共查询到20条相似文献，搜索用时 15 毫秒
1.
Demetrios D. Dionysiou 《Astrophysics and Space Science》1980,73(2):295-305
Starting with the Einstein-Maxwell field equations in general relativity we construct the general differential equations governing the components of the metric tensor. We do this in a fashion completely analogous to that which we follow in Einstein-Infeld-Hoffmann and Einstein-Infeld theory. These equations allow us to findh
if
in various orders. An answer to our problem up to the first relativistic corrections is a computational work to find4
h
00, since the other terms2
h
00,2
h
and3
h
0 are as in a pure gravitational case. On the other hand, using the defined Einstein-Maxwell tensor, we give the equations of motion of two charged particles in the 0th order; also, the generalization is given in the case ofn particles. 相似文献
2.
We study the classical problem of two-dimensional motion of a particle in the field of a central force proportional to a real power of the distancer. for negative energy and (0, 2), each energy levelI
h is foliated by the invariant toriI
hc of constant angular momentumc and, by Liouville-Arnold's theorem, the flow on eachI
hc is conjugated to a linear flow of rotation number
h
(c).A well-known result asserts that if we require
h
(c) to be rational for every value ofh andc, the, must be equal to one (Kepler's problem). In this paper we prove that for almost every (0, 2)
h
(c) is a non-constant continuous function ofc, for everyh<0. In particular, we deduce that motion under central potentials is generically non-periodic.Partially supported by CIRIT under grant No. EE88/2. 相似文献
3.
The evolution of three close binary systems of total mass 20.4M
in and after the phase of mode Br mass-transfer in caseA of mass exchange is investigated. In every case a secondary component evolves to interfere with the progress of primary's evolution and the system overflows the outer critical surface before the primary completes its nuclear-burning evolution. This strongly indicates the importance of simultaneous calculation of both components. A summary of evolution of the systems considered in this series of papers up to the stage ofL
2-overflow is given. The observational aspects of the numerical models are also discussed. 相似文献
4.
A model of two-current-loop collisions is presented to explain the impulsive nature of solar flares. From MHD equations considering the gravity and resistivity effects we find self-consistent expressions and a set of equations governing the behavior of all physical quantities just after magnetic reconnection has taken place. Numerical simulations have revealed that the most important parameters of the problem are the plasma and the ratio of initial values of pressure gradient in the longitudinal and radial directions. Thus, the low plasma case during aY-type interaction (initial longitudinal pressure gradient is comparable with initial radial pressure gradient) shows a rapid pinch and simultaneous enhancement of all physical quantities, including the electric field components, which are important for high-energy particle acceleration. However, an increase of the plasma causes a weakening of the pinch effect and a decrease of extreme values of all physical quantities. On the other hand, for anX-type collision (initial longitudinal pressure gradient is much greater than initial radial pressure gradient), which is able to provide a jet, the increase of the plasma causes a high velocity jet. As for aI-type collision (initial longitudinal pressure gradient is much less than initial radial pressure gradient) it shows neither jet production nor very strong enhancement of physical quantities. We also consider direct and oblique collisions, taking into account both cases of partial and complete reconnection. 相似文献
5.
The caseA evolution of close binary systems with total mass of 20.4M
is investigated by following the evolution of both components simultaneously. The evolution is followed up to the stage at which a system overflows the outer critical surface or evolves into the phase of modeBr mass-transfer. It is found that the evolution of the systems can be classified into six types. The ranges of initial parameters which lead systems to each type of evolution are shown on the initial-parameter plane. The evolutionary features of each evolution type are described in detail. 相似文献
6.
Enrique Guzmán 《Astrophysics and Space Science》1991,179(2):331-334
In this paper we have obtained the general vacuum solution for Bianchi type-II in the Brans-Dicke theory for total anistropyR
1R
2R
3. It is known that by use of our method, we can find the general solution for Bianchi type-II vacuum case in the general relativity theory, first given by Taub (1951). Some physical properties of this model are also discussed. 相似文献
7.
Enrique Guzman 《Astrophysics and Space Science》1990,173(1):163-164
In this paper, we again discuss the new Brans-Dicke-Bianchi type-VII
h
perfect fluid solutions, first given by us (Guzman, 1989). It is shown that the objections presented by Lorenz-Petzold (1989) are misleading. The dust case =0 is discussed. 相似文献
8.
9.
