The Internal Rotation of the Sun

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The Internal Rotation of the Sun

• Presented by Changyi Tan
• 11,03,2005

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• ? How to observe the interior of the Sun?
• 1, The method Helioseismology
• Why is Helioseismology? (opaque or optical
  thickness)
• 2, The instrumentations for Helioseismology
• Global Oscillation Network Group (GONG)
• Michelson Doppler Imager (MDI)

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• ? How Helioseismology works?
• Basically, observe the surface sound waves
  of the Sun. People can get the coupled
  multi-modes spherical harmonic oscillation
  signals, and separate them to some normal mode
  harmonic wave.
• There are two kinds of sound waves p
  mode and f mode.
• f mode is used to analyze the surface
  wave, it propagates on the surface of the Sun
  Photosphere

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• p mode wave is used to detect the interior of the
  Sun. The parameter of p mode wave is l.
• The restoring force is pressure gradient .
• from
  http//gong.nso.edu/.

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• ? The internal structure of the Sun.
• from
  http//gong.nso.edu/.

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• We concentrate on the Convection Zone.
• The parameters of Convection Zone
• From 0.8 R? 1 R?
• Cool temperature 106 K
• More opaque
• High magnetic strength 103104 Gauss
• High density?
• But the density at the top of Convection Zone
  is very low 0.0000002 gm/cm³

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• ? Dynamo of the convention Zone
• 1, Magnetic fields
• The topology of the magnetic fields is very
  complicated. Related to the poroidal field and
  toroidal field. These relate to the sunspots ,
  CMEs, flares and so on.
• The magnetic pressure and tension should be
  stronger than them in the atmosphere. But the gas
  pressure should also be stronger, so ß not
  necessarily be small.

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• 2, Convection
• Cool Temperature? Electrons reconbine with
  other particles (Ions) and the photons can be
  easily absorbed. This decreases the radiative
  conductivity and increases the temperature
  gradient. Where this occurs a volume of material
  moved upward will be warmer than its surroundings
  and will continue to rise further. These
  convective motions carry heat quite rapidly to
  the surface. The fluid expands and cools as it
  rises. At the visible surface the temperature has
  dropped to 5,700 K . The convective motions
  themselves are visible at the surface as ?
  granules and supergranules.

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• 3, Differential Rotation
• (a),The different latitude the rotation rate
  is different.2
• Tachocline, shear layers

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• (b), The Meridional Circulation
• related to butterfly

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• (c), Appear quasi-periodic oscillation1

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• ?,Butterfly

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• From 2

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• ?Physics
• Due to the differential rotation, the weak
  poroidal field will produce a strong toroidal
  field below surface when solar minimum.
• Kinks in toroidal field rise to form sunspots at
  low latitude.
• The leading polarities of south and north of the
  equator are due to the Coriolis Force when
  toroidal field rises.
• At the sun activity minimum, the leading
  polarity will reverse. Because the supergranular
  eddy diffusion.

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• From 5

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• Kink (from 5)

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• ( From 5 )

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• ? The rotation at the deep interiorlike a rigid
  body

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• References
• 1, Michael J. Thompson et al. Annu. Rev. Astron.
  Astrophys. 2003. 41599-643
• 2, R. Howe The Internal Rotation of The Sun, 2003
• 3, Michael Stix The Sun. 2002
• 4, Peter A. Gilman, Mark S. Miesch, ApJ,
  611568-574, 2004 August 10
• 5, E.R. Priest, Solar Physics and MHD, 1981

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• Thanks a lot.