共查询到20条相似文献，搜索用时 31 毫秒
1.
V. I. Ferronsky S. A. Denisik S. V. Ferronsky 《Celestial Mechanics and Dynamical Astronomy》1982,27(3):285-304
A general approach to the solution of the perturbed oscillation problem for celestial bodies is considered. The solution sought describes unperturbed virial oscillations (zero approximation) affected by external perturbing effects. In the general case, these perturbations can be expressed by an arbitrary given function of time, Jacobi's function and its first derivative. Standard methods and modes of perturbation theory are used for solution of the problem.It is shown that while studying the evolution of a celestial body as a dissipative system in the framework of perturbed virial oscillations, the analytical expression for perturbing function can be derived, assuming the celestial body to be an oscillating electrical dipole emitting electromagnetic energy.The general covariant form of Jacobi's equation is derived and its spur is examined. It is shown that the scalar form of Jacobi's equation appears to be more universal than Newton's laws of motion from which it is derived. 相似文献
2.
V. I. Ferronsky S. A. Denisik S. V. Ferronsky 《Celestial Mechanics and Dynamical Astronomy》1985,35(1):23-43
It is shown that with a virial approach to the solution of the many-body problem the integral characteristics of a system (Jacobi's function and total energy), being present in Jacobi's equation, are immanent to its own integrals. Estimating the Lyapunov stability of motion of a system they play the role of Lyapunov functions.Studying Lyapunov stability of the virial oscillations of celestial bodies we used the Duboshin criterion applicable when permanent perturbations are present. In the case of conservative systems the potential energy of the system plays the role of such a perturbation. Thus, the nature of the virial oscillations can be understood as an effect of non-linear resonance between the kinetic and the potential energies.It is shown that the stability of virial oscillations of conservative systems relative to variations of the form-factors product is only a necessary condition in the proof of the hypothesis that =const. for celestial bodies. The sufficient condition for the proof of this equality consists of the given direct derivation of the equation of virial oscillations of celestial bodies from Einstein's equation, as well as of the equivalence of Schwarzschild's solution and the solution of Jacobi's equation at
.The stability of virial oscillations for dissipative systems is studied. It is shown that the stability is limited by the period of time of its bifurcation. 相似文献
3.
V. I. Ferronsky S. A. Denisik S. V. Ferronsky 《Celestial Mechanics and Dynamical Astronomy》1978,18(2):113-140
A relationship between the potential energy and the moment of the inertia for celestial bodies is heuristically discovered. This relationship consists in the constancy of the product of formfactors for the potential energy and the moment of the inertia. The product is independent of the body mass and its radial mass distribution.We find the exact solution of Jacobi's virial equation for a gravitating spherical body based on the relationship obtained. This solution represents the unharmonic radial oscillations of the body. The solution is valid for a wide class of celestial bodies including variable stars and relativistic objects for which a relativistic analog of Jacob's equation is derived.The period of the radial oscillations of the planets is estimated with the help of the solution found. We note the coincidence of the experimental data and our theoretical calculations for the Sun.We show the important role of the Coulomb forces in the formation of the planets. It is demonstrated that the Coulomb forces result in the relation between the planet masses and their average molecular weight. 相似文献
4.
S. V. Ferronsky 《Celestial Mechanics and Dynamical Astronomy》1983,30(1):71-83
New physical principles for an explanation of seasonal variations in the Earth's rate of rotation are proposed. It is thought that the variations are caused by a variation of the total energy of the Earth's atmosphere in the course of the planet's revolution about the Sun in elliptic orbit. Jacobi's virial equation for the Earth's atmosphere is derived from the Eulerian equations. The virial theorem is obtained. The existence of the relationship between Jacobi's function and potential energy of the atmosphere is confirmed. In the framework of this relationship, Jacobi's equation is reduced to the equation of unperturbed virial oscillations. The solution of the above-mentioned equation expresses the periodic virial oscillations of Jacobi's function (moment of inertia) of the Earth's atmosphere with time. The solution of the perturbed virial oscillation problem of the atmosphere-solid Earth system is obtained. The perturbation term in Jacobi's virial equation regards, in explicit form, the energy changes occurring in the atmosphere in the course of the planet's revolution about the Sun in elliptic orbit. The annual and semi-annual periodic variations in the Earth's rate of rotation can be considered as an astrometrical result following from the obtained solution. A satisfactory accord of the theoretical results with experimental data is shown. 相似文献
5.
