TY - JOUR
T1 - Collision chains among the terrestrial planets. II. an asymmetry between earth and venus
AU - Emsenhuber, Alexandre
AU - Asphaug, Erik
AU - Cambioni, Saverio
AU - Gabriel, Travis S.J.
AU - Schwartz, Stephen R.
N1 - Funding Information:
A.E., E.A., S.C., and S.R.S. acknowledge support from NASA under grant 80NSSC19K0817 and the University of Arizona. T.S.J.G. acknowledges support from the Arizona State University Space Technology and Science (“NewSpace”) Initiative. We thank the anonymous reviewers, whose comments helped to improve the manuscript. An allocation of computer time from the UA Research Computing High Performance Computing (HPC) is gratefully acknowledged.
Publisher Copyright:
© 2021. The Author(s). Published by the American Astronomical Society.
PY - 2021/10
Y1 - 2021/10
N2 - During the late stage of terrestrial planet formation, hit-and-run collisions are about as common as accretionary mergers, for expected velocities and angles of giant impacts. Average hit-and-runs leave two major remnants plus debris: the target and impactor, somewhat modified through erosion, escaping at lower relative velocity. Here we continue our study of the dynamical effects of such collisions. We compare the dynamical fates of intact runners that start from hit-and-runs with proto-Venus at 0.7 au and proto-Earth at 1.0 au. We follow the orbital evolutions of the runners, including the other terrestrial planets, Jupiter, and Saturn, in an N-body code. We find that the accretion of these runners can take >10 Myr (depending on the egress velocity of the first collision) and can involve successive collisions with the original target planet or with other planets. We treat successive collisions that the runner experiences using surrogate models from machine learning, as in previous work, and evolve subsequent hit-and-runs in a similar fashion. We identify asymmetries in the capture, loss, and interchange of runners in the growth of Venus and Earth. Hit-and-run is a more probable outcome at proto-Venus, being smaller and faster orbiting than proto-Earth. But Venus acts as a sink, eventually accreting most of its runners, assuming typical events, whereas proto-Earth loses about half, many of those continuing to Venus. This leads to a disparity in the style of late-stage accretion that could have led to significant differences in geology, composition, and satellite formation at Earth and Venus.
AB - During the late stage of terrestrial planet formation, hit-and-run collisions are about as common as accretionary mergers, for expected velocities and angles of giant impacts. Average hit-and-runs leave two major remnants plus debris: the target and impactor, somewhat modified through erosion, escaping at lower relative velocity. Here we continue our study of the dynamical effects of such collisions. We compare the dynamical fates of intact runners that start from hit-and-runs with proto-Venus at 0.7 au and proto-Earth at 1.0 au. We follow the orbital evolutions of the runners, including the other terrestrial planets, Jupiter, and Saturn, in an N-body code. We find that the accretion of these runners can take >10 Myr (depending on the egress velocity of the first collision) and can involve successive collisions with the original target planet or with other planets. We treat successive collisions that the runner experiences using surrogate models from machine learning, as in previous work, and evolve subsequent hit-and-runs in a similar fashion. We identify asymmetries in the capture, loss, and interchange of runners in the growth of Venus and Earth. Hit-and-run is a more probable outcome at proto-Venus, being smaller and faster orbiting than proto-Earth. But Venus acts as a sink, eventually accreting most of its runners, assuming typical events, whereas proto-Earth loses about half, many of those continuing to Venus. This leads to a disparity in the style of late-stage accretion that could have led to significant differences in geology, composition, and satellite formation at Earth and Venus.
KW - Unified Astronomy Thesaurus concepts: Solar system terrestrial planets (797); Solar system formation (1530)
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U2 - 10.3847/PSJ/ac19b1
DO - 10.3847/PSJ/ac19b1
M3 - Article
AN - SCOPUS:85116812224
SN - 2632-3338
VL - 2
JO - Planetary Science Journal
JF - Planetary Science Journal
IS - 5
M1 - ac19b1
ER -