死在火星上

《死在火星上》

对火星轨道变化问题的最后解释

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AlthoughournumericalintegrationsspanthelifetimeoftheSolarsystem,thenusnecessarytoperformmoreandmorenumericalintegrationstoconfirmandexamineindetailthelong-termstabilityofourplanetarydynamics.

这只是作者君参考的一篇文章,关于太阳系的稳定性。

当然还有其他论文,不过其它论文下载一篇要九美元,作者君下不起,就不贴上来了。

4.4Long-termcouplingofseveralneighbouringplanetpairs

Letusseesomeindividualvariationsofplanetaryorbitalenergyandangularmomentumexpressedbythelow-s10and11showlong-termevolutionoftheorbitalenergyofeachplanetandtheangularmomentuminN+1andN?oticethatsomeplanetsfoarticular,hefigures,theyshownegativecorrelationsinexcnegativecorrelationinexchangeoforbitalenergymeansthattpositivecorrelationinexchangeofangularmomentu,wecanseethatMarsshowsapositivecorrelationintheangularmomentumvariationtotheVenus–curyexhibitscertainnegativecorrelationsintheangularmomentumversustheVenus–Earthsystem,whichseemstobeareactioncausedbytheconservationofangularmomentumintheterrestrialplanetarysubsystem.

ItisnotclearatthemomentwhytheVenus–Earthpairexhibitsanegativecorrelationiaypossiblyexplainthisthroughobservingthegeneralfactthattherearenoseculartermsinplanetarysemimajoraxesuptosecond-orderperturbationtheories(uwer&ClemenceBoccaletti&smeansthattheplanetaryorbitalenergy(whichisdirectlyrelatedtothesemimajoraxisa)mightbemuchlessaffectedbyperturbingplanetsthanistheangularmomentumexchange(whichrelatestoe).Hence,theeccentricitiesofVenusandEarthcanbedisturbedeasilybyJupiterandSaturn,heotherhand,thesemimajorstheenergyexchangemaybelimitedonlywithintheVenus–Earthpair,whichresultsinanegativecorrelationintheexchangeoforbitalenergyinthepair.

ThelongitudeofthenodeofPlutoreferredtothelongitudeofthenodeofNeptune,θ3=ΩP?ΩN,circulatesandtheperiodofthiscirculationisequaltotheperiodofθnθ3beeszero,i.longitudesofascendingnodesofNeptuneandPlutooverlap,theinclinationofPlutobeesmaximum,theeccentricitybeesminimumandtheargumentofperihelionbees90°.Whenθ3bees180°,theinclinationofPlutobeesminimum,theeccentricitybeesmaximumandtheargumentofperihelionbees90°liams&Benson(1971)anticipatedthistypeofresonance,laterconfirmedbyMilani,Nobili&Carpino(1989).

Anargumentθ4=?P??N+3(ΩP?ΩN)libratesaround180°withalongperiod,?5.7x108yr.

Inournumericalintegrations,theresonances(i)–(iii)arewellmaintained,andvariationofthecriticalargumentsθ1,θ2,θ3remainsimilarduringthewholeintegrationperiod(Figs14–16).However,thefourthresonance(iv)appearstobedifferent:thecriticalargumentθ4alternateslibrationandcirculationovera1010-yrtime-scale(Fig.17).ThisisaninterestingfactthatKinoshita&Nakai‘s(1995,1996)shorterintegrationswerenotabletodisclose.

Asfortheouterjovianplanetarysubsystem,Jupiter–SaturnandUranus–ever,thestrengthoftheircouplingisnotasstrongparedwiththatoftheVenus–Earthpair.

5±5x1010-yrintegrationsofouterplanetaryorbits

Sincethejovianplanetarymassesaremuchlargerthantheterrestrialplanetarymasses,wetreatthejovianplanetarysystemasanindce,weaddedacoupleoftrialintegrationsthatspan±5x1010yr,includingonlytheouterfiveplanets(thefourjovianplanetsplusPluto).Theresultsexhibittherigorousstabilityoftheouterplanetarysystemoverthislongtime-italconfigurations(Fig.12),andvariationofeccentricitiesandinclinations(Fig.13)showthisverylong-termsthoughwedonotshowmapshere,thetypicalfrequencyoftheorbitaloscillationofPlutoandtheotherouterplanetsisalmostconstantduringtheseverylong-termintegrationperiods,whichisdemonstratedinthetime–frequencymapsonourwebpage.

