共查询到20条相似文献，搜索用时 562 毫秒
1.
F. M. F. El-Sabaa 《Astrophysics and Space Science》1992,193(2):309-315
The equation of motion of a rigid body in the Kovalevskaya case is reduced to a plane motion. By using the method of small parameters introduced by Poincaré the existence of a periodic solution is established. 相似文献
2.
N. D. Caranicolas 《Journal of Astrophysics and Astronomy》2001,22(4):309-319
We present a map for the study of resonant motion in a potential made up of two harmonic oscillators with quartic perturbing
terms. This potential can be considered to describe motion in the central parts of non-rotating elliptical galaxies. The map
is based on the averaged Hamiltonian. Adding on a semi-empirical basis suitable terms in the unperturbed averaged Hamiltonian,
corresponding to the 1:1 resonant case, we are able to construct a map describing motion in several resonant cases. The map
is used in order to find thex − p
x
Poincare phase plane for each resonance. Comparing the results of the map, with those obtained by numerical integration of
the equation of motion, we observe, that the map describes satisfactorily the broad features of orbits in all studied cases
for regular motion. There are cases where the map describes satisfactorily the properties of the chaotic orbits as well. 相似文献
3.
Radu Balan 《Celestial Mechanics and Dynamical Astronomy》1995,63(1):59-79
The purpose of this paper is to study the motion of a spinless axisymmetric rigid body in a Newtonian field when we suppose the motion of the center of mass of the rigid body is on a Keplerian orbit. In this case the system can be reduced to a Hamiltonian system with configuration space of a two-dimensional sphere. We prove that the restricted planar motion is analytical nonintegrable and we find horseshoes due to the eccentricity of the orbit. In the caseI
3/I
1>4/3, we prove that the system on the sphere is also analytical nonintegrable.On leave from the Polytechnic Institute of Bucharest, Romania. 相似文献
4.
5.
Bin Luo Shuang-Nan Zhang Physics Department Center for Astrophysics Tsinghua University Beijing Institute of High Energy Physics Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2004,4(3):275-278
In normal one-temperature plasma the motion of ions is usually ne-glected when calculating the Bremsstrahlung radiation of the plasma. We calculatethe Bremsstrahlung radiation of a two-temperature plasma by taking into accountof the motion of ions. Our results show that the total radiation power is alwayslower if the motion of ions is considered. We also apply the two-temperatureBremsstrahlung radiation mechanism for an analytical Advection-Dominated Ac-cretion Flow (ADAF) model; we find the two-temperature correction to the totalBremsstrahlung radiation for ADAF is negligible. 相似文献
6.
Srinivas N. Mohan Ph.D. Candidate Dept. of Aeronautics Astronautics John V. Lange Benjamin O. Lange 《Celestial Mechanics and Dynamical Astronomy》1972,5(2):157-173
Interaction between orbital motion and attitude libration dynamics of an arbitrary rigid body moving in a central Newtonian field is considered to second order. Advantage is taken of the decoupling between inplane-pitch and roll-yaw out-of-plane motion to restrict the motion to the orbital plane by an appropriate choice ofinitial conditions. An averaged solution to the nonlinear inplane-pitch equations whose accuracy is determined by ignoring terms of order {·G32/a
2, 2,2,G32/a
2} and higher is presented. The results show that the near-resonant motion is characterized by a periodic interchange of energy between the attitude and orbital motion.Associate Professor, Department of Aeronautics and Astronautics. 相似文献
7.
F. M. El-Sabaa 《Celestial Mechanics and Dynamical Astronomy》1983,29(3):249-253
Equations of motion of a heavy rigid body about a fixed point in the Kowalevskaya's case are reduced to those of the plane motion of a particle under the action of potential force. In the new form of equations of motion, elliptic coordinates λ, μ are used, and motion has taken the Hamilton-Jacobi form. 相似文献
8.
Roland Sergysels 《Celestial Mechanics and Dynamical Astronomy》1988,44(1-2):155-166
As is well known, the orbital and rotational motions of a solid are coupled, and the integrals of energy and angular momentum (in a gravitational field with spherical symmetry) impose restrictions on them. We study the regions allowed to the motion in configurational space. It turns out that even in the crudest model (planar motion of a triple rod) the restrictions on the libration angle and the orbital radius of the center of mass are coupled, so that excessive ellipticity of the orbit excludes stabilization in the neighbourhood of the spoke equilibrium position by gravitational forces only.Chargé de Cours. 相似文献
9.
V. G. Demin Y. G. Markov I. S. Minyaev 《Celestial Mechanics and Dynamical Astronomy》1990,50(3):231-249
In the restricted three-body problem we consider the motion of a viscously elastic sphere (planet) with its centre of mass moving in a conditionally-periodic orbit. The approximate equations describing the rotational motion of the sphere in terms of the Andoyer variables are obtained by the method of the separation of motion and averaging; the evolution of the motion is also analysed. 相似文献
10.
