195 9MNRAS.119. .255E found thatcontainstars forwhichaluminositycalibrationisnotavailable from several groupsofstarshavebeendiscussedon thebasisofapicesandtotal amounts ofthestellarmotions.Asidefrom interestingdynamicalquestions material fromgalactic clusters. Thisisespeciallytrueifstellargroups canbe raised bytheexistenceofthesegroups (Woolley 1959),theresulting {M B—F)-diagramsareofimportance in supplementingtheavailable HIGH VELOCITYSTARSANDITSRELATIONTOTHE STELLAR GROUPS,IV.THEGROOMBRIDGE1830GROUPOF Vi © Royal Astronomical Society • Provided by theNASA Astrophysics Data System In previouspapersofthisseries(Eggen1958 a,b,c;PapersI,IIandIII) m m m m m m motions of4RRLyraevariableswithrelatively well-determined proper calibrated bytheGroombridge1830group.Itisshownthattherea of objectsinthesethreecategorieshavebeencomputedfromparallaxes motions areidentifiedwiththoseforsomenearbysubdwarfs witharesulting similar totheGroombridge1830groupwillbe found. Also,thespace and that,whenadditionalmaterialbecomesavailable,severalgroups on thebasisoftheirspectralfeatures,(2)starsthatareprobablyextreme tabulated theavailableinformationfor(1)allstarsclassifiedassubdwarfs provide theonlyaccuratecalibrationofluminositiesthesestars, classified asnormalmainsequenceobjects,and(3)starsthatmaybe subdwarfs, onthebasisoftheirobservedultra-violetexcesses,although globular clustergiants,subgiantsorhorizontalbranchstars.Spacemotions My~ +o-6forthefourvariables. it isimportanttomakeasystematicsearchforsuchgroups.Wehave sequence starsmaycontainasystematicerror. Groombridge 1830groupbecausethecolourobservationsofM3main high probabilitythatseveralofthesestarsaretravellingtogetherinspace that ikTp-~+o*5forthezRRLyraevariablesandMy=—23 derived byfittingthemtothe(iWy,F)-diagramofMi3,whichwas m —M=i5-oforthecluster.Wehavenotderivedthismodulusin by o*5withrespecttothosevariables.Byequatingtheluminosityof ikfp~ +o*8fromthemovingclusterparallax,isshowntoobey with mainsequencestarsintheglobularclusters.Thisidentificationgives main sequence,thesubdwarfsinGroombridge1830groupareidentified between theobservedultra-violetexcessanddisplacementbelownormal period-amplitude relationforthevariablesinM3andtobereddened a modulusofm—M=i4-2fortheglobularclusterM13withresult to establishtheexistenceofamovinggroupsubdwarfs(Groombridge logical wayoffittingtheM3mainsequenceto the brighteststarsincluster.RRLyraeitself,forwhichwederive RR LyraetothemeanofvariablesinM3weobtainamodulus 1830 ¿roup)whichincludesRRLyrae.Onthebasisofrelationship Because thepresenceofRRLyraevariablesinstellargroupsmay The availablepropermotionsandradialvelocitydatahavebeenused Olm J.EggenandAllanR.Sondage (Communicated bytheAstronomerRoyal) GLOBULAR CLUSTERS (Received 1959March4) Summary 195 9MNRAS.119. .255E hm are inTableIwherethe uncertaintiesinsomeofthedataareapparent; the were computedfromthe expression77^=4*74^/^sinA. À istheangulardistancebetweenstarand thepoint(A,D).Theobserved are movingwithGroombridge1830toward A=i6igandi)=—54°*4; HD 219617 RR Lyr HD 163810 galactic rotation(7=58°,b=o°);W>towardthenorthpole(690°). two valuesfortheparallax ofGroombridge1830;285km/secfor aparallax with twovaluesforVthetotalvelocityreferred totheSun,determinedfrom of o"*126and300km/sec foraparallaxofo"*n6.Thegroupparallaxes, catalogue andthecomputedvalueswereobtained fromtheexpressionF^eosA, radial velocities,p,andtheirquality,O,were takenfromR.E.Wilson’s Gmb. 1830 where thevelocityvectors,relativetoSun,aredirectedasfollows: 256 motions, 0,andthepositionanglescomputed from theassumptionthatstars stars werechosenbytheconvergentpoint(i.e.movingcluster)methoddescribed stars whichappeartosharethelargespacemotionofGroombridge1830; available, theobjectwithbyfarlargestspacemotionissubdwarf 20 parsecsoftheSun,andforwhichradialvelocitiespropermotionsare similar groups. clusters withthoseofthegroupstars,and(3)possibleexistenceother modulii forglobularclustersbytheidentificationofmainsequences high velocitysubdwarfsmovingtogetherinspaceandcontainingRRLyrae variables andsubdwarfsthatmightbeidentifiedwithglobularclusterstars. The valuesofA0wereformedfromtheobserved positionanglesoftheproper of Groombridge1830relativetothemeanthesenearbystarsbecomes Taking thevelocityofSun,relativetostarswithin20parsecs(Woolley other sources.OfparticularinterestinthisconnectionarethefieldRRLyrae Groombridge 1830(HR4550).Therelevantdataareasfollows: (Groombridge 1830group),(2)theuseofthisgroupinobtainingdistance In thispaperwewilldiscuss(1)theevidenceforexistenceofagroupvery + 72°94 in PapersIandII: 1958) as[/(0)=—il,V(0)=+17andW{Q)=+7km/sec,thespacemotion iy O U, awayfromthegalacticcentre(/=i48°,i=o°);V>indirectionof © Royal Astronomical Society • Provided by theNASA Astrophysics Data System Star A searchthroughacatalogueof700highvelocitystarsyieldedthefollowing The propermotionand radialvelocitydeterminationsforthegroupmembers i. TheGroombridge1830group.