Evolution of collisional systems

1984 ◽  
Vol 75 ◽  
pp. 361-362
Author(s):  
André Brahic
Keyword(s):  
Gravitational Field ◽  
Dynamical Evolution ◽  
Oblate Planet

AbstractThe dynamical evolution of planetary discs in the gravitational field of an oblate planet and a satellite is numerically simulated.

scholarly journals Einstein-aether theory in Weyl integrable geometry

2020 ◽  
Vol 80 (12) ◽  
Author(s):  
Andronikos Paliathanasis ◽  
Genly Leon ◽  
John D. Barrow
Keyword(s):  
Gravitational Field ◽  
Field Equation ◽  
Scalar Field ◽  
Field Model ◽  
Affine Connection ◽  
Dynamical Evolution ◽  
Field Equations ◽  
Gravitational Field Equation ◽  
Gravitational Field Equations ◽  
Geometric Origin

AbstractWe study the Einstein-aether theory in Weyl integrable geometry. The scalar field which defines the Weyl affine connection is introduced in the gravitational field equation. We end up with an Einstein-aether scalar field model where the interaction between the scalar field and the aether field has a geometric origin. The scalar field plays a significant role in the evolution of the gravitational field equations. We focus our study on the case of homogeneous and isotropic background spacetimes and study their dynamical evolution for various cosmological models.

Destruction of Globular Clusters in the Galactic Gravitational Field

2015 ◽  
Vol 24 (2) ◽  
Author(s):  
M. V. Ryabova ◽  
Yu. A. Shchekinov
Keyword(s):  
Numerical Simulation ◽  
Gravitational Field ◽  
Globular Clusters ◽  
Dynamical Evolution ◽  
Analytical Description ◽  
Simple Estimate ◽  
The Galaxy

AbstractWe present some results of numerical simulation of a dynamical evolution of globular clusters in the tidal field of the Galaxy. An analytical description of tidal destruction of such clusters and simple estimate of their lifetimes are proposed.

scholarly journals Cluster Swapping

1988 ◽  
Vol 126 ◽  
pp. 297-309
Author(s):  
Juan C. Muzzio
Keyword(s):  
Gravitational Field ◽  
Numerical Simulations ◽  
Globular Cluster ◽  
Total Mass ◽  
Dynamical Evolution ◽  
Clusters Of Galaxies ◽  
Missing Mass ◽  
Mass Problem ◽  
Test Particles ◽  
The Galaxy

The investigation of globular cluster swapping in clusters of galaxies has resulted in some interesting theoretical findings and, at the same time, it offers a promising field for observers. Numerical simulations of galaxy clusters where the galaxies have swarms of test particles around them showed that, in addition to tidal stripping, tidal accretion plays an important role in the dynamical evolution of clusters of galaxies; it also turns out that, even in clusters where the gravitational field is dominated by a massive background, the galaxy-galaxy attraction cannot be ignored when estimating the outcome of collisions. Cluster swapping is just an example of tidal accretion and, taking the globulars as probes of halo material, it might offer an opportunity to observe some consequences of that effect; besides, although the difficulties look formidable at present, the study of globulars lost through tidal stripping is a possibility that should not be neglected. Tidal stripping and accretion processes are very sensitive to the ratio of galactic mass to total mass, so that observations related to the cluster swapping phenomena may provide a new means to investigate the missing mass problem.

Size distribution in collisional systems distribution de tailles dans les systemes collisionnels

1984 ◽  
Vol 75 ◽  
pp. 397-402 ◽  
Author(s):  
S. Clairemidi
Keyword(s):  
Gravitational Field ◽  
Size Distribution ◽  
Central Body ◽  
Three Dimensional ◽  
Dynamical Evolution ◽  
Inelastic Collisions ◽  
Dimensional System ◽  
Planetary Rings ◽  
System Of Particles ◽  
Three Dimensional System

ABSTRACTThe dynamical evolution of a three dimensional system of particles of different masses and sizes, orbiting in the gravitational field of a central body, and interacting through inelastic collisions is studied here. Recent fly-bys of planetary rings and observations of flat galaxies with modern receptors indicate that a number of structures discovered in collisional systems can be understood only of three ingredients are included in the models, namely interparticles collisions , distributions of particles sizes and self attraction of the particles.

scholarly journals Characteristic radii of the Milky Way globular clusters

2019 ◽  
Vol 489 (3) ◽  
pp. 4367-4377 ◽  
Author(s):  
Andrés E Piatti ◽  
Jeremy J Webb ◽  
Raymond G Carlberg
Keyword(s):  
Gravitational Field ◽  
Globular Clusters ◽  
Milky Way ◽  
Structural Parameters ◽  
Large Fraction ◽  
Dynamical Evolution ◽  
Initial Mass ◽  
Galactocentric Distance ◽  
Data Set ◽  
Tidal Forces

ABSTRACT We report on the extent of the effects of the Milky Way gravitational field in shaping the structural parameters and internal dynamics of its globular cluster population. We make use of a homogeneous, up-to-date data set with kinematics, structural properties, current and initial masses of 156 globular clusters. In general, cluster radii increase as the Milky Way potential weakens; with the core and Jacobi radii being those which increase at the slowest and fastest rate, respectively. We interpret this result as the innermost regions of globular clusters being less sensitive to changes in the tidal forces with the Galactocentric distance. The Milky Way gravitational field also seems to have differentially accelerated the internal dynamical evolution of individual clusters, with those toward the bulge appearing dynamically older. Finally, we find a subpopulation consisting of both compact and extended globular clusters (as defined by their rh/rJ ratio) beyond 8 kpc that appear to have lost a large fraction of their initial mass lost via disruption. Moreover, we identify a third group with rh/rJ > 0.4, which have lost an even larger fraction of their initial mass by disruption. In both cases the high fraction of mass lost is likely due to their large orbital eccentricities and inclination angles, which lead to them experiencing more tidal shocks at perigalacticon and during disc crossings. Comparing the structural and orbital parameters of individual clusters allows for constraints to be placed on whether or not their evolution was relaxation or tidally dominated.

