共查询到20条相似文献，搜索用时 15 毫秒
1.
J. N. Tokis 《Astrophysics and Space Science》1974,31(2):349-362
The aim of the present paper will be to derive an equation of dissipation of energy for a rotating body of arbitrary viscosity distorted by tides, which arise from the gravitational field of its companion in a close pair of such bodies.By a transformation of the fundamental equation of energy dissipation in terms of velocity of tidal deformation (Section 2), the dissipation function is constructed for a tidally-distorted body (Section 3). From this equation, the rate of dissipation of tidal energy is formulated for a nearly-spherical rotating body distorted by second harmonic longitudinal tides (Section 4); the coefficients of viscosity (or the bulk modulus) are treated as arbitrary functions of spatial coordinates. Finally (Section 5), expressions for the total energy dissipation within the orbital cycle are given for axial rotation of the distorted body, provided its angular velocity is constant (for example, with the Keplerian angular velocity).Research financed in part by the Division of Scientific Research and Development of Ministry of Sciences and Culture of Greece. 相似文献
2.
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
3.
Victor Brumberg 《Celestial Mechanics and Dynamical Astronomy》2007,99(3):245-252
The half-century old idea of Infeld to use the variational principle of the general relativity field equations is reminded
to show that the commonly employed EIH (Einstein–Infeld–Hoffman) equations of motion may be derived from the linearized (weak-field)
metric alone. Based on it, the linearized metric might be sufficient for post-Newtonian celestial mechanics and astrometry
enabling one to derive the post-Newtonian equations of motion and rotation of celestial bodies as well as the post-Newtonian
equations of light propagation within the general relativity framework. 相似文献
4.
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
5.
6.
Zdeněk Kopal 《Astrophysics and Space Science》1968,1(1):74-91
The aim of the present paper will be to derive from the fundamental equations of hydrodynamics the explicit form of the Eulerian equations which govern the motion about the centre of gravity of self-gravitating bodies, consisting of compressible fluid of arbitrary viscosity, in an arbitrary external field of force. If the problem is particularized so that the external field of force represents the attaction of the sun and the moon, this motion would represent the luni-solar precession and nutation of a fluid viscous earth; if, on the other hand, the external field of force were governed by the earth (and the sun), the motion would define the physical librations of the moon regarded as a deformable body. The same equations are, moreover, equally applicable to the phenomena of precession and nutation of rotating fluid components in close binary systems, distorted by mutual tidal action; and the present paper contains the first formulation of the effects of viscosity on such phenomena.Investigation supported in part by the U.S. National Aeronautics and Space Administration under Contract No. NASW-1470. 相似文献
7.
B. E. Schutz 《Celestial Mechanics and Dynamical Astronomy》1981,24(2):173-181
The mutual gravitational potential of two bodies of arbitrary shape is expressed to fourth order in an extension of MacCullagh's Formula for a single body. The expressions for the gravitational torques acting on each body are derived in a form convenient for use in the differential equations describing the rotational dynamics. 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.
We consider the questions of an explosive impact on asteroids and comets that approach the Earth in the case of a late forecast of the dangerous situation. Based on models for the destruction of the material of a celestial body in the shock wave produced by a strong self-buried explosion, we estimate the radius of the destroyed region, the ejected mass, and the recoil momentum. We determine the charges needed to completely destroy bodies of various sizes and compositions or to divert bodies from the Earth by the required distance. When comets are dangerous bodies, we compare the efficiencies of the explosive and sublimation methods of changing their orbits. We discuss how to increase the efficiency of the explosive impact on a dangerous body through the use of a high relative velocity of the encounter between this body and a charge-carrying rocket. 相似文献
10.
Przemysław Bartczak Sławomir Breiter 《Celestial Mechanics and Dynamical Astronomy》2003,86(2):131-141
We propose a new, simple model to describe the gravity field of irregular, nonspherical celestial bodies, like small moons or minor asteroids. The simple idea of Duboshin to use a material straight segment for such bodies is extended by combining two perpendicular segments of different lengths and masses. In typical situations, when the longest axis of the body coincides with one segment, the remaining segment must have an imaginary length. The potential remains a real function even if one segment is imaginary. The new model is confronted with the exact form of an ellipsoid's potential and with two alternative simple models for a two-axial and a three-axial ellipsoid. 相似文献
11.