—Amongthestarsknowntobewithin 309 203 210 209 145 0 AdsinÀ O / 77 —o*116,W=22km/sec, /x =7"*042/yr,U=—263km/sec, p =—98km/sec,L=—151 + 4 + 5 — il Olin J.EggenandAllanR.SandageVol.119 o o W+ IT(0)=—15km/sec. U +U{Q)=-274km/sec, V +T(0)=—134km/sec, 0-24 0-82 0-25 7-042 1*30 // km/sec - 72 +192 -266 + 15 - 98 P var b d a c Ap “3 -8 -6 -6 — 30*0225“40*0205 Fj =285300km/sec 0*004 0*126 0*010 0*020 ~ 4 -18 + 7 Ap o o*n6 0*0035 o*oi8 0*0095 195 9MNRAS.119. .255E kinematical group. estimated thattwoor three spuriousmemberswouldbeincluded for groups in groupsofvariousvelocities asaresultofthemethodselection. Itwas have isoperiodicgalacticorbits(Woolley1958) and,therefore,toforma values ofthespacevelocitiesinTableIIitcanbe seenthat,withintheuncertainties in thedata,membersofGroombridge 1830groupcanbeconsideredto parallaxes derivedaboveonthebasisofgroupmotionandarelistedin convergent point,thenumber ofspuriousgroupmembersthatmight bepresent is reflectedalmostentirelyinthevalueof IF-velocity.Fromthespreadof computed forbothdeterminationstodemonstrate thesensitivityofthree distribution ofthetotalpropermotionHD163810 betweenthetwocoordinates components ofthespacevelocitytovariationsin theobserveddata.Forexample, Table II.Inthosecaseswherethereisalargedifferencebetweentwovalues HD 219617 RRLyr because ofitsapparentplaceinthesky, largeobserveddifferenceinthe Gmb. 1830 HD 163810 of theobservedpropermotionorradialvelocity, spacemotionshavebeen No. J,1959Stellargroups:IV257 + 72°94 improved byadditionalobservations. the radialvelocityof+72°94,HD163810and219617,couldbegreatly proper motionsof+72°94,HD163810andRRLyrae,and,toalesserextent velocities areMd=McDonald,WMountWilson,andLLickObservatories; the observatoryabbreviationsarefollowed,inparentheses,bynumberofplates. G =GreenwichObservatory,andSSproulObservatory.Thesourcesoftheradial © Royal Astronomical Society • Provided by theNASA Astrophysics Data System In PaperIIanattempt wasmadetoestimate,bytheuseofasynthetic The spacemotionsofthegroupmembershavebeencomputedfrom Star *GC =GeneralCatalogue,YYaleZoneCatalogues,CCapeObservatory, -0*512 -0*512 -0-5I3 0*121 0*122 0*473 3*995 0*321 0*195 0*240 /¿a // Proper motionandradialvelocitydeterminations for membersoftheGroombridge1830group 0*014 0*010 // PE II 10 8 9 I — 1*190 -5-800 + 0-157 + 0*2l8 Table I 0*224 o*i88 0*746 0-673 1*200 o-oio i*i86 7 Pô o-oio /f PE 10 12 6 I GC S* Y GC GC G G Y C S “ 99 “ 97 - 72 - 74 - 70 +192 +198 + 187 - 98 -266 P 23 8 Md (2) Md (2) Md (300) Md (2) W (8) W (20) W (3) W (11) L (5) S* 258 Olin J. Eggen and Allan R. Sandage Vol. 119 00 00 00 N fc a b O T3 T3 co T3 T3
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© Royal Astronomical Society • Provided by the NASA Astrophysics Data System 195 9MNRAS.119. .255E o m No. 3,1959Stellargroups:IV259 with atotalspacemotionof100km/sec.Thesamematerial(FK3)indicates compared tottyesubdwarfs,thisresultmaynotbeapplicablethepresentcase. by thesyntheticconvergentpoint(S=—90)havegenerallyverylowvelocities that nospuriousmemberswillbeincludedingroupswithtotalspacemotions simultaneously (1)resultfromplacingthestarsonadefinitesequencein in excessof150km/sec,butbecausethestarsFK3,whichweretested 300 km/secmakesithighlyunlikelythatspuriousmotionsofthissizewill On theotherhand,factthatrelativelyfewstarshavespacemotionsnear excess asGroombridge1830(Section3).Forexample,thereare33F-,G-and seems unlikelythatnearlyfiftypercentofthestarswouldaccidentallysatisfy —are inboundtowardthegalacticcentrewithvelocitiesgreaterthan200km/sec. observational programmesforsubdwarfs,whicharenowinoperation, respectively, from—120to—450km/secand—140+60km/sec,it members oftheGroombridge1830groupforwhichU—Bvaluesareavailable of these—thefirstthreestarsinTableVI,thesecondVIIand Groombridge 1830,and(3)representstarsthathavethesameultra-violet (M, 5—F)-diagram,(2)havevectors[/,VandWsimilartothosefor be possiblewhenextensiveastrometric,photometricandspectroscopic with thoseofGroombridge1830andtheglobularclusterstars.Onlyseven K-type subdwarfsinTablesVIandVIIthathaveultra-violetexcessescomparable or, byRoman(1955),inthe(B,F)-system,arelistedTableIItogetherwith the requirementsformembershipinGroombridge1830group.More completed. those givenbyJenkins(1952):^ follows; theobservatoryabbreviationsand the weights,inparentheses,are luminosities ofthegroupmembersareshowninFig.1wherePleiades-Hyades stars andthelatterhavemostlybeenobservedonthatsystem.Thecolours the spectraltypes,alsobyRoman,andrangeinluminosityresultingfrom parallaxes ofthegroupmembers,otherthanGroombridge1830,aresmalland of thegroupmembers,basedonextremerangeparallaxesshownin main sequenceisalsoplotted.Theestimateduncertaintiesintheluminosities here sinceourultimateaimistocomparethegroupstarswithglobularcluster sequence inthe(M,B— F)-diagram.Thequestionoftheexistence ofthese offer littlecheckonthederivedluminosities. Theindividualvaluesareas quantitative statisticaltestsforspuriousmembersofhighvelocitygroupswill Since thevaluesofV+V(Q)andW+W(Q)forthesesevenstarsrange, and othersubdwarfsin the(M,logTJ-diagramisdiscussedelsewhere in F Table II,areindicatedbythelengthoflinesinFig.1.Thetrigonometric group areundoubtedly subdwarfslyingi‘5belowthePleiades-Hyades main range ofparallaxshowninthetable.Thecolourson(P,F)-systemareused F Bol © Royal Astronomical Society • Provided by theNASA Astrophysics Data System The magnitudesandcolours,whichwereobservedineitherthe(P,F)^-system 2. Thedoublestars.—Fig. 1showsthatmembersoftheGroombridge 1830 HD 163810 HD 219617 RR Lyr Gmb. 1830 + 72°94. Star o M(6) 26 M(7),iiY(i2),31C(7)—mean=20 in A(28),107M(8),164St(3)—mean=116 14 M(8),39Y(i2),430(4),oC(7)-mean=24. ii A(28),-12Yk(6),5W(7),258(7)—mean=9 7r (unit=o"*ooi) t 195 9MNRAS.119. .255E 0 2ÓO therefore, veryimportantthatmassesofsubdwarfsbeindependentlydetermined. of thetwobinariesinGroombridge1830group,ADS10938and16644, the groupmotionparallaxinderivingmass.Representativeobservations subdwarfs inbinarysystems.Thebestmassdeterminationavailableisthatfor other hand,membershipofvisualbinariesinstellargroupspermitstheuse As pointedoutpreviously(Eggen1956)thereareveryfewknownorsuspected that discussionitisapparentifsubdwarfsdoexistinthe(M,logTJ-diagram, unobserved. Usingtheobservationsto1930, Parenago(1946)derivedthe since