1990ApJ. . .352. . .96F The AstrophysicalJournal,352:96-122,1990March20 © 1990.TheAmericanAstronomicalSociety.Allrightsreserved.PrintedinU.S.A. 1 Operatedbythe Association ofUniversitiesforResearch inAstronomy,Inc.,undercontract withtheNationalScienceFoundation. in thesameclusters.Thetransitionluminositybetweentwotypesofstarsgetssystematicallybrighteras composite populationwitharangeinageandmetallicitythatmustcloselyoverlapfortheclusters. clusters andhavearangeinmetallicityofaboutfactor10. comparable tothebrighteststarsinGalacticglobularclusters;withonepossibleexceptiontheyhaveno color distributionoftheMstarswhichcouldindicatetwoepochsenhancedclusterformation:oneabout important predictionofthetheorycarbonstarformationandevolution. by theircolorandluminosity.TheeffectsofagemetallicityareapparentinluminosityfunctionsforC luminous AGBstars.WededucethattheSWBVIIclustersinCloudsareasoldGalacticglobular the BarWestregionofLMC.ForLMCclustersin1Gyroldgroupweestimatespread[Fe/H] type ItoVI.Thisisduetheincreasingageofclustersalongsequence.Therearetwopeaksin results ofourinvestigationareasfollows. around theclusters.TheclusterclassificationschemeofSearle,Wilkinson,andBagnuolo(SWB),whichwe branch (AGB)stars.Weidentifiedandobtainednear-infraredphotometryforabout400suchstarsin even thoughthesearethebrighteststarsinentiresample, theystillcannotaccountforthemissinglumin- initial massforthesestarsof3-5M.Inclustersyoungerthan100Myr,thebrightestaregiants; tent witheachbeingdrawnfromthesamesampleoffieldstarsinClouds,sothatlatterisclearlya counterparts. TheshapeoftheluminosityfunctionsforCstarsfromvarioustypesclustersareconsis- that forearliertypeclusters:bothclusterandfieldSMCCstarsareintrinsicallyfainterthantheirLMC to beontheorderof0.2-0.3dex.Thisimpliesthatchemicalenrichmentwasfairlyuniformthroughout show tobecloselycorrelatedwithclusterage,isakeyelementintheanalysisofourdata.Theprincipal low as1.0MintheSMC.Inintermediate-ageclusters, ~40% ofthebolometricluminosityiscontributedby one passesfromthelatesttoearliesttypeclusters.Theexistenceofsuchatransitionluminosityisan stars: forthoseinSWBtypeVIclusterstheluminosityfunctionisseveraltenthsofamagnitudefainterthan LMC atthatepoch.ThebrighteststarsinSWBtypeVIIclustershaveluminositiesandcolorsareclosely generate andisinreasonableagreementwiththeory. types IV-V.Thiscorrespondstotheageatwhichhelium coreswitchesfrombeingdegeneratetononde- because theCstarluminosityfunctionisshiftedtofainter magnitudesthanpredicted,theagerangeinwhich C andMtypeAGBstars,asomewhatsmallerfraction thanpredictedbyRenziniandBuzzoni.However, stars. Theformercouldalsoexplainthefactthatwesee luminousCstarsinclusterswithturnoffmassesas out. Convectiveovershootingorhighmass-lossratesare promisinghypothesesfortheabsenceofluminousC ous AGBstars.Therefore,thehypothesisthatluminous CstarsturnbackintoMappearstoberuled Subject headings:clusters:globular—galaxies:Magellanic Clouds—stars:carbonevolution stars isremovedfromacluster’slight,theresultingdistribution ofintegratedJ—Kcolorsshowsajumpat AGB starsmakeasignificantcontributionisshiftedto substantially olderages.IfthecontributionofAGB 100 Myrago,theotherabout1Gyrago.ThesecorrespondtosimilarenhancementsdeducedforMstarsin 0 0 Thirty-nine clustersintheMagellanicCloudshavebeensurveyedforcarbonandM-typeasymptoticgiant In aC-MdiagramtheclusterMstarsshiftsteadilyredwardinJ—KasonegoesfromclustersofSWB The youngestclustersinwhichCstarsarefoundhaveanageofabout100Myrimplyingamaximum Luminous carbonstarsarepresentonlyinSWBIV-VIclusters.TheyeasilydistinguishedfromM For theSWB-typeclustersinwhichCstarsarepresent,theyalmostalwaysbrighterthanM © American Astronomical Society • Provided by the NASA Astrophysics Data System THE ASYMPTOTICGIANTBRANCHOFMAGELLANICCLOUDCLUSTERS stars: late-type 1 Cerro TololoInter-AmericanObservatory,NationalOpticalAstronomyObservatories Palomar Observatory,CaliforniaInstituteofTechnology Department ofAstronomy,TheOhioStateUniversity Received 1989July28;acceptedSeptember16 Jeremy Mould Jay A.Frogel V. M.Blanco ABSTRACT AND 96 1990ApJ. . .352. . .96F from anempiricalstandpoint(e.g.,IbenandRenzini1983; 4 moratthef/7.5Cassegrainfocusof1.5onTololo.In classified bySWB.Foreachoftheclusters,short-exposureR (AGB) starsandobtainedinfraredphotometryforacomplete theory ofstellarevolutionand,becausetherichnessmany (1980). Forsomeoftheclusterscrowdingcausedproblemsfor classify MandCtypegiantsinaroundeachoftheclusters. clusters. Therelevanceoftheirschemetothepresentworkis vious observationsofclustergiantsin§II.Theclassification Cloud clustersforMandCtypeasymptoticgiantbranch We havecarriedoutaspectroscopicsurveyofMagellanic of theclusters,tostudyshort-livedlatestagesevolution unique opportunitytotestanumberofkeypredictionsthe age andchemicalcomposition.Thustheypresentuswitha meter guidedbytheoverallstellardensityondirectplates. colors andmagnitudescomparabletothosestarsidentified be anefficientwaytoidentifycandidateMandCstarswith plates. Fortheseclusters,blinkingoftheSITframesprovedto identifying andclassifyinglate-typegiantsfromthegrism The techniqueisdescribedinBlanco,McCarthy,andBlanco taken witharedgrismatthe4mprimefocuswereusedto the clusterswithared-sensitiveSITtubeon1.5m.Plates addition, multicolordigitalimageswereobtainedformanyof or /directplateswereobtainedeitherattheprimefocusof with theoreticalpredictionsispresentedin§VII.SectionVIII discussed in§IVandcomparedwithothersamplesoflumin- discussed in§III.Thecolorsandmagnitudesofthestarsare hereafter SWB)providesapreliminaryagecalibrationforthe scheme establishedbySearle,Wilkinson,andBagnuolo(1980, have workedonfornearlyadecade. number ofareasAGBresearchthatweandourcolleagues sample ofthem.Withthesenewdatawecansynthesizea Renzini andBuzzoni1986;Bertelli,Chiosi,Bertola1989). would underestimateclustermembership ratherthanincluding circle. Onthewholewefeltit bettertoerrinthedirectionthat would beusedasafurtherguide insettingthediameterof Generally, acirclewasdrawnaroundeachclusterwith dia- be completeforallcarbonstarsandbuttheearliest type the totalluminosityofclustersandadetailedcomparison An examinationofthecontributionthatthesestarsmaketo and theluminosityfunctionsofAGBstarsinbothClouds. ous giants.SectionsVandVIdiscussthecolordistribution (Blanco andFrogel1990). found inandaroundtheclusters willbepresentedseparately potential fieldstars.Finding chartsfortheCandMstars available thatgavesomeestimateoffieldcontamination, it sidered tobemembers.Ifacolor-magnitudediagram was somewhat largerthan1'.Allstarswithinthecirclewere con- As itturnsout,thecirclediametersweregenerallycloseto or and inBlanco(1986,1987). spectroscopically. Ingeneral,though,thegrismsurveysshould summarizes ourconclusions. M giantsasdiscussedinBlanco,McCarthy,andBlanco(1980) The surveyanddataaredescribedcomparedwithpre- The assignmentofclustermembershipwasrathersubjective. Most oftheclustersinoursurveywerechosenfromthose The firstfour columns ofTable1contain, respectively, the The clustersoftheMagellanicCloudsspanalargerangein © American Astronomical Society • Provided by the NASA Astrophysics Data System a) SelectionofStars I. INTRODUCTION II. THEDATA AGB OFMAGELLANICCLOUDCLUSTERS if anE(B—V) for aclustercouldbederived fromphotometry 0.10 inlow-absorptionregions; 0.12asa“global”value.The 0.07 fortheforegroundvalue; 0.18inhigh-absorptionregions; latter threevaluesincludethe 0.07foregroundvalue.However, with theCTIOD3InSbsystemon4mreflectorduring photometric systemdefinedbytheCIT/CTIOstandardsof classification fromthegrismsurvey,andwhetherornot cluster name,ournumberingsequenceforthestarsidentified ments ofagivenstarmaybefound.Finally,column(15)con- indicates theassumedspectraltypeforcalculationifnot ence beamswasvariedtominimizecontaminationfromneigh- cluster background.Thespacingbetweenthesignalandrefer- Cloud clusterandfielddatawehavepreviouslypublishedwith from crowdingproblemsorthedifficultygrismtech- columns ofTable1willbemissing.Suchcasesaroseeither redness fromtheSITframes.Thenexttwocolumnscontain given incolumn(3)forstarspickedoutsolelyonthebasisof neath theclusternameisSWBtype.Nospectraltype indices weredeterminedforasubsetofthestarsinTable 1. given incolumns(3)or(6).Thecodecolumn(14)indicates (see below)aregivenincolumns(10)-(12).Fordatatakenfrom colors andmagnitudesforthestars.Observationaluncer- boring stars. rable. Typically,aperturediametersusedwerebetween3"and Elias etal.(1981).ThisisthesamesystemasMagellanic nique hasinidentifyingtheearliestMstars. cool giantsinaclusterwesurveyed,butthesestarswerenot cases wherepreviousstudiesshowedthepresenceofluminous tively, forthestars.Thesourcesbothofthesearegivenby alternative identificationnumbersandspectraltypes,respec- star laywithinthecircledefiningclustermembership.Under- on thegrismplateorfromredSITframes,spectral members; thenonmembersarelistedatendofTable2 with convenience, thecolorsandmagnitudesfromTable1 are additional identificationsforthestars. tains referencestonotesgivenattheendoftable and the dateofobservationandwhereotherinfraredmeasure- tainties >0.03magareindicatedinparentheseshundredths 6". Thesesmallsizeswillminimizethecontributionfrom our collaborators.Hence,allofthesedataaredirectlycompa- selected byus.Intheseinstancesentriesinthefirstthree the numbersinparenthesistwocolumns.Thereareafew data wereobtained. published narrow-banddataforstarsfromTable1ifno new repeated forthosestarsthatweredeemedtobecluster tional data,correctedforreddening,aregiveninTable2. For K —Lcolorsweredeterminedforasubsetofthese.Theseaddi- (1980) aregivenincolumn(13).AnMorCthis lated fromthemeanrelationsinFrogel,Persson,andCohen the literature,onlyreddeningcorrectedvaluesaregiven. of amagnitude.Reddeningcorrectedmagnitudesandcolors only theadditionaldata.Table2alsogivespreviously put incolumns(7)-(9).Apparentbolometricmagnitudescalcu- However, uncertaintiesassociatedwiththesevaluesarestill 1981 