A stable galaxy, if excited above its ground state, oscillates about that ground state. If it is reasonably robust, it can support oscillations of large amplitude. Normal mode oscillations, with surprisingly large amplitudes, have been seen in numerical experiments. Observational evidence shows that real galaxies also oscillate. Galaxies ring like a bell in the experiments, and ringing continues undamped long after initial transients have died out. Their total kinetic energy oscillates with an amplitude as large as 10% of the mean. A fundamental mode dominates. It is an homologous expansion/contraction of the entire galaxy (no nodes). Inward or outward velocities due to this mode are sufficiently large in the outer reaches of a galaxy to account for kinematic warps in observed velocity fields. A second spherically symmetrical mode has one node and is important near the center of the galaxy. It may be the driving force behind bulges in spiral galaxies. Two other normal modes have been identified as well. This appears to be the first experimental demonstration of normal mode oscillations within stable galaxy models. 相似文献
6.
Analysis of the potential field and equilibrium points of irregular-shaped minor celestial bodies 总被引：4，自引：0，他引：4
The equilibrium points of the gravitational potential field of minor celestial bodies, including asteroids, comets, and irregular satellites of planets, are studied. In order to understand better the orbital dynamics of massless particles moving near celestial minor bodies and their internal structure, both internal and external equilibrium points of the potential field of the body are analyzed. In this paper, the location and stability of the equilibrium points of 23 minor celestial bodies are presented. In addition, the contour plots of the gravitational effective potential of these minor bodies are used to point out the differences between them. Furthermore, stability and topological classifications of equilibrium points are discussed, which clearly illustrate the topological structure near the equilibrium points and help to have an insight into the orbital dynamics around the irregular-shaped minor celestial bodies. The results obtained here show that there is at least one equilibrium point in the potential field of a minor celestial body, and the number of equilibrium points could be one, five, seven, and nine, which are all odd integers. It is found that for some irregular-shaped celestial bodies, there are more than four equilibrium points outside the bodies while for some others there are no external equilibrium points. If a celestial body has one equilibrium point inside the body, this one is more likely linearly stable. 相似文献
7.
V. I. Ferronsky S. A. Denisik S. V. Ferronsky 《Celestial Mechanics and Dynamical Astronomy》1981,23(3):243-267
The Hamiltonian form of Jacobi's virial equation, which permits obtaining solution of the equation while considering both gravitational and Coulomb interactions, is given for the system of the material points constituting a celestial body.On the basis of the numerical solutions, in the framework of the plasma model of a celestial body, it is shown that for the Coulomb interactions of charged particles the product of the form-factors and , entering expressions for the potential energy and the moment of inertia, remains constant.Without any model restrictions this conclusion is confirmed in case of the asymptotic time limit of simultaneous collision of all the charged particles of the system.A relationship between the potential energy of a spherically symmetrical celestial body and its mass through a phenomenological parameter, which is the sound velocity, is found from the consideration of the hydrostatic equilibrium condition of the body, taking the Coulomb interactions into account. 相似文献
8.
The various modes of plasma turbulence waves (including MHD waves) are easily excited under cosmic circumstances. In this paper, if we consider that the celestial bodies rotate, there is a source term generated for the magnetic induced equation by the excited plasma turbulence waves. If we expand the turbulent field in the Fourier series and include rotation velocity, the dynamo equation for turbulent waves is obtained. We have also obtained the solutions of various wave forms corresponding to different rotation velocities and then we significantly discuss the magnetic fields in the Sun, planets, and other celestial bodies. 相似文献
9.