itsdiscoveryin1900;thethreelistedTableIIIshowanangularmotion parallax, thereisnecessarilyconsiderableuncertaintyinthevalue.On they willviolatethemass-luminosityrelationfornormaldwarfsanditis, system areofnearlyequalmagnitudeand indistinguishable,butadouble yet bederived.TheobservationsofADS16644 extendbackto1876andmore of i°/yearandafixedseparationnearo"-5but orbitalelementsobviouslycannot are showninTableIII.VeryfewobservationsofADS10938havebeenmade value ofP=i45years and a=o"'$2fromtheobservedrateofchange ofthe reversal ofquadrant(180motion)hasbeen assumed tohaveoccurredbetween this systemisseennearlyedge-on(inclination near 90°)andanyorbitalelements than one-halfanorbitalperiodmayhaveelapsed sincethen,butunfortunately Monthly Notices(SandageandEggen1959).Fromtheequationsdevelopedin derived untilitcanbe shownfromobservationsmadenowthatapastron has define oneendoftherectilinear apparentorbit.Theseelementsdo notsatisfy observed separationsand theassumptionthatvandenEos’sobservations in1928 must dependmainlyontheobservedseparations. Thetwocomponentsofthe 85 PegasiA,butsincethederivedmassdependsupontrigonometric later observationsand it doubtfulwhetherevenpreliminaryelements canbe Bol 1902 and1929.Theapparentorbitisnearly rectilinearwithoneendasyet given inTableII.ThecontinuouscurverepresentsthePleiades—Hyadesmainsequence. length oftheverticallinesindicatesrangeluminositiesforvariousvaluesparallax © Royal Astronomical Society • Provided by theNASA Astrophysics Data System Fig. i.—The(My,B-V)-diagramformembersoftheGroombridge1830group.The Olin J.EggenandAllanR.Sandage Vol. 119 195 9MNRAS.119. .255E m compared tothesubdwarfsratherthanordinarydwarfsnearSun. addition tothedynamicalquestionsraisedbypossibleexistenceofamoving cluster starsifthemainsequencesarefitted tothePleiades-Hyadesmain reliance isplacedontheabsolutemagnitude of RRLyraeitselfasdetermined discussion oftheavailableM3dataisgivenin Section4butinthiscasegreater of Mi3anddiscusstheresultingluminosities oftheM13stars.Asimilar of theGroombridge1830group(subdwarfs)to comparewiththemainsequence related, itseemsprobablethattheglobularclustermainsequencesshouldbe group ofsubdwarfsneartheSun,existenceRRLyraestarsinthisand axes thatwillfittheavailableobservationsindicatedtotalmassof from theassumptionthatitismovingwith Groombridge1830groupthanon sequence ratherthantothesubdwarfs.Inthis sectionweusethemainsequence an errorofmorethanamagnitudecanresultintheluminositiesglobular the Groombridge1830groupshowsthatsubdwarfsandclustervariablesare possibly otherstellargroups(Section5)providesapowerfulmethodofcalibrating system islessthantwosolarmasses,thatis,the(assumed)equalmassesare is interpretedasanerror ofabouto*iinthecoloursfaintstars inM3. of thesestars(Section 4). ThedivergenceoftheM3mainsequence fromthat available observationsoftheM3mainsequence stars.Justificationforcomparing the luminositiesofclustertypevariablesthemselves.Furthermore,since been reached.Anattempttofindtheextremerangeofperiodsandsemi-major of theGroombridge1830 group,whichresultsfromthiscomparison (Fig.8), In thepastthishasbeenaquestionofsomeimportancebecause,asFig.1indicates, both lessthanthemassofSun,butthisresultisveryuncertain. RR LyraewiththeM3variablescomesfrom similarityofthecharacteristics No. 3,1959 published byBaum,Hiltner, JohnsonandSandage(1959)forM13 Earlier © Royal Astronomical Society • Provided by theNASA Astrophysics Data System 3. Identificationofthesubdwarfgroupmemberswithglobularclusterstars.—In The mostreliabledata forfaintglobularclusterstarsareprobably those 1923*36 1947*83 1900*47 218 172 198 PA Sep.Obs. ADS 10938 0*51 0*47 0*48 Observations ofADS10938and16644 VB VB Hu Stellar groups:IV Table III 1955*62 1949*85 1948*64 1944*84 1927*80 1957*90 1943*55 1942*56 1937-53 i932'33 1929*60 1927*00 1901*73 1901*16 1898*66 1891*59 1876*28 222 226 224 223 229 226 252 223 224 180 PA Sep. ADS 16644 Too Too 47 42 48 49 42 close close 0*72 0*42 0*44 0*40 0*47 0-34 0*26 0*15 0*15 o*68 0*58 0*58 0*63 0*63 0*83 Obs. n Wor V V VB VB B B B B B Doo B Cou ß ß ß D 20 261 195 9MNRAS.119. .255E m 2Ó2 photoelectric coloursobtainedformainsequencestarsintheclusterbyBaum, results forM13byArpandJohnson(1955)providedaccuratethree-colour between U—BandB—VfortheHyadesstars(SandageEggen1959). shown inFig.2asopencircles.Thefilledcirclesthefigurerepresent observation byArpandJohnsonforgiantsubgiantmembersofMi3are magnitude 20*5inthreecoloursand22twocolours.The these areshowninFig.2ascrossedcircles.ThefaintcompaniontoHD163810 the Groombridge1830group: colour indices,U—BandB—V,obtainedfrommorethanonephotoelectric observations tovisualmagnitude17*5andthelaterresultscarriedthis The followingvaluesofU—Barealsoavailableforthreesubdwarfmembers Hiltner, JohnsonandSandage.Thecontinuouscurverepresentstherelationship that theprocedures usedinthesederivations areprobably unsatisfactory. be bluerthananystars known intheGalaxy.Arp(1955)and Johnson the (M,B—F)-diagramisdirectlycorrelated withtheobservedultra-violet HD 219617probablyhaveidenticalcolours. probably haslittleeffectonthecolourofsystem:equalcomponents to afirstapproximation,displacementbelow astandardmainsequencein assumed thatM13isfree fromreddeningsincetheblueststarsare observed to excess, wewillfitthemainsequenceofMi3to thatdefinedbytheGroombridge (1955) havederivedareddening ofo*i6and2,respectively,but webelieve Groombridge 1830groupmembersandthe M13starsisverysimilar. 1830 stars.Theresult ofthisprocedureisshowninFig.3.It hasbeen f Since wehaveshownelsewhere(Sandage and Eggen1959)that,atleast stars. main sequencemembers0/Mi3{opencircles)andGroombridge 1830groupmembers{crossed circles). Thecontinuouscurverepresentsthe{U—B,B—V)-relation fortheHyadesmainsequence © Royal Astronomical Society • Provided by theNASA Astrophysics Data System It isevidentfromFig.2thattheobserved ultra-violetexcessofthe Fig. 2.