A new equation of state applied to planetary impacts : II. Lunar-forming impact simulations with a primordial magma ocean

Summary, in English

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.

• Author: Robert Wissing; David Hobbs
• Department/s: Lund Observatory - Has been reorganised
• Publishing year: 2020-11-01
• Language: English
• Publication/Series: Astronomy and Astrophysics
• Volume: 643
• Links: http://dx.doi.org/10.1051/0004-6361/201936227
• Document type: Journal article
• Publisher: EDP Sciences
• Topic: Astronomy, Astrophysics and Cosmology
• Keywords: Earth; Equation of state; Moon; Planets and satellites: dynamical evolution and stability; Planets and satellites: formation; Planets and satellites: interiors
• Status: Published
• ISBN/ISSN/Other: ISSN: 0004-6361