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DIAGNOSTICS OF THE LOCAL INTERSTELLAR MEDIUM AND
ITS INTERACTION WITH THE HELIOSPHERE
FROM WITHINE. Möbius
with H. Kucharek, M. Bzowski, L. Saul, P. Wurz, S. Fuselier, V. Izmodenov, D. McComas, H.-R. Müller, D. B. Alexashov
5/21/08
Thanks to: IBEX Team and NASA SMEX Office ISSI He and H Team
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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Neutral LIC Flow Diagnosticswith IBEX
• IntroductionInformation Imprinted on Interstellar Gas Flow, previous Observations & current Knowledge
• New Observation Method- IBEX Mission Configuration and Simulations- IBEX Instrumentation and Sensitivity- IBEX Orbit Strategy- IBEX In-Flight Performance
• Summary & Conclusions
04/24/23
Overview
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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Rosetta Nebula
Interstellar Gas Penetrates the Barrier
Planets
MMooddeerrnn VViieeww ooff tthheeSSuunn''ss NNeeiigghhbboorrhhoooodd
Interstellar Gas
Sun
SSuunn''ss UUVV
Planets
VViieeww ooff tthhee SSuunn''ssNNeeiigghhbboorrhhoooodd <<11996688
“Strömgren Sphere”
Fahr 1967Showed that in-situ observationof the LIC is possible at 1 AU!
19671967
≈700 AU
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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Information in the Interstellar Gas Flow
Jo: ISM Density
Jmax/Jo: ISM TemperatureVISM
Velocity Vector fromKinematics of Local Flow
3 In-Situ Methods- UV Backscattering - integral, - hard to calibrate + global info- Pickup Ions - lost velocity info + composition- Neutral Imaging + full distribution - hard to do
few species
and Density Pattern
mvB2/2 ≈ GmMs/R
at ≈ 1.3 AU
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
OpensWith IBEX
-5CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC04/24/23
Pristine LIC State from He with 3 Methods(Efforts of an ISSI Team)
Neutral Image(V, T, NHe)
Neutral Gas Observations provide most accurate and detailed information
Let’s Turn to other Species!
He Parameters from Neutral Gas, Pickup & UV Scattering• VHe = 26.3 km/s; THe = 6300 K; nHe = 0.015 cm-3
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Plasma Interaction with the LICBlue & Green Solar WindPlasma Density Contours
3D MHD Model T. Linde, ThesisOrange - Pristine ISMRed - Decelerated ISM
Bow Shock?
HeliopauseISM
Termination Shock
ISM ≈ 26 km/s
He He
H & O Charge Exchange
O, Hslow & hot
H+, O+
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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• SW Slowdown Richardson et al.: 0.09±0.02 cm-3
Includes Uncertainties in Model & Parameters• UV Scattering Pryor et al.: 0.09±0.024 cm-3
Modulation Damping; Incl. Observ. & Model Uncertainties• Pickup Ions Bzowski et al.: 0.087±0.022 cm-3
Observation, Model, Ioniz. & Rad. Pressure Uncertainties
LIC He State & H Density at TS (2 ISSI Teams)
Key Value: nH from SW Slowdown, UV Scattering & Pickup
• Voyager Tails Gloeckler et al.: 0.055±0.021cm-3 Includes NHe & relative Uncertainties
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSCAnd there is more to gain with Direct Flow Observations!!
Combine He Parameters, TS Distance & H Density at the TSTo infer H and H+ Densities in the LIC
There are still large UncertaintiesLet us Expand the He Neutral Observations to H or O!
• Weighted Mean: 0.083±0.023 cm-3
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Ly Alpha Observations Have RevealedDeflected Flow of H
Asymmetric ISM Magnetic FieldDeflects the Decelerated Flow
Izmodenov et al., 2005
Lallement et al. 2005
He
H
Lat
itude
LongitudeDirect Neutral Observations & 2nd Species Highly Desirable
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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Pattern of the Interstellar Gas FlowIt Has Been Done for He, Revealing the Pristine Flow!
