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QUESTIONS
1. How do we form hypotheses about the formation of our Solar System?
2. In what ways can we scientifically test ideas about the Solar System’s formation and early events?
3. What is the Solar System’s destiny?
BUILDING A SOLAR SYSTEM
STEP 1.FUSE METALS
ORIGIN OF MATTER• All matter originated at the Big Bang
• Primordial nucleosynthesis
• A few minutes after the big bang, protons were highly dense and very energetic, allowing fusion
• For about 17 minutes, nucleosynthesis could occur
BIG BANG NUCLEOSYNTHESIS• Discussed by Alpher-Bethe-Gamow in 1940s
H + H D
• Nearly all deuterium originated in the big bang
• Also formed 3He, 4He, 7Li
• ~10:1 H:He ratio
• Beyond that energy required wasn’t amenable
T=1000 s
STARS AND FUSION
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Less fusion
Lots of fusion
NUCLEAR FUSION• The process of forming a new atomic nucleus by the fusing of two or more nuclei
• Hydrogen is “burned” to form Helium, and further fusion leads to other elements
• Fusion only occurs at high temperatures (core of the Sun, nuclear bomb, early big bang)
+ +Coulombic Barrier
2 H
D
D + H3He
2 3He
4He
2 HH HE
SYNTHESIS OF HEAVIER ELEMENTS• Requires bigger, hotter stars
• High temperature means more energy to overcome coulomb barrier
• Also means more frequent collisions between nuclei, so short-lived nuclei can act as intermediates
MORE BURNING• Triple alpha process
2 4He
8Be 8Be
4He
12C
16O
ORIGIN OF HEAVIER ELEMENTS
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From Stellar Nucleosynthesis
HEAVIER ELEMENTS• Require energy to synthesize
• No pay for their own nucleosynthesis
• Supernova
• Form new elements by proton/neutron capture
• Result in the periodic table
http://magic.mppmu.mpg.de/snr.jpg
Anders and Grevasse 1989
Anders and Grevasse 1989
Most abundant elements easiest to synthesize
Anders and Grevasse 1989
Heavy elements much rarer than light elements
Anders and Grevasse 1989
Sawtooth pattern from addition of He nuclei
Anders and Grevasse 1989
Iron peak- the dead end of nucleosynthesis
Anders and Grevasse 1989
Easy to burn light elements so Li, Be, B are depleted
STEP 2.DESTROY AN OLD STAR
• Brightest Explosion since Kepler’s time
• Guess the year it happened!
• Ring of expelled gas from earlier
• Bipolar filaments
SUPERNOVA 1987A
SUPERNOVA 1987A
http://hubblesite.org/newscenter/archive/releases/2004/09/
• Brightest Explosion since Kepler’s time
• Guess the year it happened!
• Ring of expelled gas from earlier
• Bipolar filaments
• Hubble has been watching…
• Not actually planetary at all: Herschel thought they looked like planets, that they were new planetary systems forming.
PLANETARY NEBULA
• Orion Nebula
• ~2000 Solar Masses
NEBULA
STEP 3.CONDENSE A NEW STAR
• Material condenses from “small” shock waves, perturbations in nebula
• Spinning increases (Moment of Inertia)
• Fusion begins when P/T is achieved
• Materials fall into new star and are ejected
• This modifies the solar system!
YOUNG STARS
STEP 4.GET A PROPLYD
• Material spins out like record, Earth
• North and South of Sun, material is excavated by jets
• Orion Nebula proplyds
(PRO)TO(PL)ANETAR(Y D)ISK = PROPLYD
STEP 5.BUILD PARTICLES
Anders and Grevasse 1989
Take a gas of this composition and cool it.What forms?
FIRST THING TO FORM:• Ceramics
• These are high temperature minerals
• First condensates
CALLED CALCIUM-ALUMINUM RICH INCLUSIONS
THEN COME SILICATES AND METAL• Olivine and iron
SILICATES MELTED• Formed chondrules
VOLATILE MATERIALS• Phosphorus
• Lower temeprature silicates (Na-, K-bearing)
• Sulfides
• Ices
Where do they go?
