共查询到20条相似文献，搜索用时 62 毫秒
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A form of planetary perturbation theory based on canonical equations of motion, rather than on the use of osculating orbital elements, is developed and applied to several problems of interest. It is proved that, with appropriately selected initial conditions on the orbital elements, the two forms of perturbation theory give rise to identical predictions for the observable coordinates and velocities, while the orbital elements themselves may be strikingly different. Differences between the canonical form of perturbation theory and the classical Lagrange planetary perturbation equations are discussed. The canonical form of perturbation theory in some cases has advantages when the perturbing forces are velocity-dependent, but the two forms of perturbation theory are equivalent if the perturbing forces are dependent only on position and not on velocity. The canonical form of the planetary perturbation equations are derived and applied to the Lense Thirring precession of a test body in a Keplerian orbit around a rotating mass source. 相似文献
3.
J. Henrard 《Celestial Mechanics and Dynamical Astronomy》1976,14(3):331-331
Some of the basic ideas of an analytical orbiter theory which is being developed by Hubert Claes in Namur are presented.The theory is based on the Lie transform technique and will be expressed in a closed form up to second order. The inclusion of additional terms of the third order (expanded in power series of the eccentricity) will be considered.Special attention is being given to the choice of the elements and to the final form of the theory. Three main criteria are used. The removal of the virtual singularities of small inclination and eccentricity. The simplicity of the final form of the theory once the elements have been given their numerical values. The numerical stability of the evaluation of the theory. 相似文献
4.
Farkhat Zaripov 《Astrophysics and Space Science》2014,352(1):289-305
This research is an extension of the author’s works, in which conformally invariant generalization of string theory was suggested to higher-dimensional objects. Special cases of the proposed theory are Einstein’s theory of gravity and string theory. This work is devoted to the formation of self-consistent equations of the theory of induced gravity in the presence of matter in the form of a perfect fluid that interacts with scalar fields. The study is done to solve these equations for the case of the cosmological model. In this model time-evolving gravitational and cosmological “constants” take place which are determined by the square of scalar fields. The values of which can be matched with the observational data. The equations that describe the theory have solutions that can both match with the solutions of the standard theory of gravity as well as it can differ from it. This is due to the fact that the fundamental “constants” of the theory, such as gravitational and cosmological, can evolve over time and also depend of the coordinates. Thus, in a rather general case the theory describes the two systems (stages): Einstein and “evolving”. This process is similar to the phenomenon of phase transition, where the different phases (Einstein gravity system, but with different constants) transit into each other. 相似文献
5.
The Newtonian theory of gravitation is modified to include the gravitational energy as a source of gravitational potential,
thus making the theory self-coupled and nonlinear. The modified theory can be derived from a Lorentz-invariant action principle.
The Kepler problem is discussed in this theory and it is shown that the perihelion of the orbit steadily precesses. The rate
of precession is, however, insufficient to account for the observed precession of the perihelion of Mercury. The differences
from the Newtonian theory for the bending of light and the gravitational redshift of spectral lines are shown to be marginal. 相似文献
6.
Various representations of the Jordan-Brans-Dicke (JBD) theory arising in conformal transformations of the metric are considered. Propositions are formulated that establish the mathematical equivalence of these representations, making it possible from known exact solutions in one representation to generate new ones in another. It is shown, in particular, how to obtain new solutions in the general theory of relativity from known solutions in the JBD theory and vice versa. 相似文献
7.
Maxim Varfolomeev 《Planetary and Space Science》2008,56(14):1773-1777
An attempt to build a new theory of the main Uranian satellites is being made at the Sternberg Astronomical Institute. The main difference compared to GUST86 theory is that the new theory is planned to be completely analytical. To do this, the secular frequencies of the satellites should be calculated taking into account the secular perturbations of the second order and, partly, of the third order. This allows to improve the secular frequencies and make them more close to those obtained from numerical integration. Nevertheless, discrepancies remain, which indicate that more terms in the analytical development are needed. Some other advantages of the new theory are also discussed. 相似文献
8.
Juan Getino José M. Ferrándiz 《Monthly notices of the Royal Astronomical Society》2001,322(4):785-799
In this paper we present a theory of the Earth rotation for a model composed of an inelastic mantle and a liquid core, including the dissipation in the core–mantle boundary (CMB). The main features of the theory are: (i) to be Hamiltonian, therefore the computation of some complex inner torques can be avoided; (ii) to be self-consistent and non-dependent on a previous rigid Earth theory, so there is no need to use transfer functions; (iii) to be analytical, the solution being derived by perturbation methods. Numerical nutation series deduced from the theory are compared with the IERS 96 empirical series, an accuracy better than 0.8 mas in providing celestial ephemeris pole (CEP) offsets . 相似文献
9.