and1982.Thesedatahavebeentransformedtothe For theLMCBrunet(1975) gives fourvaluesforE(B—V): The newinfrareddatapresentedinthispaperwereobtained Columns (7)-(9)ofTable1givethenewlymeasuredJHK In additiontoJHKcolors,narrow-bandH0andCO 2 c) ReddeningCorrections b) InfraredObservations 97 1990ApJ. . .352. . .96F 98 © American Astronomical Society • Provided by the NASA Astrophysics Data System Cluster #ClassMemI.D.KJ-KH-K (VI-VII) 2 Kron 31 (1) (2)(3)(4)(5)(6)(7)(8)(9) VII IV N121 N152 III (II-III) N220 N231 III-IV III N265 I N269 N299 N306 (III) VII N339 4 3 2 C 5 2 C 4 3 1 Ml 1 C 2 C 5 C 4 C 3 M 3 C 2 C 1 C 11 C 4 C 1 M2 5 2 4 3 1 5 6 7 2 C 8 4 C? 3 Ml 1 C 5 MO C C C MO C C C M M M C C C C C C C C M MO? Y C N C C M2 M3? Y M2 Ml Y? Y Y? Y Y Y Y Y Y N Y Y N Y Y Y Y Y Y N N N N N N N N N N N N N Y N N N N N N N Y N N N N Y N Y Y Y Y N Y N W24 (1) W54 (1) TLE1(2) MAI (6) VI (3) V8 (3) E12 (12) MA2 (6) TLE30(2) TLE26(2) TLE35(2) W84 (7) C19 (5) MAI 1-23 (4) H23 (5) TLE4 TLE2(2) G151 T.LE3 FROGEL, MOULD,ANDBLANCO C (2) C (2) Cp (6)12.880.870.1812.870.84 Ctm(l) 11.76(4)0.80(4)0.15(3)11.750.77 K5 (6)... K4e(6) 12.82 S (12)... MO (5)12.33 C,2 (5)11.68 K5 (6)... (C)(6) ... C,3 (6)11.36 11.63 11.94 13.07 11.71 12.26 11.62 10.75 12.59 11.85 11.62 11.36 10.11 11.78 11.35 11.90 10.77 11.33 11.46 11.62 10.59 11.56 11.43 10.95 9.91 11.13 10.12 10.16 11.78 12.24 11.54 10.86 10.49 11.06 10.76 13.19 0.870.13 12.93(3) 0.92(3)0.17 11.27 11.62 0.850.15 13.03(4) 0.950.16 11.67 0.84(3)0.13 11.51 13.15 12.22 11.80 AGB StarPhotometry 3.40 TABLE 1 0.94 0.25 1.22 1.25 1.13 1.22 1.01(3)0.16 0.86(3)0.22 1.49 0.53 1.15(3)0.30 1.12 0.30 1.13 0.29 ...(6) ...(4) •••(4) 1.00 0.18 1.21 0.35 0.80 0.23 0.99 0.25 1.06 0.20 1.16 0.32 1.40 0.48 1.06 0.23 1.53(3)0.53 1.13(3)0.32 1.05 0.20 1.34 0.43 1.60 0.58 0.91 0.15 1.30 0.43 1.55 0.56 1.64 0.58 1.04 0.23 1.39(3)0.45 1.64 1.62 1.62 0.57 1.47 0.53 1.13(3)0.35 1.27 0.38 0.18 0.05 0.71 0.13 0.81 0.13 1.58 0.56 1.45 0.48 1.33 0.43 1.47 0.50 1.01 0.28 0.33 0.35 0.39 0.31 0.60 0.58 (10) (11)(12)(13) Ko (J-K)o(H-K)om 11.70 1.22 12.25 1.10 11.93 1.19 11.62 1.19 13.35 0.78 12.73 0.85 13.06 0.98 13.37 0.80 12.81 0.91 10.74 1.46 11.61 1.09 11.84 1.10 11.61 1.18 12.58 1.12 12.64 0.92 11.52 0.88 12.32 0.97 11.99 1.05 10.83 1.48 bol 11.67 1.13 10.09 1.02 11.76 0.82 11.33 1.49 11.88 1.09 11.31 1.36 10.57 0.95 11.34 1.02 11.44 1.30 11.60 1.56 10.75 0.76 13.18 0.84 11.53 1.49 10.92 0.99 12.92 0.89 13.02 0.92 9.88 0.85 10.09 1.56 11.40 1.58 11.35 1.42 11.26 1.30 11.64 0.78 10.13 1.56 11.10 1.24 11.75 1.33 10.46 1.58 11.59 0.79 13.12 0.12 13.37 0.65 11.77 0.75 11.48 1.41 12.21 1.07 10.83 0.96 12.19 0.95 11.03 1.41 10.73 1.52 11.51 1.21 0.32 0.38 0.30 0.11 0.34 0.15 0.17 0.14 0.07 0.09 0.24 0.29 0.28 0.52 0.29 0.12 0.34 0.19 0.21 0.17 0.16 0.12 0.31 0.56 0.15 0.03 0.18 0.51 0.30 0.47 0.42 0.13 0.11 0.11 0.11 0.48 0.21 0.46 0.21 0.20 0.26 0.41 0.23 0.54 0.56 0.56 0.18 0.41 0.43 0.58 0.56 0.33 0.36 0.21 0.55 0.51 0.54 0.13 14.76 14.56 14.99 15.75 15.26 14.45 15.88 15.28 14.12 14.34 15.79 15.48 13.78 15.34 14.58 14.43 15.15 14.66 14.12 13.88 14.44 12.98 14.22 14.39 14.61 13.76 14.28 13.13 14.23 14.36 14.71 13.10 14.58 14.52 13.97 13.58 13.24 14.69 13.19 14.91 13.62 14.04 13.81 14.35 14.37 12.41 15.54 15.59 15.71 14.02 14.18 13.99 15.49 14.10 14.49 14.75 Source Notes A,E A,E,H A,H A,E I H A (14) (15) A,E A A A A,E A A A E E,I H A A A,E,H E,I A A A A A A A A A A A A A A A A A A,H A A A A A G22(7) A,H A,E,H A A A A A A A A A A TLE26 36 5-3 5-7, W87 strong Ho Vol. 352 1990ApJ. . .352. . .96F No. 1 1990 © American Astronomical Society Cluster #ClassMemI.D. (1) (2)(3)(4)(5) N346 V-VI N361 VI N411 V N416 N419 N602 9 C 8 C 21 20 C 24 C 23 22 25 C 18 C 15 C 14 C 13 - 12 C 11 C 10 C? 19 C 17 C 16 C 4 M 3 C 2 C 5 M 1 M C M2 C C C C C C C? C C c C C c c Y Y? Y Y Y Y Y N? N Y? Y N N Y Y Y Y N N Y Y Y Y Y Y N N Y N? N N N Y Y N N N N Y Y N Y? Y Y Y Y Y Y Y Y N Y Y Y N N N N TLE1 1-40 1-9 1-45(13) TLE1(2) 1-35 1-16 TLE2(2) AM-1(6) AM-2(6) TLE19 TLE18 TLE21 TLE20 TLE16(2) W135(7) TLE36 TLE29(2) TLE23 TLE22 TLE24 TLE27 TLE28 S-15 TLE25 TLE26 TLE37 TLE35 TLE30 W84 (7) TLE34 TLE33 TLE31 W71 (7) W108 (7) 6-1 AGB OFMAGELLANICCLOUDCLUSTERS (6) (7) Class K Ctm(6) ... M (2,6)11.99 C (2) C,3 (6)10.70 M0 (6) C (2)... C,1 (6)... C (2) C (2) K5 (12)... S (12) ? (6) K5 (6) K5(12) K5(12) (C)(6) K5(12) K5(12) 10.75 13.54(3) 0.91(3)0.13(3)13.530.880.1215.99 13.57 10.60(4) 11.52 10.63 11.59 10.87 11.00 12.11 11.45(4) 10.76(4) 11.28 11.43 11.34 12.04(4) 0.73(3)0.11 11.76 11.43 12.25(3) 11.05 11.17 11.06(4) 11.04(4) 11.17(4) 10.94(3) 11.67 11.12 11.71 10.64(4) 10.62 10.91 11.61 11.04 11.39 TABLE 1—Continued Provided bythe NASA Astrophysics Data System J-K H-K (8) (9) 0.84 0.06 0.98 0.80 2.51(3)1.14 1.98 1.39 1.02(3)0.28(3) 1.45 1.14 1.85 1.26 1.51 0.56 1.29 1.55 1.44 1.43 1.13 1.05(8)0.21 1.60 0.62 1.18(4)0.30(3) 1.58 0.57 1.57 0.59 1.09 0.31 1.63 0.65 1.46 0.50 1.12 1.35 1.78 0.70 1.55 0.56 1.82 0.71 1.52 1.50 0.54 1.76 0.65 1.29 (4) (6) 0.21 0.40 0.57 0.48 0.53 0.51 0.27 0.77 0.41 0.81 0.44 0.30 0.49 0.25 0.21 0.41 0.55 •(4) (10) (11)(12)(13) Ko (J-K)o(H-K)om 12.09 1.22 13.55 0.80 12.86 0.90 12.94 0.87 10.73 1.94 11.97 0.94 11.50 1.47 11.28 1.43 11.15 1.41 10.85 1.10 10.98 1.81 13.27 0.82 12.07 0.930.18 11.43 1.01 11.02 1.14 10.58 1.54 12.01 0.67 12.85 0.89 11.56 1.33 11.73 1.23 11.40 1.49 12.22 0.96 11.02 1.38 11.10 1.39 12.99 0.88 13.33 0.90 11.51 0.98 10.83 1.48 12.64 0.92 11.99 1.05 11.52 0.88 11.69 1.09 11.04 1.31 10.74 1.56 12.35 0.91 11.65 1.05 11.41 1.51 10.61 1.59 10.68 1.78 11.32 1.42 10.90 1.09 11.03 1.49 12.15 0.85 12.62 0.91 12.17 0.89 12.65 0.94 10.92 1.74 12.28 0.85 10.78 1.64 10.96 1.56 10.60 2.47 11.26 1.53 11.38 0.77 11.60 1.26 bol 11.15 1.46 10.62 1.72 0.21 0.28 0.47 0.19 0.60 0.28 0.55 0.54 0.50 0.11 0.13 0.13 0.14 0.24 0.56 0.19 0.12 0.42 0.38 0.46 0.51 0.49 0.25 0.75 0.39 0.04 0.14 0.79 0.19 0.24 0.20 0.40 0.54 0.14 0.26 0.13 0.55 0.26 0.14 0.13 0.52 0.68 0.16 0.15 0.62 0.57 0.57 0.29 0.54 0.63 0.69 0.48 0.09 0.63 1.12 15.39 14.54 15.29 14.79 14.12 14.31 14.07 13.85(C) 13.67 14.30 13.87 14.68 15.59 15.97 14.33 13.88 15.15 14.66 14.41 13.97 14.04 13.80 15.73(M) E 13.75 14.49 14.09 14.16 13.59 14.94 15.97(M) E 15.52(M) E 14.00 14.71 14.50 14.46 14.80 14.01 14.09 14.21 15.50(M) E 14.12 14.71 14.86 13.92(C) 14.48 13.73 13.90 14.34 14.18 A 15.47(M) E 14.59 14.19 13.81 13.93 14.07 14.34 14.34 Source Notes I A,E, Not6-2 A,H,I S-20 I I A,H A,H A 6-4,9 A,H E, I BR5 A A E E E,I A (14) (15) A A I E,I H EJ E A A A,E A,E,I (=BR1) A A A A,E 8 A,E,H, BR6 A A A,E A,E A,E A E,H G87(7) A,E 8 D,I W90,5-14 E,I E,I A,H A A A A 6 D, E 4- 13 5-5 5- 3 6- 2 5- 6 6- 6 5- 7, W87 6-5 ,9 3 20 19 99 1990ApJ. . .352. . .96F 100 © American Astronomical Society • Provided by the NASA Astrophysics Data System N1651 (V) N1652 Cluster #ClassMemI.D. (VI) V N1751 (1) (2)(3)(4)(5) V N1783 N1806 V 4 MO?Y 2 MO?Y 8 C 2 5 MO?N 3 MO?Y 4 3 6 MN 1 MO?Y 5 7 6 9 C 8 C 1 Ml 8 C 9 M 1 M 10 C 9 M? 8 M? 12 M6.5N 11 C 21 M 20 M 7 M 11 M 10 C 13 C 15 C 14 M 13 M 12 M 13 C 17 C 16 M 14 M 19 M 18 M 17 C 16 C 15 C 12 M 11 M C C? M? M3 M3 M M M5 C M M C C M M M Y N Y Y Y N Y Y Y Y N Y Y Y Y N N Y Y Y Y N N N Y? Y Y Y Y Y Y Y Y N Y Y Y Y Y Y? Y? Y Y Y Y Y Y? N Y Y N? N N? N? N N N AM-1 TLE 2 H2421 H4328 TLE 8 TLE 1 TLE 4 TLE 5 H3210 H3304 H4325 TLE 3 HHU2406 TLE 8 TLE 6 TLE 7 TLE 2 TLE 5 TLE 9 TLE 1 TLE15 TLE10 TLE14 TLE 4 TLE 3 TLE 11 G6 (9) TLE 2 TLE 1 TLE 5 TLE 8 TLE 7 TLE 3 AM9(6) TLE 4 TLE 6 FROGEL, MOULD,ANDBLANCO C,3 (6)... S (12)... S (12)10.50 M4 (6)... Class C (2) K3(8) (6) M (2) M4 (8) S (2) S (2) Ctm (2)11.28(3) C (10) C (2) C (2) Ml (8) M4 (8) 10.98 9.91 12.59 0.870.2912.560.810.2715.00 11.72 K 12.75 (7) 11.68 12.48 12.41 10.45 11.42 10.39 11.10 11.54 10.91 11.34 11.02 11.07 10.46 10.42 11.49 11.31 13.17 12.95(3) 11.12 10.32(3) 11.51 11.78 11.58(3) 12.17 11.53 10.61 11.79 12.04 11.41 11.08 10.09 11.23 10.93 10.26 11.36 12.73(3) 11.35 10.66 10.64 10.92 11.35 11.22 12.18 11.37(3) 10.42(3) 11.84 11.59 TABLE 1—Continued 0.98 0.16 0.92 0.15 0.99 0.16 1.16 0.28 1.18 0.39 J-K 1.35 0.42 (8) 1.07 0.21 1.72 0.64 1.62 0.57 1.12 0.23 1.05 0.21 1.11 1.23 1.Í9 0.31 1.85 0.69 1.16 1.54 0.95(3)0.17(3) 1.48 0.48 1.15 1.78 0.99 0.99 0.18 0.80 0.13 0.96(3)0.16 0.97(3 0.18 1.08 0.20 1.12 0.21 1.17 1.37 0.42 1.00 0.18 1.02 0.19 1.10 0.21 1.09 0.20 1.80 0.68 1.62 0.56 1.74 1.08 0.20 1.03 0.19 1.68 0.63 1.04 0.19 1.11 0.27 1.00(3 0.18(3) 1.93 0.77 1.00 0.18 1.06 0.21 1.15 1.07 0.22 1.02 0.21 1.04 0.21 1.81(3)0.68(3) 1.46 0.49 1.09 0.23 0.22 0.33 0.30 (9) H-K 0.50 0.37 0.66 0.65 0.29 0.25 0.16 10.95 1.120.3713.95 9.87 1.55 11.69 1.29 11.17 1.13 11.50 1.25 10.47 1.10 11.26 1.04 12.45 0.930.14 12.28 0.890.14 12.38 0.920.14 12.72 0.860.13 K (J-K)o(H-K)m 11.50 0.98 12.53 0.930.19 (10) (11)(12)(13) 11.30 1.05 10.87 1.04 11.06 1.16 10.41 1.65 11.65 1.010.19 10.35 1.78 11.03 1.09 11.38 1.12 10.38 1.71 10.98 1.47 11.27 1.41 10.42 1.08 11.56 1.01 11.46 1.02 11.08 1.03 11.49 1.05 10.88 1.10 11.31 1.30 11.75 0.94 13.17 0.74 11.33 1.00 12.70 0.90 12.92 0.89 11.31 1.02 11.24 1.07 11.54 0.93 12.13 0.95 11.31 1.02 10.57 1.55 10.60 1.67 11.55 1.01 11.18 1.08 12.14 0.92 11.75 0.92 12.00 0.96 10.38 1.61 10.28 1.74 11.07 1.03 11.20 1.03 10.90 1.05 10.23 1.87 10.62 1.73 11.37 1.00 11.33 0.95 11.24 0.97 11.04 0.97 10.06 1.38 10.33 1.54 11.81 0.91 11.48 0.94 0bo¡ 0.38 0.29 0.21 0.40 0.26 0.61 0.54 0.18 0.30 0.20 0.66 0.27 0.19 0.28 0.16 0.11 0.20 0.20 0.18 0.63 0.47 0.18 0.26 0.39 0.25 0.16 0.75 0.19 0.14 0.23 0.45 0.34 0.16 0.18 0.17 0.65 0.53 0.62 0.17 0.22 0.13 0.15 0.16 0.57 0.21 0.16 0.15 0.15 0.19 0.18 0.18 0.60 0.16 0.47 0.65 0.22 14.18 14.38 15.24 14.60 13.45 14.18 14.90 15.27 12.97 14.32 14.53 15.16 15.07 14.10 13.57 14.23 13.57 13.79 13.98 13.41 14.49 15.44 14.20 14.20 14.35 14.14 14.00 14.25 13.48 14.11 13.83 14.47 14.21 13.47 13.95 15.35 15.54(M) 14.19 13.56 14.02 14.89 13.99 14.42 13.82 13.67 13.86 14.23 14.43 14.44 13.84 13.05 13.38 14.20 13.77 14.14 14.83 14.78 14.23 14.04 13.52 14.28 14.09 A.D,E,I A D,E D,E A. B.E D,E B. E B A, D C, G A A Source Notes A,H A A A A A A.H A.E A C, D A A, H B, E B D D,H B,H D,H A A B,E B,H B.H A A A A,H A,E D, H B, H A A A A,H B, H B A A A A A,H A,E B, E , (14) (15) A,E G13 G14 G7 G32 G30 21 G4 V2 G40,LPV?