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1.
Osman Demircan 《Astrophysics and Space Science》1979,61(2):507-515
Some properties of the quantitiesB
2m
(Smith, 1977) inherent in the frequency-domain approach have been deduced, and a general expression for them in terms of the eclipse elementsr
1,2,i andL
1 of the basic model has been presented (Section 2).An expansion for the loss of light (1–l) into a Fourier sine series alone have been introduced, and its coefficientsb
m
presented (Section 3) in terms of the same eclipse elements. A method of increasing the rate of convergence of this series has been given in Section 4. The methods for obtaining the elements of eclipsing binaries by making use of all these quantities in the frequency-domain can likewise be generalized to cover the photometric effects of gravitational and radiative interaction between the components. 相似文献
2.
Osman Demircan 《Astrophysics and Space Science》1980,67(2):367-374
An integral transform called the momentsA
2m of the light curves has been introduced by Kopal (1975) and utilized in the subsequent papers for an analysis of the light curves of eclipsing variables. The aim of the present paper is to generalize this integral transform by two distinct ways: (i) by introducing an exponential factor, and (ii) a Jacobi polynomial as multiplicative factor into the integrand of the transformA
2m. Observational values of these general transforms are likewise obtainable. They have been expressed in terms of eclipse elementsr
1,2,i andL
1. These expressions can be used to solve the eclipse elements in terms of observed quantities. Free parameters in the expressions increase the flexibility in applications and may be utilized to improve the determinacy of the elements. 相似文献
3.
G. Antonacopoulos 《Astrophysics and Space Science》1972,17(2):267-276
The secular terms of the planetary disturbing function are given, after elimination of short period terms by von Zeipel's
transformation.
The adequacy of this expansion up to terms of eighth order in the inclination and eccentricity is investigated by numerical
processes, as a function of the Keplerian elementsa, e andi. The eccentricityé of the outer planet, is taken equal to zero.
It is concluded that for values ofi which are not small the inclusion of additional terms in the expression for the disturbing function, results to drastic changes
in its values, while larger values ofe do not have an equaly large effect on the disturbing function. 相似文献
4.
Osman Demircan 《Astrophysics and Space Science》1979,62(1):235-240
The aim of the present paper is to establish two further series expansions (alternative to those given in Demircan, 1979a, b, c), for the observed light changes of eclipsing binary system. The coefficients of these expansions have also been expressed in the form of general series expansions in terms of the eclipse elementsr
1.2,i andL
1 of the spherical model on which all other distorted models may be based (Kopal, 1975, 1976) in an analysis in the frequency-domain. 相似文献
5.
Osman Demircan 《Astrophysics and Space Science》1979,61(2):499-506
The Fourier techniques developed so far for an analysis of eclipsing binary light curves have been re-discussed. The Fourier coefficients for the analysis have been derived in a simple form of series expansions, in terms of eclipse elements, valid for any type of eclipse (regardless of whetherr
1r
2).These coefficients may be utilized to solve the eclipse elements in terms of the observed characteristics of the light curves. A general relation between the observed quantitiesl and , and the eclipse elementsr
1,2,i andL
1 has also been given in the form of series expansions which can be used for the synthesis of the light curves. 相似文献
6.
Paul E. Nacozy 《Celestial Mechanics and Dynamical Astronomy》1981,23(2):173-198
Time elements are introduced in terms of Keplerian (classical) orbital elements for use with time transformations of the Sundman type. Three different time elements are introduced. One time element is associated with the eccentric anomaly, a second time element is associated with the true anomaly, and a third time element is associated with theintermediate anomaly.Numerical results are presented that show accuracy improvements of from one to two orders of magnitude when time elements are employed along with Sundman time transformations, compared with using time transformations alone. 相似文献
7.
F. Darabi 《Astrophysics and Space Science》2012,338(1):171-177
We study a gravitational model in which scale transformations play the key role in obtaining dynamical G and Λ. We take a non-scale invariant gravitational action with a cosmological constant and a gravitational coupling constant.
Then, by a scale transformation, through a dilaton field, we obtain a new action containing cosmological and gravitational
coupling terms which are dynamically dependent on the dilaton field with Higgs type potential. The vacuum expectation value
of this dilaton field, through spontaneous symmetry breaking on the basis of anthropic principle, determines the time variations of G and Λ. The relevance of these time variations to the current acceleration of the universe, coincidence problem, Mach’s cosmological
coincidence and those problems of standard cosmology addressed by inflationary models, are discussed. The current acceleration
of the universe is shown to be a result of phase transition from radiation toward matter dominated eras. No real coincidence
problem between matter and vacuum energy densities exists in this model and this apparent coincidence together with Mach’s
cosmological coincidence are shown to be simple consequences of a new kind of scale factor dependence of the energy momentum
density as ρ∼a
−4. This model also provides the possibility for a super fast expansion of the scale factor at very early universe by introducing
exotic type matter like cosmic strings. 相似文献
8.
