共查询到20条相似文献，搜索用时 171 毫秒
1.
V. L. Oknyanskij 《Astrophysics and Space Science》1994,222(1-2):157-169
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
2.
On the basis of the erenkov line emission theory in the optically thick case, a new interpretation of intensity ratios H/H and H/H in broad-line radio-galaxies (BLRGs) is reported. Calculation shows that if the theoretical ratio H/H is just taken to be the mean observed value 0.21, equivalently, the parameterX(H)=3.0, then the expected ratio H/H=6.70 is almost the same as the observations. By comparing these values with the previous investigations of QSOs (X(H)=20.9), we conclude that the number density of neutral hydrogen gas in BLRGs is almost one order-of-magnitude smaller than that in the QSOs.Preliminary verification of the erenkov line emission has been obtained by Xuet al. (1981) in the laboratory. 相似文献
3.
Г. С. Бисноватый-коган 《Astrophysics and Space Science》1973,22(2):293-306
. , , .. . . , (, ) . 相似文献
4.
5.
R. Caimmi 《Astrophysics and Space Science》1988,140(1):1-32
An approximate analytical method of solving the polytropic equilibrium equations, first developed by Seidov and Kuzakhmedov (1978), has been extended and generalized to equilibrium configurations of axisymmetric systems in rigid rotation, with polytropic index,n =n
p
+
n
, nearn
p
=0, 1, and 5. Though the details of the method depend on the value ofn
p
, acceptable results are obtained for |
n
| 0.5 to describe slowly rotating configurations in the range 0n1.5, 4.5n5. In the limit of rotational equilibrium configurations, when the distorsion may be large enough, a satisfactory approximation holds only in the range 0n, 1n1.5, 4.5n5. 相似文献
6.
From spectroscopic observations of the emission lines H, 4959 and 5007[Oiii], H, 6584[Nii], 6717 and 6731[Sii] and some interferometric data in H and [Nii] it was established that NGC 6164 and NGC 6165 have characteristics of normal Hii regions for Ne and Te. They are embedded in a very tenuous medium nearly coincident with the Strömgren sphere of the central star HD 148937, corresponding to the outer peripheral structure described by Westerlund. Variations of the relative abundances of N, O, and S are discussed. 相似文献
7.
The aim of the present paper is to prove that the system of partial differential equations, which define a set of curvilinear coordinates , , that are orthogonal to the Roche equipotentials (r, , ) incorporating the effects of both rotationaland tidal distortion, does not admit of any formal integrals; and can be solved only numerically in an asymptotic manner. This fact is related with analytic properties of the problem of three bodies, in which represents the potential. 相似文献
8.
В. В. Железняков 《Astrophysics and Space Science》1968,2(4):403-416
u , . , .. (1.10), (1.2) ( (1.2)) . (1964) . (1.10), , , , (1.13). , , S
iq
,R
iglm
,K
iqlm
(1.10) . , . . , (1.3), (2.3); (2.8)–(2.10). , , , , z (2.20), .. , , (. (2.15)).
(K
e, 0
) .
S
, ( (2.24)). (2.24a)
S
±/4. , , (K
e, o<0). L, —
,
, ; , . . 相似文献
9.
M. Fracassini F. Manzolini L. E. Pasinetti M. Ruggenini 《Astrophysics and Space Science》1980,69(2):401-423
Apparent radius, visual brightness, effective temperature and absolute radius for 416 B5 v-F5 v stars of the catalogue of the Geneva Observatory (Rufener, 1976) have been determined.Twenty-eight stars, anomalous in log versus (m
v)0 diagrams, have been singled out. A good correlation for seven stars, in common with the list of Hanbury Brownet al. (1974), has been found. Similar parameters determined for 279 B5 v-F5 v stars of two preceding papers (Fracassiniet al., 1973, 1975) have allowed us to determine the averaged diagrams logq
v/q, logR/R
and logT
e versus (B-V)0 for 695 B5 v-F5 v stars.Moreover, in the present paper a good correlation logq
v/q versus logR/R
and careful relation M
v=–7.40logR/R
+3.31 for B5 v-F5 v stars have been determined. Plain correlations between logR/R
and blanketing parameterm
2 for some spectral types seem to point out that there arereal differences in the absolute radii of stars of thesame spectral type, in agreement with recent researches on the HR diagram (Houck and Fesen, 1978).Systematic differences between double (spectroscopic and visual) and single stars are found. In particular, the averaged relation m
2 versus logR/R
shows that A2 v-F5 v double stars may have a higher metallicity indexm
2 and smaller absolute radii than single stars. Finally, the diagram logv sini versus logR/R
confirms some properties of binary systems found by other researchers (Huang, 1966; Plavec, 1970; Levato, 1974; Kitamura and Kondo, 1978).Thesis for the degree in Applied Physics. 相似文献
10.
