1. Importance of Pickup Ions & Suprathermal Ions in the Inner Heliosphere
Eberhard Möbius Space Science Center and Department of Physics, UNH
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC
9/14/16

2. Pickup Ions - Critical Link in Coupled Plasma Systems
Schwadron & Gloeckler 2007
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

3. E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC
Summary & Synergies
Inner Source Pickup Ions and thus Dust are dynamically important for the SW inside 60 RS PUI Pressure > Thermal & Magnetic Pressure SPP+, Solar Orbiter w. STEREO
PUI Transport shifts Focusing Cone vs. Interstellar Flow Direction, Dependence on r Solar Orbiter, SPP+? w. STEREO + IBEX • Dedicated PUI & Suprathermal Observations • Need combined Nano Dust & Optimized PUI Observation with B-Field at 1 AU (no Dust on SPP+!)
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

4. E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC
Summary & Synergies
Energ. He+/He2+ prop. r in CIRs, different in CMEs? Solar Orbiter, SPP+ w. STEREO, ACE
Averaged Quiet Time Suprathermal Tails as v-5 Spectra vary v-g: g with SW conditions SW Compressions form PUI Tails g with ∆u/∆f  Expect distinct variations with r CIRs & CMEs Solar Orbiter, SPP+ w. STEREO, ACE Needed  High collection power & cadence to resolve variations
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

5. Influence on Bulk Solar Wind: Dust & Inner Source Pickup Ions
Inner Source Pickup Ions generated by Solar Wind – Dust Interaction close to the Sun absorption/reemission, sputtering, or penetration
Total Dust Cross-Section x100 > than observed  plenty of nano-dust? r
PUIs map r into v/Vsw
v/Vsw
Schwadron et al. 2000
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

6. Influence on Bulk Solar Wind: Dust & Inner Source Pickup Ions
Inner Source Pickup Ions generated by Solar Wind – Dust Interaction close to the Sun absorption/reemission, sputtering, or penetration
nH+ ≈ 1.2 cm-3 at 60 RS *Vsw2: p ≈ erg/cm-3 > pSWTh ≈ erg/cm-3 > pB ≈ erg/cm-3  PUI/Dust Important r
PUIs map r into v/Vsw
v/Vsw
Schwadron et al. 2000
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

7. Studying the Dynamic Interaction of Dust/Pickup Ions & Solar Wind
Dust and its Products (PUIs) important for the Solar Wind Energy Balance close to the Sun - May be greatly amplified by inhomogeneous Dust Distributions
 Combine in-situ SW Observations on SPP+ & Solar Orbiter with - Inner Source PUI Measurements on • Solar Orbiter, STEREO - Inner Source PUIs & Nano Dust Distributions Would be great to observe at 1 AU for synergy
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

8. Interstellar Pickup Ions Close to the Sun
Interstellar He substantial inside 1 AU (30% of ISN at 0.3 AU, ≈10% at 0.1 AU at Solar Min, ≈1/3 at Max) Enhanced in Focusing Cone
Allows Study of: - Interstellar Parameters - Pickup Ion Transport (Stable Cone Structure) - Variation of Ionization - Source for Energetic Ions
from Möbius et al. 2004
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

9. Interstellar Focusing Cone Close to the Sun
Gershman et al
MESSENGER FIPS
ACE SWICS
Focusing Cone observations with STEREO (Drews et al. 2012), ACE & MESSENGER suggest shift of the Cone location vs. the Interstellar Flow direction (with IBEX & Ulysses)  PUI Transport? Variation with r?
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

10. PUI Cut-Off in the Innermost Heliosphere
Radial Flow Component Vr of Interstellar Gas  PUI Cut-Off (~1/√r)  ISN Direction w. IBEX
1 AU: Vr = 50 km/s (6-20% of Vsw = km/s)
At Perihelion of Solar Orbiter 0.28 AU: Vr = 85 km/s (Vr/Vsw ≈ 11 – 30%)
At SPP+ Perihelion 10 RS: Vr ≈ 190 km/s  substantial if observed
Wouldn’t it be nice? Observations spread in l & r Solar Orbiter, STEREO +Dedicated PUI Obs
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

11. Modeling of the PUI Cone Relative to Neutral Gas Cone
Modeling of PUIs from Interstellar He Cone with EPREM highlights PUI transport effects PUI Cone shifted vs. Neutral Gas cone
ISN Flow
Quinn et al. 2016
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

12. Modeling of the PUI Cone Relative to Neutral Gas Cone
Modeling of PUIs from Interstellar He Cone with EPREM highlights shift of PUI Cone vs. Neutral Gas
Adiabatic Focusing & Diffusion | B prevalent
Quinn et al. 2016
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