(9) Vol. 352 1990ApJ. . .352. . .96F No. 1,1990AGBOFMAGELLANICCLOUDCLUSTERS © American Astronomical Society • Provided by the NASA Astrophysics Data System Cluster #ClassMemI.D. (1) (2)(3)(4)(5) VII V N1846 NT 841 (ID N1850 N1854 7 9 7 M 6 M 8 M 9 M 2 C 4 C 3 C 20 M? 12 M 23 C 22 C 21 M 13 M 11 M 10 M 5 C 25 C 24 C 15 C 14 M 1 C 26 C 16 C 19 C 18 C 17 M 9 - M2 - MO - MO: 10 C 12 M2 11 14 M4 13 C 9 10 C 11 Ml 9 ? Y MO M M M M M3? Y Ml Y ? Y ? Y MO M2? Y Ml ? 9 9 Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y Y? Y N N Y Y N N Y N Y Y Y Y N N N? Y N Y? Y N N Y Y N Y N N N TLE14 TLE 1 TLE 2 TLE10 TLE 9 TLE8 TLE 4 TLE 5 TLE 2 TLE 1 G117 TLE 3 TLE16 TLE13 TLE11 G117 TLE12 TLE17 H39 TLE 7 TLE 6 TLE15 TLE18 Cil B43 B24 C27 B4 C20 B36 A37 A39? DU B58 C77 C15 B62? D49 D41 A15 AG9 A29 C24 Cl A33 B5 B3 B93 D2 Class K (6) (7) S (12) K5 (8) M (6) C (2,6)... C (2,6). C (2,6)10.30 C (2,6)... C (2,6). 11.55(4) 11.25(3) 11.74 11.44 11.00 12.20 11.43(3) 12.55(3) 11.62 13.34 12.80 12.20 9.61 11.40 11.91 11.55(3) 10.28(3) 12.29(3) 10.82(3) 10.30(3) 13.31 11.26 10.70 10.77 11.53 12.47 12.53(4) 10.84 13.87(4) 12.44 10.37 10.76(3) 11.13(4) 11.70(3) 12.26(3) 12.26(4) 11.27 12.91 11.33 10.63 10.98 11.28 11.66(4) 0.720.13 11.45 11.03 10.67(3) 0.770.14 11.14(4) 0.860.16 11.22 11.65(6) 0.820.15 11.65(4) 0.880.17 11.89(4) 0.820.15 12.60 12.55(4) 0.740.12 TABLE 1—Continued J-K H-KK(J-K)o(H-K)m (8) (9)(10)(11)(12)(13) 0bol 0.84 0.1512.880.800.1415.30 0.71 0.12 0.78(3)0.12 0.64(4)0.12(3) 0.80(3)0.15 1.08(3)0.18(3) 0.94(3)0.15 1.01 0.17 1.03 0.18 1.12 0.22 1.69(3)0.61(3) 1.79 0.69 0.96 1.70 0.61 1.01 0.22 1.12 0.27 1.06 0.22 1.09 0.20 0.95 0.21 0.10(3)0.03(3) 0.69 0.13 1.21 0.36 1.58(3)0.51 0.72(3)0.13 0.72 0.10 0.95 0.20 0.98 0.19 1.66 0.61 1.08 0.24 0.79 0.12 0.82 0.13 1.40 0.44 1.08 0.21 0.98 0.20 1.09 0.21 1.62 0.59 1.31 0.94 0.17 0.96 0.19 1.01 0.21 1.05 0.20 0.99(3)0.17 0.88 0.16 1.62 0.58 0.83 0.1412.560.760.11 14.85 1.10 0.23 1.79 0.66 0.23 0.42 12.78 0.74 11.71 0.97 11.52 1.06 10.27 1.73 13.32 0.67 12.57 0.82 12.17 0.95 11.40 1.00 11.59 1.03 11.22 1.02 11.90 0.97 10.25 1.63 10.45 1.72 10.56 1.68 12.27 0.60 13.19 0.76 10.27 1.64 10.79 1.52 11.41 0.95 10.31 1.57 11.25 1.32 11.52 1.15 9.56 0.89 10.67 1.60 11.23 1.25 12.44 0.90 10.74 1.34 11.37 1.02 12.52 0.88 11.88 1.02 11.50 1.03 10.34 1.56 10.79 0.86 13.82 0.01 12.41 0.99 11.08 0.63 11.22 0.92 12.86 0.60 12.21 0.70 12.48 0.63 11.65 0.86 10.71 1.53 12.21 0.73 11.23 1.01 10.58 1.70 11.28 0.89 10.93 0.79 11.40 0.85 10.98 0.87 11.17 0.90 11.10 0.79 11.62 0.65 12.51 0.67 11.85 0.65 10.63 0.70 11.61 0.75 11.61 0.81 1.08 0.20 0.14 0.12 0.11 0.20 0.59 0.67 0.63 0.64 0.17 0.16 0.49 0.12 0.15 0.20 0.18 0.16 0.59 0.20 0.26 0.34 0.22 0.13 0.58 0.43 0.42 0.19 0.40 0.21 0.59 0.18 0.19 0.57 0.18 0.18 0.00 0.10 0.10 0.07 0.17 0.16 0.10 0.17 0.09 0.55 0.14 0.16 0.20 0.63 0.13 0.10 0.14 0.11 0.13 0.09 0.12 0.12 0.14 14.09 15.49 15.09 15.03 13.87 13.40 13.54 13.64 13.73 15.54 14.51 14.46 14.92 14.26 14.11 14.70 13.42 14.17 13.92 14.50 14.31 15.12 13.43 14.19 14.77 14.93 14.11 13.80 13.69 14.26 14.41 13.45 13.91 13.59 14.88 15.25(M) 14.61 13.90 14.65 12.18 14.80 13.40 14.25 13.81 13.76 13.90 13.74 14.06 13.33 14.09 14.11 13.97 13.44 13.99 14.67 13.03 13.93 Source Notes (14) (15) A.D A A A,H D A.D D H58 B,H A, B, C, IHHU4403 C,I H21 A A, H A,H, B,H B, E A A,I A B,C A,C,I HHU4508 A A,H A B, E ,GI A C, I A A A,I D, I A,H A G A G G G A,I G G G G G G G G G G G G G G G G G G G G G G113 G51 11 10,11 H1 H6,HHU1302 Hl, HHU4406 HH4251 24 26 23 25 24 13 25 26.2 27 101 1990ApJ. . .352. . .96F 102 © American Astronomical Society • Provided by the NASA Astrophysics Data System Cluster #ClassMemI.D.KJ-KH-K III (1) (2)(3)(4)(5)(6)(7)(8)(9) N1866 III 2M0-1Y VI N1978 IV N2058 1M5Y N1987 13 M2 12 C 8 MO? 15 M2 14 M4 9 C 17 M2 16 Ml 6B -Y 5 M2Y 4 M3:Y 3 M0-1Y IR1 IR1 IR1- 6 Ml:Y 20 M 9 C 8 C 12 M2 13 C 18 MO?N? 15 MO? 14 M2 11 C 10 Ml 19 M 18 C 17 C 15 M 14 M 13 M 19 C 17 MO?Y 16 C 16 M 11 M 12 M 10 M C C C? M? C M? M: M? M M M Y N N N Y Y N N Y Y Y Y N Y Y Y Y Y Y Y? N? Y Y Y Y Y Y Y? N N Y Y Y N N Y Y Y N? N N Y? Y? N N N N N N N? N N N A63 D9 TLE 4 D33 D28 TLE 8 TLE 3 TLE10 TLE5 TLE11 TLE 6 BII-16(11) M5(6)9.691.170.27 B 1-36(11)M5(6)10.241.140.25 BIV-55(11) 10.791.010.19 MA4 9.701.090.24 TLE 2 TLE 1 TLE 7 TLE 3 TLE 9 TLE 4 TLE 2 TLE 6 TLE 5 TLE 1 FROGEL, MOULD,ANDBLANCOVol.352 C (2,6)11.60(3) C (2)10.161.730.63 C (2,6). C (2,6). M (2)... 12.14(6) 0.81(30.09 12.36 11.19 1.160.26 11.41(3) 0.960.16 10.95 1.010.19 11.18(3) 0.950.1711.140.880.1413.74 12.00(3) 11.29(4) 11.50(4) 11.30 12.59(4) 11.99(3) 11.14 12.78(4) 11.16(3) 13.11(3) 10.82 1.440.44 11.98 1.07(3)0.21 11.17 10.91 10.83(4) 11.33(3) 10.46 10.83 12.56 12.25(6) 11.22(3) 10.79 1.220.31 12.11(3) 11.53(3) 1.100.24 12.24(3) 0.980.18 13.23 10.95 11.17 11.83 0.770.13 12.25(4) 0.770.15 12.76 11.49 12.25(3) 10.21 1.080.25 12.00(3) 12.17 10.71 10.22 11.52 11.48 11.14 11.10 TABLE 1—Continued 0.84 0.15 0.92(3)0.23 0.82 0.17 2.69(4)1.32 2.72(3)1.41 2.53(3)1.26 0.96(4)0.09 0.91(3)0.12 0.98(3)0.17 0.97 0.17 1.12(3)0.21(3) 1.18 0.32 1.45(3)0.44(3) 1.13(3)0.25(3) 1.13(3)0.25(3) 1.13(3)0.21(3) 1.12 0.21 1.14 0.24 1.08(3)0.19(3) 1.48(3)0.47(3) 1.35(3)0.39(3) 1.09 0.22 1.46 0.54 1.73 0.64 1.15 0.23 1.18 0.29 1.10 0.24 1.07 0.21 1.69 0.64 1.83 0.70 1.01 0.24 1.02 0.19 1.11 0.25 1.15 0.26 1.02(3)0.19 1.14 0.27 Ko (J-K)o(H-K)ornbolSourceNotes (10) (11)(12)(13)(14)(15) 9.67 1.030.22 12.32 0.770.1214.63 9.66 1.11 11.37 0.890.13 12.10 0.740.06 9.87 1.75 10.74 1.12 13.08 0.86 10.21 1.08 10.76 0.950.17 10.16 0.98 12.20 0.67 12.71 0.72 11.44 1.04 10.67 1.39 11.47 1.07 11.57 1.39 10.79 1.380.46 10.92 0.950.17 11.16 1.100.24 11.78 0.67 12.13 1.02 11.96 0.95 10.18 1.66 11.48 1.04 11.44 1.08 11.10 1.08 11.06 1.11 11.97 1.06 11.13 1.12 11.26 1.07 10.80 1.29 12.56 0.90 11.96 1.07 11.19 1.42 11.11 1.06 12.75 0.85 11.14 2.63 10.88 2.66 11.27 2.47 11.10 1.45 10.50 1.66 10.91 1.03 12.07 1.00 11.29 1.62 10.42 1.76 10.23 0.96 12.20 0.91 10.12 1.66 11.94 1.00 11.14 0.95 13.20 0.92 12.53 0.91 12.22 1.02 10.79 1.07 11.49 1.03 12.21 0.95 0.23 0.25 0.23 0.42 0.21 0.19 0.30 0.23 0.09 0.21 0.11 0.13 0.20 0.71 0.27 0.19 0.16 0.51 0.61 0.22 0.20 0.23 0.26 0.62 0.19 0.45 0.19 0.37 0.10 0.07 0.21 0.18 0.67 0.24 0.21 0.15 0.60 0.22 0.15 0.16 0.61 0.20 0.18 0.15 0.49 0.17 1.30 1.39 1.24 13.99 14.41 12.65 13.52 12.58 13.68 14.14 13.18 14.56 15.52 13.78 14.92 13.90 14.22 14.43 13.74 15.28 14.38 14.36 14.72 13.35 15.11 14.91 13.71 13.07 13.95 12.98 14.98 15.02 13.66 14.40 14.40 14.06 14.05 13.02 14.80 14.12 14.13 15.21 13.66 14.20 14.05 14.93 13.63 13.74 13.28 15.89 14.57(C) A 13.82 14.43 14.40 14.86 13.70 15.20 14.97 G A,H A A,H G A A,H A A B B,E B G A B,E B G G G A A C B,H B B G G A A A A A,E A G C B,H B A A A,E A G B B B,H A A E E A A,E G G B.E A MAI MA2 29 HHU2509 12 30 24 H1-25,IIHU H1-12,HHU 18 18 14 1990ApJ. . .352. . .96F No. 1 , 1990 © American Astronomical Society Cluster #ClassMemI.D. (1) (2)(3)(4)(5) IV N2107 N2108 1Ml (V) VI N2121 9 Ml-2Y 8 MOY 7 M7Y? 23 Ml 22 C 20 M7 12 M3 11 MO:Y? 10 Ml:Y 25 C 24 Ml 16 MO: 15 MO: 14 Ml: 13 MO 17 M5 19 CN 18 M4?N? 9 C 8 C 10 C 8 CN 11 MO:N 2 M 3 M 6 - 4 M 17 CN 10 M6N 5 1 M 19 CN 18 CN 9 M 8 M 7 M 20 M 22 M 21 M 15 M 13 M 12 M 11 M 10 M 16 M 14 M 18A- 18 M 17 M 19 M 1 C C M4 M5 M3 M4 Ml Ml M? M? M2 C Ml? Y N? N? N N? N N N N N N Y N N Y? Y Y N N N? N Y N Y N N N? Y Y Y Y Y Y Y Y? Y? Y Y Y Y Y N Y Y N? N? N? N? N? N N TLE 4 TLE 2 TLE 3 TLE 5 TLÈ 1 MA6 TLE 2 TLE 1 TLE 4 TLE 6 TLE 3 AGB OFMAGELLANICCLOUDCLUSTERS Class K (6) (T) 9.99 12.59(3) 12.45 12.33 11.67 10.39 10.50 11.49(3) 9.94 12.70 12.47 Í2.69 12.26 10.27 11.73 12.22 12.85 12.78(3) 12.69 10.14 12.78 11.79 12.29 10.49 11.18 11.39 11.80 13.06(4) 12.85(3) 13.72 12.70 13.25(3) 13.09 10.31 11.04 9.85 11.98 12.40 11.99 13.35(3) 13.73 12.25 10.73 10.66 10.13 10.50 10.59 10.93 10.73 10.62 11.08 10.07 13.30(3) 10.04 12.90(3) 13.73(3) 12.47(3) 13.10(3) 12.90 TABLE 1—Continued Provided bythe NASA Astrophysics Data System 0.56 0.12 0.92 0.17 0.80 0.16 0.95(5)0.13(4) 0.85 0.15 0.75(3)0.13(3) 0.73 0.12 0.80 0.05 0.96 0.16 0.96 0.18 0.99(3)0.17 0.94 0.16 J-K 0.94(4)0.17(3) 0.82(3)0.12 0.80 0.15 0.92(3)0.18 0.92 0.17 2.29 0.98 2.67 1.13 2.15 0.95 0.93 0.18 1.00 0.20 1.43 0.42 1.05 0.23 1.05 0.20 1.05 0.22 1.02 0.19 1.14 0.25 0.79(3)0.11(3) 1.17 0.32 1.37 0.41 1.01(3)0.18 1.23 0.29 1.54 0.51 (8) 1.01 0.18 1.08 0.22 1.08 0.22 1.12 0.22 1.13 0.23 1.39 0.42 1.29 0.39 1.24 0.31 1.36 0.37 1.82 0.68 0.95 0.20 0.81(3)0.18(3) 1.18 0.26 1.66 0.59 1.65 0.5810.541.550.5413.64 1.19 0.26 1.23 0.32 1.08 0.22 1.21 0.28 1.72 0.62 1.09 0.26 1.00 0.18 1.17 0.23 1.31 0.38 1.75 0.64 (9) H-K 12.65 11.94 9.88 1.10 12.64 12.21 10.22 12.35 12.42 13.01 9.98 1.61 9.79 1.12 10.68 10.88 10.61 10.44 1.07 11.93 11.02 1.12 10.01 1.55 10.07 0.97 12.82 0.67 9.94 1.72 13.25 0.69 12.41 1.06 10.67 1.20 10.56 1.64 12.84 0.98 11.70 0.86 12.19 0.99 12.42 0.99 12.30 0.99 13.05 0.85 12.85 0.90 12.56 0.69 12.82 0.90 11.64 0.96 10.36 1.08 13.69 0.84 12.66 0.95 13.68 0.71 12.75 0.93 13.32 0.88 12.67 0.74 13.22 0.86 13.06 0.86 10.11 2.23 10.47 2.61 11.46 1.06 12.26 1.07 10.26 1.29 13.70 0.76 12.22 1.02 12.75 0.95 11.76 1.02 10.44 2.05 10.99 1.19 11.13 1.14 11.34 1.26 11.75 0.83 (10) Ko 0.46 0.08 0.90 0.16 0.75 0.11 0.85 0.09 0.84 0.12 0.70 0.12 0.86 0.12 1.33 0.38 1.27 0.37 1.07 0.28 1.44 0.47 1.09 0.22 (11) (12)(13) (J-K)o (H-K)om M 0.25 0.22 0.55 0.24 0.22 0.28 0.15 0.21 0.11 0.18 0.20 0.10 0.58 0.34 0.18 0.16 0.17 0.23 0.03 0.16 0.16 0.14 0.60 0.15 0.15 0.10 0.13 0.20 0.15 0.96 0.20 0.91 0.38 0.35 0.27 0.64 0.14 0.07 0.19 0.16 0.20 0.33 0.14 0.16 0.21 1.11 15.05 15.54 