We present the ninth list of blue stellar objects of the second part of the First Byurakan Spectral Sky Survey (FBS). We publish 61 objects in the zone +69+73, 3
h
50m18
h
10
m
and 23 additional objects from the previous 5 zones of the survey. Of the 84 objects, 64 are discovered for the first time. We give the equatorial coordinates, stellar V magnitudes, color indices, and preliminary classes of the objects with respect to slitless low-dispersion spectra. For the 23 objects we give approximate types, among which there are 5 candidates for quasars, one for a Seyfert galaxy, 3 UV-excess galaxies, 9 white dwarfs, 4 cataclysmic variables and one probable planetary nebula.Translated fromAstrofizika, Vol. 37, No. 3, 1994.The authors are grateful to the American Astronomical Society for support of the present paper. 相似文献
11.
G. Contopoulos M. Harsoula N. Voglis 《Celestial Mechanics and Dynamical Astronomy》2000,78(1-4):197-210
We find the form of cantori surrounding an island of stable motion in the standard map for various values of the nonlinearity parameter K near the value K=5 (much larger than the critical value K
cr=0.971635...). The asymptotic curves of unstable periodic orbits inside the cantorus cross it after a certain time and then escape to the large chaotic sea. For K=5 the crossing time (in appropriate units) is t=1 and the escape time is t=2. For K=4.998 the crossing time is t=7 and the escape time t=23000. This delay of escape is due to the existence of higher order cantori, with very small gaps. We found that, as K increases the noble torus [2,4,1,1,..] is destroyed before the destruction of the higher order tori [2,4,1,1,1,1,2,1,...] and [2,4,1,1,1,1,3,1,...]. Thus the torus with the simplest noble number is not the last KAM curve to be destroyed. Then we find that nearby orbits deviate considerably, but the average times spent near various resonance before escape are very similar. 相似文献
12.
А. Л. Куницын 《Celestial Mechanics and Dynamical Astronomy》1971,3(2):222-226
. . . , , m
1, m2, m3, n ( .
The conditions of stability of the constant libration solutions of the general three-bodies problem obtained by E. Routh through investigation of the linearized perturbed motion equations are analised. To the values of the masses of the three bodies which satisfy boundary conditions of the region of stability the locus of all corresponding centers of masses is laid down in accordance with. It occurs that this locus is a circle, its centre coinciding with the geometric centre of the trianglem 1, m2, m3 and its radius being a function of exponent in the law of attraction of the bodies. The motion may be stable only if the centre of masses of the bodies lies outside the circle mentioned above. In the case of the Newtonian law of attraction the radius of this circle equals 0,943 |rmax| where |rmax| is a distance of the vertex from the centre of the trianglem 1, m2, m3. Thus stability is possible (if it is generally possible) inside a very small region in this case.相似文献
13.
TS. G. Tsvetkov 《Astrophysics and Space Science》1988,150(2):223-234
On the basis of observational data for the absolute R and relative R/R amplitudes of variations in radius of galactic classical cepheids (55 stars from Balona and Stobie (1979) and 30 stars from Sollazzoet al. (1981)), four kinds of empirical linear relations are obtained: log(P V)–logR, logP–logR, log(P V)–log(R/R), and logP–log(R/R);P, R, and V are the pulsation periods, the mean stellar radii, and the amplitudes of light variations, respectively. Three groups of stars are considered: short-period cepheids (SPC)-with logP1.1; long-period cepheids (LPC)-with logP>1.1; and s-cepheids (sC). Both the R values and the R/R values increase withP andP V, for a given group of variables. A comparison is performed with our results obtained from data in other sources (Kurochkin, 1966; Gieren, 1982; etc.). The investigated relations can be applied for determining R and R/R of galactic classical cepheids, by using their observedP and V. All studied galactic classical cepheids have R/R<0.35, R<10R
for SPC and 10R
<R60R
for LPC. The sC have smaller R and R/R values than other classical cepheids, at the same periods (the difference is about 2 times for R and 1.4–2.8 times for R/R); the studied sC have R/R in the range 0.025–0.075 and R in the range 1–3R
(only Y Oph has R8R
). 相似文献
14.
