1. Modeling the Solar Wind: A survey of theoretical ideas for the origins of fast & slow streams Steven R. Cranmer Harvard-Smithsonian Center for Astrophysics

2. Modeling the Solar Wind: A survey of theoretical ideas for the origins of fast & slow streams Steven R. Cranmer Harvard-Smithsonian Center for Astrophysics Outline: 1. Brief historical background 2. The coronal heating problem 3. Solar wind acceleration: waves vs. reconnection? 4. (Suggestive hints from collisionless ion diagnostics)

3. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά The solar wind: discovery 1860–1950: Evidence slowly builds for outflowing magnetized plasma in the solar system: 1958: Eugene Parker proposed that the hot corona provides enough gas pressure to counteract gravity and accelerate a “solar wind.” 1962: Mariner 2 provided direct confirmation. solar flares  aurora, telegraph snafus, geomagnetic storms comet ion tails point anti-sunward (no matter comet’s motion)

4. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά In situ solar wind: properties Mariner 2 detected two phases of solar wind: slow (mostly) + fast streams Uncertainties about which type is “ambient” persisted because measurements were limited to the ecliptic plane... Ulysses left the ecliptic; provided 3D view of the wind’s source regions. Helios saw strong departures from Maxwellians. By ~1990, it was clear the fast wind needs something besides gas pressure to accelerate so fast! speed (km/s) T p (10 5 K) T e (10 5 K) T ion / T p O 7+ /O 6+, Mg/O 600–800 2.4 1.0 > m ion /m p low 300–500 0.4 1.3 < m ion /m p high fastslow

5. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Solar wind: connectivity to the corona High-speed wind: strong connections to the largest coronal holes Low-speed wind: still no agreement on the full range of coronal sources: hole/streamer boundary (streamer edge) streamer plasma sheet (“cusp/stalk”) small coronal holes active regions Wang et al. (2000)

6. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Empirical trends Wind speed is roughly anticorrelated with flux tube “expansion factor” between Sun and “potential field source surface” (PFSS). Wang & Sheeley (1990) flux-tube expansion correlation, modified by, e.g., Arge & Pizzo (2000) and others: wind speed expansion factor Other correlations based on coronal hole size (Vršnak et al. 2007), surface field (Kojima et al. 2004), and chromospheric wave phase properties (Leamon & McIntosh 2007) are also useful.

7. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Empirical trends are helpful, but they are not always accurate... To make qualitative improvements in long-term space weather forecasting (i.e., to know when the empirical trends are going to work, and when they won’t), it’s key to know the physical processes that give rise to the heating & acceleration.

8. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά The coronal heating problem We still don’t understand the physical processes responsible for heating up the coronal plasma. A lot of the heating occurs in a narrow “shell.” Most suggested ideas involve 3 general steps: 1.Churning convective motions that tangle up magnetic fields on the surface. 2.Energy is stored in tiny twisted & braided magnetic flux tubes. 3.Collisions (particle-particle? wave-particle?) release energy as heat. Heating Solar wind acceleration!

9. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Coronal heating mechanisms So many ideas, taxonomy is needed! (Mandrini et al. 2000; Aschwanden et al. 2001) Where does the mechanical energy come from? vs.

10. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Coronal heating mechanisms So many ideas, taxonomy is needed! (Mandrini et al. 2000; Aschwanden et al. 2001) Where does the mechanical energy come from? How rapidly is this energy coupled to the coronal plasma? How is the energy dissipated and converted to heat? waves shocks eddies (“AC”) vs. twisting braiding shear (“DC”) vs. reconnectionturbulence interact with inhomog./nonlin. collisions (visc, cond, resist, friction) or collisionless

11. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά The Debate in ’08 Two broad classes of models have evolved that attempt to self-consistently answer the question: How are fast and slow wind streams accelerated? Wave/Turbulence-Driven (WTD) models Reconnection/Loop-Opening (RLO) models arXiv: 0804.3058

12. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Reconnection / Loop-Opening models Fisk (2005) There is a natural appeal to the RLO idea, since only a small fraction of the Sun’s magnetic flux is open. Open flux tubes are always near closed loops! The “magnetic carpet” is continuously churning... Hinode/XRT (X-ray) http://xrt.cfa.harvard.edu STEREO/EUVI (195 Å) courtesy S. Patsourakos Open-field regions show coronal jets (powered by reconnection?) that contribute to the wind mass flux.

13. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Reconnection / Loop-Opening models Emerging loops inject both mass and Poynting flux into open-field regions. Feldman et al. (1999) found correlation between loop-size & coronal temperature. Fisk et al. (1999), Fisk (2003), Gloeckler et al. (2003), Schwadron & McComas (2003), Schwadron et al. (2005) worked out the solar wind implications... Ulysses SWICS Fisk (2003) theory

14. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Wave / Turbulence-Driven models No matter the relative importance of RLO events, we do know that waves and turbulent motions are present everywhere... from photosphere to heliosphere. How much can be accomplished by only WTD processes? (Occam’s razor?)

15. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Building an Alfvén wave model In dark intergranular lanes, strong-field photospheric flux tubes are shaken by an observed spectrum of horizontal motions. In mainly open-field regions, Alfvén waves propagate up along the field, and partly reflect back down (non-WKB). Nonlinear couplings allow a (mainly perpendicular) turbulent cascade, terminated by damping → gradual heating over several solar radii.

16. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά MHD turbulence It is highly likely that somewhere in the outer solar atmosphere the fluctuations become turbulent and cascade from large to small scales: With a strong background field, it is easier to mix field lines (perp. to B) than it is to bend them (parallel to B). Also, the energy transport along the field is far from isotropic: Z+Z+ Z–Z– Z–Z– (e.g., Matthaeus et al. 1999; Dmitruk et al. 2002)

17. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Self-consistent 1D models Cranmer, van Ballegooijen, & Edgar (2007) computed solutions for the waves & background one-fluid plasma state along various flux tubes... going from the photosphere to the heliosphere. The only free parameters: radial magnetic field & photospheric wave properties. Ingredients: Alfvén waves: non-WKB reflection with full spectrum, turbulent damping, wave-pressure acceleration Acoustic waves: shock steepening, TdS & conductive damping, full spectrum, wave-pressure acceleration Radiative losses: transition from optically thick (LTE) to optically thin (CHIANTI + PANDORA) Heat conduction: transition from collisional (electron & neutral H) to collisionless “streaming”

18. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Results: turbulent heating & acceleration T (K) reflection coefficient Goldstein et al. (1996) Ulysses SWOOPS

19. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Results: other fast/slow diagnostics Frozen-in charge states FIP effect (using Laming’s 2004 theory) Cranmer et al. (2007) Ulysses SWICS

20. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Multi-fluid collisionless effects? Polar coronal hole model

21. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Multi-fluid collisionless effects? protons electrons (thermal core only) O +5 O +6

22. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Departures from thermal equilibrium UVCS/SOHO observations rekindled theoretical efforts to understand collisionless heating and acceleration effects in the extended corona. Alfven wave’s oscillating E and B fields ion’s Larmor motion around radial B-field Ion cyclotron waves (10–10,000 Hz) suggested as a “natural” energy source that can be tapped to preferentially heat & accelerate heavy ions. MHD turbulence cyclotron resonance- like phenomena something else?

23. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά What next? Both WTD and RLO paradigms have passed some basic “tests” of comparison with observations. What could this imply? A combination of both ideas could work best? Existing models don’t contain the right physics – once that is included, one or the other idea may fail to work? Comparisons with observations haven’t been comprehensive enough to allow their true differences to be seen?

24. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά What next? Both WTD and RLO paradigms have passed some basic “tests” of comparison with observations. What could this imply? A combination of both ideas could work best? Existing models don’t contain the right physics – once that is included, one or the other idea may fail to work? Comparisons with observations haven’t been comprehensive enough to allow their true differences to be seen? Do reconnections between open & closed regions cover enough of the solar surface to account for the majority of the solar wind? Does MHD turbulence produce the “right” mixture of collisionless kinetic effects? Some basic issues of “energy budget” still to resolve:

25. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Conclusions For more information: http://www.cfa.harvard.edu/~scranmer/ The debate between waves/turbulence and reconnection/loop-opening mechanisms of solar wind acceleration goes on... Theoretical advances in MHD turbulence continue to “feed back” into global models of the solar wind. The extreme plasma conditions in coronal holes (T ion >> T p > T e ) have guided us to discard some candidate processes, further investigate others, and have cross-fertilized other areas of plasma physics and astrophysics. vs.

26. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Extra slides...

27. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά The extended solar atmosphere... Heating is everywhere...... and everything is in motion

28. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά The Sun’s outer atmosphere The solar photosphere radiates like a blackbody; its spectrum gives T, and dark “Fraunhofer lines” reveal its chemical composition. Total eclipses let us see the vibrant outer solar corona: but what is it? 1870s: spectrographs pointed at corona: Is there a new element (“coronium?”) 1930s: Lines identified as highly ionized ions: Ca +12, Fe +9 to Fe +13 it’s hot! Fraunhofer lines (not moon-related) unknown bright lines

29. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Particles are not in “thermal equilibrium” Helios at 0.3 AU (e.g., Marsch et al. 1982) WIND at 1 AU (Collier et al. 1996) WIND at 1 AU (Steinberg et al. 1996) …especially in the high-speed wind. mag. field

30. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Waves? Start in the photosphere... Photosphere displays convective motion on a broad range of time/space scales: β << 1 β ~ 1 β > 1

31. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Turbulence It is highly likely that somewhere in the outer solar atmosphere the fluctuations become turbulent and cascade from large to small scales. The original Kolmogorov (1941) theory of incompressible fluid turbulence describes a constant energy flux from the largest “stirring” scales to the smallest “dissipation” scales. Largest eddies have kinetic energy ~ ρv 2 and a turnover time-scale  =l/v, so the rate of transfer of energy goes as ρv 2 /  ~ ρv 3 /l. Dimensional analysis can give the spectrum of energy vs. eddy-wavenumber k: E k ~ k –5/3

32. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Progress towards a robust “recipe” Because of the need to determine non-WKB (nonlocal!) reflection coefficients, it may not be easy to insert into global/3D MHD models. Doesn’t specify proton vs. electron heating (they conduct differently!) Does turbulence generate enough ion-cyclotron waves to heat the minor ions? Are there additional (non-photospheric) sources of waves / turbulence / heating for open-field regions? (e.g., flux cancellation events) (B. Welsch et al. 2004) Not too bad, but...

33. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά The need for extended heating The basal coronal heating problem is not yet solved, but the field seems to be “homing in on” the interplay between emerging flux, reconnection, turbulence, and helicity (shear/twist). Above ~2 R s, some other kind of energy deposition is needed in order to... » accelerate the fast solar wind (without artificially boosting mass loss and peak T e ), » produce the proton/electron temperatures seen in situ (also magnetic moment!), » produce the strong preferential heating and temperature anisotropy of ions (in the wind’s acceleration region) seen with UV spectroscopy. X

34. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Exploring the extended corona “Off-limb” measurements (in the solar wind acceleration region ) allow dynamic non-equilibrium plasma states to be followed as the asymptotic conditions at 1 AU are gradually established. Occultation is required because extended corona is 5 to 10 orders of magnitude less bright than the disk! Spectroscopy provides detailed plasma diagnostics that imaging alone cannot. The Ultraviolet Coronagraph Spectrometer (UVCS) on SOHO combines these features to measure plasma properties of coronal protons, ions, and electrons between 1.5 and 10 solar radii.

35. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Mirror motions select height UVCS “rolls” independently of spacecraft 2 UV channels: 1 white-light polarimetry channel LYA (120–135 nm) OVI (95–120 nm + 2 nd ord.) The UVCS instrument on SOHO 1979–1995: Rocket flights and Shuttle-deployed Spartan 201 laid groundwork. 1996–present: The Ultraviolet Coronagraph Spectrometer (UVCS) measures plasma properties of coronal protons, ions, and electrons between 1.5 and 10 solar radii. Combines “occultation” with spectroscopy to reveal the solar wind acceleration region! slit field of view:

36. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά UVCS results: over the poles (1996-1997 ) The fastest solar wind flow is expected to come from dim coronal holes. In June 1996, the first measurements of heavy ion (e.g., O +5 ) line emission in the extended corona revealed surprisingly wide line profiles... On-disk profiles: T = 1–3 million K Off-limb profiles: T > 100 million K !

37. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Emission lines as plasma diagnostics Many of the lines seen by UVCS are formed by resonantly scattered disk photons. If profiles are Doppler shifted up or down in wavelength (from the known rest wavelength), this indicates the bulk flow speed along the line-of-sight. The widths of the profiles tell us about random motions along the line-of-sight (i.e., temperature) The total intensity (i.e., number of photons) tells us mainly about the density of atoms, but for resonant scattering there’s also another “hidden” Doppler effect that tells us about the flow speeds perpendicular to the line-of-sight. If atoms are flow in the same direction as incoming disk photons, “Doppler dimming/pumping” occurs.

38. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Doppler dimming & pumping After H I Lyman alpha, the O VI 1032, 1037 doublet are the next brightest lines in the extended corona. The isolated 1032 line Doppler dims like Lyman alpha. The 1037 line is “Doppler pumped” by neighboring C II line photons when O 5+ outflow speed passes 175 and 370 km/s. The ratio R of 1032 to 1037 intensity depends on both the bulk outflow speed (of O 5+ ions) and their parallel temperature... The line widths constrain perpendicular temperature to be > 100 million K. R < 1 implies anisotropy!

39. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Preferential ion heating & acceleration UVCS observations have rekindled theoretical efforts to understand heating and acceleration of the plasma in the (collisionless?) acceleration region of the wind. Alfven wave’s oscillating E and B fields ion’s Larmor motion around radial B-field Ion cyclotron waves (10–10,000 Hz) suggested as a “natural” energy source that can be tapped to preferentially heat & accelerate heavy ions. MHD turbulence cyclotron resonance- like phenomena something else?

40. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Anisotropic MHD cascade Can MHD turbulence generate ion cyclotron waves? Many models say no! Simulations & analytic models predict cascade from small to large k,leaving k ~unchanged. “Kinetic Alfven waves” with large k do not necessarily have high frequencies.

41. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Anisotropic MHD cascade Can MHD turbulence generate ion cyclotron waves? Many models say no! Simulations & analytic models predict cascade from small to large k,leaving k ~unchanged. “Kinetic Alfven waves” with large k do not necessarily have high frequencies. In a low-beta plasma, KAWs are Landau-damped, heating electrons preferentially! Cranmer & van Ballegooijen (2003) modeled the anisotropic cascade with advection & diffusion in k-space and found some k “leakage”...

42. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά So does turbulence generate cyclotron waves? Directly from the linear waves? Probably not! How then are the ions heated and accelerated? When MHD turbulence cascades to small perpendicular scales, the small-scale shearing motions may be able to generate ion cyclotron waves (Markovskii et al. 2006). If MHD turbulence exists for both Alfvén and fast-mode waves, the two types of waves can nonlinearly couple with one another to produce high-frequency ion cyclotron waves (Chandran 2006). If nanoflare-like reconnection events in the low corona are frequent enough, they may fill the extended corona with electron beams that would become unstable and produce ion cyclotron waves (Markovskii 2007). If kinetic Alfvén waves reach large enough amplitudes, they can damp via wave- particle interactions and heat ions (Voitenko & Goossens 2006; Wu & Yang 2007). Kinetic Alfvén wave damping in the extended corona could lead to electron beams, Langmuir turbulence, and Debye-scale electron phase space holes which heat ions perpendicularly via “collisions” (Ergun et al. 1999; Cranmer & van Ballegooijen 2003).

43. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Coronal holes: over the solar cycle Even though large coronal holes have similar outflow speeds at 1 AU (>600 km/s), their acceleration (in O +5 ) in the corona is different! (Miralles et al. 2001) Solar minimum: Solar maximum:

44. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Waves: remote-sensing techniques The following techniques are direct… (UVCS ion heating was more indirect) Intensity modulations... Motion tracking in images... Doppler shifts... Doppler broadening... Radio sounding... Tomczyk et al. (2007)

45. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Overview of “in situ” fluctuations Fourier transform of B(t), v(t), etc., into frequency: The inertial range is a “pipeline” for transporting magnetic energy from the large scales to the small scales, where dissipation can occur. f -1 “energy containing range” f -5/3 “inertial range” f -3 “dissipation range” 0.5 Hzfew hours Magnetic Power How much of the “power” is due to spacecraft flying through flux tubes rooted on the Sun?

46. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Future diagnostics: more spectral lines! How/where do plasma fluctuations drive the preferential ion heating and acceleration, and how are the fluctuations produced and damped? Observing emission lines of additional ions (i.e., more charge & mass combinations) would constrain the specific kinds of waves and the specific collisionless damping modes. Comparison of predictions of UV line widths for ion cyclotron heating in 2 extreme limits (which UVCS observations [black circles] cannot distinguish). Cranmer (2002), astro-ph/0209301

47. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Future Diagnostics: electron VDF Simulated H I Lyman alpha broadening from both H 0 motions (yellow) and electron Thomson scattering (green). Both proton and electron temperatures can be measured.

48. Modeling the solar wind: A survey of theoretical ideas for the origins of fast and slow streams Steven Cranmer, May 6, 2008 2nd Heliospheric Network Workshop, Kεφαλλoνιά Synergy with other systems T Tauri stars: observations suggest a “polar wind” that scales with the mass accretion rate. Cranmer et al. (2007) code is being adapted to these systems... Pulsating variables: Pulsations “leak” outwards as non-WKB waves and shock- trains. New insights from solar wave-reflection theory are being extended. AGN accretion flows: A similarly collisionless (but pressure-dominated) plasma undergoing anisotropic MHD cascade, kinetic wave-particle interactions, etc. Matt & Pudritz (2005) Freytag et al. (2002)