For equatorial orbits about an oblate body, we show that the Lie series for the elliptic elementse,f,l and
diverge when the oblateness exceeds a critical multiple of the transformed eccentricity constant. The use of similar truncated series expansions for such elliptic elements by Brouwer accounts for the first-order errors at low eccentricity in his derived coordinates for an artificial satellite. 相似文献
9.
Ronald H. Estes 《Celestial Mechanics and Dynamical Astronomy》1974,10(3):253-276
The disturbing function of the Moon (Sun) is expanded as a sum of products of two harmonic functions, one depending on the position of the satellite and the other on the position of the Moon (Sun). The harmonic functions depending on the position of the perturbing body are developed into trigonometric series with the ecliptic elementsl, l′, F, D and Γ of the lunar theory which are nearly linear with respect to time. Perturbation of elements are in the form of trigonometric series with the ecliptic lunar elements and the equatorial elements ω and Ω of the satellite so that analytic integration is simple and the results accurate over a long period of time. 相似文献
10.
We study the effects of a non-singular gravitational potential on satellite orbits by deriving the corresponding time rates
of change of its orbital elements. This is achieved by expanding the non-singular potential into power series up to second
order. This series contains three terms, the first been the Newtonian potential and the other two, here R
1 (first order term) and R
2 (second order term), express deviations of the singular potential from the Newtonian. These deviations from the Newtonian
potential are taken as disturbing potential terms in the Lagrange planetary equations that provide the time rates of change
of the orbital elements of a satellite in a non-singular gravitational field. We split these effects into secular, low and
high frequency components and we evaluate them numerically using the low Earth orbiting mission Gravity Recovery and Climate
Experiment (GRACE). We show that the secular effect of the second-order disturbing term R
2 on the perigee and the mean anomaly are 4″.307×10−9/a, and −2″.533×10−15/a, respectively. These effects are far too small and most likely cannot easily be observed with today’s technology. Numerical
evaluation of the low and high frequency effects of the disturbing term R
2 on low Earth orbiters like GRACE are very small and undetectable by current observational means. 相似文献
11.
Osman Demircan 《Astrophysics and Space Science》1978,56(2):389-401
A new general expression for the theoretical momentsA
2m of the light curves of eclipsing systems has been presented in the form of infinite series expansion. In this expansion, the terms have been given as the product of two different polynomials which satisfy certain three-term recursion formulae, and the coefficients diminish rapidly with increasing number of terms. Thus, the numerical values of the theoretical momentsA
2m can be generated recursively up to four significant figures for any given set of eclipse elements. This can be utilized to solve the eclipse elements in two ways: (i) with an indirect method (for the procedures see Paper XIV, Kopal and Demircan, 1978), (ii) with a direct method as minimization to the observational momentsA
2m (area fitting). The procedures given in Paper XIV for obtaining the elements of any eclipsing system consisting of spherical stars have been automated by making use of the new expression for the momentsA
2m of the light curves. The theoretical functionsf
0,f
2,f
4,f
6,g
2 andg
4 which are the functions ofa andc
0, have been used to solve the eclipse elements from the observed photometric data. The closed-form expressions for the functionsf
2,f
4 andf
6 have also been derived (Section 3) in terms of Kopal'sI-integrals.The automated methods for obtaining the eclipse elements from one minimum alone have been tested on the light curves of YZ (21) Cassiopeiae under the spherical model assumptions. The results of these applications will be given in Section 5 which follows a brief introduction to the procedure we followed. 相似文献
12.
A recurrence relation for inclination functions 总被引:2,自引:2,他引:0
R. H. Gooding 《Celestial Mechanics and Dynamical Astronomy》1971,4(1):91-98
When the terms of the series expansion for the gravitational potential of the Earth are expressed in terms of the orbital elements of an arbitrary Earth satellite, the orbital inclination,i, appears in each, term as the argument of a function of inclination only. For the special case when the field is axi-symmetric, studied in an earlier paper, a recurrence relation was given for a normalized inclination function,A
k
l(i), with two parameters. The present paper gives a recurrence relation for a general normalized function,K
k
lm(i), with three parameters. 相似文献
13.
