin-0.1magofthose indices arealsoweaker.TheJ-Kcolorisredderthaninthe bluer andB-VisredderthanintheMilkyWay.TheCO probably weaker. bluer. Inthiscase,theLMCV—Kintrinsiccolorswouldbe later Mtypes.NocalculationsaregivenbySteiman-Cameron two-color diagrams(e.g.,Appendix A)theeffectsonAwill assumed forsimphcitythatthereisnoscatterintheintrinsic the relativeinsensitivityofBC^totemperature,luminosity, bolometric correctionstotheVandKmagnitudes(BC and redder thanintheSMCandK—Lcolorsareroughly giants, accordingtoTable10,areasfollows: ing oftheeffectsmustawaitimprovedmodels,oragood abundances. Moresophisticatedmodels(Steiman-Cameron abundance orluminosityeffects).TheH—Kvalueisex- sponding tolateKspectraltypes;theeffectisreversedfor and Johnson1984)showJ-Kbecomingmarginallybluer given byLee(1970)forBC.Themostnoteworthyfeature is Persson, andCohen1981fordetailsofthemethod).These are BC/r )byintegratingundertheenergydistribution(seeFrogel, same asintheMilkyWay. Milky Way. extinction fortheLMCandSMCsupergiantswouldbein- dance furthercausesJ-Ktobecomeslightlybluer,while redder whileV—Kbecomesbluer,butreducingtheabun- Milky WaystarstotheLMCSMC.Thereducedmetal difficult toexplain.Thereisnosimpleprogressionfromthe garded asserious. discrepancy betweentheoryandobservationcannotbere- atmospheres areatpresentstillrudimentaryenoughthatthe and JohnsonforH—K.Theobservedeffectisthatthe tween theSMCandMilkyWay,exceptthat/—ATis K —Lcolors,andredderJcolors.TheCOindicesare sample ofextrinsicallydereddenedMCsupergiants. creased by~1mag,whichseemsunlikely.Betterunderstand- B —Vcolorswouldbe-0.2magbluer.However,themean abundance intheLMCapparentlycausesJ—Ktobecome the J—Kabundanceeffectbymakingallintrinsiccolors 114 v K V — 1magbluerthanthoseoftheirgalacticcounterparts,and V —Kcontinuestogetbluer.Onecoulddecreasethesizeof 2. IntheSMC,V-R,V-I,andV-Kcolorsare The chiefdifferencesbetweendifferentgroupsofMsuper- The intrinsiccolorsinTable10wereusedtocompute 3. IntheLMC,colorsaregenerallyintermediatebe- The abundanceeffectsseeninFigure7(§VI¿/)arealso 1. LowerluminositystarsshowslightlybluerB-Vand a) BolometricMagnitudesandReddening © American Astronomical Society • Provided by theNASA Astrophysics Data System VII. DERIVEDQUANTITIES ELIAS, FROGEL,ANDHUMPHREYS less thantheuncertaintiesinbolometriccorrectionsthem- extinction andthespectraltypes. less inMforspectraltypesK5-M3.Theseuncertaintiesare produces anerrorof0.02inM,andhalfa selves. Incontrast,thevaluesdeterminedfromvisualpho- tometry aremuchmoresensitivetouncertaintiesinthevisual subclass inthespectraltyperesultsanerrorof0.06magor magnitudes areprobablyquitegood;anerrorof0.2inA colon. ThebolometricmagnitudesestimatedwhenthereareK BC. TheresultingMvaluesarethengiven,followedbya where therewasnoinfraredphotometry,theVmagnitude be 