MilkyWayGlobularClusters(RobHorvat)

47Tucanae(47Tuc).Credit:GerryAarts(WSAAG).Thisglobularclusterhasmorethanonemillionstars.

MulCpleStarSystemsAsmallCghtgroupofstars(usually2or3)thatareboundtogetherbygravityformamul3plestarsystem.Atwo-starsystemissimplyreferredtoasabinarystar.Visually,onestarmightbeseentoorbitanotheroveraperiodofdecadesorcenturies.

Mostbinarystarsareseparatedbyalotlessthan200”and0.3lightyears.

BetaMonoceroCs

AlphaCentauri

Star Distance(LtYrs) Separa3on Sep(AU) Sep(LtYrs)

AlphaCentauriAB 4.3 5” 7 0.0001

Acrux 322 4” 390 0.006

BetaMonoceroCs(A-BC) 680 7.4” 1,540 0.024

BetaCygni(Albireo) 430 35” 4,067 0.064

Beta1,2Capricorni 340 205” 21,300 0.338

Anopen cluster is a loosely bound group of a hundred, a few hundred or a fewthousandstars(M11has2,900stars).

Mostofthewell-knownopenclustersaresomewherebetween10’and100’insizeand10to30lightyearsacross.About2-3lightyearsbetweeneachstar.

BuXerflyCluster(M6).Credit: Narayan Mukkavilli (WSAAG).Approximately100stars.Clusteris50-100millionyearsold.

OpenClusters

The escape velocity of the system isless than the average velocity of itsstars so open clusters tend todisperse a\er a few 100 millionyears.

OpenCluster Distance(LtYrs) AngularSize Size(LtYrs)

M45(Pleiades) 430 120’ 15

IC2602(SouthernPleiades) 530 100’ 15

IC2391(OmicronVelorumCluster) 570 60’ 10

M44(Beehive) 610 90’ 16

M7(PtolemyCluster) 980 80’ 23

NGC2516(SouthernBeehive) 1,300 30’ 11

M6(BuXerflyCluster) 1,600 30’ 14

M47 1,600 25’ 12

M41 2,300 40’ 27

M50 3,100 15’ 14

NGC6231(NorthernJewelBox) 4,100 14’ 17

M46 4,900 20’ 29

M11(WildDuckCluster) 6,100 14’ 25

NGC4755(JewelBox) 6,400 10’ 19

NGC3766(PearlCluster) 7,200 9’ 19

NGC3293(GemCluster) 7,600 6’ 13

Mostoftheknownopenclustersarelessthan200millionyearsold.TheJewelBox(NGC4755)isoneoftheyoungestatonly7millionyearsold.

PtolemyCluster(M7).Credit:NarayanMukkavilli(WSAAG).Approximately100stars.Clusteris220millionyearsold.

Thereareover1000knownopenclusters inourgalaxybuttherecouldbe10Cmesthisnumber.OpenclustersarefoundinthegalacCcdiskandmoveinrotaConwiththedisk.Youngeropenclustersaremoredenselyconcentratedinthespiralarmsofthegalaxywherethelevelsofhydrogengasarehigher.

NGC1566.Credit:ESA/Hubble&NASA

The typical distancebetween stars in aglobular cluster isaboutonelightyear.

In the core ofOmegaCentauri,theaverage distancebetween any twostars is about1/3ofalightyear.

OmegaCentauri.Credit:CharlesYendle(WSAAG).Theclustercontainsperhaps5millionstars.

GlobularClustersAglobular cluster isaCghtlyboundgroupof tensof thousands,o\en100,000sandoccasionallymillionsofstars.Theyaresphericalinappearance.

Thedifference in shapebetweenanopenclusterandglobular cluster is somewhatlikethedifferencebetweenanasteroidandasphericalmooninthesolarsystem.

Asteroid243Ida.60kmx25kmx19km.TakenbyGalileo1993.Credit:NASA/JPL

Saturn’smoonMimas.diameter396km.LargeHerschelCrater.TakenbyCassini2010.Smallest known roundastronomicalbody.“The potato radius”,approximately200km.Credit:NASA/JPL/SSI.

Enoughmass/starsanditpullsintoasphere.

OpenclusterNGC6231.Credit:NarayanMukkavilli(WSAAG)

47Tuc.Credit:TedDobosz(WSAAG)

M22.Credit:NarayanMukkavilli(WSAAG)

WilliamHerschelwasthefirsttousethenameglobularclusterforhisdescripConoftheminhis1789catalogofdeepskyobjects.

