Kleine, Thorsten, Prof. Dr.
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Prof. Dr. Thorsten Kleine
Phone: +49 251 8333406 |
he starting place for the accretion of the Earth and other planetary bodies is the solar nebula. This circumstellar disk of gas and dust formed by the gravitational collapse of a localized dense region of an interstellar molecular cloud. Within the inner region of the solar nebula, dust grains collide and stuck together to form a large population of meter- to kilometer-sized objects. Gravity and gas drag causes these planetesimals to collide and form increasingly larger bodies in a period of runaway growth, the products of which include numerous Moon- to Mars-sized planetary embryos. Collisions among these bodies mark the late stages of accretion culminating in the formation of a few terrestrial planets that sweep up all the other bodies. The Moon probably formed during this period, and involved a 'giant impact' of a Mars-sized body with Earth at the very end of Earth's accretion.
Planetary accretion is intimately linked with heating and subsequent melting of the planetary interiors. As a consequence, all major bodies of the inner solar system and also many smaller bodies are chemically differentiated into a metallic core and a silicate mantle. Major heat sources for differentiation are the decay of short-lived Aluminum-26 and collisions among the planetary embryos.
I use isotopes to study the (i) dynamics of the solar nebula, (ii) to date the formation of asteroids and terrestrial planets, and (iii) to unravel the processes during the major differentiation of the Earth and other rocky bodies of the inner solar system.