0.1magorless,andstilllessonBC^.Ifthereisexcess may wellnotbeMsupergiants. values werethenusedtofindM.Thearegivenin The resultsaresummarizedinTables11and13.Inthosecases (Table 10)andthereddeninglaw8).TheAvalues using thespectraltype,observedcolors,intrinsiccolors ing lawinTable8,itispossibletoobtainextinctionvalues excesses areusuallyquitesmall(see§V,above).Correlated emission atK,Mwillbeestimatedtoobright,butsuch listed inTable15fortheSMC andLMC.Theexactvalues using thephotometryalonearetypicallywithin0.1mag of estimate spectraltypesaccurately,andthesestarsarethere- For starswithIRphotometryalone,itisnotpossibleto Tables 12and14forthosestarswithoutMKspectraltypes. (Table 10)wereusedtoestimatethespectraltypeandvisual does notinvolvethespectraltypedetermination,andisless used instead,togetherwiththeappropriatevaluesforAand magnitude togetherwiththebolometriccorrection,BC^,for extinction) valueisequalto0.091A\thisappliedtheK using theweightsgiveninTable10,andaveraged.TheA(K determined fromtheindividualcolorexcessesareweighted, distance modulifortheLMCandSMCwereassumedtobe equivalent toanerrorintheMKspectraltype.Effectsequiv- deviations willbemoreserious;arepresentativecasewould given differsomewhatfrom those giveninEliasetal.(1981) contamination ofthephotometry. may bestilllowerforthestarswithoutspectraltypes,since stars withoutspectraltypes,theresultingfitswerepoor.These fore notincludedinTables12and14.Inanumberofcases of H0 andCOindices.TheresultingspectraltypesA extinction iterativelyusingallthecolorsexceptK—Land accurate. Theobservedcolorsandtheintrinsiccolortable spectral typebeknown;thecolorexcessesaredetermined and absolutemagnitudesfortheLMCSMCstars.True alent toasubtypemisclassificationwouldleaderrorsof these aregenerallyfainterandpossiblysubjecttogreater there isnoinfraredphotometrytheaccuracy—0.5mag and those obtainedusingtheMKspectraltype.Forcaseswhere the particularspectraltypetoobtainabolometricmagnitude. 18.6 and19.0,respectively. bol bol v kho] bol v bol v V K 2v — 0.2maginAand0.05M. vho] Two methodswereusedforthis.Thefirstrequiresthatthe The secondmethodusedtoestimatebolometricmagnitudes Those starsthoughttohave Mbrighterthan-8.5are Using theintrinsiccolorsgiveninTable10andredden- If theV—Kcolorisknown,Mvaluesobtained bol ho] b) BrightestStars 1985ApJS...57...91E 111-26 .. 111- 24.. 110- 13.. 112-13 .. 112-7 ... 114-3 ... 107-15 .. 107-14 .. 107- 12.. 107- 7a.. 105-11 .. 106- 9... 108- 8... 105- 7... 109- 6... 106- 5... 106-4 ... 108- 3... 108- 2... 106-la .. 107- 1... 104- 18.. 104-6 ... 104- 5... 103- 5... 101-15 .. HV 2232. HV 2084. HV 1475. HV 832.. 101-6 ... 104-13 .. g e d c h d d a 106-7, 105-21:BVRIphotometrymissingacolor. l 11-23:possiblenebularcontaminationofphotometry. HV 11423:bluecomponent,estimatedtocontributelessthan10%oflight. Year ofspectralclassificationandvisualphotometry.Infraredphotometrywasdonelaterunlessyearisfollowedby“S.” A andMderivedusingspectraltypefromcol.