—Threecolourdiagramforthegiantandsubgiant membersofM13{filledcircles), HD 163810+0*625—0*06 HD 219617+o*47—0*20 Gmb. 1830+0-74—0*17 Star B-VU-B Olin J.EggenandAllanR.SandageVol.119 m 195 9MNRAS.119. .255E m m m Na. 31959Stellargroups:IV263 fainter thanM=andfromthoseofArpJohnsonto+3;theopen circles representtheindividualphotoelectricresultsforclustermembersobserved observations byBaum,Hiltner,JohnsonandSandage(1959)forluminosities ? F by ArpandJohnson.Amean,colour-luminosityrelationforthestarsfainter than M=+5inFig.3istabulatedTableIVbasedonadistancemodulus of i4'2obtainedfromtheaboveprocedure. f individual photoelectricresults.ThetwocrossesrepresenttheRRLyraevariablesinMi3. {vertical lines).Thefilledcirclesrepresentphotographicmeanpointsandtheopen to thesubdwarfmembersofGroombridge1830group.Mi3isassumedbeunreddened. The modulus0/Mi3wasdeterminedasm—M=14-2byfittingthemainsequencecfcluster © Royal Astronomical Society • Provided by theNASA Astrophysics Data System The filledcirclesinFig.3representmeanpointsfromthephotographic Fig. 3.—The(Mv,B—V)-diagramforMi3{circles)andtheGroombridge1830group Mean colour-luminosityrelationforthemainsequence ofMi3 (B-V) {P-V)M Ev + 0*65+0-75 +6-3 + o*8o+0*90 +7*o + 0*70+o*8o +6*55 + o*6o+0*705+6*05 + o*55+0*655+5*8 + 0*90 +0*99 +7*4 + 0*85+0*945 +7*15 + 0*50+0*605+5*5 + 0*45+0-565+5-1 + 0*75+0*85 +6*8 mm m Table IV 20* 195 9MNRAS.119. .255E m m m m m 264 OlinJ.EggenandAllanR,SandageVol.119 are atM=—2*3.Thisvalueshouldbecomparedwiththeusuallyadopted therefore, iftheprocedureinfittingmainsequenceofMi3tothat the brightestgiantsarethreemagnitudesbrighterthanhorizontalbranch there areavailablethreecolourdataforalargenumberofvariablesisM3 with thatoftheGroombridge1830groupisRRLyraevariableshave revision. has beenusedinmanyestimatesofgalacticandextra-galacticdistances The valueofM=—3forthebrightendglobularclustergiantsequence one of—3whichisbasedon(1)theobservedfactthatinmostglobularclusters (RR Lyraevariables)and(2)theassumptionthatthisbranchisatM=o*. discussed inthefollowingsections. M~ +o*5insteadofo.Additionalevidenceonthispointwillbe Groombridge 1830groupiscorrect,thesedistanceswillneedasubstantial v v F vF of theBaileytypeaandbstars(large amplitudes) andthetypecstars V andU,for33variablesinthisclusterisshownFig.4wheretheseparation (Sandage 1959).Therelationbetweentheperiodsandlightamplitudes,B follows : and indicatethat,inlight amplitudeatleast,thesetwofieldvariables arevery y y similar totheM3stars. TheresultsforRRLyraeandTSextantis areas 1955) andforTSextantis(TifftSmith1958) arealsoplottedinthefigure (small amplitudes)isapparent.Thethreecolour resultsforRRLyrae(Hardie the clustercentre.ThepositionofRRLyraeandTSextantis andoftwovariablesinMi3 {crosses) arealsoshown. © Royal Astronomical Society • Provided by theNASA Astrophysics Data System One consequenceoftheaboveprocedureisthatbrighteststarsinMi3 4. RRLyraeanditsrelationtotheM3variables.—Theonlyclusterforwhich A secondconsequenceoftheidentificationmainsequenceM13 Fig. 4.—Theperiod-colourrelationshipforthevariablesin M3moredistantthan180*from T Sex+0*06 +0*24 0*820*550-44 RRLyr +0*05 +0-38 0*951*15i-o8 U-B B-VAy AAjj b 195 9MNRAS.119. .255E 0 I m m in M3.Thisresultisaparticularexampleofthefactthatperiod-amplitude great variationinthespectralfeaturesobservedfieldRRLyraestars the meanperiod-amplituderelationsforM3variables.BothofMi3 in M3.However,beforethefinalcomparisoncanbemadebetweenRRLyrae variation isprobablyrelatedtothefactthatsmallvariationsinmeanluminosity variables standoff,inoppositedirections,fromthemeanperiod-amplitude and theM3variables,possiblereddeningofformermustbeinvestigated. of thevariablesmayoccurfromclusterto(Sandage1958)and relation canvarymarkedlyfromclusterto(Belserene1954).This shown abovetobesimilarthevariablesinM3,areplottedFig.5aslarge values oiU—BandB—ViorTSextantisRRLyrae,bothofwhichwere relations discussedabovethatwecanidentifyRRLyraewiththevariables represent aninhomogeneousgroupanditisonlythroughtheperiod-amplitude relations fortheabandctypeM3variablesmorethananyindividualvariable variable star“gap”inM3arealsoshownthefigureasdots.Also,mean in M3areplottedFig.5ascrosses;non-variablestarsonbothsidesofthe observed tobebluerthananyknowngalacticstars.Ontheotherhand, absorption onthebasisoftheirhighgalacticlatitudesandpresencestars On theotherhand,availabletwo-colourdataforMi3variables(Arp No. 3,1959Stellargroups:IV265 250 parsecs,maybereddened.ThevaluesoíB—VandU—Bforthevariables RR Lyraeliesnearlyinthegalacticplane{b=+11)and,atadistanceof variables inFig.4.TSextantisfallsonthemean (Iwanowski 1953,Preston1958).Thereforethefieldvariablesprobably 95S)» whicharerepresentedinFig.4bycrosses,showmarkeddeviationsfrom along thereddeninglineindicatedbyarrow. relation fortheclusterstarsbutRRLyraeneeds reddening line(U— B) =0*74(5—V)(Lindholm1957).The valueof filled circles.Thereappears tobelittleornoreddeningaffectingT Sextantis, Non-variable horizontalbranchstarsareindicated to bemovedo*04inU—Band©“-osB—V because itfallsonthe mean (U—B,B—F)-linedefinedbytheM3 stars,but by filledcircles. RR Lyraeneedstobe movedo*5inB—Vand-04U—B alongthe © Royal Astronomical Society • Provided by theNASA Astrophysics Data System We haveassumedthatthestarsinbothM3andM13areunaffectedby Fig. 5.—ThreecolourdiagramfortheM3 m tion fortheM3variablesinFig.4. (with areddeningofo*5indicatedbyan arrow) areplottedasopencircles. T Sextantis(unreddened)andRRLyrae Fig. 6.