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1.
Masaya Saitou 《Astrophysics and Space Science》1989,162(1):47-56
Some peculiarities in the behaviour of a model self-gravitating system described by hydrodynamical equations and isothermal equation of state connected with the presence of thermodynamical fluctuations in real systems were investigated in numerical experiment. The values of density and velocity , , respectively, were computed by numerical code perturbed on each time-step and in each computational cell by random values , for modeling such fluctuations. Perturbed values
i
=
i
+
i
,v
i
=
i
+ v
i
were used to initiate the next step of computations. This procedure is equivalent to an introduction into original hydrodynamical equations of Langevin sources which are random functions. It is shown that these small fluctuations (= v =0,2 =v
2 = 10–8) grow many times in marginally-stable state. 相似文献
2.
- . . , . , . 相似文献
3.
, . , , . . . . . , , . 相似文献
4.
Kam-Ching Leung 《Astrophysics and Space Science》1968,2(3):302-306
The relation between the amplitude of light m and the amplitude of the radial velocity 2K for Canis Majoris stars is investigated. A linear relationship between m and 2K is found. However, the two stars BW Vul and Sco, which have the largest radial velocity variations, do not seem to share this relationship. 相似文献
5.
. , , . , t>1010 ( z<105) .
In this paper we continue the work of Weymann, investigating the causes of distortion of the spectrum of the residual radiation from the Planck curve. We discuss the distortion to the spectrum, resulting from recombination of primeval plasma.We then derive an analytic expression for the distortion to the equilibrium spectrum due to Compton scattering by hot electrons. On the basis of the observational data we conclude that a period of the existence of neutral hydrogen is inescapable in the hot model of the universe. It is concluded that any injection of energy att>1010 sec (red shiftz<105) give the distortions of the equilibrium spectrum.相似文献
6.
G. A. Krasinsky 《Celestial Mechanics and Dynamical Astronomy》1972,6(1):60-83
The general conception of the critical inclinations and eccentricities for theN-planet problem is introduced. The connection of this conception with the existence and stability of particular solutions is established. In the restricted circular problem of three bodies the existence of the critical inclinations is proved for any values of the ratio of semiaxes . The asymptotic behaviour of the critical inclinations as 1 is investigated.
. . . 1.相似文献
7.
P. Brosche 《Astrophysics and Space Science》1977,51(2):401-408
Since the average relation between the angular momentaP and the massesM of galaxies can be represented by a power lawPM
, we can define a relative angular momentum =P/M
(or a constant timeP/M
). For a random motion picture within protogalaxies, should follow a Maxwellian distribution and consequently the dispersion of log should be 0.210.For the reasonable range of (
to 2), the limited sample of galaxies with known dynamical parameters gives between
and 1 times the Maxwellian value. For the plausible special case =2 the reciprocal of the maximum rotational velocityv
m is already a measure of and the larger sample ofv
m-values not only yields the Maxwellian but, moreover, shows the shape of the distribution.
PM , =constP/M . , (lg )=0.210. 7/42, . =2 v m- .相似文献
8.
The problem of stability of the equilibrium points (the libration points) in the problem of motion of a mass point in the neighbourhood of a rotating triaxial ellipsoid is investigated in the strict sense.In the plane of parameters, depending on the form and dynamical characteristics of the ellipsoids, the regions of stability and instability of the libration points are obtained.It is shown that the libration points of the ellipsoids, the form and dynamical characteristics of which are close to the planets of the solar system, are stable.
( ) . , , . , , , .相似文献
9.
A limiting case of the problem of three bodies (m
0,m
1,m
2) is considered. The distance between the bodiesm
0 andm
1 is assumed to be much less than that between their barycenter and the bodym
2 so that one may use Hill's approximation for the potential of interaction between the bodiesm
1 andm
2. In the absence of resonant relations the potential, double-averaged by the mean longitudes ofm
1 andm
2, describes the secular evolution of the orbits in the first approximation of the perturbation theory.As Harrington has shown, this problem is integrable. In the present paper a qualitative investigation of the evolution of the orbits and comparison with the analogous case in the restricted problem are carried out.The set of initial data is found, for which a collision between the bodiesm
0 andm
1 takes place.The region of the parameters of the problem is determined, for which plane retrograde motion is unstable.In a special example the results of approximate analysis are compared with those of numerical integration of the exact equations of the three body problem.
m 0,m 1,m 2. , m 0 m 1. m 2, m 1 m 2 m 1 m 2 . , . . , m 0 m 1. , . .相似文献
10.
The analysis of solar wind He++ and H+ ion distribution functions, collected over five months by the satellite Prognoz 1, shows that these are in general maxwellian but that often tails appear at higher speeds. The existing relation V-T, the observation of ratios of T/Tp 3.83 and V/Vp 1.035 give evidence of preferential He++ ion heating and acceleration. The criteria for heating by dissipation of hydromagnetic waves proposed by Barnes and Hung (1973) are tested experimentally. Finally, multifluid models are likely to predict certain observations such as dependence of the velocity ratio V/Vp on the solar wind flux. 相似文献
11.
