e. möbius

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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


-304/24/23

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


-404/24/23

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


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+


-704/24/23

• 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

-804/24/23

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


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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


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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


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


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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-


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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

-1504/24/23

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


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


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Simulated O-Flow ObservationFor the Spring Flow Passage

O Flow Spring


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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!

-2104/24/23

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!


-2204/24/23

Thank You!


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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


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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


-2504/24/23 Spring AGU Mtg 2008 E. Möbius UNH/SSC

If We Could See Our Heliospherefrom Outside …

BZ Cam

ISM Gas Flow

-2604/24/23

Pattern of the Interstellar Gas FlowHe Provides Unbiased LIC Parameters

Courtesy M. WitteCSPAR Conf Voyagers in the Heliosheath Jan 2009 E. Möbius UNH/SSC


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


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


Neutral Imaging Most Accurate & Detailed


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


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


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


Why Bother?

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