—Colour-(blue)amplituderela- 195 9MNRAS.119. .255E om m m m m m m the presentvalueisundoubtedlymorereliable.Thepreviousdetermination previously (Sandage1956)but,withintheframeworkofassumptionsthat E(b-v)~ +'°5derivedinthiswaydiffersconsiderablyfrom+o-i2 266 it wascompared.TheconsistencyoftheresultthatRRLyraeisreddenedby the sameasthatofsupposedunreddened,non-variablestarswithwhich colour-amplitude relationoftheclustervariables. rests onthequestionableassumptionthatintrinsiccolourofRRLyraeis in Fig.6whichcontainsthecolour(blue)-amplituderelationforM3variables. RR LyraeissimilartotheM3variablesandthatlatterstarsareunreddened, A correctionfor+o*05reddeninginthisdiagramputsRRLyraeonthemean than o*i.ThisisparticularlytrueofM3(Johnson andSandage1956)where insufficient accuracyto compare mainsequences.Afurtherindication ofpossible in thepositionof mainsequence,theM3dataareconsidered tobeof observations offaintstarsinglobularclusters arenotofhighprecisionbecause that ofRRLyraederivedontheassumption that itisamemberofthegroup. same forRRLyraeandtheM3variables,itwouldthereforeappearlogical difficulties intheM3photometry istheanomalousU—Bvaluesderived forM3 calibrated standardstarsanditisdifficult, in thephotographicinterpolation the photographicinterpolationusuallydepends onveryfewphotoelectrically comparing theresultingmeanabsolutemagnitude oftheclustervariableswith that theirabsolutemagnitudesmightalsobethesame.Thiscouldverified of onlyo*iinthecolour indicesofthefaintM3starswillcauseanerror ofo*4 only 8photoelectricstandardswereobserved fainterthanV=igwhereas by fittingthemainsequenceofM3tothatGroombridge1830groupand 23 suchstandardswere obtainedfortheinvestigationofMi3.Because anerror However, asmentionedabove,withtheexception ofM13,thephotometric method, tocontrolthecolourindicesatfaintlight levelswithanaccuracygreater + o*05andtheassumptionthatitissimilartoM3variablesdemonstrated stars {crosses).ThebrokencurverepresentsthemeanrelationshipforM13giantsandmain sequence starsandthecontinuouscurvethatforHyadesmainstars. © Royal Astronomical Society • Provided by theNASA Astrophysics Data System The abovediscussionshowsthattheperiod-lightamplituderelationis Fig. 7.—TwocolourdiagramforM3giantsandsubgiants{filledcircles)mainsequence Olin J.EggenandAllanR.SandageVol.119 195 9MNRAS.119. .255E m m m m same stars,fainterthan V=ig,alsoshowananomalousultra-violet excess the variablestargapinM3bybrokenlines; blueextensionofthehorizontal a possibleerrorinthe measuredcolourindicesofthefaintM3stars. These systematically deviatefrom themainsequenceofGroombridge 1830 group and ofMi3.Thisdeviation isnotconsideredtoberealhowever, because of branch inM3,whichispopulatedbyonlya few stars,isshownasathinline. compared inFig.9wherethetwovariables in Mi3areshownascrossesand Figs. 8and9showthatthestarsinM3 fainter thanF=i9doindeed (Fig. 7)whichmaybe causedbythesameerror. corrected forabsorptionbeforeplottinginFig.8. variables tothatofRRLyraeinTableII,aftercorrectionfortheabsorption Fig. 8whichalsocontainsthecoloursandluminositiesofGroombridge discussed above.Theresulting(M,B—F)-diagramforM3isshownin observed M3valuesrisetoo*4-5. Groombridge 1830group,wehavefittedthemeanmagnitudeofM3 No. 3,1959Stellargroups:IV267 1830 groupmembers;thecolourandmagnitudeofRRLyraehavebeen main sequencestarshaveanexcessofabout&{U—B)=ö-2whereasthe main sequencestarsshowninFig.7.TheaccurateM13datashowthatthe F group. Themeancolourandluminositiesofrepresentative variablesinM3areplottedascrosses. of thevariableswithRRLyrae.Theverticallinesrepresent membersoftheGroombridge1830 © Royal Astronomical Society • Provided by theNASA Astrophysics Data System The (M,2?—F)-diagramsforM13(shaded) andM3(unshaded)are F Therefore, insteadoffittingthemainsequenceM3tothat m Fig. 8.—(Mp,B—V)-diagramforM3.Themodulusofi5 *o wasderivedfromacomparison 195 9MNRAS.119. .255E 268 table containsthefollowinginformation: ultra-violet excessintheircolours.Starsfor which Radialvelocityobservations velocities. Afewstars, notinthatcatalogue,areidentifiedbytheir HD orBD subdwarfs onthebasisoftheirspectralfeatures, arelistedinTableV.The are availableandwhich,asfarcanbedetermined, havebeenclassifiedas for example,velocity,positionintheHRdiagram, theappearanceofspectrum, groups, mightwellaffordtheonlydefinitivemethodofcalibratingluminosity numbers. spectra, withsomeadditionalstarsincluded onthebasisofanobserved and wewilldealhereonlywithsubdwarfssoclassified bytheappearanceoftheir and thespectraltype-colourrelationship.The interrelationsofsomethese of theglobularclusterstars.Itisthereforeimportantthatasearchbemadefor intended asanillustrationofaprocedurethat,ifitcanbeextendedtootherstellar observed photoelectrically, whichareindicatedbytwodecimalmagnitudes. criteria arediscussedelsewhereinMonthlyNotices (SandageandEggen1959) other groupsandinthissectionthedataavailableforsuchasearcharediscussed. sequences ofglobularclusterstothattheGroombridge1830groupis from thatofMi2inthisfigureandtheGroombridgegroupFig.8,isbelieved to bedueanerrorintheobservedcolours. The twocrossesrepresentthevariablesinM13.systematicdeviationofM3mainsequence © Royal Astronomical Society • Provided by theNASA Astrophysics Data System 5 Wilson No.:Thenumber inR.E.Wilson’s(1953)catalogueof radial 5. Otherpossiblegroups.—Theabovediscussionofthefittingmain Stars havebeenlabelled‘subdwarfs'onthebasisofavarietycriteria; Fig. 9.