scholarly journals Stellar Dynamics of Needles

1987 ◽  
Vol 127 ◽  
pp. 493-494
Author(s):  
Scott Tremaine ◽  
Tim de Zeeuw
Keyword(s):  
Distribution Function ◽  
Stellar Dynamics ◽  
Stellar Systems ◽  
One Dimensional ◽  
Density Distributions ◽  
Universal Distribution ◽  
Self Consistent ◽  
Triaxial Stellar Systems ◽  
Limiting Case

One dimensional “needles” are a limiting case of general triaxial stellar systems. Self-consistent, finite needles can have arbitrary longitudinal density distributions but have a fixed, universal distribution function. All needles are stable to all longitudinal perturbations but neutral to transverse perturbations.

scholarly journals 3D gas dynamics in triaxial systems

1993 ◽  
Vol 153 ◽  
pp. 273-274
Author(s):  
D. Friedli ◽  
S. Udry
Keyword(s):  
Gas Dynamics ◽  
Elliptical Galaxies ◽  
Stellar Systems ◽  
Gas Temperature ◽  
3D Simulations ◽  
Hot Gas ◽  
Chaotic Orbits ◽  
Self Consistent ◽  
Triaxial Stellar Systems ◽  
Pattern Speed

Depending on the nature of the various components (stars, gas) present in triaxial stellar systems (elliptical galaxies, bulges and bars), the dynamics is expected to be rather different. The stars are collisionless, dissipationless, and dynamically hot; they are mainly trapped by quasi-periodic or chaotic orbits. On the contrary, the gas is collisional, dissipational, and dynamically cold; the cold or warm gas (≲ 104 K) is a powerful orbital tracer, however shocks prevent it from following self-crossing orbits. The hot gas (≲ 106 K) is influenced by “repulsive” pressure forces which prevent in close encounters the flow from being strongly shocked; it rather follows chaotic trajectories. By means of fully self-consistent 3D simulations with stars and gas using PM (Pfenniger & Friedli 1992) and SPH (Friedli & Benz 1992) techniques, we investigate the response of gaseous components in the following situations: 1) slow or fast pattern speed Ωp, 2) direct or retrograde gas motion with respect to the stars, and 3) warm or hot gas temperature T. Initial parameters and final characteristics of each runs are reported in Table I.

scholarly journals Integration Methods where Force is Obtained from the Smoothed Gravitational Field

1971 ◽  
Vol 10 ◽  
pp. 168-178
Author(s):  
Frank Hohl
Keyword(s):  
Gravitational Field ◽  
Body Problem ◽  
Stellar Dynamics ◽  
Coulomb Force ◽  
Stellar Systems ◽  
Inhomogeneous Systems ◽  
Consistent Field ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Simultaneous Influence

Many problems in stellar dynamics involve phenomena occurring in inhomogeneous systems in which the interaction between the particles is fully described by a self-consistent field operating in phase space. Because the particles interact by means of the long-range Coulomb force, each particle is under the simultaneous influence of a large number of other particles. Therefore, stellar systems will respond to any perturbation in a collective manner, and a study of such systems is concerned essentially with the N-body problem.

Orbital structure of self-consistent triaxial stellar systems

2007 ◽  
Vol 99 (4) ◽  
pp. 307-324 ◽  
Author(s):  
Roberto O. Aquilano ◽  
Juan C. Muzzio ◽  
Hugo D. Navone ◽  
Alejandra F. Zorzi
Keyword(s):  
Stellar Systems ◽  
Orbital Structure ◽  
Self Consistent ◽  
Triaxial Stellar Systems

scholarly journals New Phenomena in Triaxial Stellar Systems

1983 ◽  
Vol 100 ◽  
pp. 293-294
Author(s):  
P. Magnenat ◽  
L. Martinet
Keyword(s):  
Dynamical Systems ◽  
Degrees Of Freedom ◽  
Stellar Dynamics ◽  
Stellar Systems ◽  
Numerical Investigations ◽  
Triaxial Stellar Systems ◽  
New Phenomena ◽  
Three Degrees Of Freedom