Very liXle is known about how globular clusters are formed or why they haveorbitsoutsidethegalacCcdisk.

AgeofGlobularClusters

Theuniverseisabout13.8billionyears(or13.8Gyr)old.Globularclustersaresomeoftheoldestobjects in theUniverseandwereprobably formedbefore thematerialoftheGalaxyflaXenedintothepresentthindisk.

GlobularCluster Age(billionsofyears)

OmegaCentauri 11.5

47Tuc 13

M2 13

M3 11.4

M4 12.2

M5 10.6

M10 11.4

M12 12.7

M13 11.7

M15 12

M22 12

MostglobularclustersinourgalaxyshowalackofOandBtypebluestars.

Globularclusterscontainmanylow-massredstarsandintermediate-massyellowstars<0.8solarmasses.(Source–Hyperphysics,DeptofPhysicsandAstronomy,GeorgiaStateUniversity).

StarformaConshouldhavestoppedintheseclustersalmost13billionyearsago,soonlyoldstarsareexpectedtobefoundthere.

StarsarecomposedmostlyofHydrogenandHelium.TheSunis73%Hydrogenand25% Helium. Heavier elements (oxygen, carbon, iron etc), called metals inastronomy,onlyaccountfor2%ofitsmass.

Metallicity

Metallicity [Fe/H] = log(Fe/H)STAR - log(Fe/H)SUN compares the raCo of iron tohydrogeninastarwiththeSun.BydefiniCon,theSun(4.6billionyearsold)hasmetallicity[Fe/H]=0.

Spectral analysis for thousands of stars gives the range for metallicity to bebetween-4and+1.

Hydrogen

Helium

Metals

Popula3onIStars–inthegalac3cdisk(e.g.openclusters),[Fe/H]>-1.Thesestarswereformedfromaninterstellarmediumprogressivelyenrichedwiththeejectedmaterialsof redgiantsandsupernovae. It is thereforeassumedthatthehighertheraCo,themorerecentlythestarwasformed.Astarwithmetallicity+1wouldhave10CmestheironcontentoftheSun.

Popula3onIIStars-inglobularclusters&galac3cbulge,[Fe/H]<-1.Halostarshavenothadaccesstotheheavierelementsofthedisk.Astarwithmetallicity-2wouldhave100CmeslessironthantheSun.

ThebeliefwasthatglobularclustersconsistedofasinglepopulaConofmetalpoorstarsthatformedtogether.Globularclustersshouldconsistpredominantlyofolder“populaConII”yellowtoredstars.

GlobularCluster

Metallicity GlobularCluster

Metallicity GlobularCluster

Metallicity

M15 -2.37 M19 -1.74 M12 -1.37

M92 -2.31 M22 -1.70 M28 -1.32

NGC5053 -2.27 M2 -1.65 M5 -1.29

M30 -2.27 OmegaCen -1.53 M75 -1.29

M68 -2.23 M70 -1.62 M14 -1.28

NGC2419 -2.15 M79 -1.60 M62 -1.18

M53 -2.10 M10 -1.56 M4 -1.16

NGC6397 -2.02 NGC6752 -1.54 NGC2808 -1.14

M56 -1.98 M13 -1.53 M107 -1.02

M55 -1.94 M3 -1.50 M71 -0.78

M9 -1.77 M54 -1.49 47Tuc -0.72

M80 -1.75 M72 -1.42 M69 -0.64

However,manyMilkyWayglobularclusterssuchasOmegaCentaurihavecomplexformaConhistoriesandconsistofatleasttwodisCnctpopulaConsofstars.

OmegaCentauri.Credit:TedDobosz(WSAAG)

Bluestarshavebeenfoundinthecentralregionsofmanyglobularclusters.OneexplanaConfortheseistheformaConofbluestragglers.

Thestarsinthecoreofaglobularclustercanbesoclosethatoccasionallytwowillcollide,formingalargerandhoXerstar(bluestraggler).

Duetotheoldageofglobs,manythousandsofcollisionsmayhaveoccurredsincetheclusterformed.

Anearmisscouldalsoresultinaclosebinarywhereamoremassivestarsiphonshotgasesoffitscompanion.TheincreasedmassmakesthisstarhoXerorbluer.

BlueStragglers

CoreareaofOmegaCentauri(1.3’x1’).Credit:NASA,ESA,andtheHubbleSM4EROTeam.

