共查询到20条相似文献，搜索用时 468 毫秒
1.
This paper studies the possibility of lunar capture depending on variations of the solar mass under certain well specified conditions and assumptions regarding the behaviour of the three-body dynamical system formed by the Sun, Earth and Moon. It is found that a large amount of decrease in the solar mass (approximately 37%) would be required to allow capture if the model of the planar restricted problem of three bodies is assumed, if the masses of the Earth and Moon did not change and if the angular momentum of the Sun-Earth system did not change. Such large mass-changes of the Sun can not be associated with radiation mass losses only with catastrophic events, such as stellar close approaches. 相似文献
2.
M. K. Ammar 《Astrophysics and Space Science》2008,313(4):393-408
In this paper the effect of solar radiation pressure on the location and stability of the five Lagrangian points is studied,
within the frame of elliptic restricted three-body problem, where the primaries are the Sun and Jupiter acting on a particle
of negligible mass. We found that the radiation pressure plays the rule of slightly reducing the effective mass of the Sun
and changes the location of the Lagrangian points. New formulas for the location of the collinear libration points were derived.
For large values of the force ratio β, we found that at β=0.12, the collinear point L3 is stable and some families of periodic orbits can be drawn around it. 相似文献
3.
Colin R. McInnes 《Astrophysics and Space Science》2002,282(4):765-772
As the Sun evolves along the main sequence its luminosity will grow, leading to a steadily increasing solar flux at the Earth
with corresponding catastrophic consequences for the biosphere. A novel means of avoiding this terminal route to human evolution
has recently been proposed by Korycansky et al. which utilises a series of grazing fly-pasts of the Earth with a small solar
system body to increase the orbit radius of the Earth over a timescale of order 109 years. This short paper will propose an alternative strategy which utilises a large reflective sail to generate a propulsive
thrust due to solar radiation pressure. It will be shown that if the sail is configured to be in static equilibrium relative
to the Earth, the centre-of-mass of the Earth-sail system slowly accelerates. This scheme offers some advantages in that the
mass of the sail is four orders of magnitude less than the mass to be processed in the scheme of Korycanskyet al. for trajectory
correction manoeuvres alone. In addition, the severe hazard posed by multiple grazing fly-pasts of the Earth by a small solar
system body is avoided. Although offering significant advantages, any thoughts of engineering on an astronomical scale clearly
requires a leap of the imagination and a ready use of liberal assumptions.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
D. J. Scheeres 《Celestial Mechanics and Dynamical Astronomy》1998,70(2):75-98
Starting from the four-body problem a generalization of both the restricted three-body problem and the Hill three-body problem
is derived. The model is time periodic and contains two parameters: the mass ratio ν of the restricted three-body problem
and the period parameter m of the Hill Variation orbit. In the proper coordinate frames the restricted three-body problem
is recovered as m → 0 and the classical Hill three-body problem is recovered as ν → 0. This model also predicts motions described
by earlier researchers using specific models of the Earth–Moon–Sun system. An application of the current model to the motion
of a spacecraft in the Sun perturbed Earth–Moon system is made using Hill's Variation orbit for the motion of the Earth–Moon
system. The model is general enough to apply to the motion of an infinitesimal mass under the influence of any two primaries
which orbit a larger mass.
Using the model, numerical investigations of the structure of motions around the geometric position of the triangular Lagrange
points are performed. Values of the parameter ν range in the neighborhood of the Earth–Moon value as the parameter m increases
from 0 to 0.195 at which point the Hill Variation orbit becomes unstable. Two families of planar periodic orbits are studied
in detail as the parameters m and ν vary. These families contain stable and unstable members in the plane and all have the
out-of-plane stability. The stable and unstable manifolds of the unstable periodic orbits are computed and found to be trapped
in a geometric area of phase space over long periods of time for ranges of the parameter values including the Earth–Moon–Sun
system.
This model is derived from the general four-body problem by rigorous application of the Hill and restricted approximations.
The validity of the Hill approximation is discussed in light of the actual geometry of the Earth–Moon–Sun system.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
5.