—Acomparisonofthe{Mv>V)-diagramsforMi3{shaded)andM3{unshaded). The visualmagnitude taken fromWilson’scatalogueexceptforstars Olin J.EggenandAllanR.Sandage Vol. 119 195 9MNRAS.119. .255E m that appeartohavesimilar spacemotions.Itshouldberemembered thatin in aglobularcluster(Sandage andWalker1955).Althoughthere maybea range ofo*3inluminosity ofthehorizontalbranchfromcluster tocluster for globularclusterssinceasimilardeficiency has beenobservedforA-typestars, in TableVII.Theparallaxesofthesestars havebeencomputedonthe were obtainedbyfittingthegiantormainsequence ofthe(M,B—F)-diagram assumption thattheybelongtothehorizontalbranch ofthe(M,B—F)-diagram in Fig.3.TwoA-typestars,whichshowan ultra-violet deficiency,areincluded we haveincludedthemagnitudes,coloursand spectraltypes;theparallaxes, (Sandage 1958),wehave fittedtheseA-typestarstothatofM13 inFig.3. stars areglobularclustergiants.Others,although spectroscopicallyclassified Table VIIwhere,inadditiontotheinformation suppliedforthestarsinTableVI, as luminosityclassV,maybesubdwarfs. Some ofthesestarsarelistedin to theglobularclusterandGroombridge1830groupmembers.Afewofthese that, althoughnotnotedthereassubdwarfs,haveanultra-violetexcesssimilar F v of thesolarmotionwithrespecttonearbystars(cf.Section1). in Wilson’sradialvelocitycatalogue,orBD/HDnumber,TableVIincludes. by fittingstarstothe(M,B—T)-diagraminFig.3.Inadditionnumber group) lineinFig.2.Theparallaxesusedthesecomputationswerederived and (B—V)coloursplacethemonorneartheMi3(andGroombridge1830 we havecomputedspacemotionsforthosestarsinTableVwhose(U—B) (3) theadoptedparallaxand(4)threecomponentsofspacevelocityfreed (1) thevaluesoftwocomponentspropermotion,(2)radialvelocity, displacement belowthemainsequenceisdependentuponultra-violetexcess, as welltostrengthenthedatainTableV. observations arenowinprogresstoincreasethenumberofknownsubdwarfs, table. in thelattercase(U—B)onrefractorsystemisgivennotesto brighter thanvisualmagnitude10andradialvelocity,astrometricphotometric F 20-inch reflectororattheCapeObservatorywith18-inchreflector, A fewvalues,giveninparentheses,havebeen(1)convertedfromthe various sources. (3) observedbytheCapeobservers(Stoy1958)withMcCleanrefractor— (P, EJg-systemwhennoU—Bislisted,(2)observedatHerstmonceuxwiththe E =Evans(1958)andGGreenstein(1954). c catalogue. Afewvaluesnotinthatcatalogue,orimprovedbymorerecent observations, areindicatedbytheobserver;R=Roman(1955),E=Evans column. Otherclassificationsarenotedattheendoftable. P =Popper(1942,1943),JJoy(1947),R=Roman(1955),MMünch(1944), No. 3,1959Stellargroups:IV269 (1958), G=Greenstein(1954). © Royal Astronomical Society • Provided by theNASA Astrophysics Data System In TableVIIIwehave gatheredtogetherthestarsinTablesVIand VII There areseveralobjectsinRoman’s(1955)catalogueofhighvelocitystars On theassumption,discussedelsewhere(SandageandEggen1959),that This listofsubdwarfsisundoubtedlyveryincomplete,evenamongstars, B—V, U—B:ColoursobservedbyRoman(1955)onthe(U,B,T)-system pi, d:Thetotalannualpropermotionanditspositionangle,takenfrom p, O:Theradialvelocityanditsquality,c,d,takenfromWilson’s Ob. :Theauthorityfortheclassificationlistedinthirdcolumn; Sp. :Thespectraltypeassignedbytheobservermentionedinsixth 195 9MNRAS.119. .255E 270 Wilson No.m v HD 215438*22 HD 160319*75 -f9°2i9o io*5 25°i98i 9*35 7131 9*5 7464 9*68 7567 n*7 7951 11*6 7923 12*8 7296 io*9 7547 io*5 6880 9*8 6869 io*8 6734 8*23 7170 6*49 7117 10*70 6728 12*6 7017 n*3 © Royal Astronomical Society • Provided by theNASA Astrophysics Data System 7932 8*79 7913 9*8 7308 io*i8 7266 10*1 6704 io*3 4400 io*o 6236* ii*o 6296 io*6 6294* 8*24 6237 10*2 4005 8*o8 5951 11*8 5909 9*8 5815 io*8 5908 n*5 5730 9*59 5494 9*69 5240* 8*34 5058 ii*6 3668 io*8 2851 6*97 2420 9*22 5793 lo-io 5757 n*5 3562 n*9 3314 n*5 5784* 8*74 1919 9-7 1904 io*6 1828 io*i8 1800 10*5. 1735 8*o6 1892 io*8 646* 5*20 390 10*27 987 io*o8 91* 12*0 Stars classifiedassubdwarfsonthebasisoftheirspectralfeatures F2 V-VI+95 Gi V-VI+27 G2 V-VI4-59 G8 VI-98 G2VI -240 G5VI -97 sdKs +126 sdF6 —40 sdA8 +252 sdA6 —57 sdGo 461 sdFs +74 sdF4 4-159 sdF2 +98 sdFs +186 sdGo —108 sdF2 — 34 sdF4 +143 sdA7 4-56 sdG3 +68 sdGo —128 sdF8 4-62 sdA4 —18 sdA5 +265 sdF3 -188 sdA8 —91 sdA7p -59 sdFs -51 sdG6 +276 sdFs +339 sdFs —19 sdF3 +25 sdF2 +47 sdF8 -5 sdF4 +59 sdF9 +12 sdF7 —4 sdF6 +543 sdF7 +126 sdF6 +203 sdG2 +89 sdGo +167 sdK5 -173 sdA.5 +26 sdF2 +189 sdA8 +154 sdK5 —167 sdGo —168 sdF9 —160 sdF7 -139 sdF4 +63 sdA.9 —114 sdF3 -33 sdF2 —266 sdF4 —100 Olin J.EggenandAllanR.Sandage Sp. p Table V G b R7*04 d P o*i8 d P d P1-02 R 0*35 d P0*76 d P0*43 R 0*41 G 0*25 e P0-35 b Ro*55 b Jo*88 b Ro*66 R 0*82 R 0*17 d P0*38 C P0*63 c P0-35 c R0*46 b J0*08 c P0*48 c P0*52 c J0*83 Q Ob.¡M c Po*6o c P0*34 c P0*52 d P b J0*09 b J1*36 c P0*82 c Go*i8 c Po*54 c P0*43 c P0*64 d P0*35 c P c Po*47 c J079 c R0*62 c Po*66 c Ri-97 c J0*56 c Jo*45 c R0*54 c P0*43 c Po*6o c J1-58 d P0*45 d P0*32 c P0*37 c P0*62 c P1-63 c P0*3: a R376 279 252 283 277 (40*42) 250 240 203 40*48 266 (+0*53) 226 230 210 +0*47 145 4074 180 4o*44 180 171 225 4o*86 247 (+0*38) 165 (+0-49) 166 118 154 4-0*41 160 146 4o*6o 180 180 155 158 4o*6o 165 170 197 +0*30 180 142 (4-0*42) 126 122 +0*44 138 182 +0*48 141 175 I3I ISS I4O: (+0*46) 156 149 4-0*97 120 +0*62 I94 4-0*46 115 +070 HI 153 +0-45 ... (+0-44) 72 +0*36 79 e B-v — 0-12 V,ol. 119 ( 0*25) (-0-24) (-0-25 :) -0*25 — o*i8 — 0*19 -0-25 40*23 — 0*19 — 0*12 4 O*22 — 0*19 +0-53 +0-03 — 0*24 — 0*22 — 016 40*11 U-B 0*17 195 9MNRAS.119. .255E No HD 181743* HD 181743 Wilson No. - 3>!959 H- i7°47o8 + 26°3578 + 2°3375 15042 14884 14122 14598 13543 12730 10287 10404 13782 11949 10289 15042 14598* 13543* 13327 1^754 11060 10404* 10367 14884* 14704 14568 14539 14122* © Royal Astronomical Society • Provided by theNASA Astrophysics Data System 9840 8771 