100,000StarsPicturedintheCentreofOmegaCentauri

BlueStragglersinNGC6362(Ara).Credit:ESA/Hubble&NASA

GalacCcCannibalismAsignificantnumber(?)ofglobularclustersmayhavecomefromdwarfsatellitegalaxiesthatwereabsorbedbytheMilkyWayGalaxy.

The high density of the globular clusters would allow them to survive in ourgalaxy’shalo.

There is also some debate as to whether globular clusters are disCnct andseparateobjectstodwarfspheroidalgalaxies.

OmegaCentauri isthoughttobetheremnantnucleusofadwarfsatellitegalaxycapturedandstrippedofitsouterstars.

Of similar luminosity to 47 Tuc,M54 may once have been the nucleus of theSagiXariusDwarfEllipCcalGalaxy(SgrDEG).At86,400lydistance,itbecomesthefirstextra-galacCcglobularclusterdiscovered(CharlesMessier1778).

M54.Credit:JimMisC(MisCMountainObservatory)

NGC2808.Credit:NASA,ESA,A.Sarajedini(UniversityofFlorida)andG.PioXo(UniversityofPadua(Padova))

It is thought that radiaCon pressure fromcomponent stars should drive interstellargasesoutof globular clustersearly in theirformaCon.

Perhaps massive clusters like NGC 2808exert enough gravity to hold onto gasesearlyintheirformaCon.Asaresult,asecondandathirdgeneraConofstarsmightform.

Or like Omega Centauri, it could bemasqueradingasaglobularcluster…adwarf satellitegalaxy strippedofmostofitsmaterialbytheMilkyWay.

Like47Tuc,NGC2808isthoughttocontainoveronemillionstars.Analysis of HST data for this massive glob provides evidence that star birthoccurredover3generaConsearlyinthecluster'slife.EachsuccessivegeneraConappearingslightlybluer.

AsearchforJupiter-sizedplanetsin47Tuc,carriedoutbyateamofastronomersusing theHubbleSpaceTelescope,cameupempty-handed.Thework involvedchecking34,000starsintheclusterforsignsoflargetransiCngplanets.

TheabsenceofanyposiCve results strengthens theargument thatplanetsarerareornonexistentinglobularclustersbecauseoftheirverylowconcentraConofheavyelements.

AnyPlanets?

DiametersofGlobularClustersOmega Centauri is considered to be the most massive of the Milky Way globs.However, ifyoudosomecalculaConsbasedonangularsize (visual)anddistance:NGC2419is321lightyearsindiameter.M54is229lightyearsindiameter.OmegaCentauriis6that178lightyearsindiameter!

Attheoppositeend,Terzan9isonly1lightyearindiameter.

TheaveragediameterofMilkyWayGalaxyglobularclustersisabout70lightyears.Themediandiameterisabout60lightyears.

Diameters are calculated from angular size and distance. Given angular sizes areusuallyvisualandrathersubjecCvee.g.wheredoestheclusterend?Thiswillalsodependonthesizeoftheaperture.

ThefollowingcroppedimagesofOmegaCentaurisimulatehowitsextentcanvaryunderdifferentcircumstances.

Credit:TedDobosz Credit:CharlesYendle Credit:GerryAarts

Visual:10x60binoculars18’ Visual:30inchTelescope36’ Photographed65’

Onthewhole,calculateddiametersareconsiderablyunder-esCmated.OmegaCentauri’sdiametercalculatedfromavisual36’is178ly.Fromaphotographicdiameterof65’itis320ly.

Globular clusters do notmove in lockwith the rotaCon of the galacCc disk butorbit through thehaloof thegalaxyaround thegalacCc core.Manyorbit in theoppositedirecCon(retrogrademoCon)tothegalacCcdisk.

TheOrbitsofGlobularClusters

Theorbitsofglobularclustersarelikelytobeintheformofaprecessingellipse.

RoseXeorbit

There are 17 globs lessthan 5000 ly from thegalacCc centre. If thecentralbulgeis5000lyinradius then these innerglobsareactuallypassingthroughthebulge.

DistribuConofGlobularClusters

There are 157MilkyWay globular clusters in the Catalog of ProfessorWilliamHarris, McMaster University, Canada. There are more candidates as yetunconfirmed.

ThediameteroftheMilkyWaygalaxyisabout100,000lightyears.TheSunisabout26,000lightyearsfromthegalacCccentreorabouthalfwayoutfromthecentreofthegalaxy.

There are roughly anequal number of globsabove and below thegalacCcdisk.

The average distance ofglobularclustersfromtheGalacCc Centre is about40,000lightyears.However, the median isonlyabout16,000ly.