14.27 13.95 13.63 13.50 14.86 14.97 15.28 13.35 13.91 14.90 14.25 15.03 15.26 14.98 15.46 15.41 12.79 14.02 13.39 12.86 14.77 15.14 14.42 13.32 16.20 15.11 14.40 13.17 13.12 15.66 12.87 13.11 15.46 15.92 14.98 15.77 15.61 13.43(c 15.50 14.65 13.73 13.82 14.15 13.13 15.46 13.51 16.05 13.73 15.21 14.23 14.23 15.58 15.93 15.49 15.35 13.71 G G G G G G G A A A A A A,H G G G G G A A A A A A,H G G A A A A A A A,H G G G G,H G,H G G G,E A A G A,H G G G G A G G G G G G G G Source Notes (14) (15) 32 30 24 31 30 30 32 33 15 103 1990ApJ. . .352. . .96F 104 © American Astronomical Society • Provided by the NASA Astrophysics Data System Cluster #ClassMemI.D. (1) (2)(3)(4)(5) III N2136 V N2154 V-VI N2173 III-IV N2209 V-VI N2213 II N2214 26 M 24 M 23 M 27 C 25 M 29 M 28 M 31 M 30 M 3 - 2 C 2 C 1 Ml 1 C 2 C 2 C 1 C 9 M2 8 C? 1 C 10 Ml 2 C 12 Ml 11 Ml 13 C 1 M2 16 M6 15 M2 14 M2 M C Em? N M Em? N M M M2 C M M? C M? Y Ml M3 MO? Y M? Ml Ea M? Y Y Y Y Y Y Y Y N? Y N Y Y N? Y Y Y Y Y N? Y Y Y N? Y N N Y Y Y? Y? Y Y? N? N? TLE 5 TLE 2 TLE 1 TLE 3 TLE 1 E5.MA4 TLE 5 TLE 3 TLE 4 TLE 2 TLE 4 B89,MA6 MA2 TLE 3 MAI TLE 3 TLE 1 W50 W46 K5 TLE 5 TLE 4 TLE 2 AM-12 HHU4502 AM-11 D10 D22 DI D17 D2 A100 B69 B72? FROGEL, MOULD,ANDBLANCOVol.352 Class K (6) (7) M (2) (8) 12.16 0.980.16 13.05 0.920.15 13.02(3) 0.96(3)0.15 12.33 1.030.20 12.44 13.04 10.92 1.600.56 11.62(3) 0.85 10.76(3) 1.53 12.25 12.03 12.89 11.65 11.44 11.31(5) 0.94 10.17(3) 10.18 11.39(5) 0.96(3)0.15(3) 11.28 1.150.24 12.93 12.26 11.92(3) 12.25 1.030.18 11.06(4) 1.260.32 10.12 1.900.73 10.38 1.510.50 12.13(3) 0.970.1612.110.93 11.21 10.78 11.32 1.270.37 11.86 1.050.21 11.55(3) 11.07(3) 13.92(3) 0.85(3)0.16(3) 9.93 1.040.24 10.23 13.18(3) 9.66(4) 0.830.20 12.66 0.810.2012.630.75 12.50 13.18(3) 0.86(3)0.24(3)13.150.80 14.43 11.57(3) 1.08(3)0.21 10.31 1.000.19 10.64(4) 0.850.22 10.71(3) 1.480.45 10.45 0.950.18 1.67 TABLE 1—Continued J-K H-K (8) (9) 0.74 1.06 0.18 2.05(3)1.10 0.98 0.17 1.11 0.22 1.09 0.20 1.88 0.73 2.07 1.12 1.04 0.22 1.07(3)0.24(3) 1.06 0.21 1.84(3)0.70(3) 0.99 0.16 12.461.02 0.89 0.12 1.87 0.68 1.13 0.24 1.81(3)0.67(3) 1.03 0.22 1.61(3)0.56(3) 1.13 0.31 1.05 0.32 0.22(3) 0.13 0.17 0.49 Ko (J-K)o(H-K)m (10) (11)(12)(13) 11.62 0.98 1'3.02 0.86 12.23 0.92 12.30 0.97 12.13 0.92 0bol 12.86 1.99 12.00 1.03 12.41 1.00 10.89 1.54 12.99 0.90 12.23 0.99 11.04 1.22 11.26 1.11 12.22 1.05 13.01 0.68 11.37 0.92 11.28 0.880.15 11.84 1.01 10.10 1.86 10.36 1.47 10.15 1.82 11.59 0.790.11 10.73 1.470.47 11.18 1.07 10.75 1.81 12.36 0.99 11.30 1.23 13.90 0.81 11.41 1.00 11.52 0.97 12.47 0.93 11.04 1.75 11.89 1.01 10.14 1.78 12.32 0.830.15 9.90 0.98 10.90 1.55 13.15 0.83 9.63 0.77 11.40 0.990.3014.24 11.64 1.070.2914.35 11.54 1.02 10.61 0.79 10.68 1.42 10.28 0.94 10.42 0.90 0.13 15.57 0.14 14.82 0.20 0.15 0.16 15.27 0.20 15.20 0.54 13.98 0.13 15.63 0.18 15.10 0.18 •14.91 0.14 0.20 15.15 0.15 0.20 0.17 0.31 0.23 1.08 0.71 0.72 0.22 0.19 0.36 0.49 0.14 0.22 0.66 0.21 0.68 0.22 0.54 0.10 0.19 0.15 0.18 0.20 0.65 0.19 0.18 0.22 0.20 0.43 0.16 0.17 14.44 A 14.25 A,B,D,M16 14.93(M) A,B 13.98 13.77 15.07(M) A,H 14.06 B 13.89 B 14.27 13.38 13.88 13.40 14.84 15.35 14.77 13.36 14.80 14.33(M) B,E 14.72 13.34 14.13(M) B,E 13.98 15.20 14.16 16.34 15.63(M) B 15.19(M) B 14.24 15.57 14.00 14.96 13.01 14.43 12.00 12.72 13.70 13.06 13.02 Source Notes (14) (15) A A A A A A A A A,F G,H G,H A G,H G B,E B,E H A,B, B B,E G,H G,H G,D, D,E G B,E B,E H G G G B,E 17 G G G G G G G G G G G G G 34 HHU1401 HHU2310 HHU4533 HHU3201 HHU4402 Dwarf? 1990ApJ. . .352. . .96F No. 1,1990 early-type starwasfoundnearacluster,thefollowingpro- cedure wasadopted:forclustersontheoutskirtsofCloud, of early-typestarsinitsvicinity,thatvaluewasused(see line ofthebar,Brunet’shighvaluewasused;onperiphery E(B—V) =0.7wasused.Forclusterslocatedneartheridge Persson etal.1983,hereafterPACFM).Ifnot,oronlyone its E(B—V)valueservedasaguideinchoosingthe final in theSMCismeanequaltoweakvaluefor the value wasused.Ifanearbyclusterwithearly-typestarsexisted, of thebar,globalvaluewasused.Forothercases,weak clusters. Galactic reddeningalone.Weassumedthatinternal E(B —V)valuefortheclusterinquestion. (1980, 1982,hereafterAMMA IandIII,respectively), LMC and,therefore,usedE(B—V)=0.07foralloftheSMC Bessell, Woods, andLloydEvans(1983,hereafter BWLE),as after AMMAIIandIV,respectively), MouldandAaronson also beenpublishedbyAaronson andMould(1982,1985,here- In thedirectionofSMCE(B-V)=0.04for47Tuefrom Photometry of117thestars withnewdatainTable1has d) ComparisonwithPublished Photometry © American Astronomical Society • Provided by the NASA Astrophysics Data System Westerlund (n.b.:theauthorshavebeenunabletotracethisreference);(11)Robertson1974;(12)BWLE;and(13)Arp N419-16 and17areveryclose;seenote(7).(9)StarsN419-2324(10)Allstarsinsurveyof N419-20 and21areveryclose;measurementofoneisprobablycontaminatedbyradiationfromtheother.(8)Stars however, itisnotparticularlybrightorred.(6)Measurementprobablyaffectedbyfaintstarinaperture.(7)Stars was obtained.(4)ForthisstarH=14.73(3),J—0.53(4).(5)Memberofclosepair—couldnotdophotometry; photometry. (3)FiveCstarswerefoundinclustervicinity,noneofwhichareconsideredasmembers.NoIRphotometry not morethan1".ThemeasurementsofG117inFrogelandCohen1982hereweremadewithbothstarsthe N1841 areMlorearlier.(11)StarsN1841-1and2averyclosepairofaboutequalmagnitudewithseparation (21) N1783-8appearsratherblueongrismplate.IsitanœCentypeCstar?(22)N306-6.TheapparentTiObands data point,useK+0.7.(18)AsnotedbyAMMA,starsTLE1and2ofNGC1987weremeasuredtogether.(19)N416-6 but quitebrightonSIT-directframes.ItdoesnotappeartobeanMstar.(16)Thisis“starA”ofFrogelandCohen aperture. (12)Bright,redstarlocatedclosetoclustercenter.(13)N1846-24isratherblueongrismplate.(14)TLE7,8,9, is toocrowdedtoclassifyongrismplate.(20)N416-7notaCstar;earlyplatebeanM;nonmember? 1963; (5)Hodge1981;(6)AMMAI-IV;(7)Walker1972;(8)FrogelandCohen1982;(9)Gascoigne1962;(10) in IRbecauseofstartowest.(28)Photometryallstarscenterclustersuffersfromcrowding.(29)Inreferences be earlyMs.NGC1850wasassignedSWBtypeIIonbasisofC-Mcomparisonwith1854.(27)Couldnotobserve two clusteraslistedbyRobertson1974werealsoobserved.AlloftheC?StarsshowonlyweakCNbands;theycouldall Crowded andpoorseeing.(26)Inadditiontostarsselectedfromgrismsurvey,thereddestbrightestinthese grism platemaybeflares.(23)N1850-7.Twoorthreefaintstarsinaperture.(24)Severecrowdingproblems.(25) 1980; (D)FrogelandCohen1982;(E)AMMAIII;(F)J.H.Elias,1982privatecommunication;(G)Thispaper, 1958. unresolved clusterofstars.(34)AllbrightstarsincentervisibleonTVwerecheckedatK.Somearesocloseto class veryuncertain.(31)NotvisibleonTV.(32)Toocrowdedtodophotometry.(33)OnTVthisappearsbean noted nootherphotometryofindividualstarsexistsforcluster.(30)Faint(andtoocrowded)IR;spectral 1982 Feb;(H)AMMAIII;(I)BWLE. nonmembership isnotclearcut.(37)KorMtypefromCCDspectra. large-amplitude variablesimilartoVIandV8.Also,sinceitisquiteclosethecenterofcluster,casefor star 3inthepresentlist.(36)AMMAconsideredthistobeaforegroundstar.Lloyd-Evans1980anotesthatitis one anotherthattheycouldnotbemeasuredindividually;however,noneappearedtosignificantlybrighteratKthan 10 inN1987werenotpickedoutbygrismsurvey.(15)N2121-5isveryfaintonanddirectplatestakenforsurvey 1982. (17)N2213-7,8aredoublestarswithaseparationlessthan1"andapparentlyequalmagintheIR.Whenplotting Cluster #ClassMemI.D. V (1) (2)(3)(4)(5) N2231 References forCols.(5)and(6).—(1)Walker1970;(2)LloydEvans19806,1983,1984;(3)Thackeray1958;(4)Tifft Notes.—(1) ClustersurveyedbyAMMAIIbutnoredstarsfound.(2)Memberofclosepair—couldnotdo References forCol.(14).—(A)Thispaper,1981Dec;(B)Mar;(C)Frogel,Persson,andCohen 4 M? 3 C 6 M? 1 - 7 M? 8 M2N 9 C?N 10 M2N 11 M?N Y Y Y Y Y TLE 2 TLE 1 AGB OFMAGELLANICCLOUDCLUSTERS Class (6) (7) K 10.71 13.60(3) 0.78(4)0.16 13.99(3) 14.13(3) 12.08 10.36 10.41 14.51(5) 13.03 TABLE 1—Continued J-K 0.87(5)0.13(3) (8) 0.80(3)0.15 1.47 0.49 0.77 0.80 0.78 1.68 (9) H-K 0.62 0.25 0.20 0.20 0.019, 0.000magforthe117stars.Thereisnosignificantdiffer- ence betweencarbonstarsandnon-carboninthiscom- given byEliasetalforJ—XandH—Kasred2.0 1.0, linear transformationsbetweenthetwophotometricsystems parison. Nordowefindanysystematicdeviationfrom the Elias etal(1983).Themeandifferencesinthesense(Table tendency forthetransformedphotometryofBWLEto be respectively. Theonlyhintofinhomogeneityinthedata is a measurements inX,J—X,and H—Kis0.19,0.13,and0.13 the clusterbackground.Inany case,theeffectistoosmalltobe than fortheCTIOones,thusincreasingcontaminationfrom aperture andgreaterchopperthrowfortheAAOobservations mag, respectively,andisdominated byafewstars.Thisis of concernforthepresentpurposes. illustrated inFigure1.Asnoted above,themeasuringerrorsin indicated inthetable.Inordertocompareournewdatawith the presentwork arealmostalwaysless than 0.03mag;a 1 —published)forK,JK,andHrespectivelyare0.002, metry totheCTIO/CITsystemwithequationsgivenby these publishedsourceswefirsttransformedBWLE’sphoto- ^0.03 brighterinK.Thistrendcouldarisefromuseofalarger The varianceofanindividual pair(Table1—published)of (10) (11)(12)(13) Ko (J-K)o(H-K)om, 13.57 0.72 10.68 1.41 14.10 0.74 13.96 0.81 10.38 0.71 14.48 ... 