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1.
Report of the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements: 2003 总被引:1,自引:1,他引:0
P. K. Seidelmann B. A. Archinal M. F. A’Hearn D. P. Cruikshank J. L. Hilton H. U. Keller J. Oberst J. L. Simon P. Stooke D. J. Tholen P. C. Thomas 《Celestial Mechanics and Dynamical Astronomy》2005,91(3-4):203-215
Every three years the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the
directions of the north poles of rotation and the prime meridians of the planets, satellites, and asteroids. This report introduces
a system of cartographic coordinates for asteroids and comets. A topographic reference surface for Mars is recommended. Tables
for the rotational elements of the planets and satellites and size and shape of the planets and satellites are not included,
since there were no changes to the values. They are available in the previous report (Celest. Mech. Dyn. Astron., 82, 83–110, 2002), a version of which is also available on a web site. 相似文献
2.
Alexei V. Tsygvintsev 《Celestial Mechanics and Dynamical Astronomy》2007,99(1):23-29
We consider the Newtonian planar three-body problem with positive masses m
1, m
2, m
3. We prove that it does not have an additional first integral meromorphic in the complex neighborhood of the parabolic Lagrangian
orbit besides three exceptional cases ∑m
i
m
j
/(∑m
k
)2 = 1/3, 23/33, 2/32 where the linearized equations are shown to be partially integrable. This result completes the non-integrability analysis
of the three-body problem started in papers [Tsygvintsev, A.: Journal für die reine und angewandte Mathematik N 537, 127–149
(2001a); Celest. Mech. Dyn. Astron. 86(3), 237–247 (2003)] and based on the Morales–Ramis–Ziglin approach. 相似文献
3.
We use a three dimensional generalization of Szebehely’s invariant relation obtained by us (Makó and Szenkovits, Celest. Mech.
Dyn. Astron. 90, 51, 2004) in the elliptic restricted three-body problem, to establish more accurate criterion of the Hill stability. By
using this criterion, the Hill stability of four extrasolar planets (γ Cephei Ab, Gliese 86 Ab, HD 41004 Ab and HD 41004 Bb) is investigated. 相似文献
4.
Jacques Henrard 《Celestial Mechanics and Dynamical Astronomy》2005,93(1-4):101-112
In a previous paper (The Rotation of Europa, Henrard, Celest. Mech. Dyn. Astr., 91, 131–149, 2005) we have developed a semi-analytical theory of Europa, one of the Galilean satellites of Jupiter. It is based
on a synthetic theory of the orbit of Europa and is developed in the framework of Hamiltonian formalism. It was assumed that
Europa is a rigid body and Jupiter a point mass. Several additional effects should be investigated in order to complete the
theory. The present contribution considers the effect of the shape of Jupiter and of the gravitational pull of Io. The sensitivity
of the main theory to a change in the values of the moments of inertia of Europa is also considered. 相似文献
5.
6.
Christos Efthymiopoulos 《Celestial Mechanics and Dynamical Astronomy》2005,92(1-3):29-52
A symplectic mapping model for the co-orbital motion (Sándor et al., 2002, Cel. Mech. Dyn. Astr. 84, 355) in the circular restricted three body problem is used to derive Nekhoroshev stability estimates for the Sun–Jupiter Trojans. Following a brief review of the analytical part of Nekhoroshev theory, a direct method is developed to construct formal integrals of motion in symplectic mappings without use of a normal form. Precise estimates are given for the region of effective stability based on the optimization of the size of the remainder of the formal series. The stability region found for t=1010 yrs corresponds to a libration amplitude Dp=10.6°. About 30% of asteroids with accurately known proper elements (Milani, 1993, Cel. Mech. Dyn. Astron. 57, 59), at low eccentricities and inclinations, are included within this region. This represents an improvement with respect to previous estimates given in the literature. The improvement is due partly to the choice of better variables, but also to the use of a mapping model, which is a simplification of the circular restricted three body problem. 相似文献
7.