D. Nesvorný F. Thomas S. Ferraz-Mello A. Morbidelli 《Celestial Mechanics and Dynamical Astronomy》2002,82(4):323-361
We develop a formalism of the non-singular evaluation of the disturbing function and its derivatives with respect to the canonical variables. We apply this formalism to the case of the perturbed motion of a massless body orbiting the central body (Sun) with a period equal to that of the perturbing (planetary) body. This situation is known as the co-orbital motion, or equivalently, as the 1/1 mean motion commensurability. Jupiter's Trojan asteroids, Earth's co-orbital asteroids (e.g., (3753) Cruithne, (3362) Khufu), Mars' co-orbital asteroids (e.g., (5261) Eureka), and some Jupiter-family comets are examples of the co-orbital bodies in our solar system. Other examples are known in the satellite systems of the giant planets. Unlike the classical expansions of the disturbing function, our formalism is valid for any values of eccentricities and inclinations of the perturbed and perturbing body. The perturbation theory is used to compute the main features of the co-orbital dynamics in three approximations of the general three-body model: the planar-circular, planar-elliptic, and spatial-circular models. We develop a new perturbation scheme, which allows us to treat cases where the classical perturbation treatment fails. We show how the families of the tadpole, horseshoe, retrograde satellite and compound orbits vary with the eccentricity and inclination of the small body, and compute them also for the eccentricity of the perturbing body corresponding to a largely eccentric exoplanet's orbit.This revised version was published online in October 2005 with corrections to the Cover Date. 相似文献
6.
The rotation of the surface layer of the Sun is found to have been accelerated secularly from the sunspot data of 1943 to 1986. To represent the overall state of rotation of the differentially rotating Sun, we define an indexM, by integrating the angular momentum density over the whole surface of the Sun, and call it the angular momentum layer density. The indexM increased monotonically or secularly from 1943 to 1986. This period corresponds to solar cycles 18, 19, 20, and 21. The monotonic increase ofM indicates that a net angular momentum must have steadily been coming from the layer down below the surface. The differential rotation latitudinal dependence profile did not change much from cycle 18 to cycle 20, but at cycle 21 the degree of equatorial acceleration dropped. This aspect is discussed in the context of the 55-year grand cycle. Cycle 21 is the start of grand cycle VI. The latitudinal dependence is less steep at cycle 21. The time scale of secular change of the indexM reflects the time scale of change of linkage of the surface and the deep layer in form of the angular momentum transfer, and that the time scale of the profile change of the differential rotation reflects the time scale of the angular momentum transfer within the surface layer. 相似文献
7.
Maria Gousidou-Koutita 《Earth, Moon, and Planets》1985,32(1):21-45
The present study deals with numerical modeling of the elliptic restricted three-body problem as well as of the perturbed elliptic restricted three-body (Earth-Moon-Satellite) problem by a fourth body (Sun). Two numerical algorithms are established and investigated. The first is based on the method of the series solution of the differential equations and the second is based on a 5th-order Runge-Kutta method. The applications concern the solution of the equations and integrals of motion of the circular and elliptical restricted three-body problem as well as the search for periodic orbits of the natural satellites of the Moon in the Earth-Moon system in both cases in which the Moon describes circular or elliptical orbit around the Earth before the perturbations induced by the Sun. After the introduction of the perturbations in the Earth-Moon-Satellite system the motions of the Moon and the Satellite are studied with the same initial conditions which give periodic orbits for the unperturbed elliptic problem. 相似文献
8.
The theory of optimal control is applied to obtain minimum-time trajectories for solar sail spacecraft for interplanetary
missions. We consider the gravitational and solar radiation forces due to the Sun. The spacecraft is modelled as a flat sail
of mass m and surface area A and is treated dynamically as a point mass. Coplanar circular orbits are assumed for the planets. We obtain optimal trajectories
for several interrelated problem families and develop symmetry properties that can be used to simplify the solution-finding
process. For the minimum-time planet rendezvous problem we identify different solution branches resulting in multiple solutions
to the associated boundary value problem. We solve the optimal control problem via an indirect method using an efficient cascaded
computational scheme. The global optimizer uses a technique called Adaptive Simulated Annealing. Newton and Quasi-Newton Methods
perform the terminal fine tuning of the optimization parameters. 相似文献
9.
Arun Kumar Yadav Badam Singh Kushvah Uday Dolas 《Journal of Astrophysics and Astronomy》2018,39(6):72
An attempt was made to study the dynamics close to the collinear libration point \( L_{2} \) of the radial solar sail circular-restricted three-body problem (RSCRTBP) in the Sun–Jupiter System, where the third massless body is a solar sail. We analyse the qausi-periodic (Lissajous solutions) orbits about the libration point \( L_{2} \). The Lindstedt–Poincaré approximation for the qausi-periodic orbits was used for numerical simulations. We utilized linear quadratic regulator (LQR) to stabilize the full nonlinear model, and linear state-feedback controller was designed to stabilize the trajectory. 相似文献
10.