98 globular clusters arewithin 25,000 ly of thegalacCccentre.

There are 13 globsfurtherthan100,000lightyears.

TheIntergalacCcWanderer

NGC2419wasdiscoveredbyWilliamHerschelin1788.

It is also known as the Intergalac/c Wanderer, a name given when it waserroneouslybelievednottobeinorbitabouttheMilkyWay.

NGC 2419 lies about 270,000 ly fromtheSun.NearlytwiceasfarastheLMC.At thisdistance, it takessome3billionyears to make one trip around thegalaxy.

This dense glob is very luminous andrankswithOmegaCentauriand47Tucinabsolutebrightness.

NGC2419.Credit:AdamBlock/MountLemmonSkyCenter/UniversityofArizona

SkySafariscreenclipfor9pmon15thMarch2016.NGC2419alCtude18degrees.

ObservingGlobularClusters

Ofthe157MilkyWayglobularclustersinWilliamHarris’cataloguehalf(79)arefoundtowardsthegalacCccentreinjust3constellaCons:

SagiXarius:35globularclusters.7Messier:M22,M28,M54,M55,M69,M70,M75.

Ophiuchus:25globularclusters.7Messier:M9,M10,M12,M14,M19,M62,M107.

Scorpius:19globularclusters.2Messier:M4,M80.

Thereare29Messierglobularclusters:M2,M3,M4,M5,M9,M10,M12,M13,M14,M15,M19,M22,M28,M30,M53,M54,M55,M56,M62,M68,M69,M70,M71,M72,M75,M79,M80,M92,M107.

SagiXariushas22globularclustersbrighterthanmagnitude10

NGC 6522 and NGC 6528 in SagiXarius areprobably the two globular clusters closest tothe GalacCc Centre as the closer posiCon ofDufay1(mag11.6)isnowinquesCon.

Thepairareseparatedbyonly16’andareonly710lightyearsapart.

GlobularCluster Galac3cLongitude

Galac3cLa3tude

DistancefromSun(ly)

DistancefromGalac3cCentre(ly)

Dufay1 357.44° 2.12° 26,700 1,600

NGC6522 1.02° -3.93° 25,100 2,000

NGC6528 1.14° -4.17° 25,800 2,000

UKS1 5.13° 0.76° 25,400 2,300

Terzan2 356.32° 2.3° 24,400 2,600

Liller1 354.84° -0.16° 26,700 2,600

GlobsNearesttotheGalacCcCentre

M69 and M70 are separated by2.5°andareonly1400lyapart.

M22 andNGC 6544 are separatedby6.7°andareonly1320lyapart!

Ophiuchushas18globularclustersbrighterthanmagnitude10.

M4andM80areinScorpius.

M10andM12areseparatedby3.3°andareonly1,560lyapart.

FromaplanetaroundastarnearM12,theglobularclusterM10wouldlooksixCmesbigger*intheskythantheEarth’sFullMoon.(*diameter).

Scorpiushas7globularclustersbrighterthanmagnitude10.

NGC6453hasmag10.08andisalsoshown.

Coincidently, NGC 6441 and NGC 6453 lie at the samedistancefromtheSun,separatedby2.5°and1,620lyapart.

TheEarth’sorbitabout theSun (EclipCcshown inblue) isCltedto theplaneofthegalaxyatabout60degrees.Thenormal(axisoforbit)isthereforeCltedtotheplaneofthegalaxyat30degrees.

The Earth’s axis is Clted away from the normal at 23.5 degrees and somewhattowardsthegalacCcplane.TheEarth’saxismakesanangleofabout27degreestotheplaneofthegalaxy.

TheEarth’saxiskeepsthesameorientaConinspaceastheEarthorbitstheSun.AstheEarthrotates,theNorthCelesCalPole(NCP)andSouthCelesCalPole(SCP)arefixedpointsinthesky(ignoringprecession).TheNCPhasgalacCccoordinates:longitude123°,laCtude+27°.TheSCPhasgalacCccoordinates:longitude303°,laCtude-27°.

NotethattheNCPfacesawayfromtheGalacCcCentrebuttheSCPfacesmoretowardstheGalacCcCentre.

Because theNCP faces away from theGalacCc Centre, there are only 27 globularclustersinthenorthernhemispherebut130inthesouthernhemisphere.

Only13northernglobularsarebrighterthanmagnitude10,comparedto81inthesouthernhemisphere.

