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1.
In the theory of supergravity (N=1), the supersymmetric version of general relativity, and for the Kasner cosmological model (Bianchi type I) we find a non-trivial solution (for the metric and spinor-vector) under the most simple assumption =11 + 22; 12+21=0 and for a special choosed gaugeN=1,N
j=0, 0=0. This method could be also applied to other cosmological metrics and extended to enlarged Grassmann basis.O. Obregón was partially supported by the Alexander von Humboldt Stiftung. 相似文献
2.
The effect of small perturbations and in the coriolis and the centrifugal forces respectively on the stability of the triangular points in the restricted problem of three bodies with variable mass has been studied. It is found that the range of stability of triangular points increases or decreases depending upon whether the perturbation point (, ) lies in one or the other of the two parts in which the (, ) plane is divided by the line J8–J9=0 where J8 and J9 depend upon , the constant due to the variation in mass governed by Jeans' law. 相似文献
3.
W. E. Alnaser 《Earth, Moon, and Planets》1990,48(2):177-181
The clear sky emissivity 0 and the ground emissivity
g
in Bahrain is studied. The study reveals that the annual value of 0 is 0.88 ± 0.039 relating to the maximum and the minimum values in August and February, respectively. Meanwhile, the annual value of
g
is 0.338 ± 0.228, where the maximum and the minimum values are in July and January, respectively. These two parameters are related to the transmittance factor . 相似文献
4.
S. Selak 《Astrophysics and Space Science》1989,159(1):153-156
In this Letter we propose to consider the four-energy-space whose coordinates are composed as follows: (i) the coordinate 0 refers to the internal energy of the body (it is involved as an unknown function of the rest-energy and the kinetic energy of the body), and (ii) the coordinates 1, 2, 3 relate to the presence of gravitational, electromagnetic, and thermal energy at the location of the body respectively. We involve yet the proper energy interval d2 by analogy to the four-interval ds
2 in general relativity. From such metric field we calculate the Ricci tensor in the simplest case. In addition, we require its form to be the same one as that considered by Schwarzschild. Comparing both solutions we obtain Einstein's relationE=mc
2. 相似文献
5.
E. E. Shnol 《Celestial Mechanics and Dynamical Astronomy》1984,33(2):159-167
The equilibrium point O of an autonomous Hamiltonian system of two degrees of freedom is considered for small-oscillation frequencies related as 2=21+. If under the precise resonance (=0) the equilibrium is unstable, the inner diameter () of the domain of stability containing the point O is estimated. It is shown that for the normalized variables ()/b where b is the corresponding resonance coefficient. The estimates () for other main resonances are reported. 相似文献
6.
P. G. D. Barkham V. J. Modi A. C. Soudack 《Celestial Mechanics and Dynamical Astronomy》1977,15(1):5-20
A small particle moves in the vicinity of two masses, forming a close binary, in orbit about a distant mass. Unique, uniformly valid solutions of this four-body problem are found for motion near both equilateral triangle points of the binary system in terms of a small parameter , where the primaries move in accordance with a uniformly-valid three-body solution. Accuracy is maintained within a constant errorO(8), and the solutions are uniformly valid as tends to zero for time intervalsO(–3). Orbital position errors nearL
4 andL
5 of the Earth-Moon system are found to be less than 5% when numerically-generated periodic solutions are used as a standard of comparison. 相似文献
7.
In our preceding paper {see [L. Sh. Grigorian and S. Gottlöber, Astrofizika (in press)]} we investigated a self-gravitating system consisting of a scalar field and a linear tensor field ik= ki with minimal coupling and with allowance for the action of vacuum polarization effects. In the present paper we investigate the case of a nonlinear tensor field ik. The action S
()
of the field ik is determined by the difference Rik — ik, where Rik is the space-time Ricci tensor and Rik is the analogous quantity constructed using the metric ik=gik+ik induced by ik ( is a free parameter). Here
S
()
coincides with the previously known expression for the action of a linear field ik. Equations of motion are derived for ik in curved space-time. The energy-momentum metric tensor, determining the contribution of ik to the gravitational field equations, is calculated.Translated from Astrofizika, Vol. 39, No. 1, pp. 135–144, January-March, 1996. 相似文献
8.
