The energy budgets of giant impacts
- Creators
- Carter, P. J.
- Lock, S. J.
- Stewart, S. T.
Abstract
Giant impacts dominate the final stages of terrestrial planet formation and set the configuration and compositions of the final system of planets. A giant impact is believed to be responsible for the formation of Earth's Moon, but the specific impact parameters are under debate. Because the canonical Moon‐forming impact is the most intensely studied scenario, it is often considered the archetypal giant impact. However, a wide range of impacts with different outcomes are possible. Here we examine the total energy budgets of giant impacts that form Earth‐mass bodies and find that they differ substantially across the wide range of possible Moon‐forming events. We show that gravitational potential energy exchange is important, and we determine the regime in which potential energy has a significant effect on the collision outcome. Energy is deposited heterogeneously within the colliding planets, increasing their internal energies, and portions of each body attain sufficient entropy for vaporization. After gravitational re‐equilibration, post‐impact bodies are strongly thermally stratified, with varying amounts of vaporized and supercritical mantle. The canonical Moon‐forming impact is a relatively low‐energy event and should not be considered the archetype of accretionary giant impacts that form Earth‐mass planets. After a giant impact, bodies are significantly inflated in size compared to condensed planets of the same mass, and there are substantial differences in the magnitudes of their potential, kinetic, and internal energy components. As a result, the conditions for metal‐silicate equilibration and the subsequent evolution of the planet may vary widely between different impact scenarios.
Additional Information
© 2019 American Geophysical Union. Received 14 MAY 2019; Accepted 7 DEC 2019; Accepted article online 17 DEC 2019. We thank the anonymous reviewers for their constructive comments which have improved the quality of this manuscript. This work was supported by NASA grant 80NSSC18K0828 (PJC and STS). SJL gratefully acknowledges support from Harvard University's Earth and Planetary Sciences Department and Caltech's Division of Geological and Planetary Sciences. A summary of the simulations is available in the supplementary material. The data used to produce the figures in this article, the EOS table for use with the modified version of GADGET‐2, the input files for all the simulations discussed in this work, and code to read them are available from https://doi.org/10.7910/DVN/YYNJSX (Carter et al., 2019). The modified GADGET‐2 code is available in the online supporting information of Ćuk and Stewart (2012). The HERCULES code is available in the supplement of Lock and Stewart (2017) and through the GitHub repositry: https://doi.org/10.5281/zenodo.3509365(Lock, 2019).Attached Files
Published - Carter_et_al-2020-Journal_of_Geophysical_Research__Planets.pdf
Supplemental Material - jgre21277-sup-0001-2019je006042-si.eps
Supplemental Material - jgre21277-sup-0002-2019je006042-s2.pdf
Supplemental Material - jgre21277-sup-0003-2019je006042-s3.pdf
Supplemental Material - jgre21277-sup-0004-2019je006042-ts01.csv
Supplemental Material - jgre21277-sup-0005-2019je006042-ms01.mp4
Supplemental Material - jgre21277-sup-0006-2019je006042-ms02.mp4
Supplemental Material - jgre21277-sup-0007-2019je006042-ms03.mp4
Supplemental Material - jgre21277-sup-0008-2019je006042-ms04.mp4
Supplemental Material - jgre21277-sup-0009-2019je006042-ms05.mp4
Supplemental Material - jgre21277-sup-0010-2019je006042-ms06.mp4
Supplemental Material - jgre21277-sup-0011-2019je006042-ms07.mp4
Supplemental Material - jgre21277-sup-0012-2019je006042-ms08.mp4
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Additional details
- Eprint ID
- 100357
- Resolver ID
- CaltechAUTHORS:20191218-133828132
- 80NSSC18K0828
- NASA
- Harvard University
- Caltech Division of Geological and Planetary Sciences
- Created
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2019-12-18Created from EPrint's datestamp field
- Updated
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2023-06-01Created from EPrint's last_modified field