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Solar Surface Dynamics convection & waves

Solar Surface Dynamics convection & waves. Bob Stein - MSU Dali Georgobiani - MSU Dave Bercik - MSU Regner Trampedach - MSU Aake Nordlund - Copenhagen Mats Carlsson - Oslo Viggo Hansteen - Oslo Andrew McMurry - Oslo Tom Bogdan - HAO O. Simulations. Computation. Solve

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Solar Surface Dynamics convection & waves

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  1. Solar Surface Dynamicsconvection & waves Bob Stein - MSU Dali Georgobiani - MSU Dave Bercik - MSU Regner Trampedach - MSU Aake Nordlund - Copenhagen Mats Carlsson - Oslo Viggo Hansteen - Oslo Andrew McMurry - Oslo Tom Bogdan -HAOO

  2. Simulations

  3. Computation • Solve • Conservation equations • mass, momentum & internal energy • Induction equation • Radiative transfer equation • 3D, Compressible • EOS includes ionization • Open boundaries • Fix entropy of inflowing plasma at bottom

  4. Equations

  5. Method • Spatial derivatives - Finite difference • 6th order compact or 3rd order spline • Time advance - Explicit • 3rd order predictor-corrector or Runge-Kutta • Diffusion

  6. Boundary Conditions • Periodic horizontally • Top boundary: Transmitting • Large zone, adjust <r> mass flux, ∂u/∂z=0, energy ≈ constant, drifts slowly with mean state • Bottom boundary: Open, but No net mass flux • (Node for radial modes so no boundary work) • Specify entropy of incoming fluid at bottom • (fixes energy flux) • Top boundary: B  potential field • Bottom boundary: inflows advect 1G or 30G horizontal field, or B vertical

  7. Wave Reflection Gravity wave Acoustic Wave

  8. Radiation Transfer • LTE • Non-gray - multigroup • Formal Solution Calculate J - B by integrating Feautrier equations along one vertical and 4 slanted rays through each grid point on the surface.

  9. Simplifications • Only 5 rays • 4 Multi-group opacity bins • Assume kLa kC

  10. Opacity is binned, according to its magnitude, into 4 bins.

  11. Advantage • Wavelengths with same t(z) are grouped together, so • integral over t and sum over l commute integral over t and sum over l commute

  12. Solar Magneto-Convection

  13. Energy Fluxes ionizationenergy 3X larger energy than thermal

  14. Fluid Parcelsreaching the surface Radiate away their Energy and Entropy t Z r Q E S

  15. Entropy Green & blue are low entropy downflows, red is high entropy upflows Low entropy plasma rains down from the surface

  16. A Granule is a fountainvelocity arrows, temperature color

  17. Stratified convective flow:diverging upflows, turbulent downflows Velocity arrows, temperature fluctuation image(red hot, blue cool)

  18. Vorticity Downflows are turbulent, upflows are more laminar.

  19. Velocity at Surface and Depth Horizontal scale of upflows increases with depth.

  20. Vorticitysurface and depth.

  21. Turbulent downdrafts

  22. Velocity Distribution Up Down

  23. Entropy Distribution

  24. Vorticity Distribution Down Up

  25. Magnetic Field Reorganization

  26. Simulation Results: B Field lines

  27. Field Distribution observed simulation Both simulated and observed distributions are stretched exponentials.

  28. Flux Emergence & Disappearance

  29. Emerging Magnetic Flux Tube

  30. Magnetic Field Lines, t=0.5 min

  31. Magnetic Field Lines, t=3.5 min

  32. Magnetic Field Lines: t=6 min

  33. Micropores David Bercik - Thesis

  34. Strong Field Simulation • Initial Conditions • Snapshot of granular convection (6x6x3 Mm) • Impose 400G uniform vertical field • Boundary Conditions • Top boundary: B -> potential field • Bottom boundary: B -> vertical • Results • Micropores

  35. Micropore Intensity image + B contours @ 0.5 kG intervals (black) + Vz=0 contours (red).

  36. “Flux Tube” Evacuationfield + temperature contours

  37. “Flux Tube” Evacuationfield + density contours

  38. Observables

  39. Solar velocity spectrum 3-D simulations (Stein & Nordlund) v ~ k-1/3 MDI correlation tracking (Shine) MDI doppler (Hathaway) TRACE correlation tracking (Shine) v ~ k

  40. Line Profiles observed simulation Line profile without velocities. Line profile with velocities.

  41. Convection produces line shifts, changes in line widths. No microturbulence, macroturbulence. Average profile is combination of lines of different shifts & widths. average profile

  42. Stokes Profiles of Flux Tubenew SVST, perfect seeing

  43. Granulation

  44. Spectrum of granulation Simulated intensity spectrum and distribution agree with observations after smoothing with telescope+seeing point spread function.

  45. Granule Statistics

  46. Emergent Intensity, mu=0.5

  47. Magnetic Field Strength

  48. Stokes Image - Quiet SunSynthetic Observation - La Palma Telescope MTF + Moderate Seeing Stokes V Surface Intensity 6 Mm 6 Mm

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