Hans Rickman Marc Fouchard Giovanni B. Valsecchi Christiane Froeschlé 《Earth, Moon, and Planets》2005,97(3-4):411-434
We investigate different approximate methods of computing the perturbations on the orbits of Oort cloud comets caused by passing stars, by checking them against an accurate numerical integration using Everhart’s RA15 code. The scenario under study is the one relevant for long-term simulations of the cloud’s response to a predefined set of stellar passages. Our sample of stellar encounters simulates those experienced by the Solar System currently, but extrapolated over a time of 1010 years. We measure the errors of perihelion distance perturbations for high-eccentricity orbits introduced by several estimators – including the classical impulse approximation and Dybczyński’s (1994, Celest. Mech. Dynam. Astron. 58, 1330–1338) method – and we study how they depend on the encounter parameters (approach distance and relative velocity). We introduce a sequential variant of Dybczyński’s approach, cutting the encounter into several steps whereby the heliocentric motion of the comet is taken into account. For the scenario at hand this is found to offer an efficient means to obtain accurate results for practically any domain of the parameter space. 相似文献
8.
Linda Dimare 《Celestial Mechanics and Dynamical Astronomy》2010,107(4):427-449
We study a particular kind of chaotic dynamics for the planar 3-centre problem on small negative energy level sets. We know
that chaotic motions exist, if we make the assumption that one of the centres is far away from the other two (see Bolotin
and Negrini, J Differ Equ 190:539–558, 2003): this result has been obtained by the use of the Poincaré-Melnikov theory. Here
we change the assumption on the third centre: we do not make any hypothesis on its position, and we obtain a perturbation
of the 2-centre problem by assuming its intensity to be very small. Then, for a dense subset of possible positions of the
perturbing centre in
\mathbbR2{\mathbb{R}^2} , we prove the existence of uniformly hyperbolic invariant sets of periodic and chaotic almost collision orbits by the use
of a general result of Bolotin and MacKay (Celest Mech Dyn Astron 77:49–75, 77:49–75, 2000; Celest Mech Dyn Astron 94(4):433–449,
2006). To apply it, we must preliminarily construct chains of collision arcs in a proper way. We succeed in doing that by the classical regularisation of the 2-centre problem and the use of the periodic
orbits of the regularised problem passing through the third centre. 相似文献
9.
Michael Efroimsky 《Celestial Mechanics and Dynamical Astronomy》2006,96(3-4):259-288
We continue the study undertaken in Efroimsky [Celest. Mech. Dyn. Astron. 91, 75–108 (2005a)] where we explored the influence of spin-axis variations of an oblate planet on satellite orbits. Near-equatorial satellites had long been believed to keep up with the oblate primary’s equator in the cause of its spin-axis variations. As demonstrated by Efroimsky and Goldreich [Astron. Astrophys. 415, 1187–1199 (2004)], this opinion had stemmed from an inexact interpretation of a correct result by Goldreich [Astron. J. 70, 5–9 (1965)]. Although Goldreich [Astron. J. 70, 5–9 (1965)] mentioned that his result (preservation of the initial inclination, up to small oscillations about the moving equatorial plane) was obtained for non-osculating inclination, his admonition had been persistently ignored for forty years. It was explained in Efroimsky and Goldreich [Astron. Astrophys. 415, 1187–1199 (2004)] that the equator precession influences the osculating inclination of a satellite orbit already in the first order over the perturbation caused by a transition from an inertial to an equatorial coordinate system. It was later shown in Efroimsky [Celest. Mech. Dyn. Astron. 91, 75–108 (2005a)] that the secular part of the inclination is affected only in the second order. This fact, anticipated by Goldreich [Astron. J. 70, 5–9 (1965)], remains valid for a constant rate of the precession. It turns out that non-uniform variations of the planetary spin state generate changes in the osculating elements, that are linear in , where is the planetary equator’s total precession rate that includes the equinoctial precession, nutation, the Chandler wobble, and the polar wander. We work out a formalism which will help us to determine if these factors cause a drift of a satellite orbit away from the evolving planetary equator.By “precession,” in its most general sense, we mean any change of the direction of the spin axis of the planet—from its long-term variations down to nutations down to the Chandler wobble and polar wander. 相似文献
10.
