Terrestrial planet formation from lost inner solar system material

ABSTRACT A successful Solar system model must reproduce the four terrestrial planets. Here, we focus on (1) the likelihood of forming Mercury and the four terrestrial planets in the same system (a 4-P system); (2) the orbital properties and masses of each terrestrial planet; and (3) the timing of Earth’s last giant impact and the mass accreted by our planet thereafter. Addressing these constraints, we performed 450 N-body simulations of terrestrial planet formation based on narrow protoplanetary discs with mass confined to 0.7–1.0 au. We identified 164 analogue systems, but only 24 systems contained Mercury analogues, and eight systems were 4-P ones. We found that narrow discs containing a small number of embryos with individual masses comparable to that of Mars and the giant planets on their current orbits yielded the best prospects for satisfying those constraints. However, serious shortcomings remain. The formation of Mercury analogues and 4-P systems was too inefficient (5 per cent and 2 per cent, respectively), and most Venus-to-Earth analogue mass ratios were incorrect. Mercury and Venus analogues also formed too close to each other (∼0.15–0.21 au) compared to reality (0.34 au). Similarly, the mutual distances between the Venus and Earth analogues were greater than those observed (0.34 versus 0.28 au). Furthermore, the Venus–Earth pair was not reproduced in orbital-mass space statistically. Overall, our results suggest serious problems with using narrow discs to explain the inner Solar system. In particular, the formation of Mercury remains an outstanding problem for terrestrial planet formation models.

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Terrestrial Planet Formation: The Solar System and Other Systems

Symposium - International Astronomical Union ◽

10.1017/s0074180900217749 ◽

2004 ◽

Vol 202 ◽

pp. 159-166

Author(s):

Shigeru Ida ◽

Eiichiro Kokubo

Keyword(s):

Solar System ◽

Final Stage ◽

Extrasolar Planets ◽

Planet Formation ◽

Terrestrial Planet ◽

The Other ◽

Terrestrial Planets ◽

Giant Impacts ◽

Earth Like Planets ◽

Jovian Planet

Accretion of terrestrial planets and solid cores of jovian planets is discussed, based on the results of our N-body simulations. Protoplanets accrete from planetesimals through runaway and oligarchic growth until they become isolated. The isolation mass of protoplanets in terrestrial planet region is about 0.2 Earth mass, which suggests that in the final stage of terrestrial planet formation giant impacts between the protoplanets occur. On the other hand, the isolation mass in jovian planet region is about a few to 10 Earth masses, which may be massive enough to form a gas giant. Extending the above arguments to disks with various initial masses, we discuss diversity of planetary systems. We predict that the extrasolar planets so far discovered may correspond to the systems formed from disks with large initial masses and that the other disks with smaller masses, which are the majority of the disks, may form Earth-like planets.

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Dynamical Shake‐up of Planetary Systems. II.N‐Body Simulations of Solar System Terrestrial Planet Formation Induced by Secular Resonance Sweeping

The Astrophysical Journal ◽

10.1086/526408 ◽

2008 ◽

Vol 676 (1) ◽

pp. 728-739 ◽

Cited By ~ 38

Author(s):

E. Thommes ◽

M. Nagasawa ◽

D. N. C. Lin

Keyword(s):

Solar System ◽

Planet Formation ◽

Planetary Systems ◽

Terrestrial Planet ◽

Secular Resonance

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Earth-size planet formation in the habitable zone of circumbinary stars

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa757 ◽

2020 ◽

Vol 494 (1) ◽

pp. 1045-1057 ◽

Cited By ~ 1

Author(s):

G O Barbosa ◽

O C Winter ◽

A Amarante ◽

A Izidoro ◽

R C Domingos ◽

...