Thereareactuallyonly8Messierglobsinthenorthernhemisphere: M3(CVn) M5(Ser)

M13(Her) M15(Peg)

M53(Com) M56(Lyr)

M71(Sge) M92(Her)}

21MessierglobsareinthesouthernhemispherebutnonearebelowDEC-33°.

M2(Aqr)istheclosestMessierglobtotheCelesCalEquatoratDEC-0.8°.

ThereareonlytwoMilkyWayglobsareaboveDEC+45°:

NGC6229(mag9.4)inHerculesatDEC+47.5°

Palomar1(mag13)inCepheusatDEC+79.6°.

Thereare25MilkyWayglobsbelowDEC-45degrees:

thelowestbeingIC4499(mag9.8)inApusatDEC-82°.

BrightestbyVisualMagnitudeThereare94globularclustersbrighterthanvisualmagnitude10.Allwithinrangeofan8inchtelescope.Thereare24brighterthanmagnitude7andviewablewithbinoculars.Onlytwoarereallynakedeye:OmegaCentauriand47Tuc.

YoumaybesurprisedtoknowthatNGC6752inPavoandNGC6397inAraareinthetop10.

Globular Cons VMag Globular Cons VMag

OmegaCen Cen 3.7 M55 Sgr 6.3 47Tuc Tuc 4.0 NGC362 Tuc 6.4 M22 Sgr 5.1 M92 Her 6.4 NGC6752 Pav 5.4 M62 Oph 6.5 M4 Sco 5.6 M2 Aqr 6.5 M5 Ser 5.7 M10 Oph 6.6 NGC6397 Ara 5.7 M12 Oph 6.7 M13 Her 5.8 NGC6388 Sco 6.7 M3 CVn 6.2 NGC3201 Vel 6.8 M15 Peg 6.2 M19 Oph 6.8 NGC2808 Car 6.2 M28 Sgr 6.8 NGC6541 CrA 6.3 NGC4833 Mus 6.9

Givenvisualmagnitudesforlargerobjects,includingglobularclusters,arerathererraCcandvaryfromsourcetosource.

ForOmegaCentauri:

Source Vmag

SIMBAD(AstronomicalDatabase) 5.33

NGC/ICProject 3.9

SkySafariPro 3.68

AtlasoftheUniversebyPatrickMoore 3.6

AtlasoftheNightSky(Massey&Quirk) 3.5

StephenO’Meara(TheCaldwellObjects)states:“Althoughmanysourcesshowitasbrightasmagnitude3.7or3.5,mynaked-eyeesCmateofmagnitude3.9isnotsoopCmisCc”.

Ifinditlaughablethatthevisualmagnitudecanbequotedtotwodecimalplaceswheninfactdifferentsourcescan’tevenagreeonthefirstdecimalplace!

AbsoluteMagnitudeandLuminosityTheabsolutemagnitudeofastariswhatitsapparentmagnitudewouldbeatastandarddistanceof10parsecs(32.6lightyears).Absolutemagnitudeallowstheintrinsicbrightnessofstarstobecompareddirectly.

Star Distance(ly) Vmag AbsMag

Sun 0.000016 -26.7 +4.83

Sirius 8.7 -1.44 +1.43

Vega 25 +0.02 +0.60

Aldebaran 67 +0.99 -0.57

Achernar 139 +0.54 -2.61

Canopus 309 -0.62 -5.50

Antares 550 +1.07 -5.07

Luminosityisthetotalamountofenergyradiatedbyastar(orsomeothercelesCalobject)perunitCme.Basically,thepoweroutputofthestar.Luminosity can be stated as so many Cmes brighter than the Sun and can becalculatedfromtheAbsMagbytheformula:

L=2.5124.83-AbsMagwhere2.512=Pogson’sraCo.

AbsoluteMagnitude LuminosityxSun

-10.17 1,000,000

-7.67 100,000

-5.17 10,000

-2.67 1,000

-0.17 100

+2.33 10

+4.83 1

+7.30 0.1

+9.80 0.01

MostLuminousGlobsLuminosity has been calculated off absolute magnitude, which in turn has beencalculatedoffdistanceandvisualmagnitude.

