共查询到20条相似文献，搜索用时 359 毫秒
1.
G P. Horedt 《Celestial Mechanics and Dynamical Astronomy》1974,10(3):319-326
The delimitations of the librational motion around the Lagrangian triangular pointsL 4,L 5 are investigated within the framework of the restricted circular three body problem according to Brown's and Thüring's theory. The isotropic mass variation of the primaries does not exceed the order of the small primary and the derivatives of the masses with respect to the time are negligible second order quantities. The amplitude of the maximum elongations with respect to the small primary remains unchanged. The expression for the maximum variation of the distance of the particle from the large mass has the same form as in the classical problem with constant masses. 相似文献
2.
Vittorio Banfi 《Earth, Moon, and Planets》1991,54(3):269-282
A theoretical model, based on particular type of the restricted three-body problem, is here presented in order to demonstrate the existence of a possible planetary motion near the center of mass in a binary star system. The superposition principle is used, with the introduction of two fictitious negative masses in order to simulate the real two primary bodies system. 相似文献
3.
Thomas Rauch 《Astrophysics and Space Science》2004,291(3-4):275-282
AA Dor is an eclipsing, close, post common-envelope binary (PCEB) consisting of a sdOB primary star and an unseen secondary with an extraordinary small mass (M 2≈ 0.066 M ⊙)—formally a brown dwarf. The brown dwarf may have been a former planet which survived a common envelope (CE) phase and has even gained mass. A recent determination of the components’ masses from results of NLTE spectral analysis and subsequent comparison to evolutionary tracks shows a discrepancy compared to masses derived from radial-velocity and the eclipse curves. Phase-resolved high-resolution and high-SN spectroscopy was carried out in order to investigate this problem. We present results of a NLTE spectral analysis of the primary, an analysis of its orbital parameters, and discuss possible evolutionary scenarios. 相似文献
4.
S. E. Abd El-Bar 《Astrophysics and Space Science》2014,350(1):155-168
An approximate solution of the encounter problem of two small satellites describing initially elliptical orbits around a massive oblate primary is obtained. The equations of motion of the center of mass of the two masses are developed in the most general form without any restrictions on the orbital elements. The method of multiple scales which seeks a solution whose behavior depends on several time scales is used. To overcome the singularity the equations of motion are transformed to the Struble variables. An analytical second order theory of the evolution dynamics is obtained. A MATHEMATICA program is constructed. The evolution dynamics of the orbital parameters between the perturbed and the unperturbed cases are plotted. The effect of changing eccentricity and changing inclination on the orbital parameters are highlighted. 相似文献
5.
The generalization of the fluid-dynamical approach from one-component star clusters to clusters with several stellar groups (as far as the star masses are concerned) has been applied to the study of two-component clusters. Rather extreme values of stellar masses and masses of groups were chosen in order to emphasize the different dynamical evolutions and asymptotic behaviours. Escape of stars from clusters and the problem of equipartition of kinetic energy among the two star groups are discussed. Comparisons of the main features of our results with those obtained by other authors have shown a good agreement. Some characteristic properties of the last computed models with an age of 18×109 yr have been pointed out and discussed in relation with some observed features of galactic globular clusters. 相似文献
6.
We establish the solution of the ninth order — in masses — canonical J-S equations of motion by Hori-Lie technique — i.e., by expressing the initial Poincaré canonical variables as functions of the new variables through the Hori-Lie canonical transformation. Terms of order higher than 9 in the masses are neglected. 相似文献
7.
The photoelectric light curves of TW Dra obtained by Baglow (1952) and by Walter (1978) have been re-analysed by means of Wood's (1972) model in order to obtain accurate photometric elements. Significantly different elements have resulted from the two sets of observations, but more confidence can be given to the elements deduced from Walter's (1978) data. Radii and luminosities have been computed with the aid of Popper's (1978) new values for masses.TW Dra is confirmed to be a typical sd-system, having a distinctly oversized and overluminous secondary. Interestingly, the primary appears to be slightly more luminous than expected for a Main-Sequences star, in agreement with theoretical predictions for present primaries of massexchange binaries systems. 相似文献
8.
