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1.
Paul S. Wesson 《Astrophysics and Space Science》1978,54(2):489-495
An exact solution of Einstein's equation is stated in which the density (), pressure (p), scale factorS and metric coefficients are functions of only one dimensionless self-similar variable,ct/R, wheret is cosmic time andR is a co-moving radial coordinate. The solution represents a cosmology that begins as a static sphere having R
–2 and evolves into an expanding model which is pressure-free and has a hierarchical type of density law ( R
–, approximately, with =a number, 02). It is suggested that this model should supersede the previous models of Wesson and other workers, since it appears to be the simplest cosmology for a hierarchy. 相似文献
2.
, ii (2000–3000 Å) i . , i . i (. 2). i i i i + ( 7–10). ii (. 13). ii i i (, 2400 Å) (. 14 15). i i i , iu , i (. 1). i i ii i i . . 相似文献
3.
E. Gosset 《Astrophysics and Space Science》1985,108(2):323-335
Using Fourier analysis techniques, we have analysed all the available sets of visual photometric data concerning the X-ray binary HD 153919. This was made in order to clear up the controversy on the possible existence or absence of the small amplitude light variability (T90 min).In this work, great effort has been made to keep a good level of homogeneity and objectivity. The main conclusion is that at the 99.4% confidence level, a periodicity (=15.5 day–1) is detected in one data set. In this case, we can safely conclude that the short time-scale variability does exist! No other self-conclusive detection can be definitely reported; nevertheless, at the 90% confidence level, the star has a tendency to vary with characteristic frequencies of 15 day–1, 30 day–1 and possibly higher multiples.HD 153919 4U1700-37 V884 Sco. 相似文献
4.
, kT
b
mc
2 . . , , . E
–5, - E
2, mc
2(kT
/mc
2)1/7. , (>2.105
cm
–3) . , -, , . 相似文献
5.
Formulae containing the elements of the variational matrix are obtained which determine the linear iso-energetic stability parameters of periodic orbits of the general three-body problem. This requires the numerical integration of the variational equations but produces the stability parameters with the effective accuracy of the numerical integration. The procedure is applied for the determination of horizontally critical orbits among the members of sets of vertical-critical periodic orbits of the threebody problem. These critical-critical orbits have special importance as they delimit the regions in the space of initial conditions which correspond to possibly stable three-dimensional periodic motion of low inclination. 相似文献
6.
В. А. Сарычев В. В. Саэонов V. A. Sarychev V. V. Sazonov 《Celestial Mechanics and Dynamical Astronomy》1977,15(1):75-98
, ; . , , , , . . . -. . .
The stability of the stationary motions of a spin-stabilized satellite is investigated using the Lyapunov second method. The nutating motion of the satellite is damped by a special-purpose device. In case the damping device consists of several independent dampers with one degree of freedom little affecting the satellite motion, their optimal parameters ensuring a maximal rate of damping the nutating motion of the satellite are determined with the hypothesis of resonance adjustmentsof the dampers. The Krylov-Bogolyubov method is used to investigate the influence of external moments on the motion of the satellite rotation axis.相似文献
7.
By solving the Euler hydrodynamical equations we have obtained closed form solutions for the angular velocities and pressures of a three stratified non-confocal heterogeneous oblate spheroid. Limiting and particular solutions cases, such as a spheroid with N layers, a stratified spheroid with the same eccentricities, as well as confocal layered spheroids are also explicitly written down. As an application, we have numerically estimated planet Earth's outer and inner cores' ellipticities to be o=1/413.318 and i=1/424.616, respectively. These Earth's ellipticities values are in good agreement with those found in the literature. 相似文献
8.
. , ; . , , . (10% ) , . . 相似文献
9.
, , . , . ( , , ), - qqi . - ; , - . , , . 相似文献
10.
11.
, , , , . , . , () (), , , . — . 相似文献
12.