T. C. Van Flandern 《Celestial Mechanics and Dynamical Astronomy》1982,26(2):197-197
We have developed a new algebraic manipulator at the Naval Observatory, for application to lunar and planetary theories. The manipulator is quite general in that it is written in IBM FORTRAN IV language, but otherwise is independent of the bit and word structure of any particular computer. If the user desires, the number of polynomial and trigonometric arguments may be varied without limit. The math and order subroutines use an efficient one-to-one core mapping process. A higher level set of operation codes to simplify programming is built in. For example, the problemh=[(ab)/(cd)]1/2, wherea, b, c, d are series, is computed by the statement: CALL EXPR (H, *,A, B, *,C, D, DV, $1, $2, R, $3, =).Applications to planetary theory are already developed with enough accuracy for analytical partial derivatives. Special problems encountered in the analytical theory of Pluto will be described, since Pluto represents a worst case situation in planetary theory. The manipulation had to be performed with a nonsingular element set. Operations had to be reordered to improved convergence, and a 3-to-2 resonance with Neptune had to be assumed. Even then, the analytical partial derivatives for Pluto had to be developed with nearly four significant figures because of the relatively short arc of observations and the consequent difficulty of separating unknowns.Proceedings of the Conference on Analytical Methods and Ephemerides: Theory and Observations of the Moon and Planets. Facultés universitaires Notre Dame de la Paix, Namur, Belgium, 28–31 July, 1980. 相似文献
10.
In this paper we consider almost integrable systems for which we show that there is a direct connection between symplectic methods and conventional numerical integration schemes. This enables us to construct several symplectic schemes of varying order. We further show that the symplectic correctors, which formally remove all errors of first order in the perturbation, are directly related to the Euler—McLaurin summation formula. Thus we can construct correctors for these higher order symplectic schemes. Using this formalism we derive the Wisdom—Holman midpoint scheme with corrector and correctors for higher order schemes. We then show that for the same amount of computation we can devise a scheme which is of order O(h
6)+(2
h
2), where is the order of perturbation and h the stepsize. Inclusion of a modified potential further reduces the error to O(h
6)+(2
h
4).This revised version was published online in October 2005 with corrections to the Cover Date. 相似文献
11.
M. S. Petrovskaya 《Celestial Mechanics and Dynamical Astronomy》1970,3(1):121-128
The negative powers of the mutual distance
–
between two bodies are developed into series converging at any moment but that of collision. On the base of these expansions the series have been constructed representing
–
in the perturbation theory of celestial mechanics. In the general case, including intersecting orbits, the terms are quasi-periodic functions of the time. In the case of non-intersecting orbits the expansion is a double Fourier series in the mean anomalies. All the expansions have a literal form with respect to osculating elements. 相似文献
12.
We consider the particular case of the planar three body problem obtained when the masses form an isosceles triangle for all time. Various authors [1, 2, 12, 8, 9, 13, 10] have contributed in the knowledge of the triple collision and of several families of periodic orbits in this problem. We study the flow on a fixed level of negative energy. First we obtain a topological representation of the energy manifold including the triple collision and infinity as boundaries of that manifold. The existence of orbits connecting the triple collision and infinity gives some homoclinic and heteroclinic orbits. Using these orbits and the homothetic solutions of the problem we can characterize orbits which pass near triple collision and near infinity by pairs of sequences. One of the sequences describes the regions visited by the orbit, the other refers to the behaviour of the orbit between two consecutive passages by a suitable surface of section. This symbolic dynamics which has a topological character is given in an abstract form and after it is applied to the isosceles problem. We try to keep globality as far as possible. This strongly relies on the fact that the intersection of some invariant manifolds with an equatorial plane (v=0) have nice spiraling properties. This can be proved by analytical means in some local cases. Numerical simulations given in Appendix A make clear that these properties hold globally. 相似文献
13.
J. Ziółkowski 《Astrophysics and Space Science》1969,3(1):14-30
The evolution of close binary systems was followed for ten systems with the initial mass of the primary in the range 1–4M
and with different initial mass ratios and initial separations. A brief discussion of the evolution of the contact component is presented for two separate cases: when the primary reaches its Roche lobe during central hydrogen burning (case A) and after the exhaustion of hydrogen in the center (case B).The models obtained are compared with observed semi-detached systems separately for massive (with total mass greater than 5M
) and low mass (with total mass below 4M
) binaries. It is shown that the contact components of the observed massive binaries are probably burning hydrogen in the core. On the contrary, the majority of contact components of the observed low-mass binaries are burning hydrogen in the shell. The observed distribution of such binaries as a function of different luminosity excesses of contact components seems to indicate that their origin is connected with case A rather than with case B. 相似文献
14.
