InterstellarHeFlowAnalysisoverthePast8YearswithIBEXNeutralObserva=onsE.Möbius1,E.Bower1,M.Bzowski2,S.A.Fuselier3,4,D.Heirtzler1,M.A.Kubiak2,H.Kucharek1,M.A.Lee1T.Leonard5,D.J.McComas6,7,N.Schwadron1,P.Swaczyna2,J.M.Sokol2,P.Wurz8

1SpaceScienceCenter&DepartmentofPhysics,UniversityofNewHampshire,Durham,NH03824 2SpaceResearchCenterPolishAcademyofSciences,Warszawa,Poland

SH31A-2528

Supportedby:NASAUSAPASPolandSNFSwitzerland

•ISNFlowPeakLongitude:λISNPeak=130.45±0.10ofrom2009-15Χ2fitandλISNPeak=130.45±0.06ofromweightedmeanofall2-year(2009-14)fitsaReradjusTngfor:E-dependentefficiency&SecondaryNeutrals

•ISNParameterTube:AdopTngλISN∞=75.0o[3,5]theparametertubegivesVISN∞=26.0±0.1km/s,infullagreementwithvaluesin[3,5].

•YearlyVaria=onsofλISNPeak:Yearlyvalues2009–2015varywith±0.55oStandardDeviaTon.2015strongestdeviaTon,butonly5usablevaluesàeliminated(only0.05odifferenceincombinedfit)

•Varia=onofSorted2-YearFits:2-yearfitsshowmuchreducedvariaTon(±0.32oStdDev)andnovisibletemporaltrendWeightedmeaninfullagreementwithcombinedfitresults.

•NextStepsinAnalysis:-ReplacelinearfitforeachorbitbyfittoAnalyTcModelResultsàWillincreasenumberofusableorbits-Add2016resultsaRerdespinningdatafromoperaTonswithoutIBEXStarTracker&useIBEX-LoEnergySteps1through4àExtendsexisTngdatabase

Conclusions&Outlook

FIGURE5:ISNfluxesatperihelionforeachusableIBEXorbit2009-15asafuncTonofλEcladjustedforaberraTonduetoIBEXmoTon.ErrorbarscontainallknownandesTmatedcontribuTons.obtainedfromaΧ2fittoaGaussian.

Introduc=on Determina=onoftheISNFlowPeakLongitude ISNFlowPeakLongitudeFiang ISNFlowPeakResultsfromMul=-YearFitsTheInterstellarBoundaryExplorer(IBEX)obtainsapreciserelaTonbetweentheinterstellarneutral(ISN)flowlongitudeλISN∞andspeedVISN∞,withsubstanTallylargeruncertaintyinλISN∞,whichdefinesaparametertubethatconnectsISNlongitude,laTtude,speed(velocityvectorVISN∞),andtemperature[1,2,3,4,5],inagreementwithUlyssesGAS[6,7,8](Figure1).TheinterstellarmagneTcfieldBISisdeducedfromtheIBEXribbon,consistentwiththeheliosphericasymmetryandTeVcosmicrayanisotropy[9].ThetwovectorsdefinetheBIS-VISN∞plane,whichcontrolstheshapeof,andtheflowdeflecTonin,theouterheliosheath[10,11].AcomplementarydeterminaTonofλISN∞(PosterSH31A-2529)togetherwithTghteningandtrackingoverTmetheparametertubewillrefinetheBIS-VISN∞planeandconstrainanypotenTaltemporalvariaTons[12,13,14].

•ISNParameterTubeDetermina=on:TheparametertubeissolelydeterminedbytheISNbulkflow(ISNflowmaximum)longitudeλISNPeakat1AUobservedwithIBEX[4,15](discussedonthisPoster).•FlowLongitudeDetermina=on:TheISNflowlongitudeλISN∞isdeterminedfromthevariaTonoftheradialISNflowspeedVr(orthepickupioncut-offalongtheEarth’sorbit,whichissymmetricaboutλISN∞(discussedonPosterSH31A-2529).