12.05 0.74 10.33 1.62 13.00 0.72 bo 0.47 0.14 0.13 0.11 0.60 0.23 0.18 0.18 13.69 15.84 16.40 13.39 12.63 14.36 13.47 15.27 Source Notes A,H A,H G A (14) (15) G G G G G Dwarf 105 1990ApJ. . .352. . .96F 106 © American Astronomical Society • Provided by the NASA Astrophysics Data System N1651 N299 N1751 N1846 N1783 I Cluster # N419 N231 N220 N1866 V N1850 N1806 N1651 N602 N269 non-members N2107 N2058 5 N1978 V V N2214 N2121 N2108 III V N2209 VI IV III 6B II III-IV VI V D41 IR1 IR1 IR1 D2 19 15 10 10 13 18 15 14 4 4 4 4 2 9 2 7 3 5 5 3 5 7 1 1 1 FROGEL, MOULD,ANDBLANCOVol.352 2 Additional PhotometryforAGBStars M C MO 0.85 C? C M4 1.10 c C C C C C M M M M Ml 0.98 M M Ml M C M M c Ml 0.97 M7 M2 0.98 M M C M sp J-KH-KM, M0 M M M M 0.77 M? 0.98 c M M M 0.97 0.94 0.95 2.42 2.59 1.13 1.02 1.01 1.10 1.04 1.86 1.12 1.11 1.08 1.03 1.72 1.07 1.25 1.66 1.57 1.32 1.64 1.68 1.54 1.87 1.47 1.72 1.33 0.16 0.20 0.29 0.18 0.16 0.26 0.27 0.25 0.23 0.17 0.58 0.59 0.63 0.64 0.57 0.75 0.20 0.23 0.18 0.21 0.38 0.13 12.11 0.22 0.72 0.49 0.64 0.18 0.24 0.38 0.21 0.62 0.22 0.43 0.53 1.31 TABLE 2 13.43 13.42 13.64 13.73 13.41 13.47 14.32 14.38 12.72 13.34 13.40 13.58 13.13 12.87 12.86 13.35 13.66 14.19 12.98 14.37 14.20 14.18 14.51 14.49 14.20 14.19 13.45 14.18 12.00 13.74 13.52 12.58 12.65 13.18 bol 0.22 0.48 8 0.67 6 0.64 5 0.20 12 0.23 0.33 1.08 8 1.09 1.05 1.88 1.73 5 1.74 8 K-L 0.06 3 0.03 3 0.18 4 0.19 3 0.09 3 0.07 0.08 4 0.08 3 0.21 0.16 0.05 0.15 0.15 3 0.21 0.18 0.18 4 0.07 0.23 4 0.16 0.14 4 0.09 0.10 0.14 3 0.07 4 0.02 0.11 4 0.07 3 0.06 0.06 0.06 0.31 3 0.41 3 0.14 3 0.12 3 0.22 4 0.08 0.10 3 0.08 0.06 ho 2 -0.06 -0.04 -0.01 3 -0.01 3 -0.01 -0.15 -0.24 0.18 0.25 3 0.03 0.19 0.24 0.01 0.15 0.12 0.16 0.15 0.19 0.04 0.20 0.39 0.31 0.00 0.01 0.00 0.03 0.15 0.24 0.19 0.23 0.21 0.21 0.19 0.24 0.24 0.14 0.19 0.21 0.12 3 CO 1990ApJ. . .352. . .96F the differenceinK magnitude. instead toassignatypeofVI-VII.SWBtypesassignedbyus (implied byitsUBVcolors)thatweusedtheC-Mdiagram (1982) andtheintegratedUBVcolorsofvandenBergh(1981). be inerror,subsequentworkhasshownthatSWB’sunderlying are parenthesizedinTable1. bright star.TheC-MdiagramforKron3(Rich,DaCosta,and This wasnotpossibleforNGC361becauseofasuperposed to theclusterstheyobservedcorrespondingincreasingage tonie changeinageandmetallicity.SWBassignedtypesI-VII dimensional sequenceandthatthisreflectsamono- clusters intheMagellanicCloudscouldbearrangedaone- Mould 1984)differssomuchfromthatofatypeVIIcluster they didnotobservebasedonFigure8ofFrenkandFall and decreasingmetallicity.WeassignedSWBtypestoclusters aids interpretationofourclusterdata.Theyarguedthatthe cooler (redder)whenthestarbecomesfainter. No. 1,1990 a weakcorrelationinFigure1theexpectedsense(Elias, amplitude variationsinthelightofredgiantstars.Thereis Frogel, andHumphreys1985):thestellaratmospheresbecome studies. Evidently,thevaluesforvariancereflectsmall- similar errordistributionpertainstotheotherpublished Fig. 1.—ForstarsinTable1withpreviously publishedphotometrythisfigureillustratesthedifference(in senseTable1—published)inJXasafunctionof Although someoftheindividualclusterclassificationsmay The classificationschemeofSWBprovidesaframeworkthat © American Astronomical Society • Provided by the NASA Astrophysics Data System III. THESWBTYPEASANAGEINDICATOR Cluster #spK-LH0CO N2231 M2N N2154 7Em N2108 19C N2107 2C N1987 12M N1978 16C N1866 6M Frogel, Persson,andCohen1980Frogel1982. 2 a forSMCstarshasbeenadjustedby—0.3mag.SomeoftheCOandH0dataarefrom 2 6 M AGB OFMAGELLANICCLOUDCLUSTERS TABLE 2—Continued delta K (m —M)oftheLMC,followingMould’s(1988)review,and slower pacethanintheGalaxy(see,forexample,Twarog (1983). Hisageswereincreasedby0.115dextomatchtheLMC (m —M)=18.6fortheSMC.Bothvaluesaresystematically Absolute agesrequireknowledgeofthedistancemodulus determined agestabulatedbyMouldandDaCosta(1988). not welldetermined,however,andsowehaveaddedafurther uncertain by±0.2mag.Theseadoptedmodulinecessitatean the MagellanicClouds.Inthispaperweshalladopt18.3as seven, mostlyyounger,clustersfromthereviewbyHodge adjustment of—0.029dextotheclusteragescollectedby the precisioninspecifyingtype.Theslopeofthisrelationis age, whichcorrespondsto0.6inSWBtype,i.e.,approximately by SWBtypewithavarianceof0.25inthelogarithm these agesandSWBtype.Forthissubsampleageispredicted Mould andDaCosta.Figure2showsthecorrelationbetween shown, metalenrichmentinbothCloudsproceededatamuch and SMCweredifferent(e.g.,SWB).AsCohenothershave two CloudsifthechemicalenrichmenthistoriesofLMC these twoquantities,however,mayconceivablydifferforthe premise iscorrect,namelythattheageandmetallicityof 1980). Bica, Dottori,andPastoriza1986).Therelationshipbetween Magellanic Cloudclustersarecloselylinked(e.g.,Cohen1982; 0 0 Thirteen ofthe35clustersinpresentsamplehavewell 0.22 30.00 0.49 5 1.68 12 1.09 4 0.20 0.23 0.17 40.25 0.09 30.22 0.12 -0.01 107 1990ApJ. . .352. . .96F 4 108 distance modulusof18.3adoptedhere.Unadjustedagesfor solid lineistheleast-squares fittoallofthepoints. three moreyoungclustersweretakenfromMateo(1988). based onvaluesinMouldandDaCosta(1988),foreachSWB Iben andRenzini1984). type asspecifiedinthetable(Becker,Iben,andTuggle1977; these agesarealsogiveninTable3.Thesewerecalculatedfor sample aregiveninTable3.Turnoffmassescorrespondingto an assumedheliumcontentY=0.25,andmeanmetallicities, Mean agesforSWBtypesII-VIIfromthefittothislarger colors andmagnitudesoftheclustermembers.Anumber left panel;typesIII-IVandIVareintheupperright cluster membersinTable1areplottedFigure3.They subsequent sections. trends withclustertypeareobvious.Thesewillbequantifiedin grouped accordingtoage:typesI,II,andIIIareintheupper right panelas“late-type.”TheCandMstarsshowlittle type Vinthelowerleftpanel;andtypesV-VI,VI,VII sharp andoccursat(H—K)^0.25forallgroupsthatpossess overlap inFigure3.Thetransitiontocarbonspectraisquite the upperleftpanelas“early-type”andthoseinlower the lowerrightpanel.Wesubsequentlyshallrefertoclustersin 0 I _____is10.8 VII 15.1-1.4101.0 VI 14.614.114.4-1.033001.4 V 14.513.614.1-0.611002.0 IV 14.112.913.5-0.83702.7 III 13.412.813.1-0.11204.0 II 13.912.913.4—406.9 a Half-integraltypesareroundeddown. IV. PHOTOMETRICCHARACTERISTICSOFTHECLUSTERSTARS Near-infrared two-colordiagramsforstarsidentifiedas This sectionpresentsabriefqualitativedescriptionofthe Fig. 2.—SWBtypeforclustersasafunction ofageastabulatedbyMouldandDaCosta(1988)(soliddots),Hodge (1983)(circles),andMateo(1988)(squares).The Type m[M/H](Myr)M boMto © American Astronomical Society • Provided by the NASA Astrophysics Data System 3 Properties ofClustersbySWBType a) Colors TABLE 3 FROGEL, MOULD,ANDBLANCO Age displayed separately.Tobetterdefinethetrendforthislatest Dwarf interlopershavebeenexcluded.Thegroupsareasin Figure 4forthestarsdesignatedasclustermembersinTable1. panel ofFigure4.Threeobviousfeatures4,pre- 2257 fromFrogelandCohen(1982)AMMAIII. Figure 3,exceptthatthestarsfromSWBVIIclustersare viously notedforsmallersamplesofclusterstars(Frogel, the LMCdistance.TwoexceptionallyredstarsfromNGC type, wehaveaddedadditionaldataforNGC121,1841,and SMC starshavebeenbrightenedby0.3magtocorrectthem There isatendencyforthestarsfromlatestSWBtypes,i.e., by solarneighborhoodfieldgiantsandglobularclustergiants. youngest andmostmetal-rich,lieclosertothefieldline.Sucha globular clusterline,whilestarsfromtheearliesttypes,hence sequence. Theymostlyliebetweenthemeansequencesdefined variation withmetallicitywouldbeexpectedfromtheanalysis the oldestandmostmetal-poorclusters,toliecloser (J —H)<0.6and(JT—K)~0.2.TheseareprobablyM been identifiedwithanycertainty.AfewoftheMstarsin although theabsorberresponsibleforthesecolorshiftshasnot of GalacticbulgestarsbyFrogelandWhitford(1987), 1978 and2121lieofftheright-handedgeoflowerright Figure 3liesignificantlybelowthemeansequenceswith metallicity-related blanketingeffectbyCFPE.TheSMCC et al1981,hereafterCFPE);bothclearlydifferfromthatfor dwarfs andaresodesignatedinTable1. the LMCandMilkyWayCstarsisinterpretedasa Galactic Cstars,theupperstraightline.Thedifferencebetween with themeanrelationfornonclustercarbonstarsin exception ofthosefromthelatesttypeclusters.Itagreesclosely these stars.Thecarbonstarsfollowawell-definedsequence effect. stars mayshowagreaterdisplacementfromthelocalcarbon that appearstobeindependentofSWBtypewiththepossible star linethantheLMCones.Again,thiscouldbeametallicity Magellanic Clouds,thelowerstraightlineinFigure3(Cohen 0o Apparent bolometricmagnitudeisplottedversus(J—K)in Cluster MgiantsinFigure3alsofollowawell-defined 0 b) TheH-RDiagram Vol. 352 19 90ApJ. . .352. The solidcurvedlineisthemeanrelationforglobularclustergiants(Frogel,Persson,andCohen1983).dasheddot-dashedlines arethemean carbon stars(CPFE).ThesymbolcodeisthesameasonFig.4. relations forfieldgiantsanddwarfs,respectively(Frogeletal.1978).ThestraightlinesarethemeanGalactic{upper)Magellanic Cloud (lower)field panel islabeledwith theSWBtypespresent.Thelongsolid lineistheapproximatedivision betweenstarsfromtheyoungest(I-III) clustersandfromallothertypes. Fiducial linesforthe brightestpartsofthegiantbranches oftheGalacticglobularclustersM92, M3,and47Tueareindicatedinthe lastpanel. No. 1,1990 Fig. 3.—J—H,HKrelationsforclustermembersfromTable1.Theclustersaredividedintofourgroupsinorderofincreasingageanddecreasing metallicity. © American Astronomical Society • Provided by the NASA Astrophysics Data System AGB OFMAGELLANICCLOUDCLUSTERS (H-K) 0 109 1990ApJ. . .352. . .96F color andprobablycorrelated withluminosityaswell.The present dataarenotadequate toseparatetheeffectsoflumin- have strongerCOindices.If not duetoluminosity,thiscould may beatendencyforthestars fromtheearliestSWBtypesto osity andmetallicity ontheH0indices. H0 indicesarestronglycorrelated withSWBtypeatconstant be aresultofhighermetallicities fortheyoungerclusters.The fore, wecannotdrawanyconclusionsfromdifferencesin the stars donothavethestrongestCOindices.However,there Figure 6showsthatinanygivenintervalofJ-Kthebrightest relative distributionsoftheCOindicesclusterand field selected tobethelatestMstarsinBarWestfield.There- lay systematicallyabovetheGalacticline,butformer are indices fortheMstarsiswellrepresentedbymeanline for also systematicallyredderthantheclusterMstarsastheywere Galactic stars.MagellanicCloudfieldMstars(CFPE,Fig. 4) its cluster’sSWBtype.Inthemeandistributionof CO Magellanic Mstars. tions fromFigure5.Eachstarisplottedwithanumbergiving cluster sampleinFigure5aresimilartothoseofthereddestC also notethatthelocationsoftworeddestCstarsfrom for thedifferencesinJHKcolorspointedoutabove.We in theyoungerclusters.TheCstarsSWBVIIclustersare clusters appeartobesomewhatfainterthantheircounterparts present onlyinclustersoftypesIV-VI.ThosefromthetypeVI colors. Withonepossibleexception,luminousCstarsare 110 2 stars intheCloudfieldsampleofCFPE. weaker CObands,thesameexplanationadvancedtoaccount themselves fromMstarsintheH-Rdiagrambytheirred comment. 