The application of Fourier analysis to study leaky waves has the advantage of simplicity, but it is not clear why the complex roots of the dispersion relations represent leaky waves, nor how the leakage occurs. We investigate the different kinds of leakage that can occur in a three layer plasma, and to which Fourier pseudomodes they are associated. We find four basic mechanisms, called surface mode ..., single interface ..., trapped wave ... and lost insulation leakage. These mechanisms appear in pure form only near certain limiting cases, in which the parameters of the problem take some special values. As soon as the parameters depart significantly from the limiting values, the behavior of the leaky wave complicates and mixtures of the mechanisms occur, in varying amounts. In consequence different points of the same complex branch of the spectrum may correspond to different mechanisms. All the complex branches of the spectrum correspond to leaky waves, but in general it is not possible to classify them according to type of leakage, except close to a limiting case. Since in a three layer configuration there are many of these, the spectrum of leaky waves is very complicated. 相似文献
13.
, — . , , . , , . 相似文献
14.
В. М. Чаругин 《Astrophysics and Space Science》1975,37(2):441-447
, . N/E, E
r, (E
r)=1. , (, ) . . 相似文献
15.
. - . . , . - . - , , , -. ., , .
English translation will appear in the next issue ofAstrophys. Space Sci.
Receipt delayed by postal strike in Great Britain 相似文献
The structure of rotating magnetic polytropes is considered in Roche approximation. Investigation of the influence of poloidal as well as toroidal magnetic fields on the conditions of the beginning of matter outflow due to rotational instability is carried out. The influence of the turbulent convection and twisting of magnetic force-lines on the time of smoothing of differential rotation is considered. The estimate of the magneto-turbulence energy generated by differential rotation is presented. Both maximum possible energy output and duration of the quasi-statical evolution phase up to the appearance of hydrodynamic instability due to the effects of general relativity are calculated for supermassive magnetic polytropes of index three with uniform or differential rotation. The radius-mass relation is obtained for supermassive differentially-rotating magnetic polytropes referring to the longest part of the quasi-statistical evolution stage; some consequences are pointed out, including the period-luminosity relation.The evolution of the considered models of supermassive rotating magnetic polytropes with different character of rotation and different geometry of a magnetic field is discussed.The results obtained are summarized in the last section.
English translation will appear in the next issue ofAstrophys. Space Sci.
Receipt delayed by postal strike in Great Britain 相似文献
16.
Г. А. ГурзадЯн 《Astrophysics and Space Science》1979,62(1):55-66
, oqn ANS (1500–3300 Å) , I , 3–15 . , <2000 Å nepexo , 1.5 MB . 0 , . . 相似文献
17.
Р. М. Мурадян 《Astrophysics and Space Science》1980,69(2):325-337
, J=(m/m
p)1+1/n
, n=2 , n=3 , . , . , , . - wc m
P, G c . -. 相似文献
18.
Isabelle Vauglin 《Astrophysics and Space Science》1990,171(1-2):275-278
We describe three recent infrared cameras, developed in France and based on mosaïcs of infrared detectors. They are optimized for ground-based observations in the 1–5 m or 5–17 m ranges. The results already obtained, emphasize the interest of studying the sky in that domain.Paper presented at the 11th European Regional Astronomical Meetings of the IAU on New Windows to the Universe, held 3–8 July, 1989, Tenerife, Canary Islands, Spain. 相似文献
19.
V. A. Brumberg L. S. Evdokimova V. I. Skripnichenko 《Celestial Mechanics and Dynamical Astronomy》1975,11(1):131-138
Based on a general planetary theory, the secular perturbations in the motion of the eight major planets (excluding Pluto) have been derived in polynomial form. The results are presented in the tables. The linear terms of second order with respect to the planetary masses and the nonlinear terms of first order up to the fifth (and partly seventh) degree with respect to eccentricities and inclinations were taken into account in the right-hand members of the secular system. Calculations were carried out by computer with the use of a system that performed analytic operations on power series with complex coefficients.
qA ( ). . ( ) . .相似文献
20.
We give the fifth list of red stars of the First Byurakan Spectral Sky Survey. The objects are located in the zone 5h 18h 30m and +65 +69. The list contains the data on 18 new objects, one of which is a star of class R. We also give the first determination of the spectral class of 11 variable objects, for four of which we give the spectrograms in the range of wavelengths 4700–6700å.Translated fromAstrofizika, Vol. 37, No. 4, 1994. 相似文献