Status of current work on Faculae and Sunspots

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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

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Grand Plan
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Today Progress Report

• Faculae
• Center-to-limb behavior
• Light bridges
• Relation to pores, umbrae and penumbrae
• Sunspots
• Importance of resolution

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Photospheric physics

• Equation of state
• Qualitative HHeMe
• 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

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Coronal physics

• Equation of state
• Qualitative HHeMe
• Accurate Lookup table
• Heat conduction
• Spitzer conductivity
• Conduction parallel to B
• Radiative cooling
• Optically thin
• Cooling functions from the litterature

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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

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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., divB0)
• accuracy conservative, 5th order

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Radiative Transfer Equation

• Solve in a form that directly gives the cooling

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Opacity is binned, according to its magnitude,
into 4 bins.
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5 Rays Through Each Surface Grid Point
Interpolate source function to rays at each height
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Benchmarks Timing Results
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Altix Itanium-2 Scaling
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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

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Vertical magnetic field
250x250x125, duration 35 min Average flux
density slowly growing from 400 G to 600 G
12 Mm
-2
kG
2
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Vertical slice, entropy
Resolution 250x250x125 Duration 35 min
3 Mm
12 Mm
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High resolution (500x500x125)
Vertical magnetic field
Surface temperature
Size 12 Mm Resolution 24 km
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Lites et al. AR 3-D structure
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Sunspot lightbridges

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

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Sunspot lightbridges

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

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Faculae, continuum, G-band

• Hot walls
• Seen in projection
• Evacuated foreground
• G-band molecule bands
• Temperature sensitivity

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Center-to-LimbVariation
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Lites et al (Solar Physics)
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G-band, inclined view
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G-band, center to limb
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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
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Temperature structure
Granule (G) Intergranular lane (IG) G-band
bright point (BP) Dark flux concentration (FC)
TTgband TTgcont
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Striated Bright Walls
Observed
Model
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Dark striations weaker B larger r see higher
cooler layer
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Solar velocity spectrum
Velocity spectrum v(k) (k P(k))1/2
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Velocity driving for corona sims
Voronoi tessellation ensemble
Velocity spectrum from three superposed ensembles
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Scale Free Spectrum?Doppler Image of the
SunMichelson Doppler Interferometer (SOHO/MDI)
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Solar horizontal velocity (observed)Scales
differ by factor 2 which is which?
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Solar horizontal velocity (model)Scales differ
by factor 2 which is which?
24 Mm
12 Mm
6 Mm
3 Mm
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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
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Solar velocity spectrum24 Mm simulation will
fill gap
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Summary

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