Download The Sun

The Sun
• G-Type star
• contains approximately 98% of the total
solar system mass.
• One hundred and nine Earths would
be required to fit across the Sun's disk
• its interior could hold over 1.3 million
Earths
• The Sun appears to have been active for
4.6 billion years and has enough fuel to go
on for another five billion years or so
Life Cycle of the Sun
• At the end of its life, the Sun will start
to fuse helium into heavier elements
and begin to swell up
• ultimately growing so large that it will
swallow the Earth
• After a billion years as a red giant, it
will suddenly collapse into a white
dwarf
•
Not to scale
Sun Statistics
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Mass (kg)
Mass (Earth = 1)
Equatorial radius (km)
Equatorial radius (Earth = 1)
Mean density (gm/cm^3)
Rotational period (days)
Magnitude (Vo)
Mean surface temperature
Age (billion years)
Principal chemistry
– Hydrogen
92.1%
– Helium
7.8%
– Oxygen
0.061%
– Carbon
0.030%
– Nitrogen
0.0084%
– Neon
0.0076%
– Iron
0.0037%
– Silicon
0.0031%
– Magnesium
0.0024%
– Sulfur
0.0015%
– All others
0.0015%
1.989 x 1030
332,830
695,000
108.97
1.410
25-36*
-26.8
6,000°C
4.5
Luminosity classes
• Class Ia,b :
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Supergiant
Class II: Bright giant
Class III: Giant
Class IV: Sub-giant
Class V: Dwarf
The Sun is a G2 V star
Granulation
Photosphere granulation
“Eruptive prominence" or blob of
60,000°C gas, over 80,000 miles
long, moving at 15,000 mph
Extreme Ultraviolet Imaging
Telescope
X-Ray
1994 Solar eclipse (one of the few times you
can actually see the CORONA)
Distance from Earth to the sun
• 93 million miles
• We call this distance the “ASTRONOMICAL
UNIT” or AU.
– It becomes a standard of measurement in the
solar system.
Core
• extends from the
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•
•
center to about 0.2
solar radii
temperature of close
to 14,500,000 kelvin
The core is the only
location in the Sun
that produces an
appreciable amount of
heat via fusion
the rest of the star is
heated by energy that
is transferred outward
from the core
Radiative zone
• From about 0.2 to about 0.7 solar radii
• no thermal convection; Heat is transferred
by radiation
Convection zone
• In the Sun's outer layer (down to
approximately 70% of the solar radius)
• thermal convection occurs as thermal columns
carry hot material to the surface (photosphere)
of the Sun
• Once the material cools off at the surface, it
plunges back downward to the base of the
convection zone, to receive more heat from the
top of the radiative zone
Photosphere granulation
Photosphere
• The visible surface of the Sun
• temperature is about 6,000 K
Photosphere
Chromosphere
• thin layer of the Sun's
atmosphere just above
the photosphere
• roughly 10,000
kilometers deep
• For reasons not fully
understood the
temperature of the
chromosphere is hotter
than that of the
photosphere (from
6000K to 20000K)
Chromosphere
Corona
• type of plasma "atmosphere" of the Sun
• extending millions of kilometres into space
• Temperature is about 1,000,000 K to 4,000,000
•
K
“Coronal Loop” on the following slide
Corona
•sunspot
–An area seen as a dark spot on the
photosphere of the Sun. Sunspots are
concentrations of magnetic fluctuations,
typically occurring in bipolar clusters or
groups. They appear dark because they
are cooler than the surrounding
photosphere.
Sunspots are low temperature
regions in the photosphere
Sun spots are about 4000 C (2000 C cooler than solar
surface) and have magnetic fields up 1000 the normal
solar magnetic field. They can be as large as 100,000
km and last for many months.
Sunspots
• Strong magnetic field redirects
the convective flow of hot gas,
leaving the temperature cooler
• Dark b/c they are around 2,000 C
cooler than the surrounding
photosphere
• Appear as pairs in
clusters
• One will have a positive/north
magnetic field while the other will
have a negative/south magnetic
field
• Polarity – which way the
magnetic field is directed
(-/+; N/S)
Solar Activity
• Sunspots can give us information about the
sun.
• Where do most of the sunspots appear?
• Equator! Sunspots never occur on the poles
• Does the sun rotate?
• Yes!
• What is the sun’s rotational period?
• Equator – 25 days
• Poles – 36 days
• How is this possible?
• The sun IS NOT rigid like earth. It is a plasma so
it’s rotational period can be different.
• We are not sure what causes this to occur
though.
Sunspot cycle
Sunspots can be used to
measure the rotation of the
Sun
Near the equator
the Sun rotates
once in 25 days.
The poles rotate
more slowly,
about once every
36 days.
•prominence
–An eruption of hot gases above
the photosphere of the Sun.
Prominences are most easily
visible close to the limb of the
Sun, but some are also visible as
bright streamers on the
photosphere.
Prominences Cooler than
photosphere.
•solar wind
–A tenuous flow of gas and
energetic charged particles,
mostly protons and electrons -plasma -- which stream from the
Sun; typical solar wind velocities
are almost 350 kilometers (217
miles) per second.
•flare
–A sudden eruption of energy on
the solar disk lasting minutes to
hours, from which radiation and
particles are emitted.
Coronal mass
ejections eruption of
gas, can reach
Earth and
affect aurora,
satellites
Coronal mass
ejection
Coronal Mass Ejection
• ejection of
•
material from the
solar corona
consisting
primarily of
electrons and
protons (in
addition to small
quantities of
heavier elements
such as helium,
oxygen, and
iron)
CMEs, solar storms, and what
they can do to Earth.
• aurora
– A glow in a planet's ionosphere caused by
the interaction between the planet's
magnetic field and charged particles from the
Sun.
• aurora borealis
– The Northern Lights caused by the
interaction between the solar wind, the
Earth's magnetic field and the upper
atmosphere; a similar effect happens in the
southern hemisphere where it is known as
the aurora australis.
Solar Storms