Yoshio Kubo 《Celestial Mechanics and Dynamical Astronomy》2012,112(1):99-106
Kubo (Celest Mech Dyn Astron 110:143–168, 2011) investigated the kinematical structure of the perturbation in the rotation of the elastic Earth due to the deformation caused
by the outer bodies. In that paper, while the mechanism for the perturbation of the figure axis was made clear, that for the
rotational axis was not shown explicitly. In the present study, following the same method, the structure of the perturbation
of the rotational axis is investigated. This perturbation consists of the direct perturbation and the convective perturbation.
First the direct perturbation is shown to be (A − C)/A times as large as that of the figure axis, coinciding with the analytical expressions obtained in preceding studies by other
authors. As for the convective perturbation, which appears only in the perturbation of the rotational axis but not in that
of the figure axis, it is shown to be (A − C)/A times the angular separation between the original figure axis and the induced figure axis produced by the elastic deformation,
A and C being the principal moments of inertia of the Earth. If the perturbing bodies are motionless, the conclusion of Kubo (Celest
Mech Dyn Astron 105:261–274, 2009) holds strictly, i.e. the sum of the direct and the convective perturbations of the rotational axis coincides with the perturbation
of the figure axis. 相似文献
11.
A. S. Ovsak 《Kinematics and Physics of Celestial Bodies》2010,26(2):86-88
The algorithm for determining effective optical thickness of absorption line formation in a plane-parallel homogeneous planetary
atmosphere is presented. The case of anisotropic scattering is considered. The results of numerical calculations of τ
e
(μ0) at the scattering angle γ = π for some values of the single scattering albedo λ and the parameter of the Heyney-Greenstein
scattering indicatrix g are given. The refined equation for the function T
m
(−μ, μ0) is presented. 相似文献
12.
A possible correlation between the magnetic and velocity fields has been analyzed based on the SOHO/MDI magnetograms and Dopplergrams.
It is found that the observed large-scale weak magnetic field (weaker than 50 G (gauss)) is correlated with the velocity statistically.
The curves of u⋅b with latitude, where u and b are the velocity and magnetic fields in a rectangular region (±15○ in longitude, ±45○ in latitude) on the Sun, show the same patterns in the years 2000, 2004, and 2007. The patterns indicate that u and b are positively correlated near the equator but are anti-correlated at the middle latitudes. For a strong magnetic field between
50 G and 3000 G, the curves of u⋅b with latitude show the same tendencies at the middle latitudes. Near the equator, however, the slope of the curve is positive
in 2000 and is negative in 2004 and 2007. In addition, we give an estimation for the amplitude of the cross helicity h
χ
(hc=[`(u·b)]h_{\chi}=\overline{\mathbf{u}\cdot\mathbf{b}}) inferred from the MDI data, which is of the order of 103 G m s−1 near the center of the solar disk. 相似文献
13.
Alberto Escapa 《Celestial Mechanics and Dynamical Astronomy》2011,110(2):99-142
We explore the evolution of the angular velocity of an elastic Earth model, within the Hamiltonian formalism. The evolution
of the rotation state of the Earth is caused by the tidal deformation exerted by the Moon and the Sun. It can be demonstrated
that the tidal perturbation to spin depends not only upon the instantaneous orientation of the Earth, but also upon its instantaneous
angular velocity. Parameterizing the orientation of the Earth figure axis with the three Euler angles, and introducing the
canonical momenta conjugated to these, one can then show that the tidal perturbation depends both upon the angles and the
momenta. This circumstance complicates the integration of the rotational motion. Specifically, when the integration is carried
out in terms of the canonical Andoyer variables (which are the rotational analogues to the orbital Delaunay variables), one
should keep in mind the following subtlety: under the said kind of perturbations, the functional dependence of the angular
velocity upon the Andoyer elements differs from the unperturbed dependence (Efroimsky in Proceedings of Journées 2004: Systèmes
de référence spatio-temporels. l’Observatoire de Paris, pp 74–81, 2005; Efroimsky and Escapa in Celest. Mech. Dyn. Astron. 98:251–283, 2007). This happens because, under angular velocity dependent perturbations, the requirement for the Andoyer elements to be canonical
comes into a contradiction with the requirement for these elements to be osculating, a situation that parallels a similar
antinomy in orbital dynamics. Under the said perturbations, the expression for the angular velocity acquires an additional
contribution, the so called convective term. Hence, the time variation induced on the angular velocity by the tidal deformation
contains two parts. The first one comes from the direct terms, caused by the action of the elastic perturbation on the torque-free
expressions of the angular velocity. The second one arises from the convective terms. We compute the variations of the angular
velocity through the approach developed in Getino and Ferrándiz (Celest. Mech. Dyn. Astron. 61:117–180, 1995), but considering the contribution of the convective terms. Specifically, we derive analytical formulas that determine the
elastic perturbations of the directional angles of the angular velocity with respect to a non-rotating reference system, and
also of its Cartesian components relative to the Tisserand reference system of the Earth. The perturbation of the directional
angles of the angular velocity turns out to be different from the evolution law found in Kubo (Celest. Mech. Dyn. Astron.