Oxygen will be Displaced, Revealing Deflection & Braking
IBEXAsymmetryEffect
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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Modeling of H & O Flow with ISM Magnetic Field
04/24/23 CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSCIzmodenovFrom Möbius et al., 2009
O Flow Deflected by ≈ 1o
relative to He
B ISM
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Pattern of the Interstellar Gas Flow
Oxygen Displaced, Revealing Deflection & Braking
IBEX
Simulated Observationin LongitudeafterIzmodenov et al., 1996
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Pattern of the Interstellar Gas Flow
Oxygen Displaced, Revealing Deflection & Braking
Simulated Flow Angle DifferenceTrajectory ComputationBzowski et al.
Fall
Spring
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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Neutral Gas Observation, How Does it Work?II. Oxygen + ..
• Collimator CameraDirection DeterminationNeed large area: Collimator
• Use Surface Conversion into Ions- Need Mass Spectrometer for Species Identification!- Negative Ions: For O, H, (C) Not for N! Is it for He??
• Technique doesn’t Provide E - Use the Sun as Gravitational Spectrometer- Determine Arrival Direction Also for Deflection by ISM Magnetic Field
Oo
O-
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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IBEX-Lo Collimator
Imaging of Several Neutral Atom Species What Does it Take to Do this?
Diamond-Like Carbon
Hard DiskCoating e- Start 2
ion Stopionion
Start 1 +Start 2 +Stop
foil1 foil2 MCP
Analyzer
Time-of-FlightCSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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He Represents the Pristine ISM Flow Can it be Observed Simultaneously?
Yes, it Can! With Sputter Products
Wurz et al., 2008CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
Test with Neutral He at UoBern
IBEX-Lo
Spri
ng
Fall
Meta-Stable He
-16CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC04/24/23
IBEX ISM O and He Observation Conditions
• IBEX is a Sun-Pointed SpinnerIBEX-lo FoV at 90o to the Sun
• Observation Periods:Fall and Spring
• Fall: Large Angular Separation of Primary & Secondary O, but low Count RateBecause: Earth recedes from Flow
• Spring: Small Angular Separation of Primary & Secondary O, but high Count RateBecause: RAM Direction
• Observe O at 540 eV • Observe He at 135 eV (x1500 in Flux;
High Sputtering Efficiency)
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IBEX Keeps Orientation for One Full Orbit How Does that Affect the O Observation?
• Overlapping Sweeps in Spring
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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Simulated O-Flow ObservationFor the Spring Flow Passage
O Flow Spring
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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IBEX-Lo In-Flight Performance
04/24/23 CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
IBEX-Lo TOFWorksGreat!
Excellent Tool to Tackle
Background
H & OEasily Identified
e Filtered out!
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IBEX-Lo In-Flight Performance
04/24/23 CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
Arbitrary Orbit 9 SampleNo Selectionor BackgroundSubtraction!Normalized toISM Flow Viewing
Both ISM O & Hewill be well Visible!
First Spring PeriodStarts Now!
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Conclusions & Outlook• Neutral Atom Imaging
is becoming a powerful new window for Local Astrophysics• ISM He Holds Unbiased LIC Account
Neutral Gas Observations provide the most detailed and accurate LIC Parameters, in accordance with simultaneous Pickup Ion & UV Observations
• ISM H & O - affected by the Heliospheric Interface - hold clues to the interaction with the LIC
• IBEX-lo will determine the O Flow distribution in direct comparison with He and relative to star positions, thus providing slowdown, heating, and deflection of the Secondary O component
• Flow Signal 2 orders of magnitude above average sample• First Observation Campaign starts now!
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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Thank You!