We study the motion of a secondary celestial body under the influence of the logarithmic corrected gravitational force of a primary one. This kind of correction was introduced by Fabris and Campos (Gen. Relativ. Gravit. 41(1):93, 2009). We derive two equations to compute the rate of change of the anomalistic period with respect to the eccentric anomaly and its total variation over one revolution. In a kinematical sense, this influence produces an apsidal motion. We perform numerical estimations for some celestial bodies. We also compare our results to those obtained by considering a Yukawa correction. 相似文献
12.
Solar System Research - Geodetic precession is the most significant relativistic effect in the rotation of celestial bodies. In this work, for the first time, this relativistic effect is determined... 相似文献
13.
The aim of the present investigation has been to derive from the fundamental Cauchy's first law of continuum mechanics the explicit form of the Eulerian general equation which governs the three-axial generalized rotation about the centre of mass of a self-gravitating deformable finite material continuum, viscolinear (i.e., Newtonian) or not, consisting of compressible fluid of arbitrary viscosity, in an external field of force. The generalized rotation is a superposition of the so-called rigid-body (i.e., time dependent only) rotation of the continuum plus a nonrigidbody (i.e., position-time dependent) rotation of its configurations.In Section 2, which follows brief introductory remarks outlining the problem, we develop a mathematical theory which describes the whole phenomenon in terms of two rotation tensors corresponding, respectively, to the rigid-body and nonrigid-body rotation modes. In Section 3, we derive the differmation vectors of velocity and acceleration. The equations we have obtained are a very general version of Navier Stokes' equations, which were not given in previous investigations. In Section 4, we perform integration of the left-hand side of Cauchy's first law, cross-multiplied by the position vector, without any restriction. In Section 6, integration of the right-hand side of the same law, cross-multiplied by the position vector, is carried out, by taking account of actually simplifying assumptions stated in Section 5. All the integral terms occurring in both sides are expressed explicitly by quantities evaluated in terms of components of properly defined moments.Finally, in Section 7, the system of the general Eulerian equations is set up; and some easy modifications are given, which describe nicely physical models of special interest; while the concluding Section 8 contains a general discussion of the results. 相似文献
14.
R. P. Prajapati R. K. Pensia S. Kaothekar R. K. Chhajlani 《Astrophysics and Space Science》2010,327(1):139-154
The effects of arbitrary radiative heat-loss functions and Hall current on the self-gravitational instability of a homogeneous,
viscous, rotating plasma has been investigated incorporating the effects of finite electrical resistivity, finite electron
inertia and thermal conductivity. A general dispersion relation is obtained using the normal mode analysis with the help of
relevant linearized perturbation equations of the problem, and a modified Jeans criterion of instability is obtained. The
conditions of modified Jeans instabilities and stabilities are discussed in the different cases of our interest. We find that
the presence of arbitrary radiative heat-loss functions and thermal conductivity modifies the fundamental Jeans criterion
of gravitational instability into a radiative instability criterion. The Hall parameter affects only the longitudinal mode
of propagation and it has no effect on the transverse mode of propagation. For longitudinal propagation, it is found that
the condition of radiative instability is independent of the magnetic field, Hall parameter, finite electron inertia, finite
electrical resistivity, viscosity and rotation; but for the transverse mode of propagation it depends on the finite electrical
resistivity, the strength of the magnetic field, and it is independent of rotation, electron inertia and viscosity. From the
curves we find that the presence of thermal conductivity, finite electrical resistivity and density-dependent heat-loss function
has a destabilizing influence, while viscosity and magnetic field have a stabilizing effect on the growth rate of an instability.
The effect of arbitrary heat-loss functions is also studied on the growth rate of a radiative instability. 相似文献
15.
