scholarly journals Laplace surface dynamics, revisited: satellites, exo-planets and debris with distant, eccentric companions

2021 ◽  
Author(s):  
Mohammad A Farhat ◽  
Jihad R Touma
Keyword(s):  
Central Body ◽  
Surface Dynamics ◽  
Eccentric Orbit ◽  
Wide Binary ◽  
Secular Dynamics ◽  
Test Particles ◽  
Particle Orbits ◽  
Mutual Inclination ◽  
Dynamical Features ◽  
Quadrupolar Order

Abstract To date, studies of Laplace Surface dynamics have concerned themselves with test particle orbits of fixed shape and orientation in the combined field of an oblate central body (to which the particle is bound) and a distant, inclined, companion which is captured to quadrupolar order. While amply sufficient for satellites around planets on near-circular orbits, the quadrupolar approximation fails to capture essential dynamical features induced by a wide binary companion (be it a star, a planet or a black hole) on a fairly eccentric orbit. With similar such astronomical settings in mind, we extend the classical Laplace framework to higher multipoles, and map out the backbone of stationary orbits, now complexified by the broken axial symmetry. Eccentric and inclined Laplace equilibria, which had been presaged in systems of large enough mutual inclination, are here delineated over a broad range of mutually inclined perturbations. We recover them for test particles in the field of a hot Jupiter and a wide eccentric stellar binary, highlighting their relevance for the architecture of multi-planet systems in binaries. We then extend and deploy our machinery closer to home, as we consider the secular dynamics of Trans-Neptunian Objects (TNOs) in the presence of a putative ninth planet. We show how generalized Laplace equilibria seed islands for Trans-Neptunian objects to be sheltered around, islands within chaotic seas which we capture via Poincaré sections, while highlighting a beautiful interplay between Laplace and Kozai-Lidov secular dynamical structures. An eminently classical tale revived for the exo-planetary 21st century!

Simulating vortices and jets in deep atmospheres of gas giant planets

2020 ◽  
Author(s):  
Rakesh Yadav ◽  
Jeremy Bloxham ◽  
Moritz Heimpel
Keyword(s):  
Giant Planets ◽  
Self Organization ◽  
Surface Dynamics ◽  
Spherical Shells ◽  
Zonal Flows ◽  
Rich Picture ◽  
The Third ◽  
First Case ◽  
Dynamical Features ◽  
Over Time

<p>Decades of observations have painted a dynamic and rich picture of the atmosphere on Saturn and Jupiter. Both planets have a dominant prograde equatorial jet, and strong zonal flows that alternate in direction at higher latitudes, with Saturn also having a mysterious hexagon shape embedded in one of the polar jets. Both planets also have numerous vortices or storms of different sizes scattered on their surface. All these features are striking examples of turbulent self-organization. While observations abound, the physics behind the formation of these dynamical features is still uncertain. Two interpretations have emerged over time: In one, the surface features are shallow, extending to depths ranging from 10s to 100s of kilometers, while, in the other, they extend to 1000s of kilometers. Here we utilize the deep interpretation and investigate the properties of rotating convection in deep spherical shells. We present three cases: In the first case a giant polar cyclone, alternating zonal flows, and a high latitude eastward jet having polygonal patterns form simultaneously; The second case generates alternating zonal flows as well as numerous cyclones and anticyclones on various latitudes; And, the third case exclusively generates anticyclones with few being as large as Jupiter's great red spot. We discuss what drives these features in these turbulent simulations, and what can we learn from these cases about the interior and surface dynamics of Saturn and Jupiter. </p>

scholarly journals Rapid dynamical evolution of ITCZ events over the east Pacific

2021 ◽  
pp. 1-48
Author(s):  
Marie C. McGraw ◽  
James G. Larson
Keyword(s):  
Coriolis Force ◽  
Dynamical Evolution ◽  
Gradient Force ◽  
Pressure Gradient Force ◽  
Surface Dynamics ◽  
Near Surface ◽  
East Pacific ◽  
Dynamical Features ◽  
East Pacific Ocean ◽  
Meridional Advection

Abstract The latitudinal location of the east Pacific Ocean intertropical convergence zone (ITCZ) changes on time scales of days to weeks during boreal spring. This study focuses on tropical near-surface dynamics in the days leading up to the two most frequent types of ITCZ events, nITCZ (Northern Hemisphere) and dITCZ (double). There is a rapid, daily evolution of dynamical features on top of a slower, weekly evolution that occurs leading up to and after nITCZ and dITCZ events. Zonally-elongated bands of anomalous cross-equatorial flow and off-equatorial convergence rapidly intensify and peak one day before or the day of these ITCZ events, followed one or two days later by a peak in near-equatorial zonal wind anomalies. In addition, there is a wide region north of the southeast Pacific subtropical high where anomalous northwesterlies strengthen prior to nITCZ events and southeasterlies strengthen before dITCZ events. Anomalous zonal and meridional near-surface momentum budgets reveal that the terms associated with Ekman balance are of first-order importance preceding nITCZ events, but that the meridional momentum advective terms are just as important before dITCZ events. Variations in cross-equatorial flow are promoted by the meridional pressure gradient force (PGF) prior to nITCZ events and the meridional advection of meridional momentum in addition to the meridional PGF before dITCZ events. Meanwhile, variations in near-equatorial easterlies are driven by the zonal PGF and the Coriolis force preceding nITCZ events and the zonal PGF, the Coriolis force, and the meridional advection of zonal momentum before dITCZ events.

scholarly journals Gravitomagnetic effects of a massive and slowly rotating sphere with an equatorial mass current on orbiting test particles

2009 ◽  
Vol 5 (S261) ◽  
pp. 152-154
Author(s):  
Leonardo Castañeda ◽  
Fernando Fandiño ◽  
William Almonacid ◽  
Edilberto Suárez ◽  
Giovanni Pinzón
Keyword(s):  
Test Particle ◽  
Equatorial Plane ◽  
Spherical Body ◽  
Einstein Field Equations ◽  
Field Equations ◽  
Rotating Sphere ◽  
Test Particles ◽  
Particle Orbits

AbstractWithin the framework of linearized Einstein field equations we compute the gravitomagnetic effects on a test particle orbiting a slowly rotating, spherical body with a rotating matter ring fixed to the equatorial plane. Our results show that the effect on the precession of particle orbits is increased by the presence of the ring.

A semi-analytical model for secular dynamics of test particles in hierarchical triple systems

2019 ◽  
Vol 490 (4) ◽  
pp. 4756-4769 ◽  
Author(s):  
Hanlun Lei
Keyword(s):  
Analytical Model ◽  
Equations Of Motion ◽  
Semimajor Axis ◽  
Axis Ratio ◽  
Triple Systems ◽  
Secular Dynamics ◽  
Test Particles ◽  
Orbital Periods ◽  
Averaged Model

ABSTRACT In this work, a semi-analytical model is formulated up to an arbitrary order in the semimajor axis ratio of the inner and outer binaries to describe the long-term (secular) dynamics of test particles in hierarchical triple systems. The third-body disturbing function is expressed as a Fourier series, where the harmonic arguments are linear combinations of the perturber’s mean anomaly, and the test particle’s mean anomaly, longitude of the ascending node, and argument of pericentre. Based on the series expansion, it is straightforward to arrive at the secular equations of motion by directly eliminating those terms that are irrelevant to the long-term dynamics. When the perturbations are so strong that the system’s hierarchy is no longer high, the conventional double-averaged model fails to predict the long-term behaviours of test particles. To overcome the difficulty, we develop a corrected double-averaged model by taking into account the short-term effects within the orbital periods of the inner and outer binaries. The resulting averaged model is applied to Jupiter’s irregular satellites, and simulation results show that the corrected model can reproduce the behaviours on time-scales much longer than the orbital periods. Moreover, we retrieve a triple-averaged model and discuss the associated dynamics in the phase space. It is found that the Kozai resonance in the corrected model occurs at a higher inclination than that in the conventional model.

scholarly journals Stability in the most external region of the Oort Cloud: evolution of the ejected comets