G. E. O. Giacaglia 《Celestial Mechanics and Dynamical Astronomy》1971,4(3-4):468-489
We study the linear stability of the triangular points in the elliptic restricted problem by determining the characteristic exponents with a convergent method of iteration which in essence was introduced by Cesari (1940). We obtain the general term of such exponents as a power series in the eccentricity of the primaries, valid for sufficiently small and at all values of except one in the interval of stability of the circular problem. 相似文献
9.
Multiple expansion of the tidal potential 总被引：1，自引：0，他引：1
F. Mignard 《Celestial Mechanics and Dynamical Astronomy》1978,18(3):287-294
The Earth tidal deformation causes an additional gravitational potential. Its effect on the Moon orbital motion has been studied by several authors.In this contribution, we develop this additional potential without specifying the inertial frame chosen.For this purpose, we use the properties of the representation of rotation groups in 3 dimensions space. We finally obtain the interaction potential between the distorted Earth and the Moon which is a necessary preliminary to the study of the evolution of the Earth-Moon system.Nomenclature T.R.O
Tide raising object
- (, , )
Spherical coordinates of the T.R.O.
- (J,
E
)
Earth spin axis orientation.
E
is the longitude of the ascending node of Earth's equator on thexy-plane
- (a
,I
,e
, , ,M
)
Elliptics elements of the T.R.O 相似文献
10.
Masanori Yoshizawa Shunsaku Suzuki Rikinosuke Fukaya 《Astrophysics and Space Science》1991,177(1-2):41-45
The catalog of positions of 1007 stars (792 FK4 and FK4S stars, 57 OB stars, 49 NPZT stars, and 109 SAO stars) is presented. They were observed during the period from December 1984 to September 1985 with the Tokyo Photoelectric Meridian Circle (Tokyo PMC). The positions in the catalog are referred to the equinox and equator of J2000, and are based on the FK4 system. The internal errors of a single observation were estimated to be (
cos,
)=(0.16, 0.19), whereas the mean internal errors of the catalog positions were (0.08, 0.08) for FK4 stars and (0.09, 0.11) for FK4S stars. A comparison of the positions of the FK4 stars in the present catalog with those of the FK4 catalog shows significant differences
cos and
in some declination zones. Some of those differences are commonly found in other recent catalogs. Thus they may be considered to be real systematic errors in the FK4 system. Neither significant magnitude nor color equations exist in the Tokyo PMC 85 catalog. 相似文献
11.
V. Markellos C. Goudas G. Katsiaris G. Georgantopoulos 《Astrophysics and Space Science》1976,45(1):99-103
A generalization is expressed of the Poisson theorem referring to the invariance of the planetary semi-major axes using the restricted problem model. In particular, it is shown that first and second approximation in terms of a change in the initial states of planets describing closed motions in the solar system remain invariant in modulus after any number of revolutions. But third-order terms contain secular parts and, thus, they undergo a secular change in their orbital motion. Such change would be apparent after
-2 Jovian years, where is a constant and is the maximum initial deviation of each planet from its reference orbit. 相似文献
12.
A model of a first generation intermediate star of 5M
, with Z=0 has been considered. The model is at an advanced stage of its evolution and has a double shell burning. It burns helium in the inner shell, and hydrogen, via CNO cycle, in the outer shell.
=(log/log)
T
and
T
=(log/logT)
were computed allowing for the oscillations of the relative mass abundance of the reagents in nuclear reactions. Including
=(log/log)
T
and
=(log/logT)
of mean molecular weight and the effect of the oscillations of abundances due to nuclear reactions, stability was studied. Contrary to the results of the static calculations, we found that instability due to the excitation mechanism provided by the high temperature sensitivity of energy generation rate propagates up to the surface. Thus the model in question was found to be unstable against radial adiabatic pulsations, in its fundamental mode. 相似文献
13.
Boris Garfinkel 《Celestial Mechanics and Dynamical Astronomy》1983,30(4):373-383
In a previous publication (1977) the author has constructed a family () of long-periodic orbits in the Trojan case of the restricted problems of three bodies. Here he constructs the domain of the analytical solution of the problem of the motion, excluding the vicinity of thecritical divisor which vanishes at the exact commensurability of the natural frequencies 1 and 2. In terms of thecritical masses mj(2), or the associatedcritical energies
j
2
(m), is the intersection of the intervals ofshallow resonance, of the form. Inasmuch as the intervals |2–
j
2
|<j ofdeep resonance aredisjoint, it follows that (1) the disjointed family () embraces the tadpole branch, 021, lying in: and (2) despite the clustering of
j
2
(m) atj=, the family () includes, for 2=1, an asymptoticseparatrix that terminates the branch in the vicinity of the Lagrangian pointL
3.In a similar manner, the family () can be extended to the horseshoe branch 1<2
2
2
. 相似文献
14.
