19 6 6ApJ. . .14 6. .743D 041 monitored bytheAirForceOfficeofScientificResearch theOfficeofAerospaceResearch. Mount Wilson.Theintensitiesatsixteendiscrete wavelengths(selectedbyOke[1964] Py/(p/po) —QrelationshipindicatethateitherpPuppisispulsatinginahigher-orderharmonicmode trum scanner(usedwitharefrigerated1P21photomultiplier) onthe60-inchreflectorat manner ofAmstars.McNamaraandAugason(1962)reportedthattheK-line(Can) photoelectric indexisweakforitsspectraltype. than thefirstortheoryofitspulsationisnotunderstood. star, pPuppis,arereported.Theamplitudesofradial-velocity,light,andtemperaturevariations are relativelymoreabundantthanthelighterelementscomparedtoSun,in type cvariables.Estimatesoftheabsoluteluminosityandmassfromobservedgravity space velocity. Puppis hasthelowesttemperatureofallknownôScutistars,andasignificantlygreater remain constant,andthereisnoevidencefortheexistenceofasecondaryperiod.Rlio none ofthemultiple-periodcharacteristicsassociatedwithsuchstarshasbeenfoundto variables inordertouseanobservedperiod-luminosityrelation.Strömgren’sc-lsys- ability andevolutionaryroleofsuchstars. 1965. Thecontinuumobservationsweremadewith theCassegrainphotoelectricspec- apply toit.Forexample,theamplitudesofbothlightandradial-velocityvariations -* 300° K.AnintrinsicluminosityofpPuppis,Mg=+2.4,wasobtainedbyKinman brightness occursapproximately0.02dayslaterthanminimumradialvelocity.Bappu variation inradialvelocitywithatotalamplitudeof10km/secandthatmaximum and amass9J£=3.2$)îofromtheperiod-densitylawwithpulsationconstantQ~ tions wereobtainedforthedurationofacomplete cycleonthenightofJanuary22-23, 11 km/sec,0.15mag.,and280°K,respectively.Therelativephasesdifferfromthoseobservedincluster- tude of0.15mag.Struve,Sahade,andZebergs(1956)showedthatthereisanassociated (1959). Heassumeditfittedtheobservedperiod-luminosityrelationofcluster-typec to bevariableinlight(period0.141days)byEggen(1956)whomeasuredatotalampli- tem indicesweremeasuredbyMcNamaraandAugason(1962)toderiveM=+1.7 (1959) reportedthattwo-colormeasurementsindicateavariationintemperatureof P pg © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem * ThisresearchwassupportedinpartbytheUnitedStatesAir ForceundercontractAF49(638)-1323, f PresentlyattheBerkeleyAstronomicalDepartment,University ofCalifornia. The observationsreportedbelowweremadetoprovidegreaterinsightintothevari- The brightstarpPuppis,classifiedintheMKKsystemastypeF6II,wasfirstshown The resultsofsimultaneousspectrophotometricandspectralobservationstheshort-periodvariable Simultaneous high-dispersionspectraandspectrophotometric continuumobserva- It isofinteresttonotethat,althoughpPuppishasbeenclassifiedasaôScutistar, Greenstein’s (1948)abundanceanalysisofthisstarshowedthattheheavyelements Carnegie InstitutionofWashington,CaliforniaInstituteTechnology THE VARIABILITYOFRHOPUPPIS* Mount WilsonandPalomarObservatories I. J.DanzigerandL.V.Kumf Received April30,1966 II. OBSERVATIONS I. INTRODUCTION ABSTRACT 743 19 6 6ApJ. . .14 6. .743D secondary standard,16Puppis,wasobservedintermittentlyduringthecycleand night. Acheckonthevalidityofmeanextinctioncoefficientswasalsoprovidedby atmospheric extinctionbyusingmeancoefficientsforMountWilson.Anearby observations of16Pupatdifferentzenithdistances.Nodeviationsindividualfluxes to berelativelyfreeoflines)weremeasuredwithanexitslitSOÂ,andcorrectedfor tied toOke’ssystemofabsolutestandardsbyobserving€OriandaLeoonthesame 744 