2019 ◽  
Vol 490 (2) ◽  
pp. 2495-2506
Author(s):  
J A Correa-Otto ◽  
M F Calandra
Keyword(s):  
Binary Stars ◽  
Outer Boundary ◽  
Oort Cloud ◽  
Dynamical Behaviour ◽  
Dynamical Structure ◽  
Wide Binary ◽  
External Region ◽  
Test Particles ◽  
The Galaxy ◽  
Galactic Tide

ABSTRACTIn this paper, we present a study of the dynamical effects of the Galaxy on the external region of the Oort Cloud. The aims of this paper are: (i) to determine an outer limit for the Oort Cloud; and (ii) to analyse the dynamical behaviour of the most external objects of the Oort Cloud and how they are ejected from the Solar system. To achieve these aims, we follow the temporal evolution of massless test particles in the Galactic environment of the solar neighbourhood. We show that the effect of the perturbations from the Galactic tide in the particles is similar to that found for the evolution of the population of wide binary stars. Moreover, in the Oort Cloud, we find a dynamical structure around 105 au conformed by objects unbound from the Sun. This structure allows us to define a transition region of stability and an outer boundary for the Oort Cloud, and it is also in agreement with previous results about the disruption of wide binary stars.

scholarly journals Orbital dynamics of circumbinary planets

2019 ◽  
Vol 490 (4) ◽  
pp. 5634-5646 ◽  
Author(s):  
Cheng Chen ◽  
Alessia Franchini ◽  
Stephen H Lubow ◽  
Rebecca G Martin
Keyword(s):  
Numerical Simulations ◽  
Semimajor Axis ◽  
Quantitative Agreement ◽  
Eccentric Orbit ◽  
Secular Dynamics ◽  
Evolutionary Changes ◽  
Planetary Orbits ◽  
Monotonically Decreasing Function ◽  
Formation And Evolution ◽  
Analytic Models

ABSTRACT We investigate the dynamics of a non-zero mass, circular orbit planet around an eccentric orbit binary for various values of the binary eccentricity, binary mass fraction, planet mass, and planet semimajor axis by means of numerical simulations. Previous studies investigated the secular dynamics mainly by approximate analytic methods. In the stationary inclination state, the planet and binary precess together with no change in relative tilt. For both prograde and retrograde planetary orbits, we explore the conditions for planetary orbital libration versus circulation and the conditions for stationary inclination. As was predicted by analytic models, for sufficiently high initial inclination, a prograde planet’s orbit librates about the stationary tilted state. For a fixed binary eccentricity, the stationary angle is a monotonically decreasing function of the ratio of the planet-to-binary angular momentum j. The larger j, the stronger the evolutionary changes in the binary eccentricity and inclination. We also calculate the critical tilt angle that separates the circulating from the librating orbits for both prograde and retrograde planet orbits. The properties of the librating orbits and stationary angles are quite different for prograde versus retrograde orbits. The results of the numerical simulations are in very good quantitative agreement with the analytic models. Our results have implications for circumbinary planet formation and evolution.

The morphology and ultrastructure of pollen grains of Scutasporites nanuki Utting (Sashiniaceae, Coniferales) from the Permian of the East-European Platform

Palaeobotany ◽  
2012 ◽  
Vol 3 ◽  
pp. 5-11
Author(s):  
A. V. Gomankov ◽  
V. F. Tarasevich
Keyword(s):  
East European Platform ◽  
Central Body ◽  
Pollen Grains ◽  
Irregular Shape ◽  
East European ◽  
Sem And Tem

Dispersed bisaccate pollen grains of Scutasporites nanuki were studied by means of LM, SEM and TEM. Sacci ultrastructure of these pollen grains was rather peculiar. Sacci were like a thin fi lmy fringe attached to the central body near the equator. They were fi lled with sporopollenin elements of irregular shape and various dimensions with equally various cavities between them. Such an ultrastructure is called as spongy. The morphology and ultrastructure of S. nanuki is discussed in the context of the evolution of early conifers.

Plasma-Sheath-Surface Dynamics

1990 ◽  
Author(s):  
Charles K. Birdsall
Keyword(s):  
Plasma Sheath ◽  
Surface Dynamics
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