(2).AfisgivenwithacoloniftherewasnoIRphotometry.Seetext. 115-2.. 115-7.. 117-6.. 110- 3. 106-22. 106- 21. 105- 20. 109- 14. 109-12. 105-12. 107-6. 105-5. 106-2.. 104- 9. 101-13. 102-4.. SpectraltypetakenfromTable1. 105-6.. 105- 4. *117-15, 122-14,HV2228:spectralclassificationdonein1979,BVRIphotometry1978. yboïbol c h d a Year ofvisualobservations, asinTable11. Ay andMasinTable11. Thesefourstars showverylargeresiduals;theymay notbesupergiants. Spectraltypederivedfromphotometry, asdescribedintext.Aquestionmarkindicateslargeresiduals orothercauseofuncertainty. Star hol Star © American Astronomical Society • Provided by theNASA Astrophysics Data System 3 MO K5-M0 MO MO K5-M0 MO K5-M0 MO MO MO K5-M0 KO-2 MO K5-M0 MO K5-M0 MO K5-M0 MO MO K5-M0 M0 M0 K5-M0 M0 M0 Ml Ml M2 K0-5 M0 Spectral M2 a Spectral Type Type K3 K3 M0? K3 K3 M0? M0 M0? K5 Ml? M2? K3 M0? K4 K4 Ml M2? Ml-2 Visual ExtinctionsandBolometricLuminositiesforSuspectedSMCSupergiants Visual ExtinctionsandBolometricLuminositiesforConfirmedSMCSupergiants b b A(inag) Ay(mag) y -0.2 -0.2 -0.2 -0.2 -0.2 -0.2 -0.1 -0.2 -0.1 0.8 0.4 0.7 0.4 0.7 0.2 0.7 0.5 0.2 0.6 0.4 0.3 0.2 0.5 0.1 0.6 0.1 0.4 0.5 0.8 0.5 0.8 0.6 0.6 0.8 0.7 0.9 0.8 1.0 1.4 1.1 1.0 0.9 0.7 0.6 0.2 0.5 1.0 1.1 1.4 1.0 M. k M, -7.5 -7.0 -6.5 -6.8 -7.3 -6.2 -7.2 -6.5 -6.9 -6.7 -7.5 -7.7 -6.8 -7.5 -6.6 -6.6 -7.5 -6.8 -8.2 -7.4: -8.2 -7.4 -7.9 -7.4 -7.6 -7.9 -8.1 -8.2 -7.2 -6.5 -8.2 -7.7 -7.3 -7.6: -7.0 -7.9 -8.3 -8.7 -9.0 -8.4 -8.1 -8.0 -8.7 -8.2 -8.3 -8.5 -7.8 -8.8 -8.4 -7.9 bol c c Year Year 1978 1979 1979 1979 1978 1979 1979 1979 1978 1979S 1979 1978 1979S 1978 1979S 1979 1979 1979 1979 1979S 1978 1978 1979 1978 1978 1978 1978 1979 1979 1979 1978 1978 1978 1979 1978 1978 1978 1978 1978 1978 1978 1978 1978 1978 1978 1978 1978 1978 1978 1978 TABLE 12 TABLE 11 d d 120-19 . 120-12 . 122- 1 3 . 120-10 . 121- 9 .. 120- 9 . 121- 7 ., 122-6 .. 120- 4 . 120-3 .. 118- 2 , 117- 17 . 115-14 , 117-12 . 116- 12 , 117-11 , 115- 8 ., d g g f f f e HV 11423 120-6 105-21 .... 106-7 HV 2228. 122-14 117- 1 5 lll-23 120-14 120-13 120-8 120-7 116-20 116- 19 118-18 115- 17 116-16 118- 15 116-15 117- 14 116- 13 115- 13 115-12 118-9a 116- 7 115- 6 117- 4 115-4 116-2 115-9 118- 5 116-1 Star Star 3 Spectral K5 K3 K4 M0-1 K4 K4 M0-1? K3 K3? K5 K4 K3 M0? K5 Ml M0 M0-1 Type ah MO K5-M0 K5-M0 K5 MO K5-M0 K5-M0 K5-M0 K5-M0 MO-1 K5-M0 MO K5-M0 MO MO MO K5-M0 K5-M0 MO K2 MO K5 K5 Kl-3 K5 K5 K5-M0 MO Spectral MO K5-M0 K5 MO Type A(m

aAbsolute bolometric, visual, and K magnitudes corrected for extinction. Values for 46-19 are for the M supergiant component only. See text and Tables 11, 13, and 14 for more details.