Unrestricted second-order tensor virial equations for linear oscillations of magnetic configurations
M. Goossens 《Astrophysics and Space Science》1979,60(2):401-421
This paper deals with the second-order tensor virial equations for the linear oscillations of a gaseous mass in the presence of a magnetic field. It is shown that the commonly used linearized versions of the tensor virial equations are restricted integral equations that incorporate the linearized equation of motion but not the boundary condition. These restricted equations only allow trial functions that fulfil the boundary condition and are of limited practical value.The unrestricted variational principle for the linear oscillations of a magnetic configuration is used to derive a more general formulation of the second-order tensor virial equations so that the linear trial function i =X
ij
x
j can be used to study the oscillations of a configuration with a magnetic field that extends in the exterior vacuum. The unrestricted virial equations have been applied to Ferraro's model and approximate results for the eigenfrequencies and eigenfunctions have been obtained for nine oscillation modes. 相似文献
10.
L. P. Osipkov 《Astrophysics》2000,43(1):40-44
An analysis of the Lagrange-Jacobi equation for a nonstationary system with a negative total energy enables one to find the
upper limit on the angular momentum of a nonstationary, self-gravitating system undergoing socalled quasi-homologous, virial
oscillations.
Translated from Astrofizika, Vol. 43, No. 1, pp. 55-61, January–March, 2000. 相似文献
11.
(7)Formation of celestial bodies. The basic concepts of the accretional process are discussed, and the inadequacy of the contractional model is pointed out. A comparison is made between the general pre-planetary state on the one hand and the present state in the asteroidal region on the other. A model for accretion of resonance-captured grains leading to the formation of resonance-captured planets and satellites is suggested.(8)Spin and accretion. The relation between the accretional process and the spin of planets is analyzed.(9)Accretion of planets and satellites. It is shown that jet streams are a necessary intermediate stage in the formation of celestial bodies. The time sequence of planet formation is analyzed, and it is shown that the newly accreted bodies have a characteristic internal heat structure; the cases of the Earth and the Moon are considered in detail. A region of high initial temperature is found at 0.4 of the present Earth radius, whereas the culminating temperature of the Moon is near its present surface. An accretional heat wave is found to proceed outwards, and may produce the observed differentiation features. 相似文献
12.
In the three dipole problem we assume each one of the magnetic dipoles to be located on one member of a three celestial bodies system moving in circles according to the equilaterial solution of Lagrange. Using the method of characteristic exponents we study here for first time the stability of planar and three dimensional equilibrium points of charged particles moving under the electromagnetic force of the system. Applying this theoretical procedure we give an extensive numerical investigation for the stability of the equilibria for a lot combinations of the values of the parameters of the electromagnetic field. 相似文献
13.
In the current study, the existence of periodic orbits around a fixed homogeneous cube is investigated, and the results have
powerful implications for examining periodic orbits around non-spherical celestial bodies. In the two different types of symmetry
planes of the fixed cube, periodic orbits are obtained using the method of the Poincaré surface of section. While in general
positions, periodic orbits are found by the homotopy method. The results show that periodic orbits exist extensively in symmetry
planes of the fixed cube, and also exist near asymmetry planes that contain the regular Hex cross section. The stability of
these periodic orbits is determined on the basis of the eigenvalues of the monodromy matrix. This paper proves that the homotopy
method is effective to find periodic orbits in the gravity field of the cube, which provides a new thought of searching for
periodic orbits around non-spherical celestial bodies. The investigation of orbits around the cube could be considered as
the first step of the complicated cases, and helps to understand the dynamics of orbits around bodies with complicated shapes.
The work is an extension of the previous research work about the dynamics of orbits around some simple shaped bodies, including
a straight segment, a circular ring, an annulus disk, and simple planar plates. 相似文献
14.