P. Hellings 《Astrophysics and Space Science》1984,104(1):83-109
The post-RLOF structure of the secondary after relaxation towards thermal equilibrium is calculated for a large grid of massive close binaries evolving through an early caseB of mass transfer. The initial primary masses range between 15 and 30M
o, the initial mass ratio between 0.3 and 0.9. The possibility that matter leaves the system during RLOF is included using an additional free parameter . The calculations are based on the accretion and relaxation properties of massive accretion stars. Conclusions on the post-RLOF secondaries are presented in function of , M1i, andq
i
, in the form of tables and figures on the post-RLOF positions in the HR diagram, the final masses, mass ratios, chemical profiles and the remaining core-hydrogen burning lifetime. It is found that all systems starting from initial conditions in the grid specified above evolve sequentially, i.e. the primary evolves into a supernova before the end of core H burning of the secondary. No WR+WR systems are encountered. The results are used to determine the masses of ten double lined spectroscopic WR+OB binaries. Most of the WR masses are in the range 8–14M
o, although the sample is subject to some important selection effects. One WR+OB binary has a WR mass between 4 and 5M
o. It is argued that mass determinations based only on the spectral type of the secondary yield WR masses that are too high up to a factor two. 相似文献
9.
Tilemahos J. Kalvouridis 《Celestial Mechanics and Dynamical Astronomy》2008,102(1-3):191-206
The focus of this contribution is an effort to review and report the main results obtained so far, concerning the periodic motions of a small body in the combined gravitational field created by a regular ν-gon arrangement of ν big bodies with equal masses, where ν > 7, and another central primary with different mass. Various types of planar periodic motions are presented and networks of characteristic curves of families are depicted, in order to show their distribution in the space of the initial conditions, as well as the evolution of their members that are also examined under the variation of the parameters of the system. Furthermore, the regions of the allowed three-dimensional motions, as well as their variation, are illustrated by means of the zero-velocity surfaces. All this new material is added to the already existing data, and completes thus the profile of the dynamical behavior of the system. 相似文献
10.
For coplanar circular orbits, the mutual perturbations between two bodies can be expressed in term of the argument of Jacobian elliptic functions instead of the difference of the mean longitudes. For a given pair of planets, such a change of time variable improves the convergence of the developments. At the first order of planetary masses an integration of Lagrange's equations for the osculating elements is performed. When compared to classical developments the results are reduced by an important factor. The method is then extended to the mutual perturbations of Jupiter and Saturn, at any order of planetary masses, either with Fourier series with two arguments, or with one argument solely, taking advantage of the close commensurability of the mean motions. 相似文献
11.
Zhi-Yao Yu Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2005,5(2):159-164
Many galaxies are thought to contain massive black holes, with masses in excess of ten million solar masses, at their centres and warped circumnu-clear toruses. The best evidence comes from observing gas or masers rotating rapidly within a circumnuclear torus surrounding a central body. Here we report on the first MERLIN observations of line emission from the OH megamaser toward IRAS 10173+0828. The position of peak flux contours of the OH megamaser is consistent with that of the continuum in IRAS 10173+0828. This means that the OH megamaser is a diffuse unsaturated maser which could amplify the diffuse 18 cm continuum emission with an amplification factor of order unity. 相似文献
12.
A model is presented consisting of two different axially deformed polytropic spheroids, homocentric and coaxial — with arbitrary values for the two masses, the two equatorial radii and the two polytropic indices — interacting with each other only gravitationally. The model represents the two main components, halo and bulge plus disk, of a galaxy. The flattening of the two spheroids is assumed to be due to rigid-body rotation and tidal interaction, and the treatment follows closely the method of Chandrasekhar and Lebovitz for single polytropic structures. All useful quantities are evaluated up to first order in the two rotation frequencies. The main properties of sequences of models intended to mimic evolution at constant masses and constant angular momenta are presented. 相似文献
13.
Higher order corrections (up to n-th order) are obtained for the perihelion precession in binary systems like OJ287 using the Schwarzschild metric and complex integration. The corrections are performed considering the third root of the motion equation and developing the expansion in terms of \(r_{s}/ (a(1-e^{2}) )\).The results are compared with other expansions that appear in the literature giving corrections to second and third order. Finally, we simulate the shape of relativistic orbits for binary systems with different masses. 相似文献
14.
Bryan C. Brown 《Celestial Mechanics and Dynamical Astronomy》1981,23(3):203-221
This paper presents the results of an investigation into the secular behavior of the orbits of the Galilean satellites of Jupiter. Kamel's perturbation method is used to remove all the explicitly periodic variables from the differential equations that describe the long period behavior of the orbits to third order in the masses, and the resulting differential equations for the secular behavior are then solved. Several numerical examples are given to illustrate the sensitivity of the solution to variations in the masses of the satellites. 相似文献
15.
