GEOL3045: Planetary Geology Lysa Chizmadia 16 Jan 2007 The Origin of Our Solar System Lysa Chizmadia 16 Jan 2007 The Origin of Our Solar System

Images from: Interstellar 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 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: and Orion Nebula

Thermodynamic 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

Ca, Al-rich Inclusions  Ca, Al, Ti, Si, Mg  Oxides & Silicates  T >1300 K  Pb-Pb dating  Ga  Confirmed by Rb-Sr & Sm-Nd dating  26 Al excess  > 2 Ma older than all other materials  Ca, Al, Ti, Si, Mg  Oxides & Silicates  T >1300 K  Pb-Pb dating  Ga  Confirmed by Rb-Sr & Sm-Nd dating  26 Al excess  > 2 Ma older than all other materials Images from personal archive

Dust Balls  Solids start to accrete together into dust balls Image from:

Chondrule Formation  Transient heating events form chondrules & igneous CAIs fgr olv Images from: Jones (1990) Geochemica et Cosmochimica Acta v54 p1785 and

Run-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  Ma  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  Ma  planetary embryos in inner solar system Images from: and

Summary  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