Models and Observations of Sunspots

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Models and Observations of Sunspots
Juan Manuel Borrero Max Planck Institut for
Solar System Research Lindau, Germany High
Altitude Observatory, Boulder, USA
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Models and Observations of Sunspots
Penumbral magnetic field - Embedded horizontal
flux tubes - Field-Free Gaps Observations _at_ lt
0.4 MHD Simulations Comparison
Simulations/Models/Observations And what about
velocities ? Umbral magnetic field See work by
Reithmüller et al., Socas-Navarro et al.,
Schüssler Vögler Canopy magnetic field Moving
magnetic features See work by Kubo et al.,
Cabrera Solana et al.
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Penumbra Embedded flux tubesHorinzontal flux
tube, carrying the Evershed flow embedded in a
magnetic background
Motivated by the observations of Net Circular
Polarization in Sunspots Solanki Montavon
(1993), Martinez Pillet (2000,2001)? Schlichenmaie
r et al. (2002), Müller et al. (2002)? Thin-flux
tubes simulations Montesinos Thomas
(1997,stationary), Schlichenmaier et al.
(1998,dynamic), Schlichenmaier (2002,dynamic)? Thi
ck-flux tubes simulations Borrero (2007,static)?
Successes - Reproduces observed Stokes
profiles - Reproduces observed NCP - Explains
penumbral grain migration, Moving Magnetic
Features Problems with Penumbral
heating Schlichenmaier et al. (1999),
Schlichenmaier Solanki (2003). See however
Ruiz Cobo Bellot Rubio (2008)?
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Penumbra Embedded flux tubes
Moving penumbral flux tube model Schlichenmaier
(2002)? 1D thin flux tube in a 2D magnetic
background
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Penumbra Embedded flux tubes
Borrero et al. (2005)?
Borrero et al. (2006)?
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Penumbra Embedded flux tubes
Borrero, Bellot Rubio Müller (2007)?
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Penumbra Embedded flux tubes
Ruiz Cobo Bellot Rubio (2008)? 3D stationary
energy equation
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Penumbra Embedded flux tubes
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Penumbra Gappy penumbraIntrusions of
field-free plasma into the sunspot magnetic field
from below
Motivated by the problem of penumbral heating and
brightness - Spruit Scharmer (2006), Scharmer
Spruit (2006) only for the magnetic field
configuration Modified to include convective
velocity fields and the Evershed flow - Scharmer
et al. (2008) for the velocity field
configuration Successes - Detailed comparison to
observed Stokes profiles have not been carried. -
Calculations to show that this model actually
solves the problem of penumbral heating have not
been carried out.
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Penumbra Gappy penumbra
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Results from Hinode/SP_at_0.32
Borrero, Lites Solanki (2008)?
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Results from DLSP_at_0.4
Tritschler et al. (2007)?
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Results from Hinode/SP_at_0.32
Borrero Solanki (2008)?
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Penumbra 3D MHD simulations
Rempel, Schüssler Knölker (2008)? 3D grey
radiative MHD simulation 323221 km
resolution 374.76.1 Mm box
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Penumbra 3D MHD simulationsvertical slice
perpendicular to filaments
Rempel, Schüssler Knölker (2008)? 3D grey
radiative MHD simulation 323221 km
resolution 374.76.1 Mm box
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Penumbra 3D MHD simulationsvertical slice
perpendicular to filaments
Rempel, Schüssler Knölker (2008)? 3D grey
radiative MHD simulation 323221 km
resolution 374.76.1 Mm box
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Penumbra 3D MHD simulationsvertical slice
perpendicular to filaments
Rempel, Schüssler Knölker (2008)? 3D grey
radiative MHD simulation 323221 km
resolution 374.76.1 Mm box
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And what about velocities ?
Embedded flux tubes posses a velocity aligned
with the tube's axis Evershed flow Field free
gaps posses a convective velocity field within
the field-free plasma
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And what about velocities ?
Rempel, Schüssler Knölker (2008)? 3D grey
radiative MHD simulation 323221 km
resolution 374.76.1 Mm box
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And what about velocities ?
Zakharov et al. (2008)? SST/SOUP observations _at_
0.3
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Conclusion
Magnetic field configuration embedded horizontal
flux tube Velocity field configuration
field-free gap
Embedded horizontal gap ?
Convective rolls in a horizontal magnetic field
Danielson (1961)?
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Immediate challenges
Convective velocities field inside horizontal
field needs further confirmation. This new
hybrid models needs to reproduce observations
via forward modeling of Stokes profiles and the
NCP. What about velocity field found in outside
the horizontal field (Ichimoto et al. 2008). MHD
simulations suggests this to be an inverse
Evershed flow in the Photosphere.
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