2 to thelowermetallicityofCloudsthatwouldresultin the continuumslope).ThisdifferencewasattributedbyCFPE actually presentinacarbonstar,thisindexisjustmeasureof cally weakerby0.05-0.10mag(sincenoH0absorptionis carbon starsofthesamecolor,COindicesaresystemati- for MagellanicCloudfieldcarbonstars(CPFE,Figs.4and6). (J —K).Thecarbonstardistributionscloselyparallelthose ters. significantly lessluminousthanthoseintheearliertypeclus- In particular,whiletheH0indicesoverlapthoseofGalactic youngest (I-III)groupofclustersplottedandthosefromthe particularly noticeabledifferencebetweenthestarsfrom Persson, andCohen1980;AMMAIV;Frogel1984),deserve and H0indicesforallclustermembersfromTable2on cool giantsobserved. type :thosefromyoungerclusterslieonbluerAGBs.Thereisa ignition intheglobularclusters. comparable toorlessthanthepointofdegenerateheliumcore stars, butMstars.Thesearealsoamongthebrightestof second youngestgroup.Also,theluminosityachievedby M starspopulategiantbranchesthatareorderedbySWB Galactic globularclusters.Allothersfoundhaveluminosities one starthatisbrighterthanthetipofgiantbranches M starsincreaseswithdecreasingclusterage. 2 0 2 2 An examinationoftheluminositiesclusterMstars in Figure 6isanexpandedviewoftheclusterMstardistribu- The twopanelsofFigure5showthedependenceCO 2. WiththeexceptionofthosefromtypeVIIclusters, 4. AmongtheSWBVIIclustersthereappearstobeonly 3. ThemostluminousAGBstarsinyoungclustersarenotC 1. Asinthecolor-colorplot(Fig.3),carbonstarssegregate © American Astronomical Society • Provided by the NASA Astrophysics Data System c) COandH0Indices 2 FROGEL, MOULD,ANDBLANCO lines forGalacticstarsareshown. more detail.TheSWB typeoftheparentclusterforeach Mstarisindicated. Fig. 5.—TheCOandH0indicesforclustermembersfromTable3.Mean Fig. 6.—Sameas5exceptthat the Mstardistributionsareshownin 2 1 2 (J-K)o (J-K)o Vol. 352 1990ApJ. . .352. . .96F most likelytheoriginofredJHKcolorsaswell,duetoa No. 1,1990 correct. TwoobservationsofNGC2121-5giveninTable1 Table 1.NGC419-10isjustoutsideofthemembershipcircle center, soitsclassificationasanonmemberismorelikelytobe NGC 2108-19,ontheotherhandisabout5'fromcluster have colorsthatclearlyseparatethemfromallotherstarsin NGC 1978-IR1isthereddeststarinoursurveyandwasfound indicate thatthisstarisprobablyalong-periodvariable(LPV). red stars,though,suggeststhatitmaybeaclustermember. so isclassifiedasanonmemberinTable1.Therarityofsuch by accident.ItwasnotvisibleontheacquisitionTVatany (Table 2)indicativeofextensivecircumstellardust.Thisdustis large-amplitude variationsinitscolorsandmagnitudesis time andisjudgedtobefainterthan19atV.Ittoodisplays combination ofreddeningandthermalemission.Bolometri- also alikelyLPV.AllfourofthesestarshaveredK—Lcolors wavelengths. ThatLPVshavecolorsdistinctfromnon-LPVs cally, thesestarsdonotstandoutfromtherestofAGB latest type.FortypesIV-VItheshiftsaresmall,whereas ford 1987).Inallcases,ahighmass-lossratethatresultsfrom stars observed,exceptthatNGC1978-IR1appearssomewhat between thesetypesandtheI-IIIclustersshiftislarge. shift steadilyredwardasoneadvancesfromtheearliestto and Elias1988)Mgiantsinthebulge(FrogelWhit- has beenfoundtobetrueforGalacticglobularclusters(Frogel underluminous ;itmayhavesignificantluminosityatlonger lower panelofFigure7isthefieldstardistributionforBar line anddisplaytheresultingdistributioninFigure7.In define xtobetheperpendiculardistanceofeachstarfromthis separates starsfromclustersoftypeI-IIItherest.We the large-amplitudepulsationmustresultinlargeamounts in thesamemannerasclusterstardistribution.Both dis- West regionoftheLMC(FrogelandBlanco1983)calculated Figure 4wehavedrawnafiduciallinethatapproximately Stars fromtheSWBVIIclustersdonotfollowthistrend. of dustthatinturncausethedistinctcolorsLPVs. cluster formationaswell.Thepeaksatpositivexaresimilar to epochs ofstarformationoccurredinthewesternpart the tributions showastrongpeakatx0.2magandweaker hundred Myrago.Figure7isconsistentwithtwoepochs of bar oftheLMC—oneseveralGyrinpast,othera few one atx<0mag.Onthebasisofthisdistributionfor the sponding toAGBstarsfromtherecentepochofstarforma- one another.ThepeakatnegativexintheSWBsample,corre- LMC fieldMstars,FrogelandBlancoarguedthattwomajor tion, isenhancedbecauseofselectioneffectsinthecluster formation inanotherregion of thebarfromastudyCep- heids andlong-periodvariables. Chiosietal.(1986)suggest, sample itselfinfavorofyoungobjects.Wood,Bessell, and also onthebasisofcluster agedistribution,thatamajor strong discontinuities intherateofformation ofLMC although fromananalysisof thecolorsofclusters,Chiosi, star-forming eventhappened intheLMC~4Gyrago, Paltoglou (1985)havefoundevidencefortwoperiodsof star Bertelli, andBressan(1988)find “noconvincingevidencefor The reddestCstarsobservedinthecourseofoursurvey In ordertomeasuretherelativelocationofMgiantsin Figure 4showsthatforSWBtypesI-VItheclusterMstars V. MSTARS,CLUSTERMETALLICITIES,ANDAGES © American Astronomical Society • Provided by the NASA Astrophysics Data System a) MStarColorsandClusterAges d) TheReddestStars AGB OFMAGELLANIC clusters theyadd,though,thattheirdataarenotadequateto rule outsuchdiscontinuities. all clusterMstarsfromthelongsolidlineinpanelsofFig.4.Bottom:a epoch. Thisepochcouldcorrespondwiththetimeofformation indicates thatclusterformationalsooccurredatamuchearlier similar distributionforMstarsintheBarWestfieldofLMC(Frogeland clusters, namely,theycorrespondcloselyinluminosity with lation accountsforabout6%ofthetotalmassbothClouds, predicted valuesforcoreheliumflashinfirstascentgiants. In and Persson(1983)forthebrighteststarsinGalacticglobular these clustersshowthesameeffectfoundbyFrogel,Cohen, about thesameasratioofhalomasstototalfor the Blanco 1983). the lowerleftpanelofFigure4NGC1841([M/H]=—2.3; that exceptforonestarinNGC121,thebrighteststarsfrom of themanyfieldRRLyraestars.Suchanoldstellarpopu- fication asMagellanicCloudanalogsoftrueglobularclusters. VII clustersinFigure4isthereforeconsistentwiththeiridenti- 2257 ([M/H]=—1.4)withM3.ThelocationoftheLMC type Cohen 1982)canbedirectlycomparedwithM92,andNGC Milky Waywithinthesolarcircle(Frogel1984).Wealsonote contrary totheinferencebyAMMA IIIthattheLMCglobu- They aretoooldandmetal-poor tohaveAGBstars.Thisis mean locationofthestars from typeVIIclustersspreads larger thanwearepresently using.Second,thefactthat Galaxy. Theseauthorsadopted adistancemodulus0.4mag lar clustersystemcouldbe^ 3Gyryoungerthanthatofthe across theloci of thegiantbranchesglobular clusterswitha CLOUD CLUSTERSHI The locationofthestarsfromtypeVIIclustersinFigure4 Fig. 7.—Top:Thedistributionoftheperpendiculardistance,x(inmag) 1990ApJ. . .352. . .96F cluster’s giantbranchismonotonicallycorrelatedwithmetal- cated aone-to-onecorrelationbetweenclusterageandcom- clusters ofanyage.However,foralargeenoughrangeinage, expect thatthesametrendshouldbepresentforagroupof licity inthesensethathighermetallicityclustershaveredder younger ageshouldhavehotterandbluergiantbranchesthan giant branches(Frogel,Cohen,andPersson1983).Wewould the metallicityeffectmaybecomemaskedasclustersof position fortheMagellanicClouds.Ourdatashowaclear older clustersofthesamecomposition.SWB’sanalysisindi- considerable rangeinabundanceisconsistentwithabun- siderably improvedagedeterminationsforanumberof nic Cloudclustersbasedondigitaldatahaveresultedincon- trend ofbluercolorsforclusterMstarswithearlierSWBtype. 112 In thepastfewyears,color-magnitudediagramsforMagella- dances derivedfortheindividualtypeYIIclusters. At agivenKmagnitudelevel,theJ—Xcolorofglobular b) TheCorrelationofAgeandMetallicity © American Astronomical Society • Provided by the NASA Astrophysics Data System determined afteradjustingitsdistance modulusby—0.3magtocorrespondthatoftheLMC.Thevalues of Cluster SWB Kron 3 N1978 N1850 N1846 N1806 N1751 N1652 N1651 N2213 N2209 N2173 N2154 N2136 N2121 N2108 N2107 N2058 N1987 N1866 N1854 N1841 N1783 N2257 N2231 N2214 3 N339 N231 N152 N121 N416 N361 N306 N299 N269 N265 N220 N419 N411 TheAGBinthistablereferstoall starswith<—3.6.TheGBcolorsforSMCclustershavebeen tabulated havenot beensoadjusted:theyaretheobserved values. 4.0 7.0 0.0 7.0 2.5 4.0 5.0 5.0 5.0 5.0 6.0 5.5 6.5 5.0 4.0 2.0 7.0 5.0 6.0 5.0 3.0 3.5 3.0 3.0 7.0 2.0 5.5 5.5 5.0 2.0 5.0 6.0 3.0 6.0 3.0 3.5 3.0 1.0 m bol 12.45 12.05 10.77 11.60 10.40 10.38 10.94 12.35 12.16 10.95 11.79 12.68 11.61 12.25 11.25 10.20 11.37 11.40 10.86 13.38 10.51 10.88 11.60 14.51 12.85 10.42 12.74 10.88 11.18 10.06 9.98 9.44 9.95 8.81 FROGEL, MOULD,ANDBLANCO J-K H-K 0.71 0.61 0.55 0.81 0.23 0.49 0.56 0.49 0.63 0.60 0.82 0.66 0.74 0.48 0.56 0.12 0.68 0.48 0.52 0.66 0.65 0.11 0.49 0.73 0.56 0.65 0.80 0.56 0.43 0.11 0.74 0.44 Cluster colors 1.20 minus AGB 3 Integrated ClusterParameters -0.15 -0.01 -0.21 0.10 0.13 0.09 0.16 0.19 0.39 0.09 0.06 0.07 0.13 0.13 0.07 0.13 0.06 0.14 0.06 0.23 0.04 0.08 0.29 0.11 0.16 0.01 0.18 0.14 0.11 0.15 0.10 0.22 0.10 TABLE 4 0.00 0.36 0.00 0.00 0.31 0.28 0.20 0.00 0.22 0.11 0.00 0.37 0.03 0.20 0.00 0.00 0.00 0.00 0.00 0.05 0.46 0.00 0.58 0.22 0.00 0.13 0.00 0.00 0.14 0.13 0.00 0.00 0.00 0.04 0.23 AGB fraction C andM of mi city ofstars.Extrapolationassumedthatclustergiantbranches includes someclustersthathavesparsedataat12.8.Theresults Table 4aretheJ—KvaluesatX=12.0inLMCwhich in Table4.ThesearefromC-Mdiagramsandisochronefit- present dataorfromFrogel,Persson,andCohen(1983).The considered, thereisnoevidencetothecontraryfrom extrapolation orisparticularlyuncertainbecauseofthescar- values. Avalueinparenthesesmeansthatitisbasedon best availableageandmetallicitydeterminationsarealsogiven are linearintheK,J—Kplane.Ifnon-LPVMstarsonly of thefollowinganalysis,though,areidenticalfortwo