Issue |
A&A
Volume 643, November 2020
|
|
---|---|---|
Article Number | A40 | |
Number of page(s) | 22 | |
Section | Planets and planetary systems | |
DOI | https://doi.org/10.1051/0004-6361/201936227 | |
Published online | 29 October 2020 |
A new equation of state applied to planetary impacts
II. Lunar-forming impact simulations with a primordial magma ocean
1
Lund Observatory, Department of Astronomy and Theoretical Physics, Lund University,
Box 43,
22100
Lund, Sweden
e-mail: david@astro.lu.se
2
Institute of Theoretical Astrophysics, University of Oslo,
Postboks 1029,
0315
Oslo,
Norway
e-mail: robertwi@astro.uio.no
Received:
2
July
2019
Accepted:
11
August
2020
Observed FeO/MgO ratios in the Moon and Earth are inconsistent with simulations done with a single homogeneous silicate layer. In this paper we use a newly developed equation of state to perform smoothed particle hydrodynamics simulations on the lunar-forming impact, testing the effect of a primordial magma ocean on Earth. This is investigated using the impact parameters of both the canonical case, in which a Mars-sized impactor hits a non-rotating Earth at an oblate angle, and the fast-rotating case, in which a half-sized Mars impactor hits a fast-spinning Earth head-on. We find that the inclusion of a magma ocean results in a less massive Moon and leads to slightly more mixing. Additionally, we test how an icy Theia would affect the results and find that this reduces the probability of a successful Moon formation. Simulations of the fast-spinning case are found to be unable to form a massive-enough Moon.
Key words: equation of state / planets and satellites: formation / planets and satellites: dynamical evolution and stability / planets and satellites: interiors / Moon / Earth
© ESO 2020
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