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1.
It is found that the relationship between the potential energy and the moment of the inertia independent of the radial mass distribution obtained earlier for the sphere also holds in the case of the ellipsoidal mass distribution for the ellipsoid of rotation.The possibility of application of the energy virial relations for solution of the evolutionary problems of the gravitating gaseous sphere, with the help of the relationship found earlier, is demonstrated. The physical conditions on the gaseous sphere boundary are introduced. The existence of two branches of evolution, the proton one and the electron one, is established. The problem of the gravitational contraction velocity during sphere evolution is solved. The relationship between the boundary temperature and the gaseous sphere radius as well as between the luminosity and the body mass is obtained. Some limiting relations for the final stage of the gaseous sphere evolution are found.
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2.
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3.
In this paper we investigate the effect of twisting motions at the photosphere on a curved loop confined by overlying field lines. We find that the twisting motions form a twisted loop along which a current builds up. However, the toroidal curvature of the loop appears to have a stabilising effect as there is no sign of the kink instability for a twist of 3.4  whereas in a straight cylinder for the same twist profile the critical twist is approximately 2.5 . When we include resistivity in the simulation there are indications that reconnection occurs and releases a substantial proportion of the free magnetic energy.  相似文献   

4.
1.40M . C12+C12Mg24+. Bruenn (1972) . , ( ), . , URCA . ( , ) . .  相似文献   

5.
The Norma specialized program package, intended for normalization of autonomous Hamiltonian systems by means of computer algebra, is used in studies of small-amplitude periodic motions in the neighbourhood of regular precessions of a dynamically symmetric satellite on a circular orbit. The case of hyperboloidal precession is considered. Analytical expressions for normal forms and generating functions depending on frequencies of the system as on parameters are derived. Possible resonances are considered in particular. The 6th order of normalization is achieved. Though the intermediate analytical expressions occupy megabytes of computer's main memory, final ones are quite compact. Obtained analytical expressions are applied to the analysis of stability of small-amplitude periodic motions in the neighbourhood of hyperboloidal precession.  相似文献   

6.
In the present paper, the regular precessions about the mass center are studied, for a Volterra-type gyrostatic satellite in a circular orbit under a Newtonian force field. All the possible regular precessions are determined.  相似文献   

7.
Optical identification of infrared sources from the IRAS Point Source Catalogue (PSC) is made by means of low-dispersion spectra of the First Byurakan Survey (FBS) and Palomar Observatory Sky Survey (POSS) red and blue images. The purpose of this work is to examine the composition of the PSC sample of fainter sources at high galactic latitudes and to reveal QSOs, infrared galaxies, red stars (C and M), planetary nebulae, for their further investigation at the optical range. 100 of 108 unknown IRAS sources in the region with 3h50m 7h40m and + 69° + 73° are optically identified. Optical coordinates, V magnitudes, color indices, and preliminary classes are determined. According to preliminary classification 3 objects turned out to be QSOs, 36 are galaxies with very interesting morphology, 5 are faint planetary nebulae, 9 are carbon stars, and 47 are late M-type stars.Published in Astrofizika, Vol. 38, No. 4, pp. 625–629, October–December, 1995.  相似文献   

8.
This work contains a transformation of Hill-Brown differential equations for the coordinates of the satellite to a type which can be integrated in a literal form using an analytical programming language. The differential equation for the parallax of the satellite is also established. Its use facilitates the computation of Hill's periodic intermediary orbit of the satellite and provides a good check for the expansion of the coordinates and frequencies. The knowledge of the expansion of the parallax facilitates the formation of differential equations for terms with a given characteristic. These differential equations are put into a form which favors the solution by means of iteration on the computer. As in the classical theory we obtain the expansions of the coordinates and of the parallax in the form of trigonometric series in four arguments and in powers of the constants of integration. We expand the differential operators into series in squares of the constants of integration. Only the terms of order zero in these expansions are employed in the integration of the differential equations. The remaining terms are responsible for producing the cross-effects between the perturbations of different order. By applying the averaging operator to the right sides of the differential equations we deduce the expansion of the frequencies in powers of squares of the constants of integration.Basic Notations f the gravitational constant - E the mass of the planet - M the mass of the satellite - t dynamical time - x, y, z planetocentric coordinates of the satellite - u x+y–1 - s x–y–1 - the planetocentric distance of the satellite - w 1/ - 0 the variational part of - w 0 the variational part ofw, - n the mean daily sidereal motion of the satellite - a the mean semi-major axis of the satellite defined by means of the Kepler relation:a 3 n 2=f(E+M) - a the mean semi-major axis defined as the constant factor attached to the variational solution - e the constant of the eccentricity of the satellite - the sine of one half the orbital inclination of the satellite relative to the orbit of the sun - c(n–n) the anomalistic frequency of the satellite - c 0 the part ofc independent frome,e, and - g(n–n) the draconitic frequency of the satellite, - g 0 the part ofg independent frome,e, and - exp (n–n)t–1 - D d/d - e the eccentricity of the solar planetocentric orbit - a the semi-major axis of the solar orbit - n the mean daily motion of the sun in its orbit around the planet - m n/(n–n) - a/a-the parallactic factor - the disturbing function  相似文献   