Keyword(s):

Numerical Simulations ◽

Planet Formation ◽

Terrestrial Planet ◽

Close Binary ◽

Habitable Zone ◽

Density Profiles ◽

Habitable Planets ◽

Habitable Zones ◽

Test Particles ◽

The Stability

ABSTRACT This work investigates the possibility of close binary (CB) star systems having Earth-size planets within their habitable zones (HZs). First, we selected all known CB systems with confirmed planets (totaling 22 systems) to calculate the boundaries of their respective HZs. However, only eight systems had all the data necessary for the computation of HZ. Then, we numerically explored the stability within HZs for each one of the eight systems using test particles. From the results, we selected five systems that have stable regions inside HZs, namely Kepler-34,35,38,413, and 453. For these five cases of systems with stable regions in HZ, we perform a series of numerical simulations for planet formation considering discs composed of planetary embryos and planetesimals, with two distinct density profiles, in addition to the stars and host planets of each system. We found that in the case of the Kepler-34 and 453 systems, no Earth-size planet is formed within HZs. Although planets with Earth-like masses were formed in Kepler-453, they were outside HZ. In contrast, for the Kepler-35 and 38 systems, the results showed that potentially habitable planets are formed in all simulations. In the case of the Kepler-413system, in just one simulation, a terrestrial planet was formed within HZ.

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Machine learning applied to simulations of collisions between rotating, differentiated planets

Computational Astrophysics and Cosmology ◽

10.1186/s40668-020-00034-6 ◽

2020 ◽

Vol 7 (1) ◽

Author(s):

Miles L. Timpe ◽

Maria Han Veiga ◽

Mischa Knabenhans ◽

Joachim Stadel ◽

Stefano Marelli

Keyword(s):

Machine Learning ◽

Planet Formation ◽

Critical Role ◽

Ensemble Methods ◽

Terrestrial Planet ◽

Data Driven ◽

Analytic Methods ◽

Accurate Treatment ◽

Post Impact ◽

The Cost

AbstractIn the late stages of terrestrial planet formation, pairwise collisions between planetary-sized bodies act as the fundamental agent of planet growth. These collisions can lead to either growth or disruption of the bodies involved and are largely responsible for shaping the final characteristics of the planets. Despite their critical role in planet formation, an accurate treatment of collisions has yet to be realized. While semi-analytic methods have been proposed, they remain limited to a narrow set of post-impact properties and have only achieved relatively low accuracies. However, the rise of machine learning and access to increased computing power have enabled novel data-driven approaches. In this work, we show that data-driven emulation techniques are capable of classifying and predicting the outcome of collisions with high accuracy and are generalizable to any quantifiable post-impact quantity. In particular, we focus on the dataset requirements, training pipeline, and classification and regression performance for four distinct data-driven techniques from machine learning (ensemble methods and neural networks) and uncertainty quantification (Gaussian processes and polynomial chaos expansion). We compare these methods to existing analytic and semi-analytic methods. Such data-driven emulators are poised to replace the methods currently used in N-body simulations, while avoiding the cost of direct simulation. This work is based on a new set of 14,856 SPH simulations of pairwise collisions between rotating, differentiated bodies at all possible mutual orientations.

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Forming terrestrial planets and delivering water

Proceedings of the International Astronomical Union ◽

10.1017/s174392131600572x ◽

2015 ◽

Vol 11 (A29B) ◽

pp. 427-430

Author(s):

Kevin J. Walsh

Keyword(s):

Planet Formation ◽

Semimajor Axis ◽

Giant Planet ◽

Terrestrial Planet ◽

Giant Planets ◽

Asteroid Belt ◽

Terrestrial Planets ◽

The Earth ◽

Building Models ◽

Rich Material

AbstractBuilding models capable of successfully matching the Terrestrial Planet's basic orbital and physical properties has proven difficult. Meanwhile, improved estimates of the nature of water-rich material accreted by the Earth, along with the timing of its delivery, have added even more constraints for models to match. While the outer Asteroid Belt seemingly provides a source for water-rich planetesimals, models that delivered enough of them to the still-forming Terrestrial Planets typically failed on other basic constraints - such as the mass of Mars.Recent models of Terrestrial Planet Formation have explored how the gas-driven migration of the Giant Planets can solve long-standing issues with the Earth/Mars size ratio. This model is forced to reproduce the orbital and taxonomic distribution of bodies in the Asteroid Belt from a much wider range of semimajor axis than previously considered. In doing so, it also provides a mechanism to feed planetesimals from between and beyond the Giant Planet formation region to the still-forming Terrestrial Planets.

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