The internal structure of prominences appearing as twisted tubes was studied. The sample embraced 15 stable and 13 eruptive prominences, exposing patterns which possibly reflect a helical configuration. The equivalent pitch angles () of twisted fine structure features were measured. In some cases the evolution of the internal structure was followed and 49 independent measurements of the parameter were performed in total. The results are presented in the plane relating the parameter and the normalized prominence height. The eruptive prominences occupy the region characterized by > 50° and h > 0.8d, where h and d are the prominence height and the footpoint half-separation, respectively. All prominences characterized by h < 0.6d or by < 35° were stable. Such a result is in good agreement with an order of magnitude treatment of the forces acting in a curved magnetic tube, anchored at both ends in the photosphere. 相似文献
15.
Unsteady two-dimensional hydromagnetic flow of an electrically conducting viscous incompressible fluid past a semi-infinite porous flat plate with step function change in suction velocity is studied allowing a first order velocity slip at the boundary condition. The solution of the problem is obtained in closed form and the results are discussed with the aid of graphs for various parameters entering in the problem.Notations
B
intensity of magnetic field
-
H
magnetic field parameter,H=(M+1/4)1/2–1/2
-
h
rarefaction parameter
-
L
1
slip coefficient;
;I, mean free path of gas molecules;f, Maxwell's reflection coefficient
-
M
magnetic field parameter
-
r
suction parameter
-
t
time
-
t
dimensionless time
-
u
velocity of the fluid
-
u
dimensionless velocity of the fluid
-
U
velocity of the fluid at infinity
-
v
suction velocity
-
v
1
suction velocity att<=0
-
v
2
suction velocity att>0
-
x
distance parallel to the plate
-
y
distance normal to the plate
-
y
nondimensional distance normal to the plate
-
v
kinematic viscosity
-
electric conductivity of the fluid
-
density of the fluid
-
shear stress at the wall
-
nondimensional shear stress at the wall
- erf
error function
- erfc
complementary error function 相似文献
16.
The main goal of this paper is to show that the elliptic restricted three-body problem has ejection-collision orbits when the mass parameter µ is small enough. We make use of the blow up techniques. Moreover, we describe the global flow of the elliptic problem when µ = 0 taking into account the singularities due to collision and to infinity. 相似文献
17.
V. A. Ruban 《Astrophysics and Space Science》1977,46(2):L23-L28
It is shown that, for the scalar-tensor cosmology (STC) by Jordan-Brans-Dicke (JBD), in general anisotropic solution the oscillatory mixmaster regime near the singularity will be destroyed by the scalar source-free field and replaced by monotonousV
3-collapse into the point or into the line and plane (only in caseG0) even in the presence of the primordial source-free electromagnetic (EM) field. 相似文献
18.
For a cylindrical wave guide, filled with hot collisional and moving plasma, the expression for damping coefficientK
i (imaginary part of the wave vector) has been derived and discussed in case of TM modes. It is observed that due to the effects of ion collisions,K
i remains less than zero for all values of (=/c) and waves suffer strong reflections for 0.5. The damping is however not affected for moderate changes in collision frequencies, while for low values of electron collision frequency and plasma density, the damping coefficient varies in a parabolic fashion with sharp reflections at 0.3. 相似文献
19.
The proton flare of August 28, 1966 began on H records at 15h21m35s UT. It presented an unusually complex development with flare emission occurring in two distinct plages. The brightest part of the flare attained maximum intensity, 152 % of the continuum, between 15h30m and 15h32m UT. Photometric measurements show that a long-enduring part of the flare continued to decline in intensity until at least 21h20m UT.The flare developed first in parts of the plages that were near the extremities of a filament and a complex system of curvilinear absorption structures, possibly an eruptive prominence in projection. During the rise to maximum intensity a large expanding feature moved southward from the site of the flare with a velocity 700 km/sec. Its appearance on monochromatic records of the chromosphere made in the center of H and 0.5 Å on either side was consistent with the effect of an advancing phenomenon that induces a small shift of the H absorption line, first to longer, and then to shorter wavelengths.Two bright flare-filaments were obvious aspects of the event by 15h28m and dominated the main phase of the flare. Loop-type prominences were observed in absorption as early as 15h40m.This investigation was supported in part by the Office of Naval Research through funds from Nonr-1224(19), and in part by the National Science Foundation through funds from GA-632. 相似文献
20.
Donald G. Saari 《Celestial Mechanics and Dynamical Astronomy》1976,14(1):11-17
A selective survey of then-body problem of celestial mechanics is given where the emphasis is on the asymptotic behavior of all solutions ast, the possible configurations the particles can assume in phase space and in physical space, and collision and non-collision singularities.Supported in part by NSF Grant MPS 71-03407 A03. 相似文献