TheUncertain=esofDataforeachOrbitcontain:-Χ2-fiterror(x2asfitisrestrictedtolinearandpossiblecurvatureomimed)-uncertaintyinadjusTngforIBEXmoTon(translatedintotherate,usingtheslopesoftheΧ2-fitandofthemodelGaussianinFigure5)-uncertainTesoftheefficiencyandionizaToncompensaTon

References1.  M.Bzowskietal.,Astrophys.J.Supp.220:28(2015).2.  T.Leonardetal.,Astrophys.J.804:42(2015).3.  D.J.McComasetal.,Astrophys.J.Supp.220:22(2015).4.  E.Möbiusetal.,Astrophys.J.Supp.220:24(2015).5.  N.A.Schwadronetal.,Astrophys.J.Supp.220:25(2015).6.  M.Wime,Astron.&Astrophys.426,835(2004).7.  M.Bzowskietal.,Astron.&Astrophys.569,A8(2014).8.  B.Wood,H.-R.Mueller&M.Wime,Astrophys.J.801:62(2015).9.  N.A.Schwadronetal.,Science343,988(2014).10. R.Lallementetal.,Science307,1447(2005).11. V.Izmodenov,D.Alexashov&A.Myasnikov,Astron.&Astrophys.437,L35(2005).12. P.C.Frischetal.,Science341,1080(2013).13. P.C.Frischetal.,Astrophys.J.801:61(2015).14. R.Lallement&J.-L.Bertaux,Astron.&Astrophys.565,A41(2014).15. M.A.Lee,E.Möbius&T.Leonard,Astrophys.J.Supp.220:23(2015).16. E.Möbiusetal.,Astrophys.J.Supp.198:11(2012).17. M.A.Kubiaketal.,Astrophys.J.Supp.223:25(2016).18. C.Drewsetal.,J.Geophys.Res.117,A09106(2012).

ISNParameterTubeandFlowLongitude

3SouthwestResearchInsTtute,SanAntonio,TX

AsseeninFigure5,thereisnoentryfor2012,andtheyearlyfitvaluesforvarysubstanTally,with2015offsetbymorethan2xthestandarddeviaTon.Accordingtothecriteriaforusableorbits,the2012setonlycontains3datapoints,notenoughforafittoaGaussianwith3freeparameters.Thus2012wascompletelyomimed.2015contains5usableorbitsoverarestrictedrangeinλEcl,whichbyitselfdoesnotconstrainλISNPeakwellenough,butcanbeusedintheoverallcombinaTon.Omisng2015fromthefitinFigure5resultsinλISNPeak=130.40±0.11o,onlydifferentby0.05o.

•Reduc=onofSystema=cEffectswithstochas=cDistribu=on:ISNGoodTimesinfluencetheresultssystemaTcally,forexample,byforcingextrapolaTonordataeliminaTon,buttheyaredistributedstochasTcallyeachyear.UsingmulT-yeardatareducessuchsystemaTceffects,asdemonstratedin[18].Hereweuseall2-yearcombinaTons.

FIGURE2:SchemaTcviewofsampleISNtrajectories(darkblue)andtheISNflowvectoralongtheEarth’sorbit(lightblue).ThedarkbluedashedlineindicatesanalternateBulkFlowTrajectorythatsaTsfieseq.1),arrivesatλISNPeak,andthusalsobelongstotheISNparametertube.ThelightbluedashedarrowsindicatethepamernofVr,whichissensedbythepickupioncut-offandfollowseq.2).

FIGURE3:ISNPSDdistribuTon(solidblackline)asafuncTonofeclipTclongitudeλEcl.ThespinintegratedISNflux(dasheddarkblueline)ismodifiedrelaTvetothePSDdistribuTondueto:-  ISNFluxvariaTonwithVISN-  SlightIBEX-LoEfficiencyvariaTonEISN

-  FluxexTncTonfromIoniza=on

asafuncTonofλEcl.TodetermineλISNPeakfromthecenteroftheobservedfluxdistribuTon,theseeffectshavetobecompensatedfor.

FIGURE7:λISNPeakasobtainedfromΧ2fitstoaGaussianfordatasetsof3-yearcombinaTonsinallpermutaTons,alongwiththeweightedmean,combinedfitvaluefromFigure5,standarddeviaTonanderror.

FIGURE1:RelaTonshipbetweenVISN∞andλISN∞accordingtotheIBEXparametertubebasedonvariousIBEXanalysesincomparisonwithUlyssesresults(adaptedfrom[5]).AlsoshownwithaverTcalbarishowanindependentmeasurementofλISN∞willconstraintheISNflowvector.TheeffectofapreciseindependentdeterminaTonoftheISNflowlongitudeλISN∞ontheknowledgeoftheISNflowparametersisindicatedbythegreenverTcalbar.

70 8078767472λISN∞ [

o]

30

28

26

22

24

VISN

∞ [km/s]

λISN∞[o]

ThedeterminaTonofthetheISNFlowPeakLongitudeλISNPeakinvolvesthefollowingsteps[16]:•ISNGoodTimesforeachIBEXorbit[2],butretainTmeintervalsthataredespunatgroundbecauseofmissingStarTrackerpoinTnginformaTon•SpinintegratedISNcountrates±3σ ofpeakdividedbyσper512spins•LinearΧ2fittotheseratesasfuncTonofλEclàobtainrateatλEclwhereIBEXspinpointsexactlyattheSuninλ,adjustedforIBEXmoTon•Compensaterates(seeFigure3)for-ObservaTonofISNflux,whileISNbulkflowcorrespondstopeakinPhaseSpaceDensity(PSD)oftheISNdistribuTonandFlux~PSDxV3-WeaklyE-dependentIBEX-LoefficiencyduetovariaTonofISNenergy(EISN)withλEcl(relaTvein-flightcalibraTonfordifferentIBEX-LoE-Steps)-ExTncTonbyionizaTonalongtrajectoryinλEclusingTIMED&SDOdata.

