The Origin of the Moon Within a Terrestrial Synestia
| Autor: | Matija Ćuk, M. Mace, Sarah T. Stewart, Simon J. Lock, Michail I. Petaev, Stein B. Jacobsen, Zoë M. Leinhardt |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2018 |
| Předmět: |
Angular momentum
010504 meteorology & atmospheric sciences volatile elements FOS: Physical sciences isotopic equilibration Lunar orbit angular momentum 01 natural sciences Mantle (geology) Astrobiology Physics::Geophysics giant impact chemistry.chemical_compound Geochemistry and Petrology lunar chemistry 0103 physical sciences Vaporization Origin of the Moon Earth and Planetary Sciences (miscellaneous) 010303 astronomy & astrophysics Volatiles 0105 earth and related environmental sciences Earth and Planetary Astrophysics (astro-ph.EP) lunar accretion Silicate Geophysics chemistry Space and Planetary Science Physics::Space Physics Terrestrial planet Astrophysics::Earth and Planetary Astrophysics Geology Astrophysics - Earth and Planetary Astrophysics |
| Zdroj: | Lock, S J, Stewart, S T, Petaev, M I, Leinhardt, Z, Mace, M T, Jacobsen, S B & Cuk, M 2018, ' The Origin of the Moon Within a Terrestrial Synestia ', Journal of Geophysical Research: Planets, vol. 123, no. 4, pp. 910-951 . https://doi.org/10.1002/2017JE005333 |
| DOI: | 10.1002/2017JE005333 |
| Popis: | The giant impact hypothesis remains the leading theory for lunar origin. However, current models struggle to explain the Moon's composition and isotopic similarity with Earth. Here we present a new lunar origin model. High-energy, high-angular momentum giant impacts can create a post-impact structure that exceeds the corotation limit (CoRoL), which defines the hottest thermal state and angular momentum possible for a corotating body. In a typical super-CoRoL body, traditional definitions of mantle, atmosphere and disk are not appropriate, and the body forms a new type of planetary structure, named a synestia. Using simulations of cooling synestias combined with dynamic, thermodynamic and geochemical calculations, we show that satellite formation from a synestia can produce the main features of our Moon. We find that cooling drives mixing of the structure, and condensation generates moonlets that orbit within the synestia, surrounded by tens of bars of bulk silicate Earth (BSE) vapor. The moonlets and growing moon are heated by the vapor until the first major element (Si) begins to vaporize and buffer the temperature. Moonlets equilibrate with BSE vapor at the temperature of silicate vaporization and the pressure of the structure, establishing the lunar isotopic composition and pattern of moderately volatile elements. Eventually, the cooling synestia recedes within the lunar orbit, terminating the main stage of lunar accretion. Our model shifts the paradigm for lunar origin from specifying a certain impact scenario to achieving a Moon-forming synestia. Giant impacts that produce potential Moon-forming synestias were common at the end of terrestrial planet formation. Accepted for publication in Journal of Geophysical Research: Planets. Main text: 44 pages, 24 figures. Supplement: 16 pages, 5 figures, 3 tables |
| Databáze: | OpenAIRE |
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