Space Station Info >> Layers Of Sun
Layers of sun
The sun
has many different layers that describe its structure.
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Core
X
Radiation zone
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Convection zone
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Photosphere-sunspots
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Chromosphere
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Transition region
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Corona
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Core
The core is the innermost layer
of the sun and it is a source for all the Sun's
energy. The material in the core is firmly attached
and has very high temperature, which is about
15 million degrees Kelvin. In the core the intense
heat destroys the internal structure of an atom
and therefore all atoms are broken down into their
constituent parts. An atom is composed of protons,
electrons and neutrons. Neutrons have no electric
charge and so they do not interact a lot with
the surrounding medium. Thus neutrons go away
the core fairly and quickly. The protons, which
have positive electric charge, and the electrons,
which have negative electric charge, remain in
the core and force the reactions which fuel the
Sun. The charge neutral material of protons and
electrons that makes up the core is called plasma.
The high temperature provides the protons and
electrons with a great amount of thermal energy
and therefore they moved pretty quickly and they
combine with the high density of the plasma, causes
the particles to continuously slam into one another
creating nuclear reactions. It is the fusion,
or slamming together, of particular combinations
of particles that provides the energy source of
the Sun.
The core is the innermost layer
of the sun and it is a source for all the Sun's
energy. Thermonuclear reactions takes place inside
the core ,thus hydrogen atoms are comnbined with
each other to make helium atoms and produces energy
which keeps the Sun in a state of equilibrium.Thus
this thermonuclear reaction is called nuclear
fusion.
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Radiation
Zone
Once the energy is produced
in the core of the sun, it has to travel from
the solar center to the outer regions. Hence the
radiation zone provides an efficient means of
transferring energy near the core. The temperature
in the radiation zone of the sun is cooler than
the core. The material 0.2 to about 0.7 solar
radii is hot and dense enough that thermal radiation
is sufficient to transfer the intense heat of
the core outward. Heat is transferred by ions
of hydrogen and helium emitting photons, which
travel a brief distance before being re-absorbed
by other ions.
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Convection Zone
Ranging from 0.7 solar radii to 1.0 solar
radii, the material in the Sun is not that
much dense or hot to transfer the heat energy
from interior to outward. Hence, thermal convection
occurs as thermal columns carry hot material
to the surface (photosphere) of the Sun. As
soon as the material cools off at the surface,
it plunges backside downward to the base of
the convection zone, to obtain more heat from
the top of the radiative zone. Convective
exceed is thought to occur at the base of
the convection zone, moving turbulent down
flows into the outer layers of the radiative
zone. |
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The thermal columns in the convection
zone shape mark on the surface of the Sun, in
the form of the solar granulation and supergranulation.
The turbulent convection of this outer part of
the solar interior gives rise to a 'small-scale'
dynamo that produces magnetic north and south
poles all over the surface of the Sun.
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Photosphere
Photosphere is the visible surface
of the Sun. Above the photosphere, sunlight is
free to disseminate into space and its energy
escapes the Sun completely. Sunlight has approximately
a black-body spectrum that indicates its temperature
is about 6,000 K, interspersed with atomic absorption
lines from the tenuous layers above the photosphere.
The photosphere has a element density of about
1023/m3 (this is about 1% of the particle density
of Earth's atmosphere at sea level). The parts
of the Sun above the photosphere are referred
to collectively as the solar atmosphere. They
can be seen with telescopes across the electromagnetic
spectrum, from the visible light to gamma rays.
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Chromosphere
This a thin layer present above
the visible surface, which is about 2,000 km thick,
specifically dominated by a spectrum of emission
and absorption lines. It is called the chromosphere
from the Greek root chromos, meaning color, for
the reason that the chromosphere is visible as
a colored flash at the beginning and end of total
eclipses of the Sun.
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Corona
The corona is the outer atmosphere
of the Sun, which is much larger in volume than
the Sun itself. The corona merges slickly with
the solar wind so as to fill the solar system
and heliosphere. The low corona, which is very
close to the surface of the Sun, has a particle
density of 1011/m3 (Earth's atmosphere near sea
level has a particle density of about 2x1025/m3).
The temperature of the corona is several million
degrees K.
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