Structure of the Sun
The Sun could be devide in the atmosphere and an inner part. The atmosphere sends electromagnetic
radiation and so you can see it.
The inner part of the Sun
|
|
|
The image shows the structure of the Sun
- Core (source of energy)
- radiation zone (transport of energy by radiation)
- Convection zone (transport of energy by convection)
- Photosphere (visible solar surfacwe)
- Sunspots
- Granulation
- Chromosphere
- Prominences
- Corona
(Grafics: Kiepenheuer Institut Freiburg)
|
The inner part you can divide in core, radiation zone and konvective zone. In the core
four hydrogencors fusion to one heliumcore and so energie ist produced. The four hydrogencors
have more mass than the one heliumcore. Where goes the mass? Einstein has invented the formular
E = Δm c2
the different mass convert in energie. In the formular E stands for the energie, Δm for
the differnt mass und c for the light velocity. Every seconds Sun losts about 4 billion tons.
In the radiation zone energie is transported outside with absorption and reemission.
That means the atoms in the radiation zone takes the energie and gives it up again. The radiation
needs about 170 000 years to pass this zone.
The transport of energie in the convective zone is so:
Gasmasses on the bottom of the zone become higher temperature, increase and
become less density than the gas around it. It is a physical law that gas with
less density is over gas with high density. That means that this gasmasses with less
density go up. When they are on the over part of the convective zone they cold up, become
higher density and slump again.
Atmosphere of the Sun
From inside to outside the atmosphere can be divided in photosphere, cromosphere, transition
region and corona.
Would you look at the Sun without a approviate filter (you shouldn't that really)
you would see the photosphere, which is considered as the surface. Nevertheless we
should mention that the photosphere isn't solid, it consists of plasma, like the remaining Sun.
The most phenomen of this shell are the Sun spots. They are about 2000 K cooler than the remaining
photosphere and for that reason they seem to be darker. In contrast there are also plages, brigth
regions on the photosphere. Do you look more exactly you can also see the granulation, a cellar formed
pattern.
 |
|
The image of the visible solar "surface" - the
photosphere - showing several sunspot groups, observed on June
22nd, 2000. The enlarged image in the inset shows the dark umbra and the structured
penumbra of a sunspot. The "quiet" regions are
composed of the solar granulation, a convective flow pattern that
brings hot matter and energy from inner layers to the surface. The full
solar disk is recorded in the blue spectral range by Precision Solar Photospheric Telescope (RISE/PSPT) in
Rome and the detail view was obtained by the Vacuum Tower Telescope (VTT) on Tenerife operated
by the Kiepenheuer Institut für Sonnensphysik, Freiburg im Breisgau.
|
|
The cromophere you can only observe with approviate
filter but the phenemoens are similar
to that at the photosphere. There are also plages and a chromospheric network. The most
intesting phenomen are flare, the most energetic erruptic in our solar system.
The image shows the chromosphere in the spectral line of Hα observed at Kanzelhöhe Observatory
(2005-01-18).
|
|
|
Copyright: Alson Wong
|
|
The outer most shell is the corona. In former times it could only be observed during
solar eclipses when the moon covered the brigth photosphere. Nowadays it can be observed
with a coronograph. The most important feature of the corona is its high temperatures. At
the outer most shell of the photosphere you would measure temperature of only 4100 K, the
absolute temperature minimum of the Sun. In the chromosphere temperature increases at about 6000 K
but in the corona you suddenly find temperatures of 10 billion Kelvin. The coronal radiation reaches from
x-rays to extreme UV.
In the corona you can observe:
- bright loop-like structures: coronal loops
- far into space reaching open structures: streamers
- dark regions of lower density: coronal holes
- thin enlongated regions of cooler plasma:
prominences or filamnets
|
|