GlobCluster Con Distance VMag AbsMag Luminosity

OmegaCentauri Cen 17,000 3.7 -9.91 785,000

M54 Sgr 86,400 7.6 -9.52 548,000

47Tuc Tuc 14,700 4.0 -9.32 458,000

NGC2419 Lyn 269,300 10.4 -9.18 400,000

M15 Peg 33,900 6.2 -8.88 306,000

M3 CVn 33,300 6.2 -8.86 298,000

M2 Aqr 37,500 6.5 -8.83 292,000

M5 Ser 24,400 5.7 -8.72 263,000

NGC2808 Car 31,300 6.2 -8.71 261,000

M53 Com 58,400 7.6 -8.66 248,000

M13 Her 23,100 5.8 -8.47 209,000

NGC5824 Lup 104,600 9.1 -8.44 204,000

ClassificaConofGlobularClustersAClassificaConofGlobularClustersbyHarlowShapleyandHelenB.Sawyer1927.Globularclusterswereplacedin12classesonthebasisofapparentconcentraConofstars tocentre.Class1globsarehighlyconcentrated towardscentre,whilst class12globsappearfairlyhomogeneouswithliXlecentralconcentraCon.

Class1GlobularCluster Class12GlobularCluster

SimulaConshowinghowtheproporConofstarsshi\sgraduallyfromthecentreintothehalofromclasstoclass.Note:imagesmaynotexactlyreflectactualobservaCons.

Glob Class Table byHarlow Shapley andHelenB.Sawyer1927.

Totalof95globs.Asterisked (*) globs(usually bright) werechosen as beingrepresentaCve of theirclass.

The classes for someglobs were uncertain -indicatedbyacolon.

Daggered NGCs hadquesCons about theirstatusasglobs.

Shapely and Sawyer used photos of the clusters taken with the Bruce 24inchphotographic refractor at Arequipa in Peru (southern staConof theHarvard CollegeObservatory)toderivethefollowingdata.

Class 1 2 3 4 5 6 7 8 9 10 11 12

MeanVmag 8.7 7.5 6.8 8.6 7.4 8.4 8 8.2 8.8 8.9 9.4 9.6

Frequency 3 6 7 10 10 9 8 11 10 9 8 4

Theircomments…

“Thevariousclassesarewidelyspreadinapparentbrightnessanddiameteranddonot depend on integrated magnitude, except for a slight tendency of the leastcondensed clusters in themean to be faint. In apparent galacCc distribuCon theclassesarethoroughlymixed.

TheclassesofglobularclustersareprobablyanindicaConofdevelopmentalage.”

Class GlobularClusters

1 M75,NGC2808,NGC7006

2 M2,M80,NGC1851(Col),NGC2419(Lyn)

3 47Tuc,M54,NGC362(Tuc),NGC6388(Sco),NGC6541(CrA)

4 M15,M28,M62,M92

5 M5,M13,M30,M53,M69,M70,M79,NGC5286(Cen)

6 M3,NGC6752(Pav)

7 M10,M22

8 OmegaCentauri,M9,M14,M19,NGC4833(Lup)

9 M4,M12,M72,NGC6397

10 M56,M68,M107,NGC288(Scl),NGC3201(Vel)

11 M55,M71,NGC6352(Ara)

12 NGC4372(Mus)

Class2:M80(Scorpius).Credit:TheHubbleHeritageTeam(AURA/STScl/NASA)

Class4:M15(Pegasus).Credit:ESA/Hubble&NASA

Class6:M3.Credit:JimMisC(MisCMountainObservatory)

Class8:ωCentauri.Credit:GerryAarts(WSAAG)

Class10:M107(Ophiuchus).Credit:ESA/NASA

Class12:Palomar1(Cepheus).Credit:ESA/Hubble&NASA

MostofthedatausedforglobularclusterswastakenfromtheSIMBADdatabase,operatedatCDS,Strasbourg,Franceandfromthe…

CATALOGOFPARAMETERSFORMILKYWAYGLOBULARCLUSTERS:THEDATABASE

CompiledbyWilliamE.Harris,McMasterUniversityThisrevision:December2010

Exceptwhereotherwiseindicated(pages33and53),alltables,chartsanddiagramsinthispresentaConwerecreatedbyme.

Themapsof globular clusters in SagiXarius,OphiuchusandScorpiuswereploXed fromcomputerprogramscreatedbymeusingJ2000.0coordinatesofstarsandclustersfromSIMBAD.LabelsandotherinformaCononchartswereaddedusingEazyDrawonaMac.

ThecelesCal(RA,DEC)andgalacCcchartsforglobularclusterswereploXedfromcomputerprogramscreatedbymeusingequatorialandgalacCccoordinatesfromHarris’database.

SimulaConsforclassesandorbitsofglobularclusterswerealsoploXedfromcomputerprograms.

AllotherdiagramswerecreatedinEazyDraw.

RobHorvat(WSAAG)November2015