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Status of current work on Faculae and Sunspots

Status of current work on Faculae and Sunspots. Åke Nordlund, University of Copenhagen Tobias Heinemann, University of Copenhagen Mats Carlsson, University of Oslo Boris Gudiksen, University of Oslo Bob Stein, Michigan State University Sacha Kosovichev , Stanford

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Status of current work on Faculae and Sunspots

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  1. Status of current work onFaculae and Sunspots Åke Nordlund, University of Copenhagen Tobias Heinemann, University of Copenhagen Mats Carlsson, University of Oslo Boris Gudiksen, University of Oslo Bob Stein, Michigan State University Sacha Kosovichev , Stanford Dali Georgobiani, Stanford Nagi Mansour, NASA-Ames

  2. Chromosphere Corona Sunspots Faculae 20 Mm 30 Mm 50 Mm Convection: from granulation to supergranulation scales Grand Plan

  3. Today: Progress Report • Faculae • Center-to-limb behavior • Light bridges • Relation to pores, umbrae and penumbrae • Sunspots • Importance of resolution

  4. Photospheric physics • Equation of state • Qualitative: H+He+Me • Accurate: Lookup table • Opacity • Qualitative: H-minus • Accurate: Lookup table; Opacity Distribution Function • Radiative energy transfer • Qualitative: Vertical & horizontal rays • Accurate: Comprehensive set of rays

  5. Coronal physics • Equation of state • Qualitative: H+He+Me • Accurate: Lookup table • Heat conduction • Spitzer conductivity • Conduction parallel to B • Radiative cooling • Optically thin • Cooling functions from the litterature

  6. Chromospheric physics • Equation of state • Qualitative or accurate • Energy fluxes • Spitzer heat conduction • Convective transport (driven) • Radiation; continuum and ke • Radiative cooling • Optically thick • Approximation of key spectral lines

  7. Code: Staggered Mesh Code • Cell centered mass and thermal energy densities • Face-centered momenta and magnetic fields • Edge-centered electric fields and electric currents • Advantages: • simplicity; OpenMP (MPI btw boxes) • consistency (e.g., divB=0) • accuracy; conservative, 5th order

  8. Radiative Transfer Equation • Solve in a form that directly gives the cooling

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

  10. 5 Rays Through Each Surface Grid Point Interpolate source function to rays at each height

  11. Benchmarks: Timing Results

  12. Altix Itanium-2 Scaling

  13. Plage & Sunspot simulations • Dimensions: 12x12x3 Mm • Intermediate resolution: 250x250x125 • dx = 48 km, dz = 24 km • Duration ~ 60 min, production run • Higher resolution: 500x500x125 • dx = 24 km, dz = 24 km • Duration ~ 15 min, testing high res. effects • Target resolution: 1000x1000x250 • dx = 12 km, dz = 12 km • Duration ~ hours

  14. Vertical magnetic field 250x250x125, duration ~ 35 min Average flux density slowly growing from 400 G to ~ 600 G 12 Mm -2 kG 2

  15. Vertical slice, ~entropy Resolution 250x250x125 Duration ~ 35 min 3 Mm 12 Mm

  16. High resolution (500x500x125) Vertical magnetic field Surface temperature Size: 12 Mm Resolution: 24 km

  17. Lites et al.: AR 3-D structure

  18. Sunspot lightbridges • Model, scale 1.5 x 1.5 x 3 Mm • resolution 12x12x12 km • with radiation and ionization

  19. Sunspot lightbridges • Model, scale 1.5 x 1.5 x 3 Mm • resolution 12x12x12 km • with radiation and ionization

  20. Faculae, continuum, G-band • Hot walls • Seen in projection • Evacuated foreground • G-band; molecule bands • Temperature sensitivity

  21. Center-to-LimbVariation

  22. Lites et al (Solar Physics)

  23. G-band, inclined view

  24. G-band, center to limb

  25. Magnetic concentrations: cool, low r,low opacity.Towards limb,radiation emerges from hot granulewalls behind.On optical depth scale,magneticconcentrations are hot, contrast increases with opacity

  26. Temperature structure: Granule (G) Intergranular lane (IG) G-band bright point (BP) Dark flux concentration (FC) *: T=Tgband +: T=Tgcont

  27. Striated Bright Walls Observed Model

  28. Dark striations: weaker B larger r see higher cooler layer

  29. 3-D simulations (Stein & Nordlund) V~k-1/3 MDI correlation tracking (Shine) MDI doppler (Hathaway) TRACE correlation tracking (Shine) V ~ k Solar velocity spectrum Velocity spectrum: v(k) = (k P(k))1/2

  30. Velocity driving for corona sims Voronoi tessellation ensemble Velocity spectrum from three superposed ensembles

  31. ~Scale Free Spectrum?Doppler Image of the SunMichelson Doppler Interferometer (SOHO/MDI)

  32. 400 Mm 100 Mm 50 Mm 200 Mm Solar horizontal velocity (observed)Scales differ by factor 2 – which is which?

  33. Solar horizontal velocity (model)Scales differ by factor 2 – which is which? 12 Mm 24 Mm 3 Mm 6 Mm

  34. Supergranulation scale convection:first relax 24x24x9 Mm, then 50x50x20 Mm • Origin of supergranulation • Role of HeII ionization • Role of magnetic field • Emergence of magnetic flux • Maintenance of magnetic network • Driving coronal heating simulations Vertical velocity

  35. Solar velocity spectrum24 Mm simulation will fill gap

  36. Summary • High resolution, large resources needed • Faculae • Sunspots • Lightbridges; illusion! • Large scale convection • Approx. scale free horizontal motions!

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