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A Whole-Heliosphere View of the Solar Wind Hale Lecture American Astronomical Society 5/24/2010 Marcia Neugebauer University of Arizona.

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Presentation on theme: "A Whole-Heliosphere View of the Solar Wind Hale Lecture American Astronomical Society 5/24/2010 Marcia Neugebauer University of Arizona."— Presentation transcript:

1 A Whole-Heliosphere View of the Solar Wind Hale Lecture American Astronomical Society 5/24/2010 Marcia Neugebauer University of Arizona

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

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 n a /n p = in slow wind (~0 at HCS) n a /n p = in fast wind Greatly enhanced in CMEs (up to 0.40!) Hotter than protons T a /T p = 4 to 6 in fast wind Approaches isothermal in slow wind Faster than protons V ap up to 100 km/s in fast wind V ap -> 0 in dense, slow wind Anisotropic and double peaked

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

20 Heliospheric Current Sheets, Embedded in the Slow Wind, are Also Stable Solar MaximumSolar MinimumDeclining Activity

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 (Lazarus et al., 1999) SI at density drop HCS on Day 138

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 AU Formation 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 (Gosling, 2010) Bifurcated structure Opposite  V/  /B Decreased B, Increased V, T Observed even for small angle changes Created by turbulence?

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

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 V sw –Drag –Hot ions with V th  V sw

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

43 Turbulence

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

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

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”

51 Summary A lot of interesting physics in the solar wind Several unsolved issues –Turbulent processes –Relaxation of anisotropic and multi-beams –Physics of high-energy tails –Acceleration of ACR –Prevalence of reconnection –Stability/sources of discontinuities Applications to many other astrophysical settings


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