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The Sun
The Sun - Important Topics Today
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How Did the Sun (& Solar System) Form?
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What is it Made Of? – Solar Anatomy
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What is it's Fate? – Contrast Low and High
Mass Star Death
How Does It Influence the Planets in Our
Solar System?
Sun and Planet Interactions
How Did the Sun and Planets Form?
Star (and Planet) Formation
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Disturbance of
GMC by something
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Supernova
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Collision
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Density wave
Compressed gas
cloud collapses
How It All Began
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GMC collapses
(previous slide & 1)
Cloud spins faster (2);
eddies form
Flattens into a disk (2
& 3); M accretes
Density/temperature in
center increase, forms
proto-sun (4)
Sun 'turns on' (5;
fusion); radiation
clears out nebula
Anatomy of the Solar Nebula
Solar Nebula & Planet Comps
Ice, Rock & Metals
Ice: 1 g/cm3 Rock: 3 g/cm3 Iron: 8 g/cm3
What is the Sun Made of and What Does the
Interior Look Like?
Solar Composition
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Mostly Hydrogen (92%)
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Some Helium (7.8%)
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Everything Else (0.2%)– Carbon, Nitrogen,
Oxygen, Neon, Magnesium, Silicon, Sulfur,
Iron...and about 50 others in trace amounts
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Universe's composition is similar
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M = 1000MJ
The Solar Interior
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Core: source of
photons & energy
(from H→He fusion;
E=mc^2)
Millions of years for
photon to reach
surface of Sun
Corona: hottest part
(above visible solar
surface)
What Will the Sun (and Other Stars)
Become?
Other 'Suns': H-R Diagram
The Evolving Sun
The Fate of Low Mass Stars
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M< 10 M
Not enough M to
fuse beyond C or O
Evolves to become
a 'White Dwarf'
Sheds outer layers
in 'Planetary
Nebula'
WD is core (C/O) of
former star
The Fate of High Mass Stars
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M > 10M or so
Enough M to fuse
up to Fe
Remaining layers
collapse & explode
in Supernova
Seeds universe w/
heavy elements
Leaves 'remnant' –
neutron star or BH
The Sun's Influence
Solar Mass
Toby Smith 2011
Toby Smith 2011
Temperature & Radiation
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M = 1000MJ
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R = 10RJ
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Gravity and Energy fall
off as 1/distance2
(inverse square law –
next slide)
Planet location
(distance) dictates
composition & mass
Inverse Square Law
Radiative Energy
Gravity
Distance from Sun is Important!
Solar System Objects & Their Interactions
with the Sun
CMEs & Magnetosphere
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Sun is losing mass to space
– CMEs & solar wind
CME takes 2-3 days to
reach Earth (light = 8 min)
Coronal Mass Ejections are
dangerous for life/biology
Magnetosphere protects
planet from CME/solar wind
Source of Van Allen Belts &
Aurora
Magnetosphere Generation
Toby Smith 2011
CME Dangers
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CMEs are bad for
biology and
technology!
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CMEs
damage
satellites
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GeoMag
Storms
damage
power grids
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Kill astronauts
in high earth
Lucky Astronauts!
Pretty Aurora
Solar Wind & Comets
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Solar Wind: 500km/s
Comets (dirty
snowballs) 'turn on'
close to sun
Solar wind deflects
comet tails (like a flag
in the wind)
Two tails:
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Debris tail
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Charged
particle tail
Planet Walk