1引言尽管有诸多的不满之处,由于其物理上的直观性和应用上的简单性,至今混合长理论仍几乎是唯一一个广泛用于恒星结构、演化和脉动计算的恒星对流理论.混合长理论预言,在红、黄巨星和超巨星大气中,对流是超声速的.我们曾指出,混合长理论隐含了一个假定,对流是亚声速的.对于超声速对流,无论从物理的真实性,还是从混合长公式的数学表述来看,混合长理论都是不正确的.因此超声对流的真实性是存在问题 相似文献
10.
E.G. Blackman 《Astronomische Nachrichten》2010,331(1):101-109
The origin of large scale magnetic fields in astrophysical rotators, and the conversion of gravitational energy into radiation near stars and compact objects via accretion have been subjects of active research for a half century. Magnetohydrodynamic turbulence makes both problems highly nonlinear, so both subjects have benefitted from numerical simulations.However, understanding the key principles and practical modeling of observations warrants testable semi‐analytic mean field theories that distill the essential physics. Mean field dynamo (MFD) theory and alpha‐viscosity accretion disc theory exemplify this pursuit. That the latter is a mean field theory is not always made explicit but the combination of turbulence and global symmetry imply such. The more commonly explicit presentation of assumptions in 20th century textbook MFDT has exposed it to arguably more widespread criticism than incurred by 20th century alpha‐accretion theory despite complementary weaknesses. In the 21st century however, MFDT has experienced a breakthrough with a dynamical saturation theory that consistently agrees with simulations. Such has not yet occurred in accretion disc theory, though progress is emerging. Ironically however, for accretion engines, MFDT and accretion theory are presently two artificially uncoupled pieces of what should be a single coupled theory. Large scale fields and accretion flows are dynamically intertwined because large scale fields likely play a key role in angular momentum transport. I discuss and synthesize aspects of recent progress in MFDT and accretion disc theory to suggest why the two likely conspire in a unified theory (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
11.
Eric Bois 《Celestial Mechanics and Dynamical Astronomy》1987,42(1-4):141-168
This work presents the expansion of the second-order of an analytical theory of the attitude evolution of an artificial satellite perturbed by given torques. The first-order of the theory has already been presented by the author in Celestial Mechanics39 (1986) 309–327. It is a theory that is valid under very general conditions including slow rotation and inequal axes of inertia. The present theory is suitable for any internal or external disturbing forces producing the torques. A formal solution is expanded in the second-order according to powers of a small parameter characteristic of the order of magnitude of the disturbing torques. These torques are expanded in Fourier series and the theory applies whatever is the length of these series. The coefficients of the solution are given by an iterative formation law. The comparison of the results with a numerical integration based upon a HIPPARCOS model shows that the second order has brought an improvement to the theory by at least one order of magnitude over the results of the first order. 相似文献
12.
The stability of radial solar acoustic oscillations is studied using a time-dependent formulation of mixing-length theory. Though the radiation field is treated somewhat simplistically with the Eddington approximation, and we appreciate that any coupling of the pulsation to the radiation field is important, for the lower frequency radial modes that have been computed this should not produce too serious an error. Instead, we have concentrated upon treating the coupling with convection as accurately as is currently possible with generalized mixing-length theory in order to learn something about its pertinence. Our principal conclusion is that, according to this theory, solar radial acoustic oscillations are expected to be stable and generated by turbulence. Moreover, the theory predicts changes in mode frequency that may, in part, explain the discrepancy between solar observations and the adiabatic pulsation frequencies of theoretical models. We also compute the amplitudes of the modes using a theory of stochastic excitation. These are in good agreement with observed power spectra. 相似文献
13.
Luni-solar perturbations of an Earth satellite 总被引：1，自引：0，他引：1
A. E. Roy 《Astrophysics and Space Science》1969,4(4):375-386
Luni-solar perturbations of the orbit of an artificial Earth satellite are given by modifying the analytical theory of an artificial lunar satellite derived by the author in recent papers. Expressions for the first-order changes, both secular and periodic, in the elements of the geocentric Keplerian orbit of the earth satellite are given, the moon's geocentric orbit, including solar perturbations in it, being found by using Brown's lunar theory.The effects of Sun and Moon on the satellite orbit are described to a high order of accuracy so that the theory may be used for distant earth satellites. 相似文献
14.
