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Forming Mercury by Giant Impacts


Chau, Alice; Reinhardt, Christian; Helled, Ravit; Stadel, Joachim (2018). Forming Mercury by Giant Impacts. The Astrophysical Journal, 865(1):35.

Abstract

The origin of Mercury's high iron-to-rock ratio is still unknown. In this work we investigate Mercury's formation via giant impacts and consider the possibilities of a single giant impact, a hit-and-run, and multiple collisions, in one theoretical framework. We study the standard collision parameters (impact velocity, mass ratio, impact parameter), along with the impactor's composition and the cooling of the target. It is found that the impactor's composition affects the iron distribution within the planet and the final mass of the target by up to 25%, although the resulting mean iron fraction is similar. We suggest that an efficient giant impact has to be head-on at high velocity, while in the hit-and-run case the impact can occur closer to the most probable collision angle (45°). It is also shown that Mercury's current iron-to-rock ratio can be a result of multiple collisions, with their exact number depending on the collision parameters. Mass loss is found to be more significant when the collisions are close together in time.

Abstract

The origin of Mercury's high iron-to-rock ratio is still unknown. In this work we investigate Mercury's formation via giant impacts and consider the possibilities of a single giant impact, a hit-and-run, and multiple collisions, in one theoretical framework. We study the standard collision parameters (impact velocity, mass ratio, impact parameter), along with the impactor's composition and the cooling of the target. It is found that the impactor's composition affects the iron distribution within the planet and the final mass of the target by up to 25%, although the resulting mean iron fraction is similar. We suggest that an efficient giant impact has to be head-on at high velocity, while in the hit-and-run case the impact can occur closer to the most probable collision angle (45°). It is also shown that Mercury's current iron-to-rock ratio can be a result of multiple collisions, with their exact number depending on the collision parameters. Mass loss is found to be more significant when the collisions are close together in time.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute for Computational Science
Dewey Decimal Classification:530 Physics
Uncontrolled Keywords:Space and Planetary Science, Astronomy and Astrophysics
Language:English
Date:18 September 2018
Deposited On:05 Mar 2019 13:28
Last Modified:17 Sep 2019 19:39
Publisher:IOP Publishing
ISSN:1538-4357
OA Status:Green
Free access at:Publisher DOI. An embargo period may apply.
Publisher DOI:https://doi.org/10.3847/1538-4357/aad8b0

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