Evolutionary processes in binary and multiple stars PDF
Preview Evolutionary processes in binary and multiple stars
This page intentionally left blank Binarysystemsofstarsareascommonassinglestars.Starsevolveprimarilybynuclear reactionsintheirinteriors,butastarwithabinarycompanioncanalsohaveitsevolution influencedbythecompanion.Multiplestarsystemscanexiststablyformillionsofyears, butcanultimatelybecomeunstableasonestargrowsinradiusuntilitengulfsanother. This volume discusses the statistics of binary stars; the evolution of single stars; andseveralofthemostimportantkindsofinteractionbetweentwo(andeventhreeor more)stars.SomeoftheinteractionsdiscussedareRoche-lobeoverflow,tidalfriction, gravitationalradiation,magneticactivitydrivenbyrapidrotation,stellarwinds,magnetic braking and the influence of a distant third body on a close binary orbit. A series of mathematicalappendicesgivesaconcisebutfullaccountofthemathematicsofthese processes. Peter Eggleton is a physicist at the Lawrence Livermore National Laboratory in California.FollowinghiseducationinEdinburgh,heobtainedhisPh.D.inAstrophysics fromtheUniversityofCambridgein1965.HelecturedforashortperiodatYorkUni- versitybeforereturningtotheUniversityofCambridgetoconductresearchfrom1967 to2000asaFellowofCorpusChristiCollege.In2000,hetookuphiscurrentpositionat LLNL.Heiswellknownthroughoutthecommunityasoneofthemostknowledgeable expertsinbinarystarevolution. CambridgeAstrophysicsSeries Serieseditors AndrewKing,DouglasLin,StephenMaran,JimPringleandMartinWard Titlesavailableinthisseries 10. QuasarAstronomy byD.W.Weedman 17. MolecularCollisionsintheInterstellarMedium byD.Flower 18. PlasmaLoopsintheSolarCorona byR.J.Bray,L.E.Cram,C.J.DurrantandR.E.Loughhead 19. BeamsandJetsinAstrophysics editedbyP.A.Hughes 22. Gamma-rayAstronomy2ndEdition byP.V.RamanaMurthyandA.W.Wolfendale 23. TheSolarTransitionRegion byJ.T.Mariska 24. SolarandStellarActivityCycles byPeterR.Wilson 25. 3K:TheCosmicMicrowaveBackgroundRadiation byR.B.Partridge 26. X-rayBinaries byWalterH.G.Lewin,JanvanParadijsandEdwardP.J.vandenHeuvel 27. RRLyraeStars byHoraceA.Smith 28. CataclysmicVariableStars byBrianWarner 29. TheMagellanicClouds byBengtE.Westerlund 30. GlobularClusterSystems byKeithM.AshmanandStephenE.Zepf 32. AccretionProcessesinStarFormation byLeeW.Hartmann 33. TheOriginandEvolutionofPlanetaryNebulae bySunKwok 34. SolarandStellarMagneticActivity byCarolusJ.SchrijverandCornelisZwaan 35. TheGalaxiesoftheLocalGroup bySidneyvandenBergh 36. StellarRotation byJean-LouisTassoul 37. ExtremeUltravioletAstronomy byMartinA.BarstowandJayB.Holberg 38. PulsarAstronomy3rdEdition byAndrewG.LyneandFrancisGraham-Smith 39. CompactStellarX-raySources byWalterLewinandMichielvanderKlis EVOLUTIONARY PROCESSES IN BINARY AND MULTIPLE STARS PETER EGGLETON LawrenceLivermoreNationalLaboratory,California Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo Cambridge University Press TheEdinburghBuilding,Cambridge,UK Published in the United States of America by Cambridge University Press, New York www.cambridge.org Information on this title: www.cambridg e.org /9780521855570 ©P.Eggleton2006 Thispublicationisincopyright.Subjecttostatutoryexceptionandtotheprovisionof relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. Firstpublishedinprintformat 2006 - ---- eBook(EBL) - --- eBook(EBL) - ---- hardback - --- hardback Cambridge University Press has no responsibility for the persistence or accuracy ofs forexternalorthird-partyinternetwebsitesreferredtointhispublication,anddoesnot guaranteethatanycontentonsuchwebsitesis,orwillremain,accurateorappropriate. Contents Preface pagevii 1 Introduction 1 1.1 Background 1 1.2 Determinationofbinaryparameters 2 1.3 Stellarmultiplicity 13 1.4 Nomenclature 16 1.5 Statisticsofbinaryparameters 17 1.6 AMonteCarlomodel 27 1.7 Conclusion 29 2 Evolutionofsinglestars 31 2.1 Background 31 2.2 Mainsequenceevolution 35 2.3 Beyondthemainsequence 69 2.4 Stellarwindsandmassloss 97 2.5 Heliumstars 104 2.6 Unsolvedproblems 106 3 Binaryinteraction:conservativeprocesses 109 3.1 TheRochepotential 109 3.2 Modificationstostructureandorbit 117 3.3 ConservativeRoche-lobeoverflow 128 3.4 Evolutionincontact 