A one-dimensional self-gravitating stellar gas

1966 ◽  
Vol 25 ◽  
pp. 46-48 ◽  
Author(s):  
M. Lecar
Keyword(s):  
Gravitational Field ◽  
Phase Space ◽  
Motion Picture ◽  
Space Distribution ◽  
Two Dimensional ◽  
One Dimensional ◽  
Phase Space Distribution ◽  
Dimensional Phase Space ◽  
The Mean

“Dynamical mixing”, i.e. relaxation of a stellar phase space distribution through interaction with the mean gravitational field, is numerically investigated for a one-dimensional self-gravitating stellar gas. Qualitative results are presented in the form of a motion picture of the flow of phase points (representing homogeneous slabs of stars) in two-dimensional phase space.

Statistical results on discovered near-Earth asteroids

1999 ◽  
Vol 173 ◽  
pp. 81-86
Author(s):  
S. Berinde
Keyword(s):  
Dynamical Evolution ◽  
Minor Planet ◽  
Orbital Elements ◽  
The Earth ◽  
Near Earth Asteroids ◽  
Statistical Results

AbstractThe first part of this paper gives a recent overview (until July 1st, 1998) of the Near-Earth Asteroids (NEAs) database stored at Minor Planet Center. Some statistical interpretations point out strong observational biases in the population of discovered NEAs, due to the preferential discoveries, depending on the objects’ distances and sizes. It is known that many newly discovered NEAs have no accurately determinated orbits because of the lack of observations. Consequently, it is hard to speak about future encounters and collisions with the Earth in terms of mutual distances between bodies. Because the dynamical evolution of asteroids’ orbits is less sensitive to the improvement of their orbital elements, we introduced a new subclass of NEAs named Earth-encounter asteroids in order to describe more reliably the potentially dangerous bodies as impactors with the Earth. So, we pay attention at those asteroids having an encounter between their orbits and that of the Earth within 100 years, trying to classify these encounters.

From the Oort cloud to Halley-type comets

1999 ◽  
Vol 173 ◽  
pp. 327-338 ◽  
Author(s):  
J.A. Fernández ◽  
T. Gallardo
Keyword(s):  
Total Population ◽  
Complex Function ◽  
Dynamical Evolution ◽  
Oort Cloud ◽  
Capture Process ◽  
Influx Rate ◽  
Short Period ◽  
Dynamical Properties ◽  
Orbital Periods ◽  
Probability Of Capture

AbstractThe Oort cloud probably is the source of Halley-type (HT) comets and perhaps of some Jupiter-family (JF) comets. The process of capture of Oort cloud comets into HT comets by planetary perturbations and its efficiency are very important problems in comet ary dynamics. A small fraction of comets coming from the Oort cloud − of about 10−2− are found to become HT comets (orbital periods < 200 yr). The steady-state population of HT comets is a complex function of the influx rate of new comets, the probability of capture and their physical lifetimes. From the discovery rate of active HT comets, their total population can be estimated to be of a few hundreds for perihelion distancesq <2 AU. Randomly-oriented LP comets captured into short-period orbits (orbital periods < 20 yr) show dynamical properties that do not match the observed properties of JF comets, in particular the distribution of their orbital inclinations, so Oort cloud comets can be ruled out as a suitable source for most JF comets. The scope of this presentation is to review the capture process of new comets into HT and short-period orbits, including the possibility that some of them may become sungrazers during their dynamical evolution.

Exploring Coronal Structures with SOHO

2000 ◽  
Vol 179 ◽  
pp. 403-406
Author(s):  
M. Karovska ◽  
B. Wood ◽  
J. Chen ◽  
J. Cook ◽  
R. Howard
Keyword(s):  
Solar Corona ◽  
Image Enhancement ◽  
Coronal Mass Ejections ◽  
Dynamical Evolution ◽  
Small Scale ◽  
Low Contrast ◽  
Contrast Structures ◽  
Scale Structures ◽  
Small Scale Structures ◽  
Coronal Structures

AbstractWe applied advanced image enhancement techniques to explore in detail the characteristics of the small-scale structures and/or the low contrast structures in several Coronal Mass Ejections (CMEs) observed by SOHO. We highlight here the results from our studies of the morphology and dynamical evolution of CME structures in the solar corona using two instruments on board SOHO: LASCO and EIT.

The Jovian ring

1984 ◽  
Vol 75 ◽  
pp. 203-209
Author(s):  
Joseph A. Burns
Keyword(s):  
Equatorial Plane ◽  
Charged Particles ◽  
Dynamical Evolution ◽  
Main Band ◽  
Small Grains ◽  
Three Components

ABSTRACTLying in Jupiter's equatorial plane is a diaphanous ring having little substructure within its three components (main band, faint disk, and halo). Micron-sized grains account for much of the visible ring, but particles of centimeter sizes and larger must also be present to absorb charged particles. Since dynamical evolution times and survival life times are quite short (≲102-3yr) for small grains, the Jovian ring is being continually replenished; probably most of the visible ring is generated by micrometeoroids colliding into unseen parent bodies that reside in the main band.

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