Extreme close encounters between proto-Mercury and proto-Venus in terrestrial planet formation

ABSTRACT Modern models of terrestrial planet formation require solids depletion interior to 0.5–0.7 au in the planetesimal disc to explain the small mass of Mercury. The Earth and Venus analogues emerge after ∼100 Myr collisional growth, while Mercury forms in the diffusive tails of the planetesimal disc. We carried out 250 N-body simulations of planetesimal discs with mass confined to 0.7–1.0 au to study the statistics of close encounters that were recently proposed as an explanation for the high iron mass fraction in Mercury. We formed 39 Mercury analogues in total and all proto-Mercury analogues were scattered inwards by proto-Venus. Proto-Mercury typically experiences six extreme close encounters (closest approach smaller than six Venus radii) with Proto-Venus after Proto-Venus acquires 0.7 Venus Mass. At such close separation, the tidal interaction can already affect the orbital motion significantly such that the N-body treatment itself is invalid. More and closer encounters are expected should tidal dissipation of orbital angular momentum accounted. Hybrid N-body hydrodynamic simulations, treating orbital and encounter dynamics self-consistently, are desirable to evaluate the degree of tidal mantle stripping of proto-Mercury.

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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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Evolution of the Earth’s atmosphere during Late Veneer accretion

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3210 ◽

2020 ◽

Vol 499 (4) ◽

pp. 5334-5362

Author(s):

Catriona A Sinclair ◽

Mark C Wyatt ◽

Alessandro Morbidelli ◽

David Nesvorný

Keyword(s):

Terrestrial Planet ◽

Hydrodynamic Simulations ◽

Substantial Growth ◽

Early Atmosphere ◽

The Earth ◽

Wide Range ◽

History Of ◽

Current Mass ◽

Low Mass ◽

Late Veneer

ABSTRACT Recent advances in our understanding of the dynamical history of the Solar system have altered the inferred bombardment history of the Earth during accretion of the Late Veneer, after the Moon-forming impact. We investigate how the bombardment by planetesimals left-over from the terrestrial planet region after terrestrial planet formation, as well as asteroids and comets, affects the evolution of Earth’s early atmosphere. We develop a new statistical code of stochastic bombardment for atmosphere evolution, combining prescriptions for atmosphere loss and volatile delivery derived from hydrodynamic simulations and theory with results from dynamical modelling of realistic populations of impactors. We find that for an initially Earth-like atmosphere, impacts cause moderate atmospheric erosion with stochastic delivery of large asteroids, giving substantial growth (× 10) in a few ${{\ \rm per\ cent}}$ of cases. The exact change in atmosphere mass is inherently stochastic and dependent on the dynamics of the left-over planetesimals. We also consider the dependence on unknowns including the impactor volatile content, finding that the atmosphere is typically completely stripped by especially dry left-over planetesimals ($\lt 0.02 ~ {{\ \rm per\ cent}}$ volatiles). Remarkably, for a wide range of initial atmosphere masses and compositions, the atmosphere converges towards similar final masses and compositions, i.e. initially low-mass atmospheres grow, whereas massive atmospheres deplete. While the final properties are sensitive to the assumed impactor properties, the resulting atmosphere mass is close to that of current Earth. The exception to this is that a large initial atmosphere cannot be eroded to the current mass unless the atmosphere was initially primordial in composition.

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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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Tidal interactions in rotating multiple stars and their impact on their evolution

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314006735 ◽

2014 ◽

Vol 9 (S307) ◽

pp. 208-210

Author(s):

P. Auclair-Desrotour ◽

S. Mathis ◽

C. Le Poncin-Lafitte

Keyword(s):

Fluid Model ◽

Orbital Evolution ◽

Tidal Dissipation ◽

Tidal Waves ◽

Physical Mechanisms ◽

Tidal Interactions ◽

The Earth ◽

Half Height ◽

Multiple Stars ◽

Stellar Interiors

AbstractTidal dissipation in stars is one of the key physical mechanisms that drive the evolution of binary and multiple stars. As in the Earth oceans, it corresponds to the resonant excitation of their eigenmodes of oscillation and their damping. Therefore, it strongly depends on the internal structure, rotation, and dissipative mechanisms in each component. In this work, we present a local analytical modeling of tidal gravito-inertial waves excited in stellar convective and radiative regions respectively. This model allows us to understand in details the properties of the resonant tidal dissipation as a function of the excitation frequencies, the rotation, the stratification, and the viscous and thermal properties of the studied fluid regions. Then, the frequencies, height, width at half-height, and number of resonances as well as the non-resonant equilibrium tide are derived analytically in asymptotic regimes that are relevant in stellar interiors. Finally, we demonstrate how viscous dissipation of tidal waves leads to a strongly erratic orbital evolution in the case of a coplanar binary system. We characterize such a non-regular dynamics as a function of the height and width of resonances, which have been previously characterized thanks to our local fluid model.

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QUARK ORBITAL ANGULAR MOMENTUM IN THE BARYON

International Journal of Modern Physics A ◽

10.1142/s0217751x01005018 ◽

2001 ◽

Vol 16 (22) ◽

pp. 3673-3697 ◽

Cited By ~ 6

Author(s):

XIAOTONG SONG

Keyword(s):

Angular Momentum ◽

Orbital Angular Momentum ◽

Orbital Motion ◽

Magnetic Moments ◽

Sum Rule ◽

Quark Spin ◽

Quark Flavor ◽

Quark Orbital Angular Momentum ◽

Quark Flavors ◽

Partition Factor

Analytical and numerical results, for the orbital and spin content carried by different quark flavors in the baryons, are given in the chiral quark model with symmetry breaking. The reduction of the quark spin, due to the spin dilution in the chiral splitting processes, is transferred into the orbital motion of quarks and antiquarks. The orbital angular momentum for each quark flavor in the proton as a function of the partition factor κ and the chiral splitting probability a is shown. The cancellation between the spin and orbital contributions in the spin sum rule and in the baryon magnetic moments is discussed.

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How to Predict Earthquakes by Using Simple and Reliable Method? Peru, Chile, Italy, Greece, New Zealand, Andaman and Nicobar Islands, India

Austin Environmental Sciences ◽

10.26420/austinenvironsci.2021.1059 ◽

2021 ◽

Vol 6 (2) ◽

Author(s):

Prakash Pillai S ◽

Keyword(s):

Centrifugal Force ◽

Reliable Method ◽

Orbital Motion ◽

Earthquake Precursors ◽

Generation Process ◽

Tectonic Plates ◽

The Earth ◽

Eruption Precursors ◽

Weather Anomalies ◽

Seasonal Weather

This paper intended to highlight the simple, quick and reliable method to detect impending earthquake�s location. Volcanic eruption precursors are originated only around the volcanos, like that the onshore earthquake precursors are originated only from earthquake epicenter zones. Epicenter zones are earthquake zones, a little variation of fault zone, it comprises movable tectonic plates. Due to the orbital motion of the earth, centrifugal force generated, this centrifugal force is the major driving force of tectonic plates. The position of the orbital motion of the earth generated seasonal variations/atmospheric weather anomalies as onshore earthquake precursors and earthquakes, year after year repeating at same places. The generation process of seasonal weather anomalies is the part of generation process of earthquakes at epicenter zones. Both seasonal weather anomalies and seismic anomalies are not continued all through the year at same places. When earth comes to particular position, tectonic plates of particular epicenter zones are set to more active and becomes unstable epicenter zones, causes identifiable, observable, recordable and testable onshore earthquake precursors 1-15 days prior to earthquakes occur.

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