For a number of years the Geneva Observatory stellar dynamics group has undertaken numerical investigations of stellar orbital behaviour in conservative dynamical systems with three degrees of freedom. Compared to results for 3-D axisymmetrical models (2 degrees of freedom), this work displayed the advent of several new phenomena which may appear in rotating or non-rotating stellar systems with three unequal axes (ellipticals, bulges, bars). Some of these phenomena deserve particular attention.

scholarly journals Two-component galaxy models with a central BH – II. The ellipsoidal case

2020 ◽  
Vol 500 (1) ◽  
pp. 1054-1070
Author(s):  
Luca Ciotti ◽  
Antonio Mancino ◽  
Silvia Pellegrini ◽  
Azadeh Ziaee Lorzad
Keyword(s):  
Dark Matter ◽  
Stellar Dynamics ◽  
Azimuthal Velocity ◽  
Dark Matter Halo ◽  
Gas Flows ◽  
Total Density ◽  
Density Distributions ◽  
Stellar Component ◽  
Two Component ◽  
Analytical Formulae

ABSTRACT Recently, two-component spherical galaxy models have been presented, where the stellar profile is described by a Jaffe law, and the total density by another Jaffe law, or by an r−3 law at large radii. We extend these two families to their ellipsoidal axisymmetric counterparts: the JJe and J3e models. The total and stellar density distributions can have different flattenings and scale lengths, and the dark matter halo is defined by difference. First, the analytical conditions required to have a nowhere negative dark matter halo density are derived. The Jeans equations for the stellar component are then solved analytically, in the limit of small flattenings, also in the presence of a central BH. The azimuthal velocity dispersion anisotropy is described by the Satoh k-decomposition. Finally, we present the analytical formulae for velocity fields near the centre and at large radii, together with the various terms entering the virial theorem. The JJe and J3e models can be useful in a number of theoretical applications, e.g. to explore the role of the various parameters (flattening, relative scale lengths, mass ratios, rotational support) in determining the behaviour of the stellar kinematical fields before performing more time-expensive integrations with specific galaxy models, to test codes of stellar dynamics and in numerical simulations of gas flows in galaxies.

scholarly journals RuSseL: A Self-Consistent Field Theory Code for Inhomogeneous Polymer Interphases

Computation ◽  
2021 ◽  
Vol 9 (5) ◽  
pp. 57
Author(s):  
Constantinos J. Revelas ◽  
Aristotelis P. Sgouros ◽  
Apostolos T. Lakkas ◽  
Doros N. Theodorou
Keyword(s):  
Field Theory ◽  
Polymer Melt ◽  
Polymer Chains ◽  
Solid Polymer ◽  
One Dimensional ◽  
Consistent Field ◽  
Adsorbed Polymer ◽  
Self Consistent ◽  
Self Consistent Field ◽  
Self Consistent Field Theory

In this article, we publish the one-dimensional version of our in-house code, RuSseL, which has been developed to address polymeric interfaces through Self-Consistent Field calculations. RuSseL can be used for a wide variety of systems in planar and spherical geometries, such as free films, cavities, adsorbed polymer films, polymer-grafted surfaces, and nanoparticles in melt and vacuum phases. The code includes a wide variety of functional potentials for the description of solid–polymer interactions, allowing the user to tune the density profiles and the degree of wetting by the polymer melt. Based on the solution of the Edwards diffusion equation, the equilibrium structural properties and thermodynamics of polymer melts in contact with solid or gas surfaces can be described. We have extended the formulation of Schmid to investigate systems comprising polymer chains, which are chemically grafted on the solid surfaces. We present important details concerning the iterative scheme required to equilibrate the self-consistent field and provide a thorough description of the code. This article will serve as a technical reference for our works addressing one-dimensional polymer interphases with Self-Consistent Field theory. It has been prepared as a guide to anyone who wishes to reproduce our calculations. To this end, we discuss the current possibilities of the code, its performance, and some thoughts for future extensions.

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