105:261–274, 2009), where it was stated that the evolution of the angular velocity vector mimics that of the figure axis. We investigate comprehensively
the source of this discrepancy, concluding that the difference between our results and those obtained in Ibid. stems from an oversimplification made by Kubo when computing the direct terms. Namely, in his computations Kubo disregarded
the motion of the tide raising bodies with respect to a non-rotating reference system when compared with the Earth rotational
motion. We demonstrate that, from a numerical perspective, the convective part provides the principal contribution to the
variation of the directional angles and of length of day. In the case of the x and y components in the Tisserand system, the convective contribution is of the same order of magnitude as the direct one. Finally,
we show that the approximation employed in Kubo (Ibid.) leads to significant numerical differences at the level of a hundred micro-arcsecond. 相似文献
14.
Michael Nauenberg 《Celestial Mechanics and Dynamical Astronomy》2007,97(1):1-15
Numerical solutions are presented for a family of three dimensional periodic orbits with three equal masses which connects
the classical circular orbit of Lagrange with the figure eight orbit discovered by C. Moore [Moore, C.: Phys. Rev. Lett. 70, 3675–3679 (1993); Chenciner, A., Montgomery, R.: Ann. Math. 152, 881–901 (2000)]. Each member of this family is an orbit with finite angular momentum that is periodic in a frame which rotates
with frequency Ω around the horizontal symmetry axis of the figure eight orbit. Numerical solutions for figure eight shaped
orbits with finite angular momentum were first reported in [Nauenberg, M.: Phys. Lett. 292, 93–99 (2001)], and mathematical proofs for the existence of such orbits were given in [Marchal, C.: Celest. Mech. Dyn. Astron.
78, 279–298 (2001)], and more recently in [Chenciner, A. et al.: Nonlinearity 18, 1407–1424 (2005)] where also some numerical solutions have been presented. Numerical evidence is given here that the family
of such orbits is a continuous function of the rotation frequency Ω which varies between Ω = 0, for the planar figure eight
orbit with intrinsic frequency ω, and Ω = ω for the circular Lagrange orbit. Similar numerical solutions are also found for
n > 3 equal masses, where n is an odd integer, and an illustration is given for n = 21. Finite angular momentum orbits were also obtained numerically for rotations along the two other symmetry axis of the
figure eight orbit [Nauenberg, M.: Phys. Lett. 292, 93–99 (2001)], and some new results are given here. A preliminary non-linear stability analysis of these orbits is given
numerically, and some examples are given of nearby stable orbits which bifurcate from these families. 相似文献
15.
Families of Periodic Orbits Emanating From Homoclinic Orbits in the Restricted Problem of Three Bodies 总被引:2,自引:1,他引:1
We describe and comment the results of a numerical exploration on the evolution of the families of periodic orbits associated
with homoclinic orbits emanating from the equilateral equilibria of the restricted three body problem for values of the mass
ratio larger than μ
1. This exploration is, in some sense, a continuation of the work reported in Henrard [Celes. Mech. Dyn. Astr. 2002, 83, 291]. Indeed it shows how, for values of μ. larger than μ
1, the Trojan web described there is transformed into families of periodic orbits associated with homoclinic orbits. Also we describe how families
of periodic orbits associated with homoclinic orbits can attach (or detach) themselves to (or from) the best known families
of symmetric periodic orbits.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
16.