V. I. Shematovich 《Solar System Research》2018,52(5):371-381
There is an astonishing variety of celestial bodies in the outer regions of the Solar System: Europa, with its bizarre surface features, Enceladus, small but geologically active, Titan, the only moon with a significant atmosphere, Pluto, with its nitrogen glaciers, and many others. Over the past 25 years, measurements from spacecraft have shown that many of these celestial bodies are ocean worlds with large volumes of liquid water trapped under icy surfaces. This new group of celestial bodies, ocean worlds, is important for research for several reasons, but the most convincing and at the same time the simplest reason is that they can be potential habitats. Life, as we know it, requires liquid water in addition to energy, nutrients, and a sustainable environment. All these requirements can be met for some of these celestial bodies. The moons of the giant planets on which the presence of the subsurface ocean is established (Europa, Ganymede, Titan, and Enceladus) and their astrobiological potential are discussed. 相似文献
15.
Golubev Yu. F. Grushevskii A. V. Koryanov V. V. Lavrenov S. M. Tuchin A. G. Tuchin D. A. 《Solar System Research》2020,54(4):318-328
Solar System Research - We consider space expeditions with a long-term spacecraft stay near the studied celestial body (artificial satellites of small bodies of the Solar System), or expeditions... 相似文献
16.
With a new theory on the 1PN celestial mechanics recently developed by Damour, Soffel and Xu (1991,1992,1993,1994), definitions
and expressions of the 1PN spin angular momentum are investigated and analysed. The total spin angular momentum of a system
of extended bodies such as the solar system is calculated and expressed as the function of local parameters and observables
under reasonable assumptions, which would find its application in the evolution and dynamics of systems of celestial bodies.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
17.
Philip Chang 《Monthly notices of the Royal Astronomical Society》2009,393(1):224-228
I examine the effectiveness of Kozai oscillations in the centres of galaxies and in particular the Galactic Centre (GC) using standard techniques from celestial mechanics. In particular, I study the effects of a stellar bulge potential and general relativity on Kozai oscillations, which are induced by stellar discs. Löckmann et al. recently suggested that Kozai oscillations induced by the two young massive stellar discs in the GC drive the orbits of the young stars to large eccentricity ( e ≈ 1) . If some of these young eccentric stars are in binaries, they would be disrupted near pericentre, leaving one star in a tight orbit around the central supermassive black hole and producing the S-star population. I find that the spherical stellar bulge suppresses Kozai oscillations, when its enclosed mass inside a test body is of the order of the mass in the stellar disc(s). Since the stellar bulge in the GC is much larger than the stellar discs, Kozai oscillations due to the stellar discs are likely suppressed. Whether Kozai oscillations are induced from other non-spherical components to the potential (e.g. a flattened stellar bulge) is yet to be determined. 相似文献
18.
The results of photometric and polarimetric observations carried out for some bright atmosphere-less bodies of the Solar system near the zero phase angle reveal the simultaneous existence of two spectacular optical phenomena, the so-called brightness and polarization opposition effects. In a number of studies, these phenomena were explained by the influence of coherent backscattering. However, in general, the interference concept of coherent backscattering can be used only in the case where the particles are in the far-field zones of each other, i.e., when the scattering medium is rather rarefied. Because of this, it is important to prove rigorously and to demonstrate that the coherent backscattering effect may also exist in densely packed scattering media like regolith surface layers of celestial bodies. From the results of the computer modeling performed with the use of numerically exact solutions of the macroscopic Maxwell equations for discrete random media with different packing densities of particles, we studied the origin and evolution of all the opposition phenomena predicted by the coherent backscattering theory for low-packing-density media. It has been shown that the predictions of this theory remain valid for rather high packing densities of particles that are typical, in particular, of regolith surfaces of the Solar system bodies. The results allow us to conclude that both opposition effects observed simultaneously in some high-albedo atmosphereless bodies of the Solar system are caused precisely by coherent backscattering of solar light in the regolith layers composed of microscopic particles. 相似文献
19.
20.
A. S. Shugarov 《Solar System Research》2013,47(4):296-301
The simulation results of zones of visibility of celestial bodies potentially dangerous for a wide-field orbital telescope taking into account the basic parameters of the detector, telescope, and movement of celestial bodies are presented. Visibility zones of 50–300 m of dangerous celestial bodies 7–60 days prior to their possible collision with the Earth are calculated using telescopes with apertures of 0.4, 0.75 (VT-77), and 1.5 m. 相似文献