9.
The influence of resonance perturbations due to the gravitational field of an oblate planet on its satellite whose motion is commensurable with rotation of the planet has been investigated. It has been shown that in special case of the critical inclination or circular orbit the Lagrange equations can be integrated for all resonance terms simultaneously. The method is applied to the investigation of the motion of the 12-hour communication and navigation satellites of the Molniya and Navstar type. The computations has been performed by the use of four models of the geopotential.  相似文献   

10.
The equations for the variation of the osculating elements of a satellite moving in an axi-symmetric gravitational field are integrated to yield the complete first-order perturbations for the elements of the orbit. The expressions obtained include the effects produced by the second to eighth spherical harmonics. The orbital elements are presented in the most general form of summations by means of Hansen coefficients. Due to their general forms it is a simple matter to estimate the perturbations of any higher harmonic by simply increasing the index of summation. Finally, this paper gives the respective general expressions for the secular perturbations of the orbital elements. The formulae presented should be useful for the reductions of Earth-satellite observations and geopotential studies based on them.List of Symbols semi-major axis - C jk n (, ) cosine functions of and - e eccentricity of the orbit - f acceleration vector of perturbing force - f sin2t - i inclination of the orbit - J n coefficients in the potential expansion - M mean anomaly - n mean motion - p semi-latus rectum of the orbit - R, S, andW components of the perturbing acceleration - r radius-vector of satellite - r magnitude ofr - S jk n (, ) sine functions of and - T time of perigee passage - u argument of latitude - U gravitational potential - true anomaly - V perturbing potential - G(M++m) (gravitational constant times the sum of the masses of Earth and satellite) - n,k coefficients ofR component of disturbing acceleration (funtions off) - n,k coefficients ofS andW components of disturbing acceleration (functions off) - mean anomaly at timet=0 - X 0 n,m zero-order Hansen coefficients - argument of perigee - right ascension of the ascending node  相似文献   

11.
Observed supernovae rates in Sb and Sc galaxies, and a recent re-examination of the mean gas density in these galactic types, implies that if the clumpiness of gas in the disks of Sb and Sc galaxies is similar, the gas density isnot the primary factor in determining the overall present stellar birthrate.  相似文献   

12.
The roll-yaw attitude motion of a spinning symmetric satellite in a circular orbit is investigated with particular emphasis on the behavior near resonance. Resonance in circular orbit occurs if there is a low-order commensurability between the coupled roll-yaw attitude frequencies. For the so-called Delp region where the Hamiltonian describing the linearized attitude oscillations is not positive definite, there can exist, near resonance, a simultaneous growth or decay of the energy of the two normal modes. Two sections of the resonance line 2=3 1 permitting the largest effects are determined and the equations of motion are integrated numerically as a check on the resonance theory. In particular, resonance-induced instabilities are confirmed.  相似文献   

13.
A problem of stability of odd 2-periodic oscillations of a satellite in the plane of an elliptic orbit of arbitrary eccentricity is considered. The motion is supposed to be only under the influence of gravitational torques.Stability of plane oscillations was investigated earlier (Zlatoustovet al., 1964) in linear approximation. In the present paper a problem of stability is solved in the non-linear mode. Terms up to the forth order inclusive are taken into consideration in expansion of Hamiltonian in a series.It is shown that necessary conditions of stability obtained in linear approximation coincide with sufficient conditions for almost all values of parameters ande (inertial characteristics of the satellite and eccentricity of the orbit). Exceptions represent either values of the parameters ,e when a problem of stability cannot be solved in a strict manner by non-linear approximation under consideration, or values of the parameters which correspond to resonances of the third and fourth orders. At the resonance of the third order oscillations are unstable, but at the resonance of the fourth order both unstability and stability of the satellite's oscillations take place depending on the values of the parameters ,e.  相似文献   

14.
The rotational motion of an artificial satellite is studied by considering torques produced by gravity gradient and direct solar radiation pressure. A satellite of circular cylinder shape is considered here, and Andoyers variables are used to describe the rotational motion. Expressions for direct solar radiation torque are derived. When the earths shadow is not considered, an analytical solution is obtained using Lagranges method of variation of parameters. A semi-analytical procedure is proposed to predict the satellites attitude under the influence of the earths shadow. The analytical solution shows that angular variables are linear and periodic functions of time while their conjugates suffer only periodic variations. When compared, numerical and analytical solutions have a good agreement during the time range considered.  相似文献   