从知道某些天体具有磁场起，人们就对其磁场的起源提出种种解释，例如有电池说，转子说，化石说，发电机说等等。但由于这些学说都分别与某些观测事实相抵触而未被公认，因此星球磁场的起源一直是未能解决的命题。余先河先生提出，星球的磁场起源可能与所受的引力有关，行星的磁场强度正比于其所受卫星的引力；正比于卫星与行星的引力连线转动的相对角速度。本文对这两方面的命题分别进行了相关分析，得到其相关系数分别为：ｒ＝０．８４８１和ｒ＝０．８４２５，它们都在ａ＝０．０１的信度水平上相关。结果表明余新河关于行星磁场起源的设想是有基础的。本文还对其统计结果和可能机制进行了讨论。 相似文献
16.
《Planetary and Space Science》2007,55(4):401-406
Close approaches occur very often in celestial mechanics, giving rise to troubles in the integration process of the equations of motion. To encounter the so-appearing difficulties in the restricted ring problem of N+1 bodies, we propose new dependent and independent variables which allow the less-massive body to come very close to the central primary as well as to any peripheral primary. 相似文献
17.
Simulation of the full two rigid body problem using polyhedral mutual potential and potential derivatives approach 总被引：3，自引：0，他引：3
Eugene G. Fahnestock Daniel J. Scheeres 《Celestial Mechanics and Dynamical Astronomy》2006,96(3-4):317-339
Herein we investigate the coupled orbital and rotational dynamics of two rigid bodies modelled as polyhedra, under the influence of their mutual gravitational potential. The bodies may possess any arbitrary shape and mass distribution. A method of calculating the mutual potential’s derivatives with respect to relative position and attitude is derived. Relative equations of motion for the two body system are presented and an implementation of the equations of motion with the potential gradients approach is described. Results obtained with this dynamic simulation software package are presented for multiple cases to validate the approach and illustrate its utility. This simulation capability is useful both for addressing questions in dynamical astronomy and for enabling spacecraft missions to binary asteroid systems. 相似文献
18.
V. A. Brumberg S. V. Tarasevich N. N. Vasiliev 《Celestial Mechanics and Dynamical Astronomy》1988,45(1-3):149-162
Construction and application of the current high accuracy analytical theories of motion of celestial bodies necessitates the development of specialized software for the implementation of analytical algorithms of celestial mechanics. This paper describes a typical software package of this kind. This package includes a universal Poisson processor for the rational functions of many variables, a tensorial processor for purposes of relativistic celestial mechanics, a Keplerian processor valid for the solutions of the two body problem in the form of a Poisson series, Taylor expansions in powers of time and closed expressions, and an analytical generator of celestial mechanics functions, facilitating the immediate implementation of the present analytical methods of celestial mechanics. The package is completed with a numerical-analytical interface designed, in particular, for the fast evaluation of the long Poisson series. 相似文献
19.
Craters located in the polar regions of Mercury and the Moon are studied. The areas of permanently shadowed zones in the polar regions of both celestial bodies are computed. In the case of the Moon, variations of the position of its rotation pole with respect to the ecliptic pole during the 18.6-year period were taken into account. In the case of Mercury, the computations were performed for a period equal to one Mercurial solar day. The variations of temperature are computed for craters coinciding with the areas of high hydrogen content for the Moon and areas with anomalous reflective properties for Mercury, including craters with anomalous areas discovered with the upgraded radio telescope of the Arecibo observatory (Harmon and Perillat, 2001). Craters that may contain deposits of water ice or other volatile compounds are identified in the polar regions of both celestial bodies. 相似文献
20.
Joshua Ashenberg 《Celestial Mechanics and Dynamical Astronomy》2007,99(2):149-159
The mutual gravitational potential and the mutual gravitational torque of two bodies of arbitrary shape are expanded to the
fourth order. The derivations are based on Cartesian coordinates, inertia integrals with relation to the principal reference
frames of each body, and the relative rotation matrix. The current formulation is convenient to utilize in high precision
problems in rotational dynamics. 相似文献