I.J.DANZIGERANDL.V.KUHI greater than1or2percentgrossvariationsinextinctionduringthecourseof extinction correctionsarenotinerror. observations weredetected.Sincetheobservedcontinuumof16Pupisalsoingood dispersion of4.5Â/mmwiththe32-inchcamera100-inchtelescope.Thesespectra agreement withthatexpectedfromitsspectraltypeitisreasonabletoconcludethe Time. Radialvelocitymeasurementsarerelative,notabsolute. were usedtodefinetheradial-velocityvariationofpPupandprovideline-blanketing val aroundthecyclearegiveninTable1,together withthecontinuummeasuresof violet regionswereobtainedatafewphasestocomplete theblanketingcorrections. corrections tothecontinuumobservations.Additionalplatesofvisualandfar-ultra- where itisdifficulttojudgethepositionof continuum.BecauseOkeandConti corrections, obtainedbymeasuringtheenergyabsorbed bythelinespectrumfrom surface gravity,wewereconcernedwiththecorrections shortwardoftheBalmerjump and Conti1966).Inparticular,becausethesizeof theBalmerjumpissensitiveto smooth continuum,aresimilartothoseinHyades starsofthesametemperature(Oke program ofMihalas(1965). Amoredetaileddiscussionofthemethodhasbeen givenby obtained gravitieswhichappearedtobereasonable fortheHyadesstars,itseemslikely continuum measurescorrected forblanketingtotheoreticalmodelscomputed withthe that thegravitiesobtainedhereforpPuparenot subjecttolargeerrors. Oke (1965).InFigure1the radial-velocity,light,andtemperaturevariations areplotted 16 Pupandtheblanketingcorrectionswhichareeffectively thesameatallphases.The © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem Coudé spectraofthevioletandblueregionsweretakenonbakedIlaOplateswitha Fig. 1.—Radialvelocity,light,andtemperatureofpPupplottedasafunctionPacificStandard The uncorrectedcontinuumfluxesexpressedinmagnitudes perunitfrequencyinter- An effectivetemperature andgravityateachphasewasobtainedby fitting the 19 6 6ApJ. . .14 6. .743D © American Astronomical Society C/3 Ph o ë ►H O w u ë O £ P tn Ph O H H ►H P H Q. S CM t'-On 00rhiC<1CMOni-i©t-h t'* V©^!>•©i-t04CNCM00OO CM CO^Tfit^ico C<5 CO^LOlO»O LO CO i—I CMCO^ CM CO ©©©©©(NCOtíHtíhiOCM'^tHCS CO r^l On ©©\^»Ov©00Ort.toOn00 i>.ooooooooooooooooooi>*t^ CM CM N© 4>.!>.NOCO CM © CMCMCOCOCOCOCO©© i-HI©©CO’^»OVO©tH©i-HIO v© CM©i-i00NOVO1—1’rfl CM 00TfCOTtHOn CM NOCMCO'ON©t'’»l>.VON©©00 00 VO 00© 00 On 00 O'©OnN©wTf TfiTfiOTt»l>* •»—i On© lO TfT^H © On (P Pi pq v© 3 a •äl '■g ¿ cj P bo o 0 O CO 19 6 6ApJ. . .14 6. .743D mechanism ofpulsationinthisstarisnotyetunderstood. Neitherofthesetheoretical Lyrae maybeafactorof2lowerthanthatrequired toobtainatheoreticalmodelwhich priate. ThephaserelationshipsdiscussedabovearenottypicaloftheBailey-typec parallax forlogg=2.3 and2.6,weestimatethemassofpPuptobe 0.4 Sffioand 0.8 2fto,respectively.Because theerrorsintrigonometricparallaxmay belarge, possibilities canbeeliminatedonthebasisofcurrent work. The onlyadhocresolutionofthisproblem,sincethe observationalerrorsshouldnotbe we obtainM=+6.8.Clearlythesedistancemoduli of—5.4and—3.9arecompletely mode ofpulsation.Sincethereisevidencethatsomeshort-periodvariables,suchasclus- variables. ItmaybeseenthattheminimumtemperatureofpPup(6=0.83)is previous determinationsquotedabove.However,therelativephasesoflightandradial Either themodeofpulsationismuchhigherthan thefirstharmonicorphysical simulates theobservedbehavior.Therefore,ifwe assume thatlogg=2.6forpPuppis, same asthatofthecluster-typevariablesRRLyrae,SUDraconis,XArietis,andVZ Hy profiles,bythemethodofSearleandOke(1962).Althougheffectivetemperatures velocity aredifferent.Minimumlightoccursapproximately0.08Pbeforemaximum velocities areplotted. gravity arenotshownsincetheamplitudeofexpectedvariationsissmallerthan as afunctionoftime.Thelightvariationsarethosemeasuredat4566Â.Changesinthe small, ~0.001Sîo.If,instead, weadoptM=+0.2fromthemeasuredtrigonometric incompatible withthetrigonometricparallaxof +0'i031reportedbyEggen(1956). on thisassumptionusinganappropriatevalueoí0.030(Christy1966). ter-type c,arepulsatinginthefirstharmonicmode,followingcalculationsbased bolometric magnitude,andQisthepulsationconstantwhichdependsonharmonic where Pistheperiod,pdensity,Rradius,SDÎmass,M,absolute following relationshipswereused: continuum measurements,thedifferentialvariationsagreeinamplitudeandphase.No derived fromHyprofilesaresystematicallyhigherby300°Kthanthosethe tions are11km/sec,0.15mag.,and280°K,respectively,ingoodagreementwith than tominimumlight,aconclusionsupportedbyeffectivetemperaturesderivedfrom error inanindividualdetermination,i.e.,±0.2thelogarithm.Onlyrelativeradial sufficiently largetodoso,wouldbepostulate amuchsmallervalueofQ^0.006. relationship, combinedwithotherobserveddata,toderivealuminosityandmass.The explanation canbeofferedatpresentforthedifferenceinscaleofeffectivetempera- and hence radial velocity.Minimumtemperatureseemstooccurclosermaximumvelocity Cancri commentedonbyDanzigerandOke(1966). 746 p PupofM~+8.3.Christy(1966)hassuggested thatgravitiesobtainedforRR tures, butwebelievetheresultsofcontinuummeasurementstobemoreappro- v e v v © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem The masswhichwouldbederivedfromtheabove low luminositywouldbeincredibly If weuselogg=2.3intheaboveformulaeobtainanabsolutemagnitudefor It canbeseenthattheamplitudesofradial-velocity,light,andtemperaturevaria- Because pPupispulsatingwitharegularperiodwemayinvoketheP\/(p/po)=Q M-Mo =5(2log|-log|--21og^), log 2 L ocR*T*,mcepRS,gccm/R e mo III. INTRINSICLUMINOSITYANDMASS I. J.DANZIGERANDL.V.KUHI m Mq-m 2.5 Vol. 146 19 6 6ApJ. . .14 6. .743D more advancedstageofevolution. with normalevolutionfromthemainsequencetorightorwhetheritisastarin placed ontheparallaxprogrambeingcarriedoutbyDr.VasilevskisatLickObserva- it isnotpossibletosaywhetherthepositionofpPupinH-Rdiagramcompatible for itssupportofthisinvestigation. No. 3,1966 Bappu, M.K.V.1959,M.N.,119,400. period variableVZCancribyDanzigerandOke(1967)requiresanadequatetheo- ity mayallowamoredefinitestatementtobemadeinthefuture.Thestarhasbeen — .1965,Ann.Rev.Astr.andAp.,3,23 retical interpretation. Oke, J.B.1964,Ap.J.,140,689. McNamara, D.H.,andAugason,G.1962,ApJ,135,64 Christy, R.F.1966,Ap.144,108. edged. Oneofus(L.V.K.)wouldliketothanktheCarnegieInstitutionWashington Oke, J.B.,andConti,P.S.1966,Ap.J.,143,134. Mihalas, D.1965,Ap.J.,Suppl.,9,321. Kinman, T.D.1959,M.N.,119,134. Danziger, I.J.,andOke,J.B.1967,Ap.J(inpress). tory. Theproblemofthepulsationconstantissimilartothatencounteredwithshort- Struve, O.,Sahade,J.,andZebergs,V.1956,ApJ,124,504 Searle, L.,andOke,J.B.1962,Ap.J.,135,790 Eggen, O.J.1956,Pub.A.S.P.,68,238. Greenstein, J.L.1948,Ap./.,107,151. © American Astronomical Society •Provided bytheNASA Astrophysics DataSystem A moreaccuratedeterminationofthetrigonometricparallaxandpossiblygrav- Discussions withProfessorJ.B.OkeandDr.R.F.Christyaregratefullyacknowl- REFERENCES RHO PUPPIS 747