STEP 6.BUILD MASSES
EARTH FORMED FROM SOLAR SYSTEM DEBRIS• Earth and other planets form from a
mixture of rocky material
• Meteorites
• Asteroids
• Comets
Hoba- www.nmm.ac.uk
ORIGINS OF THE EARTH’S CONSTITUENTS• Volatile components, including key biogenic elements, were in short supply on the early
Earth
• Earth was hot
• Volatiles were lost or were not delivered
• Not primordial (20Ne, 36Ar)
LOSS OF VOLATILES ON INNER PLANETS
0 200 400 600 800 1000 1200 1400 1600 1800 20000.000E+00
2.000E-01
4.000E-01
6.000E-01
8.000E-01
1.000E+00
1.200E+00
1.400E+00
1.600E+00
1.800E+00
Earth Si and SSAE Normalized Elemental Abundances vs. Condensation Temperature
Condensation Temperature (K)
Ele
me
nta
l Ab
un
da
nc
e
H, C, N, O
P
• Carbonaceous Chondrites, with hydrated minerals, were the last accreted constituent to the early earth
• Outgassing of volatiles led to hydro + atmosphere
• Consistent with D/H ratio
• Something odd going on with PGEs
• Comets, loaded with H2O and organics, were the source of volatiles
• Loaded with water
• High flux (possibly) to early Earth
• D/H ratio is much higher than earth
• What were early comets really like?
DELIVERY OF VOLATILES TO THE EARTH
Cometary Delivery Late Veneer
STEP 7.“CRUSH THE MASSES”
-Stalin
PLANETARY ACCRETION• Dust grains and small particles collide and
stick together
• Accumulate, making larger and larger bodies
• A miracle occurs
• Planets form
http://ircamera.as.arizona.edu/NatSci102/NatSci102/images/accretion.jpg
http://blog.stackoverflow.com/wp-content/uploads/then-a-miracle-occurs-cartoon.png
STEP 8.DIFFERENTIATE THE PLANETS
PROCESSING OF PLANETS• Planets accreted and were warmed
• Radioactive decay of short-lived elements?
• Impact heating
• Warming causes differentiation of planets
STEP 9.REARRANGE AND WATCH OUT
CREATING MOONS AND RINGS• From Robin Canup:
• Gravity is hell
• Earth-Moon formed from early collision
• Jupiter kept eating its moons
• Saturn’s Rings formed from destroyed ice moon?
http://www.youtube.com/watch?v=Fwl_JBQtH9o
• Caused by a turbulent outer Solar System
• 4.1 - 3.8 Ga
THE LATE HEAVY BOMBARDMENT
http://physics.uoregon.edu/~jimbrau/astr121/notes/chapter15.html
http://www.youtube.com/watch?v=6LzQfR-T5_A
The Nice Model Gomes et al, Nature, 2005• Giants were at 5-17 AU• Now at 5-30 AU
• Caused by a turbulent outer Solar System
• 4.1 - 3.8 Ga
• Ended same time as life “?” showed up on Earth
• Effects still seen nightly
THE LATE HEAVY BOMBARDMENT
ANNOUNCEMENTS…
for
METEORITICS
MEET IN CHE313 NEXT WEEK!
• Uploaded to Canvas
• Read Chapter 8, stopping at 8.8 for next week!
• Homework:
1. Chapter 8, problems 1 & 2
2. Chelyabinsk Research Paper questions
HOMEWORK: DUE SEPT 12 IN CLASS
• We (The Solar System) is now in a cloud of gas probably blown to us by a group of super-giants. It is called the Local Interstellar Cloud(LIC) or the Local Fluff.
• Assume:
• T = 7000 K
• 0.1 atoms/cubic cm
• Using the Ideal Gas Law, Calculate its pressure. Give units.
EXTRA CREDIT (2pts, due with HW2, 9/12)
http://science1.nasa.gov/science-news/science-at-nasa/2003/06jan_bubble/