15.
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   

16.
Résumé On étudie l'effet du champ magnétique terrestre sur le mouvement d'un satellite autour de son centre de gravité. Le satellite possède une symétrie dynamique et un moment magnétique propre dirigé suivant l'un des axes principaux d'inertie; le champ magnétique terrestre est assimilé au champ d'un dipôle dont les pôles coïncident avec les pôles terrestres. On néglige les perturbations de la trajectoire du satellite qui est supposée circulaire. La position du satellite par rapport à son centre de gravité est repérée dans un système d'axes lié au plan de l'orbite et le mouvement est décrit à l'aide des angles d'Euler , , . La symétrie sphérique et le choix du moment magnétique sur l'un des axes d'inertie permettent d'éliminer l'angle .La solution pour et peut se développer en séries de puissance d'un petit paramètre . Les séries convergent pour ||<1.Lorsque le moment magnétique est faible on la rotation du satellite rapide, est faible. Les développements sont calculés effectivement jusqu'à 2.La comparaison des résultats avec l'intégration numérique du système d'équations différentielles est satisfaisante.
The effect of the Earth's magnetic field on the motion of a satellite around its centre of mass is investigated. The satellite is assumed to be dynamically symmetric and to be magnetized in the same direction as that of a principal axis. The Earth's magnetic field is assumed to be a dipole field whose poles coincide with the rotation poles of the Earth. The satellite's orbit is circular and perturbations are neglected. The position of the satellite with respect to its centre of mass is given with respect to a coordinate system fixed in the orbital plane and the motion is described by Euler's angles , , . The spherical symmetry and the coincidence of the magnetic moment with a principal axis allow one to eliminate the angle .The solution for and , can be expanded in power series for small parameter .The series converge for <1. is small for a small magnetic moment or a high angular velocity of the rotating satellite. The terms of the expansion of the series are calculated up to 2.The comparison of the results with those obtained by numerical integration of the differential equation is satisfactory.
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17.
Celestial body rotation about its center of mass, taking into account the body orbit evolution, is considered. Non-linear evolution equations of motion are constructed. Empirical Cassini's laws describing the Moon motion result from these equations as their stationary points. Bifurcation conditions of steady motions are written out and conditions of their stability are investigated. Hypothesis of Mercury's resonance motion analogous to the motion by Cassini is discussed. Consequences of this hypothesis are considered.The first information including the results mentioned in the paper was previously published in preprint [1].  相似文献   

18.
The occurrence and uniqueness of the critical inclination in satellite theory is discussed.An infinite set of canonical transformations in Hill variables are shown to exist whereby the first order secular part of the disturbing function can be changed into an alternative form. As a result of such a transformation the critical inclination can become (a)any other real or complex inclination or a function independent of the satellite's orbital inclination and (b) a function dependent on the semi-major axis, eccentricity and inclination of the satellite's orbit. It is also shown that all transformations of types (a) and (b) are only valid for short intervals of time of the order of a few satellite revolutions. Furthermore if such transformations are modified so that they become valid for greater intervals of time, then the resulting solutions in all cases containno singular divisor other than the critical inclination.It is concluded that the singularity at the critical inclination is unique and that it represents an actual physical resonance rather than something resulting from the method of solution or the type of variable used in the analysis. This conclusion is supported by numerical evidence which shows that a satellite's perigee height does suffer resonant changes when the orbital inclination is equal to the critical inclination of 63.°4.  相似文献   

19.
Numerical orbit integrations have been conducted to characterize the types of trajectories in the one-dimensional Newtonian three-body problem with equal masses and positive energy. At positive energies the basic types of motions are binary + single particle and ionization, and when time goes from – to + all possible transitions between these states can take place. Properties of individual orbits have been summarized in the form of graphical maps in a two-dimensional grid of initial values. The basic motion types exist at all positive energies, but the binary + single particle configuration is obtained only in a narrow region of initial values if the total energy is large. At very large energies the equations of motion can be solved approximately, and this asymptotic result, exact in the limit of infinite energy, is presented.  相似文献   

20.
A rapidly spinning, slowly accreting magnetic white dwarf (or X-ray pulsar) in hibernation is expected to result in rapid spindown as a result of the stretching and reconnection of magnetic field lines, leading to particle acceleration at the magnetospheric radiusoutside the corotation radius, and the propeller type ejection of magnetized synchrotron-emitting clouds. This may explain the non-thermal (radio and-rays) emission seen from the unique nearby AE Aquarii. Moving to Galactic distances we show how TeV-ray observations of pulsar-driven supernova remnants (with well-measured synchrotron X-ray spectra) allow us to obtain a direct measurement of the average magnetic field strength in the nebula. Finally, GeV to TeV observations of-ray blazars out to redshifts of 2 allow us to probe the intergalactic infrared radiation field, the Hubble constant and possibly the parameter of the Universe.  相似文献   

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