Harold Willis Milnes 《Celestial Mechanics and Dynamical Astronomy》1973,7(3):295-300
An exact, closed-form solution of the problem of the motion of a satellite in the equatorial plane of an oblate body is obtained. It is shown that the classic formula for the motion of the perihelion is a first order approximation to the exact formula. 相似文献
11.
Paule Kustaanheimo 《Celestial Mechanics and Dynamical Astronomy》1972,6(1):52-59
The ordinary spinor differential Equation (20) of the unperturbed Kepler motion is obtained from the classical equation of motion (19) if one uses the spinor regularization (9) and postulates an essential subsidiary condition (10). A natural generalization for the Kepler motion follows by dropping this subsidiary conditions; it is the 8-parameter set of solutions of the spinor equation of motion (20). The sixteen natural extensive integrals (30)–(35) for this generalized Kepler motion are here deduced by means of the relativistic motors (2), (7) of the Spinor Ring Algebra. These integrals form, with respect to the Poisson bracket operation, a 15-dimensional Lie algebra (40)–(44), closely related to the Lie algebras in quantum mechanics.Dedicated to Professor G. Järnefelt on his 70th anniversary. 相似文献
12.
John E. Cochran 《Celestial Mechanics and Dynamical Astronomy》1972,6(2):127-150
A method of general perturbations, based on the use of Lie series to generate approximate canonical transformations, is applied to study the effects of gravity-gradient torque on the rotational motion of a triaxial, rigid satellite. The center of mass of the satellite is constrained to move in an elliptic orbit about an attracting point mass. The orbit, which has a constant inclination, is free to precess and spin. The method of general perturbations is used to obtain the Hamiltonian for the nonresonant secular and long-period rotational motion of the satellite to second order inn/0, wheren is the orbital mean motion of the center of mass and0 is a reference value of the magnitude of the satellite's rotational angular velocity. The differential equations derivable from the transformed Hamiltonian are integrable and the solution for the long-term motion may be expressed in terms of Jacobian elliptic functions and elliptic integrals. Geometrical aspects of the long-term rotational motion are discussed and a comparison of theoretical results with observations is made. 相似文献
13.
TRACE observations from 13 June 1998 in 171 and 195 Å wavelengths show a propagating disturbance, initiated near the origin of a C-class flare. The wave moves through and disrupts diffuse, overarching coronal loops. Only these overlying structures are affected by the wave; lower-lying coronal structures are unperturbed. The front does not appear in contemporaneous Lyman-α observations. The disturbance creates two types of displacement: (1) that of the wave front itself, and (2) those of large anchored magnetic structures, which `bob' due to the wave and show transverse velocities an order of magnitude smaller than those of the front. Comparisons between the 171 and 195 Å data show that the front appears differently at different temperatures. Observations in 171 Å (approx. 0.95 MK) show strong displacement of individual magnetic structures, while 195 Å (approx. 1.4 MK) data reveals a strong wave front and associated dimming but resolve much less structural motion. There is also strong evidence of heating in the material engulfed by the wave front, and comparisons of the 171 and 195 Å data allow us to constrain the temperature of the plasma through which the wave is propagating to 1–1.4 MK. Examination of the trajectories and velocities of points along the front suggests that the disturbance is Alfvénic in nature but contains a compressive component. This is best explained by a fast-mode magnetoacoustic wave. A comparison of the motion of anchored structures to that of the wave front gives a constraint on pulse width. Comparisons with contemporaneous SOHO-EIT full-disk 195 Å data show evidence that the disturbance is contained within a set of transequatorial field lines, such that it propagates from a southern active region to a northern one with no extensive motion to the east or west. The associated transequatorial loops display residual motion for about a hour after they are initially disturbed. These results, coupled with the deflection of wave trajectories, lead us to speculate on field strength differences between the transequatorial loops and the region in the TRACE field of view. 相似文献
14.
N. D. Caranicolas 《Astrophysics and Space Science》1996,246(1):15-28
We use a composite galaxy model consisting of a disk-halo, bulge, nucleus and dark-halo components in order to investigate the motion of stars in ther-z plane. It is observed that high angular momentum stars move in regular orbits. The majority of orbits are box orbits. There are also banana-like orbits. For a given value of energy, only a fraction of the low angular momentum stars — those going near the nucleus — show chaotic motion while the rest move in regular orbits. Again one observes the above two kinds of orbits. In addition to the above one can also see orbits with the characteristics of the 2/3 and 3/4 resonance. It is also shown that, in the absence of the bulge component, the area of chaotic motion in the surface of section increases, significantly. This suggests that a larger number of low angular momentum stars are in chaotic orbits in galaxies with massive nuclei and no bulge components. 相似文献
15.