We investigated by numerical integrations the long-term orbital evolution of four giant comets or comet-like objects. They are Chiron, P/Schwassmann-Wachmann 1 (SW1), Hidalgo, and 1992AD (5145), and their orbits were traced for 100–200 thousand years (kyr) toward both the past and the future. For each object, 13 orbits were calculated, one for the nominal orbital elements and other 12 with slightly modified elements based on the rms residual of the orbit determination and on the number of observations. As past studies indicate, their orbital evolution is found to be very chaotic, and thus can be described only in terms of probability. Plots of the semi-major axis (a) and perihelion distance (q) of the objects treated here seem to cross each other frequently, suggesting a possibility of their common evolutionary paths. About a half of all the calculated orbits showedq- ora-decreasing evolution. This indicates that, at least on the time scale in question, the giant comet-like objects are possibly on a dynamical track that can lead to capture from the outer solar system. We could hardly find the orbits with perihelia far outside the orbit of Saturn (q>15 AU). This is perhaps because the evolution of the orbits beyond Saturn is so slow that substantial orbital changes do not take place within 100–200 kyr. 相似文献
14.
The geopotential expansion is givenentirely in terms of nonsingular orbital elements. The expansion and its derivatives are valid for zero eccentricity and inclination. The development begins with the geopotential expansion in singular, classical elements as given by Izsak (1964), Allan (1965) and Kaula (1966). The singular geopotential is then transformed into a nonsingular set of elements 相似文献
15.
A. Abdel Aziz Bakry 《Earth, Moon, and Planets》1988,41(1):77-88
In this paper, an algorithm is constructed for the determination of the perturbed motion, in both, the rectangular and the orbital elements of highly eccentric orbits in Earth's gravitational field with axial symmetry whatever the number N of the zonal harmonic coefficients may be. An application of the algorithm for the Explorer 28 satellite (e > 0.94) is given for two geopotential models corresponding to N = 2 and N = 36. In both examples extremely accurate predictions during the satellite life time are obtained. 相似文献
16.
We consider a model that describes the evolution of distant satellite orbits and that refines the solution of the doubly averaged
Hill problem. Generally speaking, such a refinement was performed previously by J. Kovalevsky and A.A. Orlov in terms of Zeipel’s
method by constructing a solution of the third order with respect to the small parameter m, the ratio of the mean motions of the planet and the satellite. The analytical solution suggested here differs from the solutions
obtained by these authors and is closest in form to the general solution of the doubly averaged problem (∼m
2). We have performed a qualitative analysis of the evolutionary equations and conditions for the intersection of satellite
orbits with the surface of a spherical planet with a finite radius. Using the suggested solution, we have obtained improved
analytical time dependences of the elements of evolving orbits for a number of distant satellites of giant planets compared
to the solution of the doubly averaged Hill problem and, thus, achieved their better agreement with the results of our numerical
integration of the rigorous equations of perturbed motion for satellites. 相似文献
17.
M. T. Edalati 《Astrophysics and Space Science》1978,59(2):333-345
The theoretical values of the momentsA
2m
for any type of eclipses, expressed in terms of the elementsL
1,a andc
0, have been derived in the simple forms of rapidly convergent expansions to the series of Chebyshev polynomials, Jacobi polynomials and KopalJ-integrals (Kopal, 1977c) and hold good for any real (not necessarily integral) value ofm0.The aim of the present paper has been to establish explicit expressions for the Jacobian and its fast enough computation in the light changes of close eclipsing systems, arising from the partial derivative of different pairs ofg-functions (Kopal and Demircan, 1978, Paper XIV) with respect toa andc
0
2
, for any type of eclipses (be these occultations or transit, partial, total or annular) and for any arbitrary degreel of the adopted law of limb-darkening. The functional behaviour of this Jacobian would determine the reasonable light curve in connection with geometrical determinacy of the parametersa andc
0. In the expansion of Jacobian, the terms consist of two polynomials which satisfy certain three-term recursion relations having the eclipse parametersa andc
0, as their arguments.Closed form expressions forf-functions, as well as of the Jacobian (e.g.,m=1, 2, 3), obtaining in the case of total eclipses, are given for a comparative discussion with the theoretical values of Jacobian derived from partial derivative of different pairs ofg-functions.The numerical magnitude of Jacobian would determine the best combination of the momentsA
2m
in the different pairs ofg-functions and definite results would follow in the subsequent paper of this series (Edalati, 1978c, Paper XXIV). 相似文献
18.
A. I. Kaskambas 《Astrophysics and Space Science》1979,64(2):427-432
The aim of the present paper has been to analyse the light changes of the close eclipsing system V78 in Centauri in the frequency domain. In two of his recent papers, Kopal (1977b, c) has developed new methods for the analysis of light curves using Hankel transforms of zero order. He succeeded in expressing the momentsA
2m of light curves in a closed form. The expansions, in terms of which the momentsA
2m can be expressed, converge in all circumstances. Their analytical structure presents no difficulty for automatic computation. The light variations of the eclipsing system V78 in Centauri have been studied by use of the above method. New geometrical elements are also given. 相似文献
19.