It is tempting to ascribe the differences in variability be- tween the LMC and SMC to differences in the spectral type distributions. However, the amplitude of stellar variability cannot depend on temperature alone, since the difference in mean effective temperature between the LMC and SMC is small (see § III); LMC stars of a given effective temperature are probably more variable than their SMC counterparts. When the color changes are plotted against magnitude changes (e.g., Figs. 10-13), they show strong correlations in several cases. Least-square fits (see Appendix B) were com- puted, and the best-fit slopes are given in Table 17. The slopes give the relative size of the variations. There are significant correlations for 5 - F in the LMC, and for V- R, F- /, and H20 in both Clouds. Marginally significant correlations exist for / - and H - K in both Clouds and for CO in the SMC. Because of the lack of simultaneous observations, no direct correlation could be determined between K and F variability. That is, the slope dK/dV cannot be determined from the data. An upper limit on this slope can be set by assuming that the F and K variations are completely correlated. Taking stars with multiple observations at both F and K, one com- putes rms variations, A F and A AT, similar to those in Table 16, and makes small corrections for the effects of measure- ment errors. The ratios of these amphtudes are given in Table 17. The chief effect seen in Table 17 is that as the stars get Fig. 9.—Histogram of visual extinction values for the SMC and fainter, they also get redder (cooler). Two colors which show LMC. The shaded areas include only stars with known spectral types, while the unshaded areas include stars with spectral types estimated from an additional effect are 5 - F and the H20 index. The B — V photometry. Median reddening values are indicated by arrows. A v values colors in the LMC get redder as the stars get brighter (Fig. less than - 0.2 mag are included in the leftmost bin. 11), even though mean B - V color is relatively insensitive to

© American Astronomical Society • Provided by the NASA Astrophysics Data System 1985ApJS...57...91E best fitslopetothecombinedsamples. TheLMCdataforchangesfrom1976to1977havebeencorrected fortheVmagnitudeshift;SMCdata crosses. (changes from1978to1979)have not beencorrected,andtheinterceptoflinethereforedoespass throughtheorigin.Uncertaintiesassociatedwith fit isalsoshownasadottedlinein theSMCplot.supergiantsofspectraltypeM0orlaterare plotted asopencircles:thoseearlierare each pointareshownintheupper leftcomeroftheplots.Somepointshavebeenomittedinareas crowding. long-period redvariables(e.g.,Smak1966;Eggen1975).The ity effectinferredintheintrinsiccolorsofsupergiants(§Vic) absence ofsuchaneffectintheSMCmaybeduetoearlier similar effectcanbeseeninthelightcurvesofgalactic spectral type.Thischangeisinthesamesenseasluminos- and betweengiantssupergiants(see§Vic;Lee1970).A No. 1,1985 Fig. 11.—Plotofchanges'mB- V againstchangesinK,asFig.10.Thedifferentbestfitlinesareshown fortheSMCandLMC,LMCbest Fig. 10.