8691 6236 9236 9069 8771* 8691* 8554 8236 6294 5784 4005 9840* 9401 8603 8296 8249 8246 8554 5240 646 91 Stars classifiedassubdwarfsonthebasisof io*8 sdF8+91cM n*7 sdF6—67cP 10*52 sdF+103dM 10*20 sdF7—172cR n*4 sdAs—68G n*o sdF8—216cJ io*6 sdFo—319cM n*4 sdG2+167dP 10*46 sdG2—138dJ 11*6 SCÍG3+16dP 10*04 sdF3--162cP io*5 sdFo~ioodP io*o sdF5—157cP 10*62 sdF6—32dP lo-oo sdG2—113bP 14*4 sdKs-157dJ d m, m 111, m 9*47 sdF6—296R 7*38 F9VI-45bR 9*62 sdF8+191cM 6*98 sdA2—363bR 8*5 sdGo—172cM 9*95 sdF5-389R 7*20 sdF5—171bR 7*ov sdF2—15cJ 9*36 sdF4—128R 9*64 sdF+18E 9*13 sdGi—51cP 9*06 KoVI+292cP 9*74 sdF4+34cR 9*7 sdF7+126cJ 6*20 sdF5p—22cJ 8*5 sdA9+167cP 8*92 sdA8+50dM 8*17 sdF8+10bR ADS 16644. ADS 17173- A companion,300"distant,hascommonpropermotion andvelocity. Astronometric binary,P^i300. Spectroscopic binarywith arangeof37km/sec. (U—B)c= +i45,which isroughlyequivalenttoU—B=—o*20. SX Phe. ADS 10938. (U—B)c= +i49,which isroughlyequivalenttoU—B=—o*i7. Roman (1955):G2V. Roman (1955):G6V. Roman (1955):sdF2. Roman (1955)assignstheclassificationG5IVand states:“veryweak Roman (1955):“veryweaklines Roman (1955)classifiesthisstarasG2IIIandstates:“Alllinesaré P Cas. LDS iA. Spectroscopic binarywitharangeof83km/sec. m Sp.pQOb. v very weak”. lines andstrongCH Stellar groups:IV Notes toTableV Table V(cont.) i their spectralfeatures 0*37 281+0*44—0*20 0*55 88+0*43—o*2i 0*53 183+0*48—o*i2 0*26 184 0*44 148 0*08 218+o*i6+0*10 0*47 85 0*82 180(+0*46) 0*83 2140*62—0*06 o*6o 181 0*29 229+0*67+0*10 0*54 161+0*42—o*2i 0*34 204(+0*33)(-0*20) 0*48 188(+0*40) 0*90 187+0*51—0*09 0*17 180+0*37—0*23 0*51 213 °*35 85+0*42—0*22 0*87 270+0*70+0*11 o*88 164 0*90 163 0*57 129(+0*42) 0*44 183 0*75 229 0*50 215 o*2i 290+0*90+0*38 3*68 196+o*8o0*15 1*19 254+0*48:—o*io 1*29 203+0*47—0*20 1*21 153 1*29 189(+0*48) i*68 164 H eB-VU-B 271 195 9MNRAS.119. .255E Wilson No. 272 HD 16031 HD 21543 HD 181743 be fittedtothedwarf(orgiant)sequenceof(M,B—F)-diagramforM13 each casethespacemotionwascomputedonassumptionthatstarscould and theGroombridge1830group.Thisassumptionisbasedonobserved velocity materialbecomesavailableforsubdwarfs,webelievethatadditional ultra-violet excessinthecoloursofstars.Whenmorephotometricandradial until onewasfoundthatgavespacemotionvectorssimilartothoseforsome for whichphotoelectric,photometricdataarenotavailable.Forthesestarswe star inTablesVIandVII.Itshouldbeemphasized thatthismethodisexactly stars willundoubtedlybefoundtomembersofthesepossiblegroups.In have triedseveralparallaxes,guidedbyaroughspectraltype-colourrelationship, support ofthisviewweincludeinbracketsTableVIIIafewstarsfromV for anindividualstar,anecessaryandsufficient conditionforgroupmembership is thatthecomponentsofspacemotionbe identicalwiththoseofthegroup. equivalent totheconvergentpointmethoddescribed inPapersIandIIsince, An illustrationoftheaccuracyparallax whichcanbeobtainedbythis F Nos. 6294(HD84937)and5909(—3°2525). Thisillustration,aswellthe method, ontheassumptionofgroupmembership, isgivenbelowforWilson sensitivity ofthecomputedspacemotionsto theaccuracyoffundamental implies thatthespace vectors ofthegroupstarsareidentical,this may notbe discussion oftheGroombridge1830starsgiven inTableII,alsoshowsthe precisely true.Deviations fromthisrequirementcanocur,inUand F,of1to data. 2 km/sec/100pcasaresult ofsmalldifferencesintheeccentricities isoperiodic + 2°3375 + i7°47o8 13327 10287 © Royal Astronomical Society • Provided by theNASA Astrophysics Data System 8771 5240 6294 8236 7464 5784 5730 8603 4005 7308 1735 6734 5494 8249 2420 It shouldbenotedthat, althoughwehavestatedthatgroupmembership Space motionsofstarsinTableVwithobservedultra-violetexcesses comparable tothatoftheMi3andGroombridge1830groupstars — 1*012 + 0*104 + 0*725 — 0*203 + 0*370 + 0*049 — 0*012 -0*031 — 0*112 + 0*373 + 0*078 — 0*184 — 0*268 + 0*354 — 0*077 -0*050 + 0*051 — 0*203 — 0*010 -0*368 + 0*496 + 0*455 h'OL -3*544 -0*805 -0*438 -1*836 — 0*790 — 0*900 — 0*488 — 0*082 -o*473 -0*347 -o*i55 -0*430 -0*465 — o*8i8 — 0*064 -0*056 — 0*204 — 0*062 — 0*648 + 0*069 + 0*071 -0*283 Olin J.EggenandAllani?.Sandage Pô -139 + 300 —162 — 240 + 203 -168 + 159 — 18 + 63 — 45 + 34 + 62 + 95 +167 + 59 + 18 -363 — 22 + 59 — 296 +339 -389 Table VI 0-035 0-037 0*026 0*008 0*012 0*0017 0*012 0*019 0*012 0*034 0*010 0*025 0*011 0*013 0*0395 0*006 0*003 0*0055 0*0135 0*011 0*0135 0*014 7T* u+u(o) V+V(0)W+W(oy -273 — 282 -163 — 204 —160 — 82 -I25 — 120 — I2I + -130 + + + + +160 +100 + +198 +338 +344 33 21 38 37 21 91 3 -184 • 37 ■275 • 98 •202 • 53 •272 -109 -213 ■250 ■285 -187 -132 450 211 270 177 103 195 100 135 86 Vol. 119 - 87 - 43 - 57 —140 + 29 - 40» + 67 + 66- + 65 - 53 + 26 + 45 - 44 + (y - 21 -125 + 24. + 77 + 42. + 52 - 57 o 195 9MNRAS.119. .255E /, m m m m m No. 3,1959Stellargroups:IV [0-019 —160 with UandV,wewouldexpectitsvalueforthegroupmemberstobecorrelated orbits ofwidelyseparatedstars(Woolley1958).Also,ifWisnottightlycoupled with theheightofstarsaboveorbelowgalacticplanebecause that extremedifferencesofonly10to15km/secinWwillbeencounteredand differences inthegravitationalfieldatdifferentZ-distances(Woolley1957). in calibratingtheluminositiesoffieldRRLyraevariables.Asisevident are uncertainandthisistrueofsubdwarfsRRLyraevariablesingeneral. in thispreliminaryinvestigationtheywillbeignored. However, anevaluationofthiseffectfortheZ-distancesinvolvedhereshows proper motionsinexcessofo-5and,perhaps,anotherdozenwithrelatively large butinsufficientlyobservedmotions.Thesamesituationexistsforthe variables, thathavelargeandrelativelywell determinedmotions,withthose Table I,eventheavailabledataformembersofGroombridge1830group