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Title: The structure of terrestrial bodies: Impact heating, corotation limits, and synestias: THE STRUCTURE OF TERRESTRIAL BODIES

Abstract

During accretion, terrestrial bodies attain a wide range of thermal and rotational states, which are accompanied by significant changes in physical structure (size, shape, pressure and temperature profile, etc.). However, variations in structure have been neglected in most studies of rocky planet formation and evolution. Here we present a new code, the Highly Eccentric Rotating Concentric U (potential) Layers Equilibrium Structure (HERCULES) code, that solves for the equilibrium structure of planets as a series of overlapping constant-density spheroids. Using HERCULES and a smoothed particle hydrodynamics code, we show that Earth-like bodies display a dramatic range of morphologies. For any rotating planetary body, there is a thermal limit beyond which the rotational velocity at the equator intersects the Keplerian orbital velocity. Beyond this corotation limit (CoRoL), a hot planetary body forms a structure, which we name a synestia, with a corotating inner region connected to a disk-like outer region. By analyzing calculations of giant impacts and models of planet formation, we show that typical rocky planets are substantially vaporized multiple times during accretion. For the expected angular momentum of growing planets, a large fraction of post-impact bodies will exceed the CoRoL and form synestias. The common occurrence of hot, rotating statesmore » during accretion has major implications for planet formation and the properties of the final planets. In particular, the structure of post-impact bodies influences the physical processes that control accretion, core formation, and internal evolution. Synestias also lead to new mechanisms for satellite formation. Finally, the wide variety of possible structures for terrestrial bodies also expands the mass-radius range for rocky exoplanets.« less

Authors:
ORCiD logo [1]; ORCiD logo [2]
  1. Harvard Univ., Cambridge, MA (United States)
  2. Univ. of California, Davis, CA (United States)
Publication Date:
Research Org.:
Harvard Univ., Cambridge, MA (United States)
Sponsoring Org.:
USDOE National Nuclear Security Administration (NNSA)
OSTI Identifier:
1532991
Grant/Contract Number:  
NA0001804; NA0002937
Resource Type:
Accepted Manuscript
Journal Name:
Journal of Geophysical Research. Planets
Additional Journal Information:
Journal Volume: 122; Journal Issue: 5; Journal ID: ISSN 2169-9097
Publisher:
American Geophysical Union
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; Geochemistry & Geophysics

Citation Formats

Lock, Simon J., and Stewart, Sarah T. The structure of terrestrial bodies: Impact heating, corotation limits, and synestias: THE STRUCTURE OF TERRESTRIAL BODIES. United States: N. p., 2017. Web. doi:10.1002/2016je005239.
Lock, Simon J., & Stewart, Sarah T. The structure of terrestrial bodies: Impact heating, corotation limits, and synestias: THE STRUCTURE OF TERRESTRIAL BODIES. United States. doi:10.1002/2016je005239.
Lock, Simon J., and Stewart, Sarah T. Mon . "The structure of terrestrial bodies: Impact heating, corotation limits, and synestias: THE STRUCTURE OF TERRESTRIAL BODIES". United States. doi:10.1002/2016je005239. https://www.osti.gov/servlets/purl/1532991.
@article{osti_1532991,
title = {The structure of terrestrial bodies: Impact heating, corotation limits, and synestias: THE STRUCTURE OF TERRESTRIAL BODIES},
author = {Lock, Simon J. and Stewart, Sarah T.},
abstractNote = {During accretion, terrestrial bodies attain a wide range of thermal and rotational states, which are accompanied by significant changes in physical structure (size, shape, pressure and temperature profile, etc.). However, variations in structure have been neglected in most studies of rocky planet formation and evolution. Here we present a new code, the Highly Eccentric Rotating Concentric U (potential) Layers Equilibrium Structure (HERCULES) code, that solves for the equilibrium structure of planets as a series of overlapping constant-density spheroids. Using HERCULES and a smoothed particle hydrodynamics code, we show that Earth-like bodies display a dramatic range of morphologies. For any rotating planetary body, there is a thermal limit beyond which the rotational velocity at the equator intersects the Keplerian orbital velocity. Beyond this corotation limit (CoRoL), a hot planetary body forms a structure, which we name a synestia, with a corotating inner region connected to a disk-like outer region. By analyzing calculations of giant impacts and models of planet formation, we show that typical rocky planets are substantially vaporized multiple times during accretion. For the expected angular momentum of growing planets, a large fraction of post-impact bodies will exceed the CoRoL and form synestias. The common occurrence of hot, rotating states during accretion has major implications for planet formation and the properties of the final planets. In particular, the structure of post-impact bodies influences the physical processes that control accretion, core formation, and internal evolution. Synestias also lead to new mechanisms for satellite formation. Finally, the wide variety of possible structures for terrestrial bodies also expands the mass-radius range for rocky exoplanets.},
doi = {10.1002/2016je005239},
journal = {Journal of Geophysical Research. Planets},
number = 5,
volume = 122,
place = {United States},
year = {2017},
month = {5}
}

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Cited by: 22 works
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