Persson 1983).ThesevaluesaregiveninTable4.Also calibration ofGalacticglobularclusters(Frogel,Cohen,and J —KwasdeterminedatX=12.8intheLMC(13.1 number ofMstarstodefinethegiantbranch,value bo SMC) whichcorrespondstoM=—5.5,thevalueusedfor infrared data. correlation ofageandcompositionwiththehelpnew clusters (MouldandDaCosta1988).Wecanreexaminethe K For eachclusterinthepresentsurveywithasufficient 0.05 0.03 0.00 0.26 0.00 0.00 0.36 0.05 0.00 0.39 0.57 0.28 0.06 0.24 0.28 0.16 0.24 0.17 0.06 0.03 0.40 0.00 0.25 0.44 o’oo 0.37 0.20 0.16 0.16 0.46 0.21 0.58 0.38 0.17 0.15 0.60 0.88 0.88 0.88 0.85 0.83 0.88 0.83 0.88 0.92 0.85 0.71 0.91 0.81 0.85 0.88 0.62 0.61 0.79 0.89 0.90 0.85 0.86 12.8 12.0 J-K0.85,i.e.,intherange5-9, envelope (FrogelandRicher1983;AMMAIV).Alternatively, carbon coreisaslow5-6Mduetoconvectiveover- the Mstarswithm(LMC)<13wouldberequiredtotestits with thefirsthypothesis,althoughhigh-resolutionspectraof shooting (BeckerandIben1979;Bertelli,Bressan,Chiosi themselves (WoodandFaulkner1986). cal expectations:thereisadeficiencyofAGBstarsgenerally, However, weshallseein§VlldbelowthattheAGBlumin- prediction thatthereshouldbeanitrogenexcessinthesestars. not justCstars.Thefirsthypothesis,then,failsbythiscri- osity fractioninMagellanicCloudclustersfallsbelowtheoreti- terion. FrogelandRicher(1983),MouldReid(1987, (m —M)=18.3fortheLMC).ThereisarapidriseinL in initial4Mstars(whichcorrespondstom=12.95for cate thatthermalpulsesdonotcommenceuntilL~10 of luminousstarsinfieldstheLMC. Reid, Tinney,andMould(1990)havenotedasimilardeficiency Evolutionary calculationsreviewedbyLattanzio(1990)indi- between 3and5M.Carbonstarswouldthereforenotbe expected inSWBIIIclustersuntilm<13.Thecalculations 1985; Bertelli,Chiosi,andBertola1989). function asthesestarswillnotundergothermalpulses.More masses greaterthanabout6MfromtheAGBluminosity intermediate-mass starsresultsintheeliminationofwith inclusion ofconvectiveovershootinginmodels of Bertelli,Bressan,andChiosi(1985)furthershowthatthe (1985) arguethatthesecond,ormass-loss,hypothesiswouldbe recent calculations(Bertelli,Chiosi,andBertola1989)reduce coretot0 likely tohave“devastatingconsequences”forourunderstand- the masslimitabovewhichdegeneratecoreCignitiondoesnot 0 instructive. Tocarryoutsuch acomparison,itisnecessaryto lation. Theclusterssurveyed in theMagellanicCloudscovera assembly ofcoeval,initiallycehicallyhomogeneous,single ing ofotherevolutionaryphases.However,thisisonlytrueifa occur evenfurtherto4.5-5.2M.Bertelli,Bressan,andChiosi bol tion stagestoacluster’sintegrated luminosityandtocompare determine therelativecontributions ofstarsindifferentevolu- tions ofthetheoryoutlined by RenziniandBuzzoniwillbe detailed comparisonofourresults withthefirst-orderpredic- sufficient rangeinchemical compositionandagethata stars.” Astarclustermaybeassumedtohavesuchapopu- refer toasa“simplestellarpopulation(SSP),”namely “an phase mayresultfromtheactionofa“superwind”(Ibenand red giantevolutionaryphases.TheterminationoftheAGB parameterized mass-losslawsuchasReimers’sappliesforall whose consequencesarequitelimited(butpossiblyadhoc). with convectiveovershootingandamodestexcess,overthe Renzini 1983)orenvelopeejection(WoodandFaulkner1986) in theLMC.Theovershootinghypothesisis,therefore,a real 0TP 0bol TP0 further inthenextsection. tion fortheabsenceofluminouscarbonstars;wediscuss it Reimers rate,ofmasslosscanfittheAGBluminosityfunction Finally, Chiosietal(1986)haveshownthatstellarevolution 0 rival tothesecondhypothesismentionedaboveasanexplana- bol 0 0 At firstsight,thepresentdatawouldappeartobeconsistent 3. Theminimuminitialmassfornondegenerateignitionofa The presentdataareconsistentwiththethirdhypothesis. Renzini andBuzzoni(1986)examinetheoreticallywhatthey d) ContributionoftheAGBtoIntegratedClusterLight 1990ApJ. . .352. . .96F next twosubsectionsdiscusssuchacomparison. the colorsofclusterstothosetrueglobularclusters.The 118 components inaSSPrelevanttotheclustersincludedour for theMagellanicCloudclusters.However,itisobserva- colors andmagnitudesinPACFM.Wedeterminedwhichof the AGBstarsbrighterthanthislimitasluminousstars. tenths ofamagnitudefainterthanthislimit.Wewillreferto survey isnearlycompleteforallclusterCandMgiantsseveral AGB starsfainterthanthislimitwilloccuraswell.Thepresent survey aretheredgiantbranch,RGB,andAGB.Nowfor lated bolometricmagnitudesfortheintegratedclusterlightin procedure usedformakingtheintegratedmeasurements be ontheedgeofaperturewereincludedascentering tionally establishedthatattheRGBtipisonlyaslowly a starontheAGBcannotbeseparatedfromoneRGB giants fainterthanthelevelofcoreHeflashinlow-massstars, indicate thefractionalcontributionofallluminousAGBstars light remainingfromtheclustersafterthissubtractionare band. InafewcasesitwasnecessarytoguessatÍ/—Fbased would, inalllikelihood,haveincludedthem.Wealsocalcu- total fluxesforthesestarsintheJHKbands.Starsthatwould aperture measurementmadebyPACFMandcalculatedthe the Table1starswouldhavebeenincludedwithinlargest brighter thanwhichwillonlybeAGBstars,althoughsome the theoreticallypredicteddependence(Frogel,Cohen,and varying functionofmetallicityandisincloseagreementwith given inTable4.Thesixthandseventhcolumnofthetable values fortheclusterlight.Thecolorsandmagnitudesof the luminousAGBstarsweresubtractedfromappropriate of Table4.Aprogramwasusedthattookintoaccountthe the biggestaperture;thesevaluesaregiveninthirdcolumn analogs ofGalacticglobularclusters.BeginningatSWB type marginally ifatallinSWBVIIclusters.Asargued § Yd the fractionalcontributionsforallclustersineachSWBgroup small numberstatistics,wealsodidthesumsandcalculated In ordertoillustratetheseresultsandminimizetheeffectsof and ofCstarsalonetothebolometricluminosityacluster. on theothercolors.Thesummedbolometricluminositiesfor Persson 1983).WetakeM=—3.6asthedividingpoint more orlessconstantcontribution fortypesII-III,cannotbe earliest typesorwhetherthefalloffisfollowedbyareduced but minimum intheircontributionbeforeanincreaseagainfor the VI, luminousAGBstarsrapidlybecomeanimportantcontrib- above, thisisconsistentwiththeirbeingMagellanicCloud the luminosity.Figure15showsthattheyarepresent only separately. TheseresultsareshowninFigures15and16. decided fromthepresentdata. SWBIclustersareyoung bright AGBstarsfallsrapidly.Whetherthereisa real type IVclusters.EarlierthanIV,thecontributionfrom and clustersineachSWBgroup. Uncertainties werecalculatedbasedonthenumberofstars enough thattheycouldcontain Msupergiants. utor tothebolometricluminosityandremainsothrough the C starsthattogether accountfornearlyall ofitsbolometric a CstarisNGC2209,rather poorclusterwithtwoluminous only intypeIV-VIclusters.The onepointattypeIII-IVwith UBV fluxesaswellanestimateofthefluxlongwardK bol In termsoftheirobservableimpact,thetwomostimportant Most oftheclustersinTable1haveintegratedinfrared First considerthecontributionofluminousAGBstars to Figure 16shows,like 14, thatcarbonstarsarefound © American Astronomical Society • Provided by the NASA Astrophysics Data System i) TheContributionoftheAGBtoaCluster’sM bol FROGEL, MOULD,ANDBLANCO dots withuncertaintiesindicatedaretheobservedvaluesforeachclasscalcu- luminosity. Onlyoneofthem,though,iscontainedwithinthe mass, isgiveninTable3. ters thatarisesfrombrightAGBstarsisshownasafunctionofSWBclass.The subtracted. TheconversionbetweenSWBclassandclusterage,orturnoff tion fromRenziniandBuzzoni(1986)witha25%contributiontheRGB lated asdescribedinthetext.ThedashedlineispredictedAGBcontribu- can comparetheobservedcontributionofluminousAGB AGB abovethepointofcoreHeflash. account for50%-100%ofthebolometricluminosityfrom aperture usedbyPACFM.Whenpresent,carbonstars Z =0.02,andrçi,thisfigureshowstherelativecontribu- to acluster’sMwiththeoreticalpredictions.ForT=0.28, more appropriatetotheclusterswillhaveonlyaminoreffect Although derivedwithavalueofY=0.25andsolarZvalue, evolutionary stagesasafunctionofageandturnoffmass. tions tothebolometricluminosityofaSSPfrommajorstellar differences betweenthesevaluesandthatwouldbe class. was subtractedfromtheAGBlinegivenbyRenziniand 2 andTable3.Ateachage,a25%contributionfromtheRGB Cloud clustersthatarisesfrombright CstarsisshownasafunctionofSWB the contributionofAGBfromRenziniandBuzzoni’s on thecomparison.Thelinelabeled“theory”inFigure15is Figure 4withtheagesforagivenSWBtypetakenfrom bol • rH Fig. 15.—ThefractionalbolometricluminosityofMagellanicCloudclus- With thehelpofFigure4RenziniandBuzzoni(1986)we • r—I kJ • r—H Fig. 16.