S. Bilir T. Güver I. Khamitov T. Ak S. Ak K. B. Coşkunoğlu E. Paunzen E. Yaz 《Astrophysics and Space Science》2010,326(1):139-150
We present CCD BV and JHK
s
2MASS photometric data for the open cluster NGC 1513. We observed 609 stars in the direction of the cluster up to a limiting
magnitude of V∼19 mag. The star-count method showed that the centre of the cluster lies at α
2000=04
h
09
m
36
s
, δ
2000=49°28′43″ and its angular size is r=10 arcmin. The optical and near-infrared two-colour diagrams revealed the colour excesses in the direction of the cluster
as E(B−V)=0.68±0.06, E(J−H)=0.21±0.02 and E(J−K
s
)=0.33±0.04 mag. These results are consistent with normal interstellar extinction values. Optical and near-infrared Zero Age
Main-Sequences (ZAMS) provided an average distance modulus of (m−M)0=10.80±0.13 mag, which can be translated into a distance of 1440±80 pc. Finally, using Padova isochrones we determined the
metallicity and age of the cluster as Z=0.015±0.004 ([M/H]=−0.10±0.10 dex) and log (t/yr)=8.40±0.04, respectively. 相似文献
17.
We revisit a set of symplectic variables introduced by Andre Deprit (Celest Mech 30, 181–195, 1983), which allows for a complete symplectic reduction in rotation invariant Hamiltonian systems, generalizing to arbitrary dimension
Jacobi’s reduction of the nodes. In particular, we introduce an action-angle version of Deprit’s variables, connected to the
Delaunay variables, and give a new hierarchical proof of the symplectic character of Deprit’s variables. 相似文献
18.
The distribution of pairwise distances f(l) for different dependences r(z) of the metric distance is used to reveal inhomogeneities in the spatial distribution of 201 long (T
90>2s) gamma-ray bursts with measured redshifts z. For a fractal set with dimensionality D, this function behaves asymptotically as f(l) ∼ l
D−1 for small l. Signs of fractal behavior with dimensionality D = 2.2–2.5 show up in all the models considered for the spatial distribution of the gamma-ray bursts. Several spatially distinct
groups of gamma-ray bursts are identified. The group with equatorial coordinates ranging from 23h56m to 0h49m and δ from +19° to +23° with redshifts of 0.81–0.94 is examined separately. 相似文献
19.
We have discussed non-linear stability in photogravitational non-planar restricted three body problem with oblate smaller
primary. By photogravitational we mean that both primaries are radiating. We normalized the Hamiltonian using Lie transform
as in Coppola and Rand (Celest. Mech. 45:103, 1989). We transformed the system into Birkhoff’s normal form. Lie transforms reduce the system to an equivalent simpler system
which is immediately solvable. Applying Arnold’s theorem, we have found non-linear stability criteria. We conclude that L
6 is stable. We plotted graphs for (ω
1,D
2). They are rectangular hyperbola. 相似文献
20.
B. Khalesseh 《Astrophysics and Space Science》1998,260(3):299-307
New radial velocity measurements of the Algol-type eclipsing binary AI Dra, based on Reticon observations, are presented.
The velocity measures themselves are based on fitting theoretical profiles, generated by a physical model of the binary, to
the observed cross-correlation function (ccf). Such profiles match this function very well, much better in fact that Gaussian
profiles which are generally used. Measuring the ccf's with Gaussian profiles yields following results: mp sin3 i=2.55± 0.05m⊙, ms sin3 i = 1.14 ± 0.03m⊙, (ap + as) sin i=7.34 ±0.05R⊙, and mp/ms =2.23± 0.05. Where as measuring the ccf's with theoretical profiles yields a mass ratio of 2.33 and following results:
mp sin3 i=2.84± 0.05m⊙, ms sin3 i=1.22 ± 0.03m⊙, (ap +as) sin i=7.56± 0.05R⊙.
The system comprising a semi-detached configuration. From the solution of a previously published light curved and combining
it's results with the spectroscopic orbit, one can lead to the following physical parameters: mp =2.99m⊙, ms =1.28m⊙, > Tp < =9600 K, > Ts < =5400 K, > Rp < =2.35R⊙, > Rs < =2.12R⊙. The system comprising an AO primary and a secondary of G2 spectral type.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献