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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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

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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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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

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Earth Si and SSAE Normalized Elemental Abundances vs. Condensation Temperature

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• 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/