Miki Nakajima Gives Three Talks in November of 2016

DTM Postdoctoral Fellow Miki Nakajima gave three talks this month at the University of Maryland, University of Illinois, and George Mason University in Virginia, titled "Implications of the Moon Formation for the Earth's Mantle and Magnetic Field," "Origin of the Earth, the Moon, and exomoons," and "Origin of the Moon," respectively.

The abstract for the talk at the University of Illinois is below.

Abstract: The giant impact hypothesis suggests that the Moon formed out of a partially vaporized disk created by a collision between an impactor and the proto-Earth. Three major models exist for this hypothesis: (a) standard model: a Mars-sized impactor hit Earth, (b) fast-spinning Earth model: a small impactor hit the rapidly-rotating Earth, (c) sub-Earths model: two half Earth-sized objects collided. These impact hypotheses may explain several observed features of the Earth-Moon system, such as the lunar mass and lunar iron depletion. However, it has not been clear if any of these models can explain other geochemical and paleomagnetic observations that indicate that (1) the Earth's mantle may have never been mixed even by the giant impact, and that (2) the Earth's core, on the other hand, may have been mixed. My giant impact simulations using the smoothed particle hydrodynamics (SPH) method show that the standard model can explain the preservation of the mantle heterogeneity while the other models may mix the Earth's mantle. I also show that all of the models predict the core is dynamically mixed by the impact.  These results indicate that the standard model is most consistent with the geochemical and paleomagnetic observations. Moreover, I will discuss exomoon formation by impact as an extension of the Earth's Moon-forming scenario.