GEOL3045: Planetary Geology

GEOL3045: Planetary Geology

Lysa Chizmadia16 Jan 2007

The Origin of Our Solar System

Lysa Chizmadia16 Jan 2007

The Origin of Our Solar System

Images from: http://csep10.phys.utk.edu/astr161/lect/solarsys/nebular.html

Interstellar Cloud CollapseInterstellar Cloud Collapse Initially, Interstellar Cloud of gas

and/or dust Interstellar cloud of gas and dust

disturbed and collapsed under its own gravity Probably due to shock waves from

near-by supernova

As collapses, cloud heats up, starts to rotate and compresses in center T enough to vaporize dust Takes ~ 100,000 years (100 ka)

Initially, Interstellar Cloud of gas and/or dust

Interstellar cloud of gas and dust disturbed and collapsed under its own gravity Probably due to shock waves from

near-by supernova

As collapses, cloud heats up, starts to rotate and compresses in center T enough to vaporize dust Takes ~ 100,000 years (100 ka)

Protostar & Accretion DiskProtostar & Accretion Disk Due to rotation, nebula flattens

into disk Center compresses into

protostar & rest of gas rotates around it Gas flows into protostar,

protostar grows into star Centrifugal forces keep

some gas from falling in Accretion disk

Due to rotation, nebula flattens into disk

Center compresses into protostar & rest of gas rotates around it Gas flows into protostar,

protostar grows into star Centrifugal forces keep

some gas from falling in Accretion disk

Images from: http://en.wikipedia.org/wiki/Solar_System and http://csep10.phys.utk.edu/astr161/lect/solarsys/nebular.html

Orion Nebula

Thermodynamic CondensationThermodynamic Condensation Gas starts to cool, eventually

condenses into solids First solids = most refractory

( T) E.g. Ca, Al, Ti oxides with

some silicates I.e. CAIs (Ca, Al-rich

inclusions) Thermodynamic

condensation With T, less refractory elements

condense Mg > Si > Cr > Mn > Na > K > Fe

> Ni > S

Gas starts to cool, eventually condenses into solids First solids = most refractory

( T) E.g. Ca, Al, Ti oxides with

some silicates I.e. CAIs (Ca, Al-rich

inclusions) Thermodynamic

condensation With T, less refractory elements

condense Mg > Si > Cr > Mn > Na > K > Fe

> Ni > S Image from: Davis and Richter (2007) Treatise of Geochemistry vol. 1, chpt 15, p410

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Ca, Al-rich InclusionsCa, Al-rich Inclusions Ca, Al, Ti, Si, Mg

Oxides & Silicates

T >1300 K Pb-Pb dating

4.559 + 0.004 Ga Confirmed by

Rb-Sr & Sm-Nd dating

26Al excess > 2 Ma older

than all other materials

Ca, Al, Ti, Si, Mg Oxides &

Silicates T >1300 K

Pb-Pb dating 4.559 + 0.004 Ga Confirmed by

Rb-Sr & Sm-Nd dating

26Al excess > 2 Ma older

than all other materials Images from personal

archive

Dust BallsDust Balls Solids start to accrete together into dust balls Solids start to accrete together into dust balls

Image from: http://www.psi.edu/hartmann/pic-cat/pages/100_Solar_System_Origin.html

Chondrule FormationChondrule Formation Transient heating events form chondrules & igneous CAIs Transient heating events form chondrules & igneous CAIs

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Images from: Jones (1990) Geochemica et Cosmochimica Acta v54 p1785 and http://www.psrd.hawaii.edu/Mar00/flashHeating.html

Run-Away GrowthRun-Away Growth Solids continue to accrete

into planetessimals Run-away growth

Planetessimals grow into planetary embryos Gas blown out of system

due to high solar winds Planetary embryos grow into

planets Moon to Mars sized 10-100 Ma

10-15 planetary embryos in inner solar system

Solids continue to accrete into planetessimals Run-away growth

Planetessimals grow into planetary embryos Gas blown out of system

due to high solar winds Planetary embryos grow into

planets Moon to Mars sized 10-100 Ma

10-15 planetary embryos in inner solar system

Images from: http://en.wikipedia.org/wiki/Solar_System and http://csep10.phys.utk.edu/astr161/lect/solarsys/nebular.html

SummarySummary 1) Solar System formed from collapse of

interstellar molecular cloud Heats up and vaporizes all dust

2) As nebula cools down, condensation of solid materials Most refractory elements first, followed by more and

more volatile elements

3) Solids accrete in run-away growth Dust balls Planetessimals Planetary Embryos Planets

1) Solar System formed from collapse of interstellar molecular cloud Heats up and vaporizes all dust

2) As nebula cools down, condensation of solid materials Most refractory elements first, followed by more and

more volatile elements

3) Solids accrete in run-away growth Dust balls Planetessimals Planetary Embryos Planets