In the method of variation of parameters we express the Cartesian coordinates or the Euler angles as functions of the time
and six constants. If, under disturbance, we endow the “constants” with time dependence, the perturbed orbital or angular
velocity will consist of a partial time derivative and a convective term that includes time derivatives of the “constants”.
The Lagrange constraint, often imposed for convenience, nullifies the convective term and thereby guarantees that the functional
dependence of the velocity on the time and “constants” stays unaltered under disturbance. “Constants” satisfying this constraint
are called osculating elements. Otherwise, they are simply termed orbital or rotational elements. When the equations for the
elements are required to be canonical, it is normally the Delaunay variables that are chosen to be the orbital elements, and
it is the Andoyer variables that are typically chosen to play the role of rotational elements. (Since some of the Andoyer
elements are time-dependent even in the unperturbed setting, the role of “constants” is actually played by their initial values.)
The Delaunay and Andoyer sets of variables share a subtle peculiarity: under certain circumstances the standard equations
render the elements nonosculating. In the theory of orbits, the planetary equations yield nonosculating elements when perturbations
depend on velocities. To keep the elements osculating, the equations must be amended with extra terms that are not parts of the disturbing function [Efroimsky, M., Goldreich, P.: J. Math. Phys. 44, 5958–5977 (2003); Astron. Astrophys. 415, 1187–1199 (2004); Efroimsky, M.: Celest. Mech. Dyn. Astron. 91, 75–108 (2005); Ann. New York Acad. Sci. 1065, 346–374 (2006)]. It complicates both the Lagrange- and Delaunay-type planetary equations and makes the Delaunay equations
noncanonical. In attitude dynamics, whenever a perturbation depends upon the angular velocity (like a switch to a noninertial
frame), a mere amendment of the Hamiltonian makes the equations yield nonosculating Andoyer elements. To make them osculating,
extra terms should be added to the equations (but then the equations will no longer be canonical). Calculations in nonosculating
variables are mathematically valid, but their physical interpretation is not easy. Nonosculating orbital elements parameterise
instantaneous conics not tangent to the orbit. (A nonosculating i may differ much from the real inclination of the orbit, given by the osculating i.) Nonosculating Andoyer elements correctly describe perturbed attitude, but their interconnection with the angular velocity
is a nontrivial issue. The Kinoshita–Souchay theory tacitly employs nonosculating Andoyer elements. For this reason, even
though the elements are introduced in a precessing frame, they nevertheless return the inertial velocity, not the velocity
relative to the precessing frame. To amend the Kinoshita–Souchay theory, we derive the precessing-frame-related directional
angles of the angular velocity relative to the precessing frame. The loss of osculation should not necessarily be considered
a flaw of the Kinoshita–Souchay theory, because in some situations it is the inertial, not the relative, angular velocity
that is measurable [Schreiber, K. U. et al.: J. Geophys. Res. 109, B06405 (2004); Petrov, L.: Astron. Astrophys. 467, 359–369 (2007)]. Under these circumstances, the Kinoshita–Souchay formulae for the angular velocity should be employed (as
long as they are rightly identified as the formulae for the inertial angular velocity). 相似文献
20.
Bernard De Saedeleer 《Celestial Mechanics and Dynamical Astronomy》2005,91(3-4):239-268
This paper is a contribution to the Theory of the Artificial Satellite, within the frame of the Lie Transform as canonical
perturbation technique (elimination of the short period terms). We consider the perturbation by any zonal harmonic J
n
(n ≥ 2) of the primary on the satellite, what we call here the complete zonal problem of the artificial satellite. This is quite useful for primaries with symmetry of revolution. We give an analytical formula to compute directly the first
order averaged Hamiltonian. The computation is carried out in closed form for all terms, avoiding therefore tedious expansions
in the eccentricity or in any anomaly; this feature makes the averaging process, not only valid for all kind of elliptic trajectories
but at the same time it yields the averaged Hamiltonian in a very short and compact way. The formula allows us to now skip
the averaging process, which means an asymptotic gain of a factor 3n/2 regarding the computational cost of the n
th
zonal. Our analytical formulae have been widely checked, by comparison on one hand with published works (Brouwer, 1959) (which
contained results for particular zonal harmonics, let’s say typically from J
2 to J
8), and on the other hand with the results of 3 symbolic manipulation software, among which the MM (standing for ‘Moon’s series
Manipulator’), which has already been used and described in (De Saedeleer B., 2004). Additionally, the first order generator
associated with this transformation is given into the same closed form, and has also been validated. 相似文献