13. Modeling of the PUI Cone Relative to Neutral Gas Cone
Modeling of PUIs from Interstellar He Cone with EPREM highlights shift of PUI Cone vs. Neutral Gas
Adiabatic Focusing & Diffusion | B prevalent
Distinct radial evolution in Azimuthal Transport of the PUI Cone
Observation together with Solar Orbiter, STEREO
Quinn et al. 2016
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

14. Acceleration of Pickup Ions in Compression Regions
Related EPREM Modeling with SW Compression & Rarefaction Regions shows - Reshaping of PUI Spectra - Formation of Tails in Compressions for Interstellar & Inner Source
Quinn et al. 2016, in prep.
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

15. Acceleration of Pickup Ions in Compression Regions
Related EPREM Modeling with SW Compression & Rarefaction Regions shows - Reshaping of PUI Spectra - Formation of Tails in Compressions for Interstellar & Inner Source
Power Law Index of Tail varies with Compression ∆U/∆f
Chen et al. 2015
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

16. He+/He2+ Ratio Dependence on Radial Distance from CIR Along B
R [AU]
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

17. E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC
Charge States in CIRs
He+ ≈ 25% at 1 AU but Majority at 4.5 AU
Heavy Ions Consistent with Fast Solar Wind Charge States
C and Mg Upper Limit of Singly Charged Ions Ne has Small (4.7%) Contribution of Ne+ O+ no Statistically Significant Contribution
He2+ and Most Heavy Ions are Solar Wind
He+ and Ne+ from ISM Pickup Ions (≈100x increased acceleration efficiency over solar wind)
No Noticeable Inner Source Contribution  Need Larger Collection Power and r Dependence & Solar Orbiter together with STEREO Composition variation with r on SPP+ and Orbiter?
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

18. Suprathermal Tails & Seed Particles for Acceleration
Quiet Time Averaged Tails observed with v-5 and exponential fall-off
PUIs & Remnant Impulsive SEPs preferentially accelerated
Do we have a “Reservoir”?  Are there variations?  Any almost constant source  How do Tails vary with r
Fisk & Gloeckler 2008
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

19. E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC
Variable Tail Indices
Popecki et al. 2013
STEREO Observations of He+ Tails show Average Index of -4.9 – 6.0 Steeper Indices of up to -9.0 in slow SW Variations pre- and post-shocks
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

20. A Potential Constant Source for Suprathermal Tails
Schwadron & McComas (2010) proposed ENAs as another source for PUIs
Modeling suggests that the ISN is much stronger, but ENAs could contribute to tails
≈v-9
ENA Tails ≈ v-9  super quiet time??  Dominantly H+
Bochsler & Möbius 2010
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

21. Tail Formation as a Function Distance from the Sun
EPREM Modeling for SW Compressions performed at various Solar Distance
Quinn et al. 2016, in prep.
1 AU
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

22. Tail Formation as a Function Distance from the Sun
EPREM Modeling for SW Compressions performed at various Solar Distance
Tails weaker at 0.65 AU
Quinn et al. 2016, in prep.
0.65 AU
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

23. Tail Formation as a Function Distance from the Sun
EPREM Modeling for SW Compressions performed at various Solar Distance
Tails weaker at 0.65 AU
Tails form with increasing Compression
At 0.28 AU (Solar Orbiter Perihelion) Tails are gone
CME Compressions & Shocks stronger here!
Quinn et al. 2016, in prep.
0.28 AU
Model CME Evolution Next  Different: Shocks strong at Sun
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

24. E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC
Summary & Synergies
Inner Source Pickup Ions and thus Dust are dynamically important for the SW inside 60 RS PUI Pressure > Thermal & Magnetic Pressure SPP+, Solar Orbiter w. STEREO
PUI Transport shifts Focusing Cone vs. Interstellar Flow Direction, Dependence on r Solar Orbiter, SPP+? w. STEREO • Dedicated PUI & Suprathermal Observations • Need combined Nano Dust & Optimized PUI Observation with B-Field at 1 AU (no Dust on SPP+!)
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

25. E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC
Summary & Synergies
Energ. He+/He2+ prop. r in CIRs, different in CMEs? Solar Orbiter, SPP+ w. STEREO, ACE
Averaged Quiet Time Suprathermal Tails as v-5 Spectra vary v-g: g with SW conditions SW Compressions form PUI Tails g with ∆u/∆f  Expect distinct variations with r CIRs & CMEs Solar Orbiter, SPP+ w. STEREO, ACE Needed  High collection power & cadence to resolve variations
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC

26. E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC
Questions?
9/14/16
E. Möbius, UNH SSC SPP+ Meeting, Smithsonian, Washington, DC