—PlotofchangesmV- I colorontheGaAssystemagainstchangesinVmagnitudeforLMC andSMCsupergiants.Thelinesshownarethe © American Astronomical Society • Provided by theNASA Astrophysics Data System All Unclassified M2 Ml MO M3-5... K0-K5 K5/M0 Spectral Type Fig. 10 Fig. 11 0.31 0.32 0.45 0.41 0.19 0.40 AL 64 26 12 17 N Variability bySpectralType 2 7 LMC M SUPERGIANTS 0.10 0.06 0.19 0.07 0.12 0.10 AK TABLE 16 hotter temperature.Presumablytheeffectisduetodifferential (Fig. 12)byanamountlargerthancanbeaccountedfor molecular blanketingintheBandVpassbands. ness maybecompensatedforbyadecreasein2?—Fatthe mean spectraltype;theincreaseinR—Katincreasedbright- 46 14 14 N 4 9 5 The H0indicesincreaseastheIVmagnitudegetsfainter 2 0.19 0.16 0.36 0.27 0.22 0.16 0.06 AV 26 89 30 20 N SMC 2 2 9 0.06 0.01 0.04 0.04 0.08 0.04 AK 11 11 N 15 1 1 1 119 1985ApJS...57...91E parent magnitudeandspectral typedependingonwhether mum willhaveredderB—V andweakH0. small, significantdifferences betweenstarsofthesameap- cially intheLMCwherechangemeanH0 with they arenearmaximumorminimum fight:astarnearmaxi- the changetolaterspectraltypesatfaintermagnitudes,espe- spectral typeisquitesmall. data isshown. separate datasets,whilethedottedfinesshowbestfittocombinedset. 120 2 2 Both theB—VandH0variabilityindicatethatthereare Fig. 12.—PlotofchangesinH0indexagainstKmagnitudefortheSMCandLMC,as10.Thelinewhichbestfits thecombined Fig. 13.—PlotofchangesinCOindexagainstKmagnitudesfortheSMCandLMC,as10.Thesolidlinesare best fitstothe 2 2 Combined IR... +0.15±0.06 +0.09+0.03+0.380.07-0.030.050.27 LMC: M0-1-0.22+0.05+0.140.02+0.410.03 LMC: all-0.16+0.02+0.22+0.500.03+0.120.07+0.10+0.31-0.070.060.28 SMC: MO-2-0.04+0.04+0.230.03+0.52 SMC: all+0.01+0.04+0.180.03+0.46±0.05+0.400.20-0.020.11+0.920.26+0.350.140.18 LMC: M2-5-0.14+0.03+0.26+0.530.05 b a Ampfitude ratio,representsupperlimitonslope.Seetext. Variability onJohnsonsystem.Divideby0.82toobtainapproximate variabilityon“GaAs”system. ab Sample d{B-V)/dVd(V-R)/dVd(V-I)/dVd{J-K)/dKd(H—K)/dKdK0/dKdCO/dKA/T/AF 2 © American Astronomical Society • Provided by theNASA Astrophysics Data System AK Fig. 12 ELIAS, FROGEL,ANDHUMPHREYS Slopes ofCorrelatedVariations TABLE 17 variations intheSMCcorrespond toyear-to-yearchangesin less thanthatfortheSMC.Ifvariabilityincolor(Tables provide upperlimitsofabout±1subtypeintheLMC and precisely. ThespectraltypedistributionsplottedinFigure 1 about onesubtype.Whiteand Wing(1978)findsimilaror spectral typeofaboutone-half subtype,andintheLMCof 16, 17)ismatchedbyavariation inspectraltype,thenthe The degreeofvariabilityinspectraltypeisdifficulttoassess Fig. 13 AK Vol. 57 1985ApJS...57...91E indicate thattheLtightcurveprecedesKandH tight broad-band (JHK)colorsarediscussedbyFrogel,Persson, variations arenotfixedand canevenbereversed.These have ledtoanerroneousperiod. part totheirregularityofthesevariables—anHV838period photometry fromGlass(1979),Elias,Frogel,andHumphreys individual starsareuncertain,butprobablyintherange+2.6 maxima by0.1-0.2period(Harvey etal1974),whichsuggests galactic starsusuallyhavevisual maximaprecedingtheIR curves andtheJlightcurvelagsbehindby—100days. enormous H0absorption(itsindexatminimumof1.4is the could bederivedonlybyignoringtheearhestpointfrom (1980), CatchpoleandFeast(1981)Wood,Bessell, in bolometricmagnitudesareprobablysimilartothoseatK\ Fox 1983). mass (asdiscussedbyFrogel1983andWood,Bessell, luminosities, onlythefirstseemtobetruesupergiants(see indices (usually<0.2mag),andagroupwithmuchgreater