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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Neutral AtomsA New Window for Local Astrophysics
Diffuse Source
Point Source
• Neutral Atoms:Observed up to their Mean Free Pathlength:A few 100 AU in the Neighborhood of the Sun-> Ideal for charting the Heliosphere and its Boundaries-> No Interference from farther away, But Objects outside are also beyond the Neutral Atom Horizon
• IBEX takes it up to its Horizon• Neutral Atom Imaging
knits another connection between Space Physics & Astrophysics
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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ISM Neutral Gas In Different ISM Cloud Environments
Möbius et al., 2006
• Hot Cloud like the Local Bubble:No Neutral Gas in the Bubble,Thus No In-Situ Observations
• Cold and Dense ISM Clouds:- N ≥ 100 cm-3
- He Remains most Important Species at 1 AU- Slowdown of SW inside 1 AU in Focusing Cone “He Comet”- Pickup Ions and Energetic He+
very important at 1 AU
CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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If We Could See Our Heliospherefrom Outside …
BZ Cam
ISM Gas Flow
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Pattern of the Interstellar Gas FlowHe Provides Unbiased LIC Parameters
Courtesy M. WitteCSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC
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Three Step ApproachInto the Future
• 1) Make Use of “S3C Great Observatory” with Coordinated ObservationsACE, SOHO, Wind, Ulysses, Voyagers
• 2) Be Innovative at Our Front DoorstepModerately Improved Observation Techniques at 1 AU or up to ≈3 AU IBEX Improve Resolution and Collection Power
• 3) Develop Seriously a Probe to the Frontier * Interstellar Probe *It definitely Needs Improved Technology!!
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Combined He Cone PUI ObservationsAMPTE, ACE & NOZOMI
Daily AveragesSliding 9-Day Averages
Solar Minimum
Maximum
Gloeckler et al., 2004
30 – 40Days
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Strong Variations in Pickup Ion Distributions
• Pickup Ion Distributions are Highly Variable• Pickup Ions React to:
- IMF Orientation (early Rollover)- IMF Strength (Compression and Rarefaction)- SW Density (Compression and Rarefaction)- Ionization rates &probably several unknown causes
• For Deduction of LIC Parameters Mitigation Sought with:- Long Integration Times
• Better: Attempt to Understand Causes- Also Provides Handle on Ion Transport and Acceleration
• STEREO (also ACE) Provide Simultaneous Observations
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STEREO & ACE Now Allow Simultaneous Interstellar He Cone Observations
STEREO A
STEREO B
ACE≈40o
in 2007
This provides tools to separate spatial & temporal variations
Ongoing Analysis not discussed here
-31CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC04/24/23
Pristine LIC State from He with 3 Methods(Efforts of an ISSI Team)
Simulation:Courtesy J. Raymond
Neutral Image(V, T, NHe)
SWICSPickup (NHe)
Sensitive to V, T, Ionization
Cone
Sensitive to Ionization
IndependentCheck on V
UV Ionization, Solar Illuminationfrom SOHO SEM, EIT and SUMER
G. GloecklerJ. Raymond
J. Vallerga
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Neutral Imaging Most Accurate & Detailed
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Why Did we Start with Interstellar Helium?(and not Hydrogen)
• Has the Highest Ionization Potential i.e. Reaches 1 AU
• Second Most Abundant Species i.e. Is an Important Species in the LISM
• Not Affected by the Heliospheric Interface i.e. Provides an Unbiased Account of the LISM
• Could be Observed with 3 Methods First: Neutrals, Pickup, Scattering of Solar UV
-34CSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC04/24/23
IBEX ISM O Observation Conditions
• IBEX is a Sun-Pointed SpinnerIBEX-lo FoV at 90o to the Sun
• Observation Periods:Fall and Spring
• Fall: Large Angular Separation of Primary & Secondary O, but low Count RateBecause: Earth recedes from Flow
• Spring: Small Angular Separation of Primary & Secondary O, but high Count RateBecause: RAM Direction
-3504/24/23 Spring AGU Mtg 2008 E. Möbius UNH/SSC
IBEX-lo O Conversion EfficiencyFor ISM O Observations
• O must be observed in Spring and Fall Separates Heliospheric from Gravitational Deflection
• In Fall: O Flux down x4 (lower relative speed) & Efficiency down x20
• But Lo-Res Section can be used Increases collection x12
Wurz et al., 2006
SpringFall
x 20
IBEX-Lo Energy Range
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Why Bother?
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