It is well known that magnetic activity on the Sun modulates from one cycle to the next. The most striking occurrence of this is called a grand minimum where magnetic activity all but disappears. The latest grand minimum occurred between the years 1645 and 1715 and is called the Maunder minimum. In this paper magnetic flux transport simulations are used to consider what type of surface magnetic field configurations may be produced both during and after a grand minimum depending on how the grand minimum occurs. It is shown that the surface configurations during and after a grand minimum strongly depend on the phase of the cycle in which the grand minimum starts and whether it lasts for an odd or even number of cycles. If the grand minimum starts around cycle minimum then a significant amount of large-scale magnetic flux may persist on the Sun at high latitudes during the grand minimum. In contrast, if it starts at cycle maximum during the grand minimum it is possible for there to be essentially zero large-scale magnetic flux over the entire surface of the Sun. It is shown that for a single grand minimum event the reversal of the polar fields at the presently observed time in the solar cycle is only reproduced if the event starts at cycle minimum and extends over an even number of cycles. In contrast, if the grand minimum runs for an odd number of cycles it is possible for there to be no reversal of the polar fields or for the reversals to occur at times inconsistent with our present understanding of the solar cycle. Consequences of the assumptions made in the modelling are discussed and the significance of the simulations for direct modelling of events such as the Maunder minimum are considered. 相似文献
11.
John D. Hadjidemetriou 《Astrophysics and Space Science》1976,40(1):201-224
Several families of the planar general three-body problem for fixed values of the three masses are found, in a rotating frame of reference, where the mass of two of the bodies is small compared to the mass of the third body. These families were obtained by the continuation of a degenerate family of periodic orbits of three bodies where two of the bodies have zero masses and describe circular orbits around a third body with finite mass, in the same direction.The above families represent planetary systems with the body with the large mass representing the Sun and the two small bodies representing two planets or comets. One section of a family is shown to represent the Jupiter family of comets and also a model for the Sun-Jupiter-Saturn system is found.The stability analysis revealed that stability exists for small masses and small eccentricities of the two planets. Planetary systems with relatively large masses and eccentricities are proved to be unstable. In particular, the Jupiter family of comets, for small masses of the two small bodies, and the Sun-Jupiter-Saturn system are proved to be stable. Also, it was shown that resonances are not necessarily associated with instabilities. 相似文献
12.
Long-term changes in the magnetic activity of the Sun were studied in terms of the empirical mode decomposition that revealed
their essential modes. The occurrence of grand minima was also studied in their relation to long-term changes in sunspot activity
throughout the past 11 000 yr. Characteristic timescales of long-term changes in solar activity manifest themselves in the
occurrence of grand minima. A quantitative criterion has been defined to identify epochs of grand minima. This criterion reveals
the important role of secular and bicentennial activity variations in the occurrence of grand minima and relates their amplitudes
with the current activity level, which is variable on a millennial timescale. We have revealed specific patterns in the magnetic
activity between successive grand minima which tend to recur approximately every 2300 yr but occasionally alternate with irregular
changes. Such intermittent activity behavior indicates low dimensional chaos in the solar dynamo due to the interplay of its
dominant modes. The analysis showed that in order to forecast activity level in forthcoming cycles, one should take into account
long-term changes in sunspot activity on a ≈2300-yr timescale. The regularities revealed suggest solar activity to decrease
in the foreseeable future. 相似文献
13.
A scheme, based on the expansion of solar oscillations into spherical harmonics, for the identification of sectorial modes of intermediate degree in the interval 3 < l < 20 is presented. In this range, the frequencies of modes with similar quantum numbers can be very close together, so that a careful spectral analysis of their spatial pattern is needed to effectively separate these modes. The filtering scheme proposed is intended to operate on quantized images of the Sun and reaches satisfactory resolving power by a two-step procedure, namely a straightforward filtering followed by the resolution of a system of linear equations. The results obtained are also shown to be independent on the ecliptic longitude of the Earth. 相似文献
14.
A. V. Usmanov 《Solar physics》1993,143(2):345-363
An attempt is made to infer parameters of the solar corona and the solar wind by means of a numerical, self-consistent MHD simulation. Boundary conditions for the magnetic field are given from the observations of the large-scale magnetic field at the Sun. A two-region, planar (the ecliptic plane is assumed) model for the solar wind flow is considered. Region I of transonic flow is assumed to cover the distances from the solar surface up to 10R
S (R
S is the radius of the Sun). Region II of supersonic, super-Alfvénic flow extends between 10R
S and the Earth's orbit. Treatment for region I is that for a mixed initial-boundary value problem. The solution procedure is similar to that discussed by Endler (1971) and Steinolfson, Suess, and Wu (1982): a steady-state solution is sought as a relaxation to the dynamic equilibrium of an initial state. To obtain a solution to the initial value problem in region II with the initial distribution of dependent variables at 10R
S (deduced from the solution for region I), a numerical scheme similar to that used by Pizzo (1978, 1982) is applied. Solar rotation is taken into account for region II; hence, the interaction between fast and slow solar wind streams is self-consistently treated. As a test example for the proposed formulation and numerical technique, a solution for the problem similar to that discussed by Steinolfson, Suess, and Wu (1982) is obtained. To demonstrate the applicability of our scheme to experimental data, solar magnetic field observations at Stanford University for Carrington rotation 1682 are used to prescribe boundary conditions for the magnetic field at the solar surface. The steady-state solution appropriate for the given boundary conditions was obtained for region I and then traced to the Earth's orbit through region II. We compare the calculated and spacecraft-observed solar wind velocity, radial magnetic field, and number density and find that general trends during the solar rotation are reproduced fairly well although the magnitudes of the density in comparison are vastly different. 相似文献
15.