uncertainty inthephaseoflightvariation. and oftenhaveaprobableerroraslarge25km/sec.Thereisalsoanadditional There arenotmorethanadozenRRLyraevariableswithwelldeterminedannual from theGroombridge1830group,isM = +o-6.Thisvaluemustbe for twovaluesoftheparallaxaregiven.The meanabsolutevisualmagnitude of thepropermotionandradialvelocity spacemotionsofthevariables,» of subdwarfs.ThesestarsarelistedinTable IXwherevariousdeterminations uncertainty intheradialvelocitiesofRRLyraevariablescausedby radial velocitieswhichinmanycasesdependupononlyoneortwoobservations with theusuallyadopted valueofo-determinedsolelyfrom a statistical recent determinationbased onthesestatisticsis+o*5(Pavlovskaia 1953). discussion ofthemotions ofthesestars.Itshouldalsobenotedthat themost considered aspreliminarysinceaccuratephotometry isnotyetavailablefor of thevariables,determinedbygroupparallax method,togetherwithRRLyrae But theagreementof +o-6 and5obtainedbythetwomethods should most ofthevariables. This preliminaryvalueof+o-6shouldbe compared o-oi8 —168 v 0-020 —153 77 £7+¡7(0)V+V(0)W+W(0) © Royal Astronomical Society • Provided by theNASA Astrophysics Data System jLt=+0-38 /x79GC a0 We havetentativelyidentifiedthemotionsof afewofthefieldRRLyrae One ofthemostimportantusespossiblegroupsdiscussedaboveis = +o*359=-0-791Y + 0-370 p= —i8*i = -i5*3 Wilson No.6294 —17-6 135 H? 128 -0-790 Md (1) W (5) +10 —10 O] [0-015 0-010 o-oi6 0-014 - Ma=+o3 ft«=-o-58 U +U(O)VV(O)W+W(0) — 241 —148 —172 -159 p =+20 M U = +40 + 25 No. 5909 Md (2) 202 145 128 135 W (6) Cape -5 + 4 + 2] + 1 273 195 9MNRAS.119. .255E 274 Royal Astronomical Society •Provided bythe NASA Astrophysics Data System a § 1 o S' b h ûq b co + o 05 + o + O t? a I I gpNC0C0Î^Tt"spÇ0ÇlÇ0 OIOClCOOn00 . MOW00 NO CO 00 COdNOJ> 00 + + I sO 00w + I CO J>nO ON m0010o OOOO + $ o d voJ>Oin d coONThO CO OTh10M M ONThm b 8d oco CO ThONd10 10 d d co 00 f«-bNob\b ont^obobbsbbt^bbvbbbmsbsoo Th m10co P d M ThvO M m do\ d ono On Cî00COwsOI>MCOOONCOl>OOsOi>Tf-VOCl Cï CO0010 OOOmO mOOO M sOÏO00 I # I III 00 ONO no coo l> Od co l>00 M d Olin J.EggenandAllani?.Sandage l> md 10 d00 I WM + O M O O OnCO10d M 00COvO K Q * VO M sO Om OOfrO M K*J>£> d d o IO Î^vO00 Th ocoon o Thd d 00 o OOOO OOO 0000 o cod d 00On I> COIOON On d00 d O NOM CO IOmO M SOIOvO tJ- J>CO CÍ yoCï 00 Mco + + 11III+I+I+ ÏO 10co o CO +NOsO Th dM co O m 10 0 d 00 On Th co Th + O 11 Th M00 m dco10\o 5 00 00 00 d sO O 1000 cooo b m co Thj>m + m coo Th CONO0010 IO OmsOnO + d OOnco OOOO O »OThco 10 On IO losoTj- o bobo P 00Np10 TÍ-00 CO 1 + b 9 r I >>> i> Th10 d Thoo COOO O 10 d m^h IO OnTh Th Onm tH CÍOv d M , nO l>O ffi o _ dNO + Th 00 CO NO M * + iT + + t^OO OnO 000 Th NO00 o d co 10dOnO d On dCONO
Star /xa fid S* /> S* Tr U+U(0) V+V(0) W+W(Q) vO vO \Q NO D +1 +1 lO tJ- O cï b o 9 o 00 CO 00 to vO + +1 + + +1 to to Ov to CO VO CO ó b o 9 N to O M o rt- to o M *-1 N M o I , + b vO 00 00 + + + + 10 CÏ 9 Ov M Ov b ó o o M vO 00 toM vO OM Cß VO o Olin J.EggenandAllanR.Sandage a +1 +1 to CO 0Ï 999 bob o bob iH CÖ I I M M ? 9 00 +1 +1 s- CO 0Î to 9 CO vO Ov M CO 0 b o M b b 9 Provided bythe NASA Astrophysics Data System I I 1 op + to b CO CO vO 00 ^ X s r- to to to 10 o
0*0008 +126 —200 +127 +0-2 Yol. 119 W 7932 —0749 +0-096 C +142 C (4) 0-016 + 95 -205 +120 +4-8 * i = Variable Stars, 9, 1955 ; Y = Yale ; H = Hertzsprung ; C = Cape ; W = Mt Wilson and Md = McDonald. f The radial velocity depends upon one Mt Wilson spectrogram. The dependence of the space motion vectors on the radial velocity is illustrated by assuming an alternative value of — 20 km/sec. 195 9MNRAS.119. .255E I Arp, H.C.,1955,A.J.,60,317. Arp, H.C.andJohnson,L.,1955,Ap.J.,122,171. are available. luminosity ofRRLyraevariableswhengoodastrometricandphotometricdata is sohighthatitsexploitationpromisestoprovideadefinitivecalibrationofthe No. 3,1959Stellargroups:IV277 Joy, A.H.,1947,Ap.J.,105,96. Johnson, H.L.andSandage,A.R.,1956,Ap.J.,124,379. not beemphasizedatthepresenttime,potentialaccuracyofthismethod Jenkins, L.,1952,GeneralCatalogueofTrigonometricStellarParallaxes,YaleUniv.Obs. Eggen, O.J.,1956,A.J.,61,361. Belserene, E.P.,1954,A.J.,59,406. Baum, W.A.,Hiltner,W.,Johnson,H.L.andSandage,A.R.,1959,Ap.J.,inpress. Hardie, R.H.,1955,Ap.J.,122,256. Greenstein, J.L.,1954,Pub.A.S.P.,66,126. Evans, D.S.,1958,privatecommunication. Pavlovskaia, P.,1953,VariableStars,9,349. Parenago, P.P.,1946,Astr.Jour.SovietUnion,23,31. Münch, G.,1944,Ap.J.,99,271. Lindholm, E.H.,1957,Ap.J.,126,588. Keenan, P.C.andKeller,G.,1953,Ap.J.,117,241. Popper, D.M.,1942,Ap.J.,95,307. Sandage, A.R.,1956,Ap.J.,123,278. Iwanowski, W.,1953,TorunBull.Ill,No.2. Woolley, R.v.d.R.,1957,M.N.,117,198. Wilson, R.E.andJoy,A.H.,1950,Ap.J.,in,221. Wilson, R.E.,1953,GeneralCatalogueofStellarRadial Velocities,CarnegieInst,ofWash. Stoy, R.H.,1958,M.N.A.S.S.A.,17,142. Sandage, A.R.andEggen,O.J.,1959,M.N.,119,278. Preston, G.,1958,unpublishedresults. Slettebak, A.,1952,Ap.J.,115,576. Sandage, A.R.andWalker,M.,1955,A.J.,60,230. Roman, N.G.,1955,Ap.J.Supplement,No.18. Tiíft, W.andSmith,H.J.,1958,Ap.J.,127,513. 1958a,M.N.,118,65. 1958c,M.N.,118,560. 1958b,M.N.,118,155. 1959,Ap.J.,129,596. 1958,StellarPopulations,Spec.Vat.,5,41. 1943,Ap.J.,98,209. 95>VistasinAstronomy,III,London. 1958,M.N.,118,45. Pub. No.601. © Royal Astronomical Society • Provided by theNASA Astrophysics Data System Royal GreenwichObservatory, 1959 February27. Although theaccuracyofgroupparallaxvalueikf=+o-6shouldalso F Herstmonceux Castle, Sussex : References Mt WilsonandPalomarObservatories, Carnegie InstitutionofWashington, California InstituteofTechnology, Pasadena, Cal.,U.S.A. 21