variability (<0.2magatK)andgenerallymodestH0 larger variationsinphotometricspectraltypesomeMilky sources showeffectsofthissort; therelativephasesofIR Observations byHarveyetal(1974)ofgalacticOHmaser and Cohen(1981).TheJ-KK-Lcolorvariations strongest known).TheeffectsofvariableH0absorption on star atminimum,whereitisprobablyaboutB=22,may also Glass (1979).InthecaseofHV11417,misidentification Fox (1983);theperiodsofHV838and11417differfrom given inTable18arederivedfromthedata3andIR Elias, Frogel,andHumphreys1980).Thesecondgroupare variability (>0.5magatK)andlargerH0indices0.4 Way Msupergiants. 14). Atminimumlightthestarbecomesquitered, with 11417, thebeststudiedoffivestars,appeartypical(Fig. for HV11417areshowninFigures14and15.Thevariations most likelyasymptoticgiantbranchstarsofrelativelylow mag). Althoughthestarsinbothgroupscanreachsupergiant groups intheinfrared:alargegroupofstarswithrathersmall No. 1,1985 Shapley andNail1951).Thedifferencesaredoubtlessduein those foundintheliterature(e.g.,CatchpoleandFeast1981; to +3.2mag(Wood,Bessell,andFox1983).Theperiods the bolometriccorrectionstoKmagnitudes(BC^)for 2 2 2 2 The colorandCOH0indexvariationsshownbyHV The starsmeasuredintheSMCfallintotworatherdistinct Properties ofthestarsarelistedinTable18andlightcurves 2 © American Astronomical Society • Provided by theNASA Astrophysics Data System b) Large-AmplitudeVariables HV 1719550<9.209.96>0.760.37 HV 112955709.2110.200.990.62 HV 8386608.789.710.930.20 HV 1141713008.039.701.670.97 SMCB-28 700<9.37>10.26>0.890.37 Star (days)KK^AKAH0 maxn2 Period SMC Large-AmplitudeVariables M SUPERGIANTS TABLE 18 periods, infraredphotometry (Hylandetal.1972;Harvey variables hassohighamass-lossratethatthestarsdevelop have nocounterpartsinourLMCsample(Table4).One tight. (see Humphreys1974).For the MilkyWaystarswithsimilar possible explanationcouldbethat,intheLMC,thisclassof Frogel, andHumphreys1980)weretakenverynearmaximum higher, whichcouldbothshortenthelifetimesofthesestars in luminous LPVsmustthereforeberelativelyrareintheLMC thick circumstellardustshellsandwouldnothavebeennoted in theusualBorVsurveysofLMCbecausethis that thevisualphotometryandspectrumofHV11417(Elias, faint evenat1.6pm.Mass-lossratesintheLMCmay be or elsesoheavilyobscuredbycircumstellardustastobe very found. Atslightlylowerluminositiestherearemanysimilar detected, despitethefactthatLMCiscloserand area done at1.6pm(Elias,unpublished),nosuchstars were shells. their mostluminousphaseandthickencircumstellar dust stars intheLMC(Wood,Bessell,andFox1983). Very scanned was-4timeslargerthanasimilararea in circumstellar obscuration.However,inasurveyoftheLMC the SMC,inwhichthreeofstarslistedTable18 were There arestarsintheMilky Waywithsimilarproperties These extremelyluminouslong-periodvariablesseemto Fig. 14.—//andKcurvesforHV11417 121 1985ApJS...57...91E interest, andarediscussedbrieflybelow. may wellcorrespondtomaximumOHemissionfromHV excess atKtonoticeablyaffect H—K. emission whichaffectstheCOindexalsoproducesenough The H—Kcolorsappeartooredinthesestars,because the will beweak:10-20mJypeakfluxwouldobservedfrom star hasnotbeenidentified inanyobjectiveprismsurvey, VX Sgratthesamedistance,andweak10/imemission possible thattheseSMCstarsmayhaveOHmaseremissionat 1973), whichisthesecondbrightest