—Theobservedfractional bolometric luminosityofMagellanic Sh o a o o a C O in o c o s a O O [/] SWB Type SWB Type Vol. 352 1990ApJ. . .352. . .96F No. 1,1990 cant. between thetheoreticallineandobservationalonein stars fainterthanthetipoffirstgiantbranch.Thedifference Buzzoni toallowforthefactthatwehavenotincludedAGB corresponding toaturnoffmassof~9M;theSSPunder- age intervalduringwhichAGBstarsareimportantcontrib- Figure 15forthelatesttypeclustersisjudgednottobesignifi- cores anddonotbecomeAGBstars.Lessmassivestars—older goes a“phasetransition”inRenziniandBuzzoni’sparlance. utors tothebolometricluminosity.AccordingRenziniand Buzzoni (1986),theAGBrisesrapidlyinimportanceatanage NGC 1850,1854,and2214),wecanbereasonablycertainthat hydrogen inshells.Ourobservationsshowtherapidrise ones—do havecarbondegeneratecoresandburnhelium more than40%oftheirbolometricluminosityfromsuchstars massive progenitorsforAGBstarsthatwecanidentifyare metrically thanthosefoundinthesurvey.Hence,most infrared. Nonewerefoundtobesignificantlybrighterbolo- grism surveys:foralltypeIIandIIIclusterswithpublished clusters containluminousstarsthatwerenotfoundinour II-III. SinceanumberoftheseclusterscontainCepheids(e.g., AGB contributionbeginsonlyforclusterslaterthanSWB Stars moremassivethanthisdonothavedegeneratecarbon (Sweigart, Greggio,andRenzini1989).Nowstarsonthefirst (Table 3andFig.15). in itcontributeonly6%ofitsbolometricluminosity,whereas, does itnotcontainCstars,butthefewluminousAGBMstars to oneofthemostpopulousclusters,NGC1866.Noteonly of 3-5M©(Table3).Wecanruleoutthepossibilitythatthese their ageisontheorderof100Myrwithacorrespondingmass increase inmass-loss ratecansuccessfulyreproduce boththe masses lessthan1.7M©.Thissecondtransitionoccursovera on average,clustersofthisSWBtypearepredictedtohave only intherange3-5M©.Weagaindrawparticularattention optical C-Mdiagrams,allbrightstarswereexaminedinthe al. (1988)showthatconvective overshootingplusamodest included (seetheirFig.2),the effectwouldbetoshiftthetheo- dictions forSSPevolutionhavenottakenintoaccountconvec- problem; i.e.,RenziniandBuzzoni(1986)notethattheir pre- differences betweentheoryandobservationsevidentfrom (Iben 1982;IbenandRenzini1983).Whatcanaccountfor the clusters. Inotherwords,luminousAGBstarscanbeproduced data inFigure15showthatthisdeclinedoesnothappenuntil giant branchwithdegenerateHecoresbecomeimportant.Our AGB correspondstoasecondphasetransitioninSSPfor relatively lowluminosity;and (2)thecalculationsofChiosiet retical distributioninFigure 15 totheright,resultinginbetter tive overshoot(Bertelli,Bressan,andChiosi1985).Ifit were problem ”:wherearetheveryluminouscarbonstarspredicted between theoryandobservationsubsumesthe“carbon star luminosity iscomingfromCstars.Thereforethedisagreement a somewhatolderagethanthatwhichcorrespondstoSWBVI stellar massrangeofonlyafewtenthssolar AGB wouldeffectivelyterminate anAGBstar’sevolutionata section, (1)ahigherthanpredicted mass-lossrateontheupper agreement withtheobservations. Asnotedintheprevious Figure 15?Therearecertainparallelsheretothecarbon star stars ofsignificantlylowerluminositythantheorypredicts by theorybutnotobservedandwhyarethereAGBcarbon Comparison ofFigures15and16showsthatmost this at significantlylowerturnoffmassesthantheorypredicts. 0 A majordifferencebetweentheoryandobservationisthe The theoreticallypredicteddeclineinimportanceofthe © American Astronomical Society • Provided by the NASA Astrophysics Data System AGB OFMAGELLANICCLOUDCLUSTERS dance or1.0M©instarsthataremetal-deficient. tive overshootingisnotneededforthirddredge-up,andhence have studied.Lattanzio(1989),though,pointsoutthatconvec- C starproduction,instarsaslow1.5M©withsolarabun- with luminositiescomparabletothosefoundintheclusterswe luminosity functionfortheAGBstarsknowntobepresent,i.e., absence ofluminousAGBstarsandtherelativelyreduced hypothesis andthemass-lossforexplaining change theratioofenvelopetocoremassthroughover- because theneteffectissame,whetheronechoosestoeject deficiency ofluminousAGBstars?Inprinciple,thisisdifficult contains halfofthese clusters. mass losswouldmanifestitselfasamorestochasticprocess. nism toactasasharpguillotineat5-6M©turnoff,whereas the AGBenvelopeandthusterminateevolution,orto clusters observed by Frogel,Persson,andCohen(1980). Theinnercontour shooting. Possiblyonemightexpecttheovershootingmecha- text. Thecontourlabeled“M31clusters ”containsallbutacoupleoftheM31 magnitude fewerthanpredicted.Also,sincethecandidates has beenpresentedbyWood,Bessell,andFox(1983),but Cloud clustersafterbrightAGBstars havebeenremovedasdiscussedinthe definitely establishtheirevolutionarystatus.Ifwecouldpoint Evidence thatsomeluminousAGBstarsarefoundintheLMC preferring themass-losshypothesis,althoughBertelli,Bressan, to afewirrefutableAGBstarsofsufficientluminosityintypeII suggested byWoodetal.arenotinacluster,itisdifficultto Mould andReid(1987)havearguedthattheyareanorderof can beshowntoasingleAGBmemberofNGC299,andif and Chiosi(1985)havearguedagainstthishypothesis.Ifstar5 or earlierMagellanicCloudclusters,wewouldhaveabasisfor critical fordecidingbetweenthetwohypotheses. that starsinitiallyexceeding6M©candevelopadegenerate the ageofNGC299islessthan45Myr,thenwecanbesure composition. TheoutercontourinFigure17definesthearea AGB stars.Theremainingstellarpopulationinmostofthese CO core.Furtherstudyoftheearly-typeclusterswouldbe true globularclustersexceptfordifferencesinageandchemical Cloud clustersshouldbecomparabletothestellarcontentof Magellanic CloudclustersfromTable4afterremovalofbright Can wedistinguishbetweentheconvectiveovershoot Fig. 17.—J—H,HKdiagramfor theintegratedlightofMagellanic Figure 17illustratesintegratedJ—H,HKcolorsfor ii) ClustersafterRemovalofLuminousAGBStars 119 1990ApJ. . .352. . .96F increasing contributionofmain-sequenceandhorizontal ble, thebluercolorsofCloudclustersmustresultfrom the M31andMagellanicCloudclustersisprobablycompara- whose lightisdominatedbyonlyafewbrightAGBstars. branch starsintheseyoungerclusters;see,forexample, Clusters oftypeI-IVhaveJ—Hcolorsbluerthanthosethe half. Theseextremecasestendtobeintrinsicallypoorclusters type V-VIIliewithintheoutercontourbutinblueJ—H some extremecases,theMagellanicCloudclustersofSWB the areaoccupiedbyhalfoftheseM31clusters.Exceptfor (PACFM) asthesearedominatedbytheluminousAGBstar mass betweentypeVandIVclustersis1.82.5 earlier types,themeancolorisabout0.5.Thechangeinturnoff clusters, themeanJ-Xisabout0.65independentoftype.For ignored, weseeajumpinJ—KattypeIV-V.ForV-VII Renzini andBuzzoni’s(1986)Figure4. by Frogel,Persson,andCohen(1980),whiletheinneroneis luminous AGBstarsisshowninFigure18.Iftheoutliersare M31 globulars.Sincetherangeinchemicalcompositionfor occupied byallbuttwooftheM31globularclustersobserved colors isnotduetotheredgiantbranchphase(RGB) explanations forthetransitioninB—V.Chiosi,Bertelli,and contribution. RenziniandBuzzoni(1986)considerseveral type IV-VisevidentinB—Vaswell(Fig.13ofRenziniand M (Table3).AdiscontinuityorrapidcolorchangeatSWB excellent agreementwithvaluesinTable3forSWBtypeIV-V. SWB typeforMagellanicCloudclustersafterremovalof 120 phase transitionisthemostlikelycause:sincewehavealready young, blueclusters.We,ontheotherhand,claimRGB cluster formationanddisruptiontherapidfadingof transition butratherarisesfromacombinationofrate Bressan (1988)claimthatthetransitionobservedinB—V Buzzoni 1986).ItisnotseeninthetotalintegratedJ—Kcolors occurs abruptlyatamassof2.0Mforan[Fe/H]—0.7,in Renzini (1989)showthattheappearanceofRGBtransition (e.g., Frogel1988,andreferencestherein).Recallthatfromour removed luminousAGBstars,starsontheRGBwilldominate previous discussionofAGBstarswefoundnodiscrepancy the infraredlightofintermediatetooldagestellarpopulations transition. OnlyfortheAGBphasetransitionwasaserious between thepredictedandobservedlocationofRGBphase AGB starshavebeen removedareplottedagainstSWB type. discrepancy found.ThecalculationofSweigart,Greggio,and 0 0 The distributionofintegratedJ—Kcolorasafunction Fig. 18.—TheJ— KcolorsoftheMagellanicCloud Clusters afterbright S' I .6 1.2 .8 .4 .2 0 1 © American Astronomical Society • Provided by the NASA Astrophysics Data System 0 24 6 SWB FROGEL, MOULD,ANDBLANCO colors andmagnitudesoftheirgiantbranchesoverlapthose contain carbonstarsorluminousAGBofanykind.The light bySWBandinfraredPACFM.Within the H-Rdiagram:(i)Theoldestclusters(typeVII)tendnotto is thecoincidenceofluminosityRGBtipinCloud as greatthatbetweenM92andM3.Particularlyimpressive following results: photometry forallofthesestars.Analysisthedatayields brighter thanaboutMof—3.6.Wehaveobtainedinfrared around theseclusters,oursurveyshouldbecompleteforstars Magellanic Cloudstarclustersstudiedinintegratedoptical contain bothAGBMstarsandcarbonstars.Thelatterarethe age clusters(typesVandVI)withanrangeof~2.5Gyr, Galactic globularclustersandimplyametallicityrangeatleast reddest AGBstarsinthesample,whileMare and Galacticglobularsasafunctionofcolor,(ii)Intermediate- make itsignificantlyredderasfirstascentgiantsareanimpor- 0.2 dex,isrequiredtoconfinetheMstarpartofgiant these clustersofnotmorethan0.5dex,andpossiblyaslow reddest Mgiantsinthesample.Anarrowrange[Fe/H]for for MagellanicCloudclusters(§Yb). 2.5 mag.Figure14ofRenziniandBuzzoniillustratestheeffect change inluminosityofthetipredgiantbranchabout A masschangeofonlyafewtenthssolarresultsin (types I-III)clustershavethebluestGBsinsamplecorre- correlation betweenincreasingageanddecreasingmetallicity tant contributortotheinfraredlightofanoldcluster.Counter- Obviously, theeffectonintegratedJ—Kcolorwillbeto of thesuddenappearanceaRGBonclusterC-Mdiagram. contain carbonstars.TheirMstarsareamongthebrightestof branches totheobservedsmallspreadincolor,(iii)Young acting somewhatthetendencyforJ—Xtogetbluerdue burning stars(Becker,Iben,andTuggle1977);theymostlikely sponding tohighermassHayashitracks.Theytendnot any starsinthesampleandaretoobrighttobecoreHe- when clusterMstarsintheH-Rdiagramarevieweda luminous withdecreasingageyieldsabimodaldistribution are AGBstars. ment withthatfoundbyFrogelandBlanco(1983)forfield M suitable projection.Thisdistributionisinqualitativeagree- formation intheLMC,althoughtheydonotruleoutsmall- identified inresultsl(ii)andl(iii)above.ElsonFall(1988), epochs ofstarformationwithagescorrespondingtothose stars intheLMC.Thetwopeakscouldresultfromdiscrete bol though, havefoundnoevidenceforglobalburstsincluster required totranslatetheobservedcolordistributionfunctions amplitude variationsintherate.Amoredetailedstudy is formation rateasafunctionoftime(seeChiosi,Bertelli, and for theclusterandfieldMstarsintoastatementabout star faintest Cstarisalmostalways brighterthanthebrightestM Bressan 1988). in Cloudclustersrisesmonotonically withdecreasingSWB mass, theagreementwithrecent evolutionarycalculationsby each SWBtypefromTable3. Overtherange1-4Mininitial stars. Theluminosityoftransition fromMstarstocarbon type. Figure19showsthisrise asafunctionofturnoffmassfor Lattanzio (1989a, b)isquitegood.Earlier calculationsby 0 We havesurveyedforcarbonandMstarsmostofthe 2. ThetendencyfortheAGBstobecomebluerandmore 1. TheAGBsintheseclustersarearrangedsystematically 3. IfbothMandCstarsarepresentinthesamecluster, VIII. SUMMARYANDCONCLUSIONS Vol. 352 1990ApJ. . .352. . .96F .1987,A.J.,92,321. sition luminosity. 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