G. A. Gurzadyan 《Astrophysics and Space Science》1981,80(1):211-230
It is shown that the observed color diagrams(U-B)
f
(B-V)
f
for pure flare emission of UV Cet type flare stars may be explained within the framework of a fast electron hypothesis. We point out the essential influence on these color indices of the two following factors: (a) the deviations of the normal radiation capability of the star in the infrared region of spectra (on 3.6 m, 4.4 m, and 5.5 m) from the Planckian distribution; (b) the location of the cloud (source) of fast electrons around the star (flare geometry effect). Under the real conditions of the generation of flares around the star the frequency transformation law at the photon-electron interaction has a view =n20, wheren may take the different values-from 0.15 up to 4; it depends on the cloud-star-observer geometry. By the observed colors of the flare emission may be understood, in principle, the location of flare source around the star. A possible role of reflection effect at the generation of stellar flares is outlined. 相似文献
12.
G. N. Doubochine 《Celestial Mechanics and Dynamical Astronomy》1978,17(4):357-371
Résumé Il est envisagé dans ce travail un cas particulier du problème des trois corps solides. On suppose qu'un des corps est passif, c'est-à-dire qu'il n'agit pas sur les deux autres. Chaque corps posséde la symétrie axiale, ainsi que la symétrie par rapport à plan, perpendiculaire à cet axe, Au moment initial les plans de la symétrie des corps coinsident avec le plan principal des coordonneés. Alors il est possible de choisir les conditions initiales de sorte que les centres de la symétrie resterons toujours dans le plan principal, chaque corps tournant uniformement autour son axe. Nous nommerons ce problème — le problème restreint plant. Le cas le plus simple est le problème plan circulire, quand le centre d'un des corps actif décrit orbite circulaire authour d'autre corps actif. Ce problème se reduit à l'étude du mouvement du centre d'inértie du corps passif dans le plan principal —plan d'orbite circulaire du corps actif. Nous trouvons les conditions d'existence pour les solutions particulières du ce problème et posons la question de la stabilité des points de libration correspondantes. D'une manière plus détaillée nous envisageons le cas, où toutes les forces actives sont définiérs une par loi unique.
, . , , , . . , , . . , , . , , . , , . . . , , .相似文献
13.
Jiann-Tsorng Horng 《Astrophysics and Space Science》1975,34(2):L1-L5
Cyclotron waves in the solar wind near 1 AU with frequencies well below the electron cyclotron frequency and wavelengths much larger than the electron cyclotron radius but less than the proton cyclotron radius are considered. The cyclotron radii are defined from parallel thermal velocity of electron component and proton component with respect to the interplanetary magnetic field. No LH cyclotron waves are found to propagate for
p
< 0, where
p
1 –T
p/T
p is the temperature anisotropy of the proton component with respect to the interplanetary magnetic field. The damping or growth of RH cyclotron waves is found to depend on the frequency range and the temperature anisotropy of the proton component. The RH cyclotron waves are damped in the frequency range
r
|
p
|
p
for
p
< 0, where
p
is the proton cyclotron frequency. RH cyclotron instabilities occur in the frequency range |
p
|
p
>
r
> |
p
|
p
/(1–
r
) for
p
< 0. The marginal state is at
r
=|
p
|
p
.Abstract presented at theInternational Symposium on Solar-Terrestrial, São Paulo, Brazil, 17–22 June, 1974 相似文献
14.
Frank Q. Orrall 《Solar physics》1972,23(1):30-46
An expression is derived for the fluctuation (t) in emergent intensity (observed at some wavelength in a Fraunhofer line or the continuum) caused by a perturbation in temperature (z, t) in the Sun's atmosphere. If the contribution function for the observed intensity is single-peaked near z
and if (z) and p(z) are not too rapidly varying, then
(t) m
(z
, t)+N
p(z
, t) where m
and N
depend on the structure of the atmosphere. We compute M, N, and contribution functions for several values of and in the inner wings of the K line (13933 Caii).Presently on leave of absence from the Institute for Astronomy, Honolulu, Hawaii.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
15.
D. F. Falla L. M. Bartlett M. H. L. Smith R. R. Hillier 《Astrophysics and Space Science》1994,211(1):115-126
The RS CVn binary stellar system HR 1099 is a source of both X-ray and radio flares. We present here a model of the system in which the two types of flare are produced by the same population of mildly-relativistic ( 10) electrons, injected into a coronal loop. After reviewing possible radiation mechanisms we conclude that, given the probable conditions in the flaring region, the radio emission is gyrosynchrotron radiation and the X-ray emission is thermal bremsstrahlung. The thermal X-ray source must lie in the stellar chromosphere, but the apparent absence of plasma absorption at radio frequencies indicates that the radio source is located high in the coronal loop. Using the relationships given by Dulk and Marsh (1982) for the radio emission from a power-law electron energy spectrum,N() ( - 1)–, we conclude that 3 7, with 30% of the electron population trapped in the radio source. Some implications of these results for one particular version of the model are discussed. 相似文献
16.
, 1-, 2- 3- . , . 相似文献
17.
, , , 11 , . , , . 11, , , 5×10–6–5×10–4 ( (2.5–5)×10–7). , 11 . , . 相似文献
18.
P. G. Kazantzis 《Astrophysics and Space Science》1979,61(2):477-486
Families of three-dimensional axisymmetric periodic orbits are determined numerically in the Sun-Jupiter case of the restricted three-body problem. These families bifurcate from the vertical-critical orbits (v = 1,b
v = 0) of the basic plane familiesi andI. Further the predictor-corrector procedure employed to reveal these families has been described and interesting numerical results have been pointed out. Also, computer plots of the orbits of these families have been shown in conical projections. 相似文献
19.
20.
-- () ., , , , , . , , . , . 相似文献