starinTable4atK.The and weakCO,allassociatedwithcircumstellaremission(§ V). stars havelargemeasured10/amexcesses,redK—Lcolors, stars showunusualcolors—Case37-24and45-38.These two This probablyreflectsthecombinedeffectsofareducedrate The 10/imexcessinHV11417(Elias,Frogel,andHumphreys of masslossanddecreasedgrainabundanceduetothelower counterpart, VXSgr,orwithgalacticstarsofsimilaramph- 11417 afactorof5less. cesses. TheamphtudesofvariationtheSMCstarsare et al.1974)showsthemtodifferintwoways:theyhavelarger 1612 MHz.AtthedistanceofSMC,however,emission SMC metallicity. 1980) isquiteweakwhencomparedwitheitheritsgalactic similar tothoseofgalacticstarsroughlyhalftheperiod. amphtudes ofvariabilityandstrongerlongwavelengthex- tudes ofvariability(Hylandetal.1972;Harvey1974). 122 Another starofinterestisMG 46(MendozaandGomez A fewofthestarsobservedappearpecuharorarespecial Several starsintheLMCareofparticularinterest.Two Because oftheirsimilaritytogalacticOHmasers,itseems © American Astronomical Society • Provided by theNASA Astrophysics Data System IX. UNUSUALSTARSINTHELMC Fig. 15.—ColorvariationsforHV11417{left)',H0andCO(right) 2 ELIAS, FROGEL,ANDHUMPHREYS JD-2440000 Wd-a2, isnotanMsupergiant). while MH23turnsoutto be triple(thethirdcomponent, minimizing theeffectsofnebular contamination.Thus,MH8 beam sizes(5"whererequired),thusresolvingsources con- work wasdoneonnightsofgoodtoexcellentseeing(2" to and MH35arewellresolved inthemeasurementsTable3, fused intheMcGregorandHylandmeasurements, also the IRincommonwithMcGregorandHyland(1981). The Table 14).TheseareCase40-10(=HV894),53-6 HV (1979û) forHV2556suggestsaspectraltypeofM0. for Case53-6.TheBVRIphotometryfromHumphreys spectral typeofM3.5forCase40-10andarangeM3to M5 2677), 54-26(=HV2740),and2556.Lowresolution H0 indices,suggestiveoflatespectraltypeorextremevari- have aCase(SanduleakandPhilip1977)identification.Only portion oftheLMC(Elias,unpublished).Nootherstar spectrophotometry byWood,Bessell,andFox(1983)gives a ability, forwhichMKspectralclassificationsdonotexist(see crude estimateofthespectraltypecanbemade.Judgingfrom heavily reddened.Thisstarwasfoundina1.6jamsurveyof possibly becauseitisinacrowdedregionandprobably but avalueof^near2.7magisplausible,andwouldimply comparable magnitudewasfoundinthissurveywhichdidnot estimate. giant intheLMC.Alaterspectraltypewouldreducethis M =—9.4,makingthisstarthemostluminoussuper- an apparentVmagnitudenear+14.Thesevaluesleadto relatively late,M3orM4.Thevisualextinctionisuncertain, the strengthofH0index,typeislikelytobe

TABLE 20 Galactic Supergiants American Astronomical Society •Provided bythe NASA Astrophysics Data System 1985ApJS...57...91E 2 2 130 ELIAS,FROGEL,ANDHUMPHREYSVol.57 were takenfromBaldwin,Frogel,andPersson(1973),Frogeletal.(1978),Aaronson, and McGregor been dereddenedusingextinctionvaluesdeterminedfortheindividualstarsratherthanmeanclustervalues. Thedata which thereareH0orCOindexmeasureslistedinTable21.Notethat,unlikeMcGregorandHyland(1984),the indiceshave known, soonly(untransformed)V—Kcolorsfromthesetworeferenceswereusedintheanalysis.Therearethus34 starswithMK Johnson IRphotometricsystemandthatusedbyHumphreys,Strecker,Ney(1972)Humphreys (1974)isnot uncertainties (Table19)asdiscussedabove. various