Figure4:RaToofcombinedISNandsecondaryHe(WB)fluxandISNfluxasafuncTonofλEcl(byIBEXorbit)obtainedfromthebestfitsecondarysoluTonin[17]for2009-11and2013–15(2012notshownbecausenotusedhere).TherelaTvecontribuTonoftheWBislargestatlowλEclandduringsolarminimum(2009-11).Thetwounusuallyhighpointsin2015areforIBEXspinaxisorientaTonsat+5olaTtude,indicaTngincreasedviewingoftheWBforthisorientaTon.TheobservedISNfluxesineachorbitarecompensatedfortheseraTos.

ToobtainavalueforλISNPeaktheadjustedratesfromeachIBEXorbit(ororbitarcaRer2011)areevaluatedfortheirvariaTonwithλEcl.UsableorbitssaTsfy:-ObservaTonsarewithin110o≤λEcl≤160o-PosiTonatexactSunpoinTngofthespinaxisisinsideofortheextrapolaTonislessthantherangeofthedataintervalinλEclTheseratesareΧ2fimedtoaGaussianforeachindividualyearorthecombinaTonofalldataaRernormalizingtheratestothepeakrate(asshowninFigure5).

FIGURE6:λISNPeakasobtainedfromΧ2fitstoaGaussianforthedatasetofeachyear,alongwiththeweightedmean,combinedfitvaluefromFigure5,standarddeviaTonanderror.

VISN∞

Sunθ∞ = λISN∞ + λISN Peak

1cos(θ∞ )

=1+ (rEVISN∞2

GMs

)

Vr

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+ W

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ISN&WB 2013 - 2015

20142015

2013

Contact:eberhard.moebius@unh.edu

4UniversityofTexas,SanAntonio,TX 5LaboratoryforAtmosphericandSpacePhysics,Boulder,CO6DepartmentofAstrophysicalSciences,PrincetonUniversity,NJ 7OfficeoftheVPforthePrincetonPPL,PrincetonUniversity,NJ 8PhysikalischesInsTtut,UniversitätBern,Switzerland

1)

Contribu=onofSecondaryHeNeutrals:TheobservedIBEXISNfluxdistribuTonalsocontainsavariablecontribuTonfromsecondaryHeneutralsthatoriginateintheouterheliosheath.TheISNdistribuTonisadjustedforthesecondarycontribuTonaccordingtoFigure4[from17].

0.1

1

100 110 120 130 140 150 160

2009-15 TL&DH 120516

Nor

m R

ate

(adj

. for

PSD

)

λEcl

(Aberration) [o]

y = m2*exp(-(x-m3)^ 2/m4^ 2/...ErrorValue

0.0677873.9687m2 0.11829131.78m3 0.2549412.282m4

NA15.688ChisqNA0.98868R

y = m2*exp(-(x-m3)^ 2/m4^ 2/...ErrorValue

0.0125731.0092m2 0.11154130.45m3 0.1044511.471m4

NA88.673ChisqNA0.99137R

λPeak

= 130.45±0.10o

σλ = 11.47±0.10o

126

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FitstoyearlydatasetsaresimilartothecombinedsetinFigure5,butwithlargererrors.TheyearlyfitresultsarecompiledinFigure6,alongwiththeweightedmeanofallyearlyfitresultsandthecombinedfitresultfromFigure5.

130o110o 150o λEcl

ISN PSD Distribution

λ ISN

Pea

k

Effects of- Flux ~ PSD x V3

- Efficiency Variation with EISN- Ionization

120 140133 eV76 8280 km/s

EISN

VISN(Earth)θ∞125o135o 115o

Ionization

2)vr2 =2+vISN∞2 −(1−cosλ)−vISN∞2 sin2λ+vISN∞sin |λ |⋅[vISN∞2 sin2λ+4(1−cosλ)]1/2⎧

⎨⎪

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or

Figure7showsall2-yearcombinaTonssortedbytheircenterTme.CombinaTonswithidenTcalcenterTmevarymorethanthosewithdifferentTmesàConsistentwithnotrend!AddingmoredatapointsandextendingTmewillreduceuncertainTes.