第76章 对火星轨道变化问题的最后解释(2/10)

inadditiontothevaguenessoftheceptofstability，theplasinoursolarsystemshowacharactertypicalofdynamicalchaos(sussmanwisdom1988，1992).thecauseofthischaoticbehaviourisnowpartlyuoodasbeiofresonanceoverlapping(murraylecar，franklinholman2001).however，itwouldrequireiingoveranensembleofplaarysystemsincludingallnineplasforaperiodcseveral10gyrthlyuandthelong-termevolutionofplaaryorbits，sincechaotiamicalsystemsarecharacterizedbytheirstrongdependeninitialditions.

inthispaperwepresentpreliminaryresultsofsixlong-termnumeritegrationsonallnineplaaryorbits，caspanofseveral109yr，andoftwootheriionsc

oherhand，inhisaccuratesemi-analyticalsecularperturbationtheory(laskar1988)，laskarfindsthatlargeandirregularvariationsappearintheetricitiesandinationsoftheterrestrialplas，especiallyofmercuryandmarsonatime-scaleofseveral109yr(laskar1996).theresultsoflaskar'ssecularperturbationtheoryshouldbefirmedandiigatedbyfullynumeritegrations.

dtoacloseenterinplaaryandprotoplaarysystems(yoshinaga，kokubomakino1999).ofcoursethisstatementotbesimplyappliedtosystemswithstableorbitalresonancessuchastheune–plutosystem.

fromthatpointofview，manyofthepreviouslong-termnumeritegrationsincludedonlytheouterfiveplas(sussmankinoshitanakai1996).thisisbecausetheorbitalperiodsoftheouterplasaresomugerthanthoseoftheinnerfourplahatitismucheasiertofollowthesystemfiveionperiod.atpresent，thelonumeritegrationspublishedinjournalsarethoseofdunlissauer(1998).althoughtheirmaintargetwastheeffectofpost-main-sequenasslossoabilityofplaaryorbits，theyperformedmanyiionscupto～1011yroftheorbitalmotionsofthefourjovianplaheinitialorbitalelementsandmassesofplasarethesameasthoseofoursolarsystemindunlissauer'spaper，buttheydecreasethemassofthesungraduallyintheirnumericalexperiments.thisisbecausetheysidertheeffectofpost-main-sequenasslossinthepaper.sequently，theyfoundthatthecrossingtime-scaleofplaaryorbits，whibeatypidicatoroftheinstabilitytime-scale，isquitesensitivetotherateofmassdecreaseofthesuhemassofthesunisclosetoitspresentvalue，thejovianplasremainstableover1010yr，orperhapslonger.dunlissaueralsoperformedfoursimilarexperimentsontheorbitalmotionofsevenplas(venustoune)，whichcoveraspanof～109yr.theirexperimentsonthesevenplasarepreheitseemsthattheterrestrialplasalsoremainstableduriegrationperiod，maintainingalmularoscillations.

1.2previousstudiesandaimsofthisresearch

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