fitsaregivenin§VIII¿7.Datafromallspectraltypesweregroupedtogether,althoughcomputationsmadeusingonly intrinsic colorsfortheMagellanicCloudstars. (1972), andHumphreysNey(1974).JohnsonMendozadidnotmakeHmeasurements.Thetransformation betweenthe discussion). Thestarsusedtodeterminethebroad-bandcolorsarelistedinTable20,includinglaterexcluded fromthe random uncertaintiesfromTable19multipliedby/2(becauseoneisdealingwithmagnitudedifferences).Theresultsofthe galactic starsthexvaluesrangefrom-0.6tonearlytwicethatexpected.Thelargerareforcaseswhereerrorsinspectral and Hyland(1982). spectral typesandcompleteBVRIJHKLphotometry,atotalof78withMKBVRIKphotometry. Thestarsfor analysis. from 0.6to1.2timesthoseexpected. “best fits”tovaryby50%ormore.Thiswasthechiefreasoninfluencinguseofgalacticreddeningcoefficientsinfinding Magellanic Clouddata,wherereasonablevariationsintheerrorschosenforuseanalysiscauseslopeofresulting subsets ofthedata(seeTable17).Theresultsthesecomputations(§VIII)werethenusedtoestimatecorrelated type willintroducelargeresiduals.Whenthedeviantstarsarediscardedfromsample(seeAppendixC),xvaluesrange 2 2 A checkontherealismofestimatesisprovidedbycomputationxvaluesforvarioustwo-colorrelations.For Lee’s (1970)datasetwasaugmentedbymeasurementsfromJohnsonandMendoza(1966),Humphreys,Strecker, andNey In thisAppendixthedatausedinderivinggalacticsupergiantcolorsandreddeninglawaresummarized(see §IVfora Least-square fitsofthecolordifferencesagainstVmagnitudedifferenceorKwerecomputedusing d a Sco AZCyg ... a Ori Persson 1978;(3)McGregorandHyland 1982. KYCyg .. BCCyg ... © American Astronomical Society • Provided by theNASA Astrophysics Data System — 60°3621. — 31°4916. — 53°7344. — 60°3630. — 60°3636. — 57°3346. — 8°1639.. — 53°7364. — 59°4459. d b C a B -Vcolornotusedbecauseofblue companion. Narrow bandphotometryreferences: (1)Baldwin,Frogel,andPersson1973;(2)Frogeletai1978;Aaronson, Frogel,and A fromTable20orcomputedsimilarly. ColorexcessatH0=+0.017A,CO—0.011. Spectral typereferences:(1)Table20;(2)McGregorandHyland1982; (3)Humphreys1978;(4)WhiteandWing1978. V 2v Star K4Ib K2Ib M3.3 lb M3 lab M2 lab M0 lb M0 lb Ml.5 lab-lb M2.0 lab K3.5 II M3.9 lab M4 la Ml.5 lab Ml-2 lab Spectral Type Narrow BandIndicesofGalacticSupergiants 3 GALACTIC SUPERGIANTSAMPLE Reference II. CORRELATEDCOLORVARIABILITY APPENDIX C TABLE 21 ho 0.18 0.20 0.11 0.21 0.07 2 Observed Indices 0.18 0.16 0.26 0.29 0.27 0.28 0.29 0.23 0.14 0.34 0.30 0.33 0.29 0.30 CO 5 Reference 0.9 0.7 0.8 0.7 1.4: 6.5 1.4: 1.9 1.1 1.9 3.2 5.3 1.0 1.3: 0 Intrinsic Indices 0.10 0.13 0.11 0.09 0.06 0.17 0.27 0.30 0.19 0.31 0.24 0.28 0.30 0.15 0.38 0.37 0.39 0.30 CO 0.31 n 1985ApJS...57...91E .1981,A.J.,86,149. .1983,Ap.J.,269,335. .19796,Ap.J.,231,384. .1979a,Ap.J.Suppl.,39,389. .1978,Ap.J.Suppl.,38,309. .1974,Ap.J.,186,75. .19706,Ap.J.,160,1149. .1983,A.J.,88,507. .1981h,A.J.,86,1192. .1979,M.N.R.A.S.,186,317. Jay A.Frogel:CTIO,Casilla603,LaSerena,Chile J. H.Elias:PhysicsDepartment,320-47,CaliforniaInstitute ofTechnology,Pasadena,CA91125 .1977,TheSmallMagellanicCloud(Seattle:Universityof R. M.Humphreys:Department ofAstronomy,UniversityMinnesota,Minneapolis, MN55455 Johnson, H.L.,andMendozaV.,E.1966,Ann.d’Ap.,29,525. Jefferys, W.H.1980,A.J.,85,177. Azzopardi, M.,andVigneau,J.1977,Astr.Ap.,56,151. 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