Inthesetwointegrations,therelativenumericalerrorinthetotalenergywas?10?6andthatofthetotalangularmomentumwas?10?10.

5.1ResonancesintheNeptune–Plutosystem

6Discussion

Whatkindofdynamicalmechanismmaintainsthislong-termstabilityoftheplanetarysystemWecanimmediatelythinkoftwomajorfeaturesthatmayberesponsibleforthelong-st,thereseemtobenosignificantlower-orderresonances(meanmotionandsecular)iterandSaturnareclosetoa5:2meanmotionresonance(thefamous‘greatinequality’),her-orderresonancesmaycausethechaoticnatureoftheplanetarydynamicalmotion,buttheyarenotsostrongastodestrsecondfeature,whichwethinkismoreimportantforthelong-termstabilityofourplanetarysystem,isthedifferenceindynamicaldistancebetweenterrestrialandjovianplanetarysubsystems(Ito&Tanikawa1999,2001).WhenwemeasureplanetaryseparationsbythemutualHillradii(R_),separationsamongterrestrialplanetsaregreaterthan26RH,sdifferenceisdirectlyrelatedtotherestrialplanetshavesmallermasses,yarestronglyperturbedbyjovianplanetsthathavelargermasses,ianplanetsarenotperturbedbyanyothermassivebodies.

Thepresentterrestriever,thewideseparationandmutualinteractionamongtheterrestrialplanetsrendersthedisturbanceineffecthedegreeofdisturbancebyjovianplanetsisO(eJ)(orderofmagnitudeoftheeccentricityofJupiter),sincethedisturbancecausedbyjovianplanetsisaforcedoscillationhavinganamplitudeofO(eJ).Heighteningofeccentricity,forexampleO(eJ)?0.05,isfarfromsufficienttoprovokeinsweassumethatthepresentwidedynamicalseparationamongterrestrialplanets(>26RH)isprobablyoneofthemostsignificantconditionsformaintainingthestabilityoftheplanetarysystemovera109-yrtime-detailedanalysisoftherelationshipbetweendynamicaldistancebetweenplanetsandtheinstabilitytime-scaleofSolarsystemplanetarymotionisnowon-going.

对火星轨道变化问题的最后解释 (第3/3页)

lrelatedtotheplanetaryorbitalenergyEperunitmassasE=?μ2/hesystemispletelylinear,theorb-linearityintheplanetarysystemcamplitudeofthelowest-frequencyoscilever,suchasymptomofinstabilityisnotprominentinourlong-termintegrations.

,thetotalorbitalenergyandangularmomentumofthefourinnerplanetsandallnineplanetsareshownforintegrationN+upperthreepanelsshowthelong-periodicvariationoftotalenergy(denotedasE-E0),totalangularmomentum(G-G0),andtheverticalponent(H-H0)ofthein,G0,lowerthreepanelsineachfigureshowE-E0,G-G0andH-fluctuationshowninthelowerpanelsisvirtuallyentirelyaresultofthemassivejovianplanets.

Comparingthevariationsofenergyandangularmomentumoftheinnerfourplanetsandallnineplanets,itisapparentthattheamplitudesofthoseoftheinnerplanetsaremuchsmallerthanthoseofallnineplanets:theamplitusdoesnotmeanthattheinnerterrestrialplanetarysubsystemismorestablethantheouterone:thisissimplyaresultoftherelativesmallnessofthemassesofththerthingwenoticeisthattheinnerplanetarysubsystemmaybeeunstablemorerapidlythantheouteronebecauseof,thefluctuationsintheinner4paever,wecannotneglectthecontributionfromotherterrestrialplanets,aswewillseeinsubsequentsections.

Kinoshita&Nakai(1996)integratedtheouterfiveplanetaryorbitsover±5.5xyfoundthatfourmajorresonancesbetweenNeptuneandPlutoaremaintainedduringthewholeintegrationperiod,andthahefollowingdescription,λdenotesthemeanlongitude,Ωisthelongitudeoftheascendingnodeand?scriptsPandNdenotePlutoandNeptune.

MeanmotionresonancebetweenNeptuneandPluto(3:2).Thecriticalargumentθ1=3λP?2λN??Plibratesaround180°withanamplitudeofabout80°andalibrationperiodofabout2x104yr.

TheargumentofperihelionofPlutowP=θ2=?P?ΩPlibratesaround90°nticipatedinthesecularperturbationtheoryconstructedbyKozai(1962).

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