Nils Aall Barricelli 《Earth, Moon, and Planets》1988,41(1):1-43
The main topic of this paper is to investigate the exchange of mass and angular momentum between a satellite or planetary system and its primary, and the effects of this exchange to axial rotations and satellite orbits. Various applications on the calculation of axial rotations, present and past satellite masses and orbits and other implications of the theory are presented. 相似文献
16.
Michael J. Clark 《Astrophysics and Space Science》2018,363(10):217
A theoretical basis for modifying Newtonian dynamics on a galactic scale can be obtained by postulating that cosmic rays interact with graviton exchanges between distant masses. This assumes that these charged particles move under the influence of local electromagnetic fields rather than the weak gravitational fields of distant matter. It leads to an enhancement of graviton exchanges between distant masses via an additional gravitational force term inversely proportional to distance. At planetary and local interstellar distances this predicts an extremely small additional gravitational force, but it can become significant on a galactic scale. The model is used here to predict rotational velocities in a wide range of galaxies including the Milky Way, Andromeda (M31) and some galaxies in the THINGS study. Results are obtained assuming a galactic cosmic ray density consistent with observations in the solar system. This approach is compared with the dark matter hypothesis and with Modified Newtonian Dynamics (MOND), the two primary postulates used to explain the constant rotational velocities observed in most galaxies. 相似文献
17.
N. V. Emel’yanov 《Solar System Research》2017,51(1):20-37
The general approach to studying the dynamics of moons of planets and asteroids consists in developing more and more accurate models of motion based on observational data. Not only the necessary ephemerides, but also some physical parameters of planets and moons are obtained this way. It is demonstrated in the present study that progress in this field is driven not only by the increase in accuracy of observations. The accuracy of ephemerides may be increased by expanding the observation time interval. Several problems arise on the way toward this goal. Some of them become apparent only when the procedure of observational data processing and use is examined in detail. The method used to derive astrometric data by processing the results of photometric observations of mutual occultations and eclipses of planetary moons is explained below. The primary contribution to the error of astrometric results is produced by the unaccounted noise level in photometric readings and the inaccuracy of received values of the albedo of moons. It is demonstrated that the current methods do not allow one to eliminate the noise completely. Extensive additional photometric measurements should be performed at different angles of rotation of moons and in different spectral bands of the visible wavelength range in order to obtain correct values of the albedo of moons. Many new distant moons of the major planets have been discovered in the early 21st century. However, the observations of these moons are scarce and were performed over short time intervals; as a result, some of the moons were lost. The necessity of further observations of these Solar System bodies is pointed out in the present study. Insufficient knowledge of asteroid masses is an obstacle to improving the accuracy of the ephemerides of Mars. The basic method for determining the masses of large asteroids consists in analyzing their influence on the motion of Mars, the Earth, and spacecraft. The masses of more than 100 large asteroids were determined this way. One of the principal techniques for Earth-based measurement of the masses of asteroids involves astrometric observations of binary asteroids. The determination of relative coordinates is made rather difficult by the apparent proximity of components. The success of these efforts depends on the availability of instrumentation and the expertise of observers skilled in adaptive optics and speckle interferometry. Collaboration between different research teams and observers is absolutely necessary. 相似文献
18.
V. Muntean A. F. J. Moffat A. N. Chené A. de la Chevrotière 《Monthly notices of the Royal Astronomical Society》2009,399(4):1977-1987
A spectroscopic study of the binary Wolf–Rayet (WR)+O system WR 145 is performed, in order to determine the radial velocity orbits of the individual stars, the angle of orbital inclination and the stellar masses. The emission and absorption components are separated from the original spectra, allowing us to confirm the spectral classification WN 7o/CE of the hybrid WR component and to derive a spectral classification O7V((f)) for the O star. A study of the wind-collision properties is performed. Fitting the radial velocity and full width at half-maximum of the excess emission with Lührs' model results in an inclination angle of i = 63° , leading to estimates of the stellar masses: M WR = 18 M⊙ and M O = 31 M⊙ . Both of these masses are compatible with those of other stars of similar types. 相似文献
19.
Global stability regions are found for classi orbits of the circular restricted 3-body problem for primary masses equal and Jacobi constantK>15.5. As this constant decreases, the stability, region shrinks extremely rapidly. 相似文献
20.
We extend the construction of the Jupiter-Saturn theory to include all the terms up to the seventh order in the masses. The Hori-Lie transformation technique is employed. The Jacobian coordinates are adopted and the theory is expressed in terms of the canonical non-singular variables of H. Poincaré. 相似文献