K. S. Krishna Swamy 《Astrophysics and Space Science》1970,8(1):86-89
Two hyades giant stars, and Tau, have been studied from an analysis of strong line profiles. We get for Tau,T
e
=4750K and logg=2.7, and for Tau,T
e
=4700K and logg=2.8. Hydrogen-to-metal ratio for the two stars is nearly the same as that of solar value. 相似文献
15.
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
16.
Vittorio Coti Zelati 《Celestial Mechanics and Dynamical Astronomy》1989,46(2):177-186
We prove existence and multiplicity of T-periodic solutions (for any given T) for the N-body problem in
m
(any m 2) where one of the bodies has mass equal to 1 and the others have masses 2,...,
N
, small. We find solutions such that the body of mass 1 moves close to x = 0 while the body of mass i moves close to one of the circular solutions of the two body problem of period T/k
i, where ki is any odd number. No relation has to be satisfied by k
2,...,k
N. 相似文献
17.
Ian W. Walker A. Gordon Emslie Archie E. Roy 《Celestial Mechanics and Dynamical Astronomy》1980,22(4):371-402
An expansion of the force function ofn-body dynamical systems, where the equations of motion are expressed in the Jacobian coordinate system, is shown to give rise naturally to a set of (n–1) (n–2) dimensionless parameters
ki
li
{i = 2,...,n;k = 2,...,i – 1 (i 3);l =i + 1,...,n (i n – 1)}, representative of the size of the disturbances on the Keplerian orbits of the various bodies. The expansion is particularized to the casen=3 which involves the consideration of only two parameters
23 and
32. Further, the work of Szebehely and Zare (1977) is reviewed briefly with reference to a sufficient condition for the stability of corotational coplanar three-body systems, in which two of the bodies form a binary system. This condition is sufficient in the sense that it precludes any possibility of an exchange of bodies, i.e. Hill type stability, however, it is not a necessary condition. These two approaches are then combined to yield regions of stability or instability in terms of the parameters
23 and
32 for any system of given masses and orbital characteristics (neglecting eccentricities and inclinations) with the following result: that there is a readily applicable rule to assess the likelihood of stability or instability of any given triple system in terms of
23 and
32.Treating a system ofn bodies as a set of disturbed three-body systems we use existing data from the solar system, known triple systems and numerical experiments in the many-body problem to plot a large number of triple systems in the
23,
32 plane and show the results agree well with the
23,
32 analysis above (eccentricities and inclinations as appropriate to most real systems being negligible). We further deal briefly with the extension of the criteria to many-body systems wheren>4, and discuss several interesting cases of dynamical systems. 相似文献
18.
A family of symplectic integrators adapted for the integration of perturbed Hamiltonian systems of the form H=A+B was given in (McLachlan, 1995). We give here a constructive proof that for all integer p, such integrator exists, with only positive steps, and with a remainder of order O(p + 22), where is the stepsize of the integrator. Moreover, we compute the analytical expressions of the leading terms of the remainders at all orders. We show also that for a large class of systems, a corrector step can be performed such that the remainder becomes O(p +42). The performances of these integrators are compared for the simple pendulum and the planetary three-body problem of Sun–Jupiter–Saturn. 相似文献
19.
The results of the experimental study of the interaction of polyethylene impactors with a massive flat organic-glass target are presented. The impactor speed ranged from 3.2 to 5.84 km/s. A statistical analysis of the mass and size distributions of fragments of the impact and chop craters of the target is done. As a result, some scaling relations are established for the geometric size of the craters, the cumulative ejected mass, the mass of the largest fragment ejected from the impact crater, and for the dust mass. The mass distribution of the impact-crater fragments is shown to obey a power law and agrees well with other authors" data for some materials. The critical impact energy
k
, resulting in the catastrophic disruption of the target into individual fragments, is estimated. For organic glass, the value of
k
is found to be 4 × 104J/kg. The mass of the largest (central) fragment accounts for 27 to 33% of the overall mass ejected from the impact crater. The use of the parameter 3=
p
/
p
v
2
0gives the best fit to the observational data for the masses released from the impact and chop craters. 相似文献
20.
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