V. A. Shefer 《Solar System Research》2005,39(3):239-246
The motion of minor Solar System bodies having close encounters with major planets is described using the model of motion within the framework of the perturbed restricted three-body problem. The actual motion of a minor body is represented as a combination of two motions, namely, the motion of a fictitious attracting center with a variable mass and the motion with respect to the fictitious center. The position and mass of the fictitious center are chosen so that, when the minor body collides with any of the primaries, the fictitious center carries into the center of inertia of the colliding body and the mass of the fictitious center becomes identical to the mass of this body. The regularizing KS-transformation and Sundman’s time transformation were applied to coordinates and velocities. As a result, a system of differential equations of motion that are quasilinear within the nearest vicinity of each of the primary attracting bodies was obtained. These equations are characterized by a numerical behavior during the encounters of the minor body with the primaries that is essentially better than that of the initial equations of motion. The motion of comets Brooks 2 and Gehrels 3, which have fairly close encounters with Jupiter, is simulated.__________Translated from Astronomicheskii Vestnik, Vol. 39, No. 3, 2005, pp. 272–280.Original Russian Text Copyright © 2005 by Shefer. 相似文献
16.
H. J. Sperling 《Celestial Mechanics and Dynamical Astronomy》1969,1(2):213-221
It is shown that, in the neighborhood of a collision singularity, the motion in a perturbed two-body problem \(\ddot r = - \mu r^{ - 3} r + P\) , whereP remains bounded, has the same basic properties as the motion in the neighborhood of a collision in the unperturbed two-body problemP=0. 相似文献
17.
T. G. Vozmischeva 《Celestial Mechanics and Dynamical Astronomy》2000,77(1):37-48
The generalization of a test particle motion in a central field of two immovable point-like centers to the case of a constant
curvature space, on a three-dimensional sphere, is investigated in the paper. The bifurcation set in the plane of integrals
of motion is constructed and the classification of the domains of possible motion is carried out on a two-dimensional sphere.
The regularization of the Kepler’s problem on a two-dimensional sphere is carried out.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
18.
Fathi Namouni 《Monthly notices of the Royal Astronomical Society》2010,401(1):319-332
Dynamical friction arises from the interaction of a perturber and the gravitational wake it excites in the ambient medium. This interaction is usually derived assuming that the perturber has a constant velocity. In realistic situations, motion is accelerated as for instance by dynamical friction itself. Here, we study the effect of acceleration on the dynamical friction force. We characterize the density enhancement associated with a constantly accelerating perturber with rectilinear motion in an infinite homogeneous gaseous medium and show that dynamical friction is not a local force and that its amplitude may depend on the perturber's initial velocity. The force on an accelerating perturber is maximal between Mach 1 and Mach 2, where it is smaller than the corresponding uniform motion friction. In the limit where the perturber's size is much smaller than the distance needed to change the Mach number by unity through acceleration, a subsonic perturber feels a force similar to uniform motion friction only if its past history does not include supersonic episodes. Once an accelerating perturber reaches large supersonic speeds, accelerated motion friction is marginally stronger than uniform motion friction. The force on a decelerating supersonic perturber is weaker than uniform motion friction as the velocity decreases to a few times the sound speed. Dynamical friction on a decelerating subsonic perturber with an initial Mach number larger than 2 is much larger than uniform motion friction and tends to a finite value as the velocity vanishes in contrast to uniform motion friction. 相似文献
19.
S. A. Gasanov 《Astronomy Letters》2001,27(2):124-133
The plane motion of a mass point inside an inhomogeneous rotating ellipsoidal body with a homothetic density distribution is considered. The force function of the problem is expanded in terms of the ellipsoid's second eccentricities up to the fourth order, which are taken as small parameters. We derive an expression for the perturbing function and solve the equations of perturbed motion in orbital elements. 相似文献
20.
R. S. Sengar 《Astrophysics and Space Science》1983,89(2):285-291
A discussion of gravitational instability of a finitely conducting medium with streams of variable velocity distribution is made in the presence of a uniform magnetic field. It is found that the variable streaming motion shows a destabilizing effect and affects the instability criterion only in the case of general wave propagation. For purely parallel propagation to the direction of the magnetic field and the streaming motion, the criterion is independent of the variation in the streaming motion and further the Jeans's criterion is found to remain unaffected in this case. For purely transverse propagation, the criterion is independent of any streaming motion and the Jeans's criterion remains unaffected. The criterion is further independent of the magnetic field and the finite conductivity except in the case of transverse propagation where the magnetic field exhibits a stabilizing influence in case of an infinitely conducting medium. 相似文献