Harald H. Soleng 《Astrophysics and Space Science》1987,139(1):13-19
The field equations for Barber's two self-creation theories of gravitation are solved for Friedmann-Robertson-Walker space times, using perfect fluid energy-momentum tensors. Barber's first theory is discussed for the radiation dominated case, whereas cosmologies according to Barber's second sefl-creation theory are constructed for vacuum-dominated, radiation-dominated, and dust-filled cases. 相似文献
15.
B. Kuchowicz 《Astrophysics and Space Science》1976,39(1):157-172
The Einstein-Cartan theory, which is a slight modification of the general theory of relativity, is almost indistinguishable in its practical consequences from the latter theory. A characteristic spin-spin repulsive interaction which is of some importance at ultraheavy densities, prevents the singularities occurring in the Einstein-Cartan treatment. It is shown how this mechanism of preventing the singularity applies to cosmological models in which the spins of matter are aligned along some symmetry axis. Some exact solutions without singularities of the relevant set of equations are obtained. 相似文献
16.
Static Friedmann-Robertson-Walker vacuum models are derived in the scale-covariant theory. Specific functional forms are obtained for the gauge function which occurs in the theory. This is in contrast to the nonstatic vacuum solutions where the gauge function is arbitrary. 相似文献
17.
T. V. Ivanova 《Solar System Research》2013,47(5):359-362
In order to generate an analytical theory of the motion of the Moon by considering planetary perturbations, a procedure of general planetary theory (GPT) is used. In this case, the Moon is considered as an addition planet to the eight principal planets. Therefore, according to the GPT procedure, the theory of the Moon’s orbital motion can be presented in the form of series with respect to the evolution of eccentric and oblique variables with quasi-periodic coefficients, which are the functions of mean longitudes for principal planets and the Moon. The relationship between evolution variables and the time is determined by a trigonometric solution for the independent secular system that describes the secular motion of a perigee and the Moon node by considering secular planetary inequalities. Principal planetary coordinates required for generating the theory of the motion of the Moon includes only Keplerian terms, the intermediate orbit, and the linear theory with respect to eccentricities and inclinations in the first order relative to the masses. All analytical calculations are performed by means of the specialized echeloned Poisson Series Processor EPSP. 相似文献
18.
李林森 《中国天文和天体物理学报》1997,(4)
利用双星自转同步性理论给出了６９个三类密近双星系统中９３个子星的临界同步自转参量和临界自转周期．并把利用临界自转同步参量所计算的临界自转周期与由气体星自转不稳定理论所计算的临界自转周期做了比较，其结果是两者均属同一量级． 相似文献
19.
J. H. Piddington 《Solar physics》1972,22(1):3-19
The dynamo theory of the solar cycle as developed by Parker and others, and the observational models of Babcock and Leighton have been examined, with the conclusion that the dynamo theory is not applicable to the Sun and that the models fail.An essential part of the theory is an adequate effective diffusion coefficient. Fields are continuously sheared and amplified and, in this theory, these may not be allowed to accumulate; all subsurface fields of an old cycle must be eliminated. Ohmic diffusion is negligible and turbulent diffusion is invoked. However, this requires that all solar fields are tangled to a small scale, which is contrary to observation; for Hale's polarity laws are strictly observed, and large-scale surface features are common at the end of an 11-yr cycle in the same general area where new fields are appearing.The erupted (sunspot) fields lie generally above the unerupted, toroidal fields so that, even if they are merged as required, the centroid of the new system would be above that of the old. The result is not a steady-state oscillator, as required, but the complete loss of the solar field.It is concluded that for these and other reasons a shallow, reversing field is unacceptable, and that a deeply penetrating field is required. Reference is made to an alternative theory of the solar cycle based on a deep magnetic field. 相似文献
20.
Bernard Shizgal 《Planetary and Space Science》1977,25(2):203-204
The validity of the Chapman-Enskog method in the calculation of the heat conductivity of the solar wind is studied. The predictions of the Chapman-Enskog theory are compared with known results of rarefied gas kinetic theory. The results suggest that the use of the Chapman-Enskog theory to describe the transport processes in the solar wind is not strictly justified. 相似文献