144 3.5 Evolutionaryroutes 147 4 Slownon-conservativeprocesses 158 4.1 Gravitationalradiation:modeGR 158 4.2 Tidalfriction:modeTF 159 4.3 Windprocesses:modesNW,MB,EW,PA,BP 168 4.4 Magneticbrakingandtidalfriction:modeMB 178 4.5 Stellardynamos 183 4.6 Binary-enhancedstellarwinds:modesEW,MB 192 4.7 Effectsofathirdbody:modeTB 200 4.8 OldUncleTomCobleyandall 207 v vi Contents 5 Rapidnon-conservativeprocesses 209 5.1 TidalfrictionandtheDarwininstability:modeDI 209 5.2 Commonenvelopesandejection:modesCE,EJ 210 5.3 Supernovaexplosion:modeSN 221 5.4 Dynamicalencountersinclusters:modeDE 225 6 Accretionbythecompanion 231 6.1 Criticalradii 231 6.2 Accretiondiscs 235 6.3 Partialaccretionofstellarwind:modePA 239 6.4 Accretion:modesBP,IR 241 6.5 Accretionineccentricorbits 250 6.6 Conclusions 253 AppendixA Theequationsofstellarstructure 257 AppendixB Distortionandcirculationinanon-sphericalstar 266 AppendixC PerturbationstoKeplerianorbits 276 AppendixD Steady,axisymmetricmagneticwinds 289 AppendixE Stellardynamos 295 AppendixF Steady,axisymmetric,coolaccretiondiscs 299 References 304 Subjectindex 315 Stellarobjectsindex 320 Preface Thisbookisintendedforthosepeople,perhapsfinal-yearundergraduatesandresearchstu- dents,whoarealreadyfamiliarwiththeterminologyofstellarastrophysics(spectraltypes, magnitudes, etc.) and would like to explore the fascinating world of binary stars. I hope it will also be useful to those whose main astrophysical interests are in planets, galaxies or cosmology, but who wish to inform themselves about some of the basic blocks on which muchastronomicalknowledgeisbuilt.Ihaveendeavouredtoputintoonebookanumberof concepts and derivations that are to be found scattered widely in the literature; I have also includedachapterontheinternalevolutionofsinglestars. In the interest of keeping this volume short, I have been brief, some might say cursory, in surveying the enormous literature on observed binary stars. It is almost a truism that theoreticalideasstandorfallbycomparisonwithobservation.Myintentionistoproducea second volume, with my colleagues Dr Ludmila Kiseleva-Eggleton and Dr Zhanwen Han, in which individual binary and triple stars that rate less than a line in this volume will be discussedintheparagraphortwoeach,atleast,whichtheydeserve.Inaddition,thesynthesis of largetheoretical populationsof binarystars will bediscussed. Someindividual binaries canbeseenasflyingentirelyinthefaceofthetheoreticalideasoutlinedhere–seeOWGem, Section2.3.5.IfItookatfacevaluethenotionthatonewell-measuredcounter-exampleis allthatisneededtodemolishatheory,thenIwouldhavegivenuplongago.Rather,Ithink, itisnecessarytopersevere:notbeparalysedbydisagreementwithobservation,butalsonot tosweepdisagreementunderthecarpet. Anumberofproblemsthathavetobeconsideredmaywellbecapableofbeinganswered only by detailed numerical modelling, constructing three-dimensional models of a whole star, or of a pair of stars in a binary. Massive computer resources will be needed for such investigations;forthatreasonImovedfromCambridgeUniversitytotheLawrenceLivermore NationalLaboratory,California,wheresuchresourcesarebeingdeveloped.ThisLaboratory hasstartedthe‘DjehutyProject’–namedaftertheEgyptiangodofastronomy–topursuethis long-termgoal.Wehopethatthisprojectwillsupplement,thoughitcannotentirelyreplace, thesimpleideaswhichthisbookdiscusses. Iamverygratefultomanycolleagueswhohavebeengenerousoftheirtimeindiscussing the issues of binary-star evolution. Drs Zhanwen Han, Onno Pols, Klaus-Peter Schro¨der, Chris Tout and Ludmila Kiseleva-Eggleton have kindly supplied some figures, as well as muchinsight.IparticularlywishtothankProf.PietHutforhiscarefulandcriticalreading ofthemanuscript,andsuggestionsforimprovement,andDrsKemCookandDaveDearborn fortheirpatienceinallowingmetopursuethistopic. vii viii Preface ThisworkwasperformedundertheauspicesoftheUSDepartmentofEnergy,National Nuclear Security Administration by the University of California, Lawrence Livermore National Laboratory under contract No W-7405-Eng-48; and much use was made of the archiveattheCentredeDonne´esastronomiquesdeStrasbourg.
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