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A Whole-Heliosphere View of the Solar Wind Hale Lecture American Astronomical Society 5/24/2010

This lecture discusses the different processes that occur in the solar wind after it leaves the sun, including expansion, collision, reconnection, and pickup. It also explores the behavior of alpha particles, the boundaries between different wind types, and the interaction with the interstellar medium.

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A Whole-Heliosphere View of the Solar Wind Hale Lecture American Astronomical Society 5/24/2010

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  1. A Whole-Heliosphere View of the Solar WindHale LectureAmerican Astronomical Society5/24/2010 Marcia Neugebauer University of Arizona

  2. The Things that Happen to the Solar Wind After it Leaves the Sun A Better Title:

  3. The Complex Solar Atmosphere

  4. The Sun creates both slow and fast solar wind

  5. But, it’s a complicated process

  6. Model of open and closed field lines (Wang et al., 2007)

  7. The Source-Surface Model (Cravens, 1997)

  8. Major Processes in the Solar Wind • Expansion • Collision • Reconnection • Pickup (mass loading) • All of which leads to: • Turbulence • The interstellar medium

  9. Expansion

  10. First Adiabatic Invariant(Conservation of Magnetic Moment ) • = mw2/2B  T/B = constant As B , expect T, and T||/ T 

  11. Magnetic Moment versus Distance from Sun

  12. (Hellinger et al., 2009)

  13. Proton Distribution functions (Marsch et al., 1981) Distance from Sun --> Solar wind speed -->

  14. The Strange Behavior of Alpha Particles • Abundance highly variable • na/np = 0 - .03 in slow wind (~0 at HCS) • na/np = .04-.05 in fast wind • Greatly enhanced in CMEs (up to 0.40!) • Hotter than protons • Ta/Tp = 4 to 6 in fast wind • Approaches isothermal in slow wind • Faster than protons • Vap up to 100 km/s in fast wind • Vap -> 0 in dense, slow wind • Anisotropic and double peaked

  15. Vap vs Distance in Fast Wind (Neugebauer et al., 1996)

  16. Collision

  17. Magnetized Plasmas Don’t Easily Mix

  18. Note Boundaries Between Winds from Streamers & Coronal Holes

  19. Some Stream Interfaces are Stable over Many AU (Gosling et al., 1978)

  20. Heliospheric Current Sheets, Embedded in the Slow Wind, are Also Stable Solar Maximum Declining Activity Solar Minimum

  21. Result of the Solar Dipole Tilt(Ballerina Skirt) (Jokipii & Thomas, 1981)

  22. Solar Rotation Creates Corotating Interaction Regions (Pizzo, 1978)

  23. Signatures of a CIR at ~5 AU SI at density drop HCS on Day 138 (Lazarus et al., 1999)

  24. Coronal Mass Ejections

  25. Interplanetary CMEs (Richardson, 1997)

  26. Interaction Regions at Solar Max and Min

  27. Evolution of Interaction regions from 1 to 60 AUFormation of MIRs (Wang & Richardson, 2003)

  28. Ecliptic plane view of pileup out to 100 AU

  29. Effect of GMIRs on Cosmic Rays (Burlaga et al., 2003)

  30. Anti-Correlation of Sunspots and Cosmic Rays

  31. Reconnection

  32. Petschek Reconnection Mechanism (Gosling, 2005)

  33. Reconnection Exhaust Fans Bifurcated structure Opposite V//B Decreased B, Increased V, T Observed even for small angle changes Created by turbulence? (Gosling, 2010)

  34. Pickup

  35. Pick-up is sometimes associated with Mass Loading

  36. Non-Solar Sources of Solar Wind Ions • Atoms and ions • Interstellar medium • Dust • Comets • Planets • Dust • Comets and Asteroids • Interstellar medium • Jupiter

  37. The Pick-up Process In solar-wind frame In inertial frame B Photoionization adds mass to wind. Charge exchange creates fast neutral and slow ion. Both processes provide drag on wind. U

  38. Proton Spectrum with Pickup Ions (Gloeckler et al., 2001)

  39. Inner Source of Pick-up Ions (Gloeckler et al., 2001)

  40. High-Energy Tails of H and He (Gloeckler, 2003)

  41. Effect of Pickup Ions on the Wind • Photoionization adds mass • Charge exchange may conserve mass • Results in a fast neutral atom and a slow ion • Both processes result in: • Acceleration of slow ions up to Vsw • Drag • Hot ions with Vth Vsw

  42. Slow-Down of Solar Wind due to Pick-up Ions

  43. Turbulence

  44. Power Spectra f/fpg Helios 2 Field vector spectra (Bruno & Carbone, 2005) OGO 5 Density fluctuations (Neugebauer, 1976)

  45. 2-D Simulation of MHD Turbulence Field lines + Current density (gray shade) Current sheets generated locally Reconnection heats plasma (Greco et al., 2010)

  46. The End of the Road (Approach to Alaska’s Bridge to Nowhere)

  47. Interaction with the Interstellar Medium

  48. Model of Outer Heliosphere

  49. Anomalous Cosmic Rays at TS and in Heliosheath (Courtesy A. Cummings, 2010)

  50. “The Ribbon”

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