首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 312 毫秒
1.
The empirical evidence for a connection between type and relative angular momentum of galaxies is reviewed and some constraints for the theoretical explanation are discussed.
.
  相似文献   

2.
. . .
Transfer of resonance radiation in infinite medium is considered as a process of random walks of photons. Close relation is shown to exist between the problems of transfer of line radiation and the stable distributions of the probability theory. This relation is used as a basis of a new method for the investigation of the asymptotic properties of the radiation field far from the sources.


,   相似文献   

3.
4.
The paper suggests an explanation of the deviations from the power law which are observed in frequency spectra of discrete radio sources at decametric wavelengths. It has been shown that a possible mechanism of the deviations is a combined effect of the stimulated and spontaneous scattering of relativistic electrons in the turbulent plasma of a source, as well as ionization energy losses thereof. The distribution function of the relativistic electrons, empirically established in an earlier paper (Braudeet al., 1971) has been derived from the kinetic equation. For a number of discrete sources the turbulence energy density and the plasma concentration are deduced with the aid of experimental data on low-frequency radio spectra.
. , , . , (Braude et al, 1971), . .
  相似文献   

5.
6.
. , , . , 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   

7.
(Kilyachkoet al., 1978) , . l ( I II). (Kilyachkoet al., 1978) : (1) 800 Å , , UV Cet. EV Lac; (2) UV Cet EV Lac 8000 Å , ; (3) 8000 Å . — MO-KS; (4) 1–3 m.  相似文献   

8.
2800 Mgii (. 1). (N +/N 11000) , , (N +/N 110). , . —, , . — . : ; 0.002 1 , 0.1 ; () 100 –3; ; ; , 10 ; 10–4 1 . 2800 Mgii .  相似文献   

9.
10.
. - . . , . - . - , , , -. ., , .
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   

11.
12.
13.
14.
15.
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   

16.
qp qz : (1) -, qi , (2) - (R=0.01–0.1R ) (3) - . qs. (1) - 0.1 10–4 cm –2, . - . (2) 108 . . 1042–43 , (25 ). 10% - (0.1 ). , , , , , . . (3) , , - . . (2×1041 ) (1021 ). - 1038–1039 , 0.25 . , , qq . - , , .
The following three mechanisms of generation of gamma-ray bursts at advanced phases of stellar evolution are considered; (1) gamma-ray bursts as a result of absorption of neutrino propagating through the envelope of a collapsing star, (2) gamma-ray burst due to thermal radiation of external layers of a compact star (R=0.01–0.1R ) heated by powerful shock wave, and (3) gamma-ray burst as a consequence of possible ejection of matter from neutron star at some active phases of its evolution. In the case (1) the gamma-ray flux at the top of the Earth's atmosphere is about 10–4 (0.1 MeV photons) cm–2, if a collapsing star is at Galactic distance (10 kpc). It is considerably less than observed one. The observations of such gamma-bursts however would be an important supplement to the direct detection of neutrino radiation from collapsing stars. In the case (2) external layers of a star are heated up to 108 K. As a result we have a short pulse of thermal radiation with total energy of the order of 1042–43 erg. The main fraction of the radiation is in the X-ray ( 25 keV), about 10% of total energy being radiated in gamma-ray ( 0.1 MeV). The energy of such a burst is sufficient for explaining observed gamma-bursts provided the supernova outburst probably takes place in our Galaxy and as a result we have some trouble with explanation of observed frequency and spectra of gammabursts. In the case (3) ejection from neutron star of chemically nonequilibrium matter results in the intensive gamma-radiation in consequence of superheavy nuclei fission followed by beta-decays and radiative captures of free neutrons. The ejection of matter from neutron stars may be connected with observed jumps of pulsar's periods. The total ejected mass ( 1021 g) can be evaluated from increase of kinetic energy ( 2×1041 erg.) of Crab nebula filaments. The resulting theoretical energy of gammabursts is of the order of 1038–39 erg. It is in accordance with observations provided the mean distance of gamma-ray sources is about 0.25 kpc. Contrary to the supernova-outburst mechanism in this case we have probably no troubles with frequency and spectra of gamma-bursts. Among the three mechanisms considered above ejection of matter from neutron stars seems to be a more suitable one for explanation of observations.
  相似文献   

17.
We have used long light curves in the X-ray (ARIEL V, EXOSAT, Ginga and others), UV (IUE), and optical (data of intensive ground-based monitoring) ranges of NGC 4151 to investigate connections between variations in these spectral fields. Applying Fourier (CLEAN algorithm) and modern cross-correlation analysis, we revealed the different character of the variability and the cross-correlation between high and low states of the nucleus. In contrast to earlier results, we found that X-ray and optical fluxes correlate in the active state without any apparent delay.In the power spectrum of the optical and X-ray light curves in the high state we found the existence of the same period of about 65 days, which disappeared in the low state.We confirmed previous data that X-ray variations correlate more strongly with UV and optical continuum variability during the low state, but it is possible that the optical variations appear to lag behind those involving X-rays by several tens of days.Strong variations in H line profile and [Fe X]6374 line intensity variations correlate with the observed X-ray covering dip in 1990 (Yaqoobet al., 1993).We discuss briefly the implications of these results.  相似文献   

18.
19.
20.
, . () . , , , . ( ), , , . . (2.7). ( 1 k 1 ,V — , — .) (k 1) (k) §2 ( (2.14)). , (3.6) (3.4), (3.8) . (3.9)–(3.13) ( (3.9), (3.10) (3.11) , (3.12)–(3.13) ). (3.14), (3.16)–(3.19). - . (3.15). ( (4.14)–(4.15)). (4.23)–(4.25). (4.26)–(4.28). §5. , . ((5.5)–(5.6)). , . (5.10) .  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号