I. P. Williams 《Celestial Mechanics and Dynamical Astronomy》2003,87(1-2):13-25
The role of tides in deforming and possibly disrupting a secondary body orbiting about a primary body has been known for a considerable time. This was first inspired by the observations of ocean tides on Earth and then seen as playing an important role in the formation and evolution of the Earth–Moon system. Finally, in the beginning of the 20th century it was generally thought to have a significant role in the formation of the solar system through the tidal disruption of the Sun. Here, an overview of the historical developments of the ideas concerned with tidal disruption of a secondary body that can lead to mass loss is given. Some discussion of possible extensions to consider more realistic situations where the secondary body may not be moving on a circular orbit and may not rotate so as to maintain the phase-on configuration to the primary body is also given. 相似文献
16.
J. R. Donnison 《Earth, Moon, and Planets》1984,30(2):107-111
Stars usually form as members of binary or multiple star systems, and it is likely that the Sun was no exception. The mass and position of possible past companions of the Sun is determined by considering the orbital stability of the Solar System. This is achieved by considering the stability of critical three-body subsets comprising the sun-planet-companion star which must be stable if the Solar System is to remain stable as a whole. 相似文献
17.
《Chinese Astronomy and Astrophysics》2019,43(3):305-326
The Sun is the celestial body in the sky with the closest relationship with the Earth. The violent eruptive activities happening on the Sun can greatly impact the human living environment and lead to disastrous consequences. It is well accepted that solar eruptions including the solar flare, prominence eruption and coronal mass ejection are the different manifestations of a single physical process powered by the magnetic free energy gradually stored in the corona prior to eruptions. Therefore, mapping the three-dimensional structure of coronal magnetic field is a prerequisite to understand the initiation mechanism of solar eruptions. Due to the technological and methodological difficulties, routine observations of the coronal magnetic field are still unavailable. Therefore, a number of methods have been developed to reconstruct the coronal magnetic field. This paper mainly reviews the applications of various reconstruction methods to the studies of the solar eruptions in the recent ten years. 相似文献
18.
V. Berezinsky A. Bottino J. Ellis N. Fornengo G. Mignola S. Scopel 《Astroparticle Physics》1996,5(3-4)
Neutrino telescopes of large area offer the possibility of searching for indirect signals of relic neutralinos in the galactic halo, due to annihilations in the Sun or the Earth. Here we investigate the sensitivity, using a supergravity scheme where the soft scalar mass terms are not constrained by universality conditions at the grand unification scale. We first discuss in which regions of the supersymmetric parameter space the neutralino may be considered as a good candidate for cold dark matter. The discovery potential of the search using neutrino telescopes is then compared to that of the direct search for relic neutralinos. 相似文献
19.
We compute the weak stability boundary in the planar circular restricted three-body problem starting from the algorithmic definition, and its generalization by García and Gómez. In addition, we consider a new set of primaries, Sun–Jupiter, to replace the case of Earth–Moon considered in previous studies. Numerical enhancements are described and compared to previous methods. This includes defining the equations of motion in polar coordinates and a modified numerical scheme for the derivation of both stable sets and their boundaries. These enhancements decrease the computational time. New results are obtained by considering the Sun–Jupiter case which we compare to the Earth–Moon case. 相似文献
20.
In a recent paper, published in Astrophys. Space Sci. (337:107, 2012) (hereafter paper ZZX) and entitled “On the triangular libration points in photogravitational restricted three-body problem
with variable mass”, the authors study the location and stability of the generalized Lagrange libration points L
4 and L
5. However their study is flawed in two aspects. First they fail to write correctly the equations of motion of the variable
mass problem. Second they attribute a variable mass to the third body of the restricted three-body model, a fact that is not
compatible with the assumptions used in deriving the mathematical formulation of this model. 相似文献