A critical analysis of the methods and results of estimating the optical thickness of the dust component in the Martian atmosphere 0, the particle size r
0, and the imaginary part of the refractive index n
ihas shown the following. (1) Observational data on the brightness distribution over the Martian disk as well as the phase dependences of diffusely reflected light and the azimuthal dependences of diffusely transmitted light are most appropriate to use only for verifying the reliability of the aerosol parameters determined by other methods. (2) If the morning and evening fogs in the atmosphere are disregarded, the Bouguer–Lambert–Beer method used to analyze the solar-brightness attenuation measured on the planetary surface yields overestimated extraatmospheric solar intensity I
0and atmospheric optical depth 0. At the Viking 1landing site, I
0and 0could be overestimated by a factor of 1.7 and by 0.35, respectively. (3) The aerosol size determined by analyzing measurements of the azimuthal dependences for the Martian sky brightness at low elevations of the Sun most likely corresponds to the fog particles. (4) If overestimated values of I
0were used to standardize the observations of the solar radiation transmitted by the Martian atmosphere, then n
iwere also overestimated; using overestimated 0also affected the reliability of the latter. (5) The problem of reliability of the available 0and r
0estimates for periods of high atmospheric transparency is yet to be solved. For the highest activity of the dust storm in 1971, it was found that 4.5 r
0 7.5 m for the lognormal particle size distribution with 2= 0.2 and the optical thickness of a dust cloud 0 15. (6) The spectral values of the apparent albedo of Mars measured in October 1971 at a phase angle of 42° in the spectral range 0.250 0.717 allowed the imaginary part of the refractive index to be estimated in terms of a model of a dust cloud composed of spherical particles with the lognormal size distribution with r
0= 4.5 m and 2= 0.2. 相似文献
15.
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
16.
Г. Н. Дубошин 《Celestial Mechanics and Dynamical Astronomy》1970,2(4):454-466
(, 1969). ( ), ( ), , , . , (=), , , .. , . , , - ( ), ( ). , .
This paper is a continuation and a generalization of one published earlier (Duboshin, 1969): it discusses the problem whether there exist the Lagrangian and the Eulerian solutions of the generalized three-body (material points) problem. Every point in this generalized problem acts on another, one with a force (attractive or repulsive) directed along the straight line passing through these points, and in an arbitrary manner depending on time, mutual distance and its derivatives, the first and the second. Here, generally speaking, the third axiom of dynamics (law of action and reaction) is not presupposed as fulfilled, that is, it is supposed that every two material points interact in a different way.This most general assumption being made, we establish the conditions which must dictate the laws of the interactions, so that the three points can always remain at the apexes of the equilateral triangle (Langrangian solution), or remain always on a straight line (Eulerian solution).The author believes that such general treatment of the three-body problem can be useful for theoretical studies in celestial mechanics and also for practical applications in the study of isolated stellar systems.相似文献
17.
, , 38 B=2.1±1.1 G l
o=99°±24°,b=0° N
e=0.03±0.01 –3 Z- (h400 ). , 100–150 . 相似文献
18.
Using the flux-transport equation in the absence of sources, we study the relation between a highly peaked polar magnetic field and the poleward meridional flow that concentrates it. If the maximum flow speed
m greatly exceeds the effective diffusion speed /R, then the field has a quasi-equilibrium configuration in which the poleward convection of flux via meridional flow approximately balances the equatorward spreading via supergranular diffusion. In this case, the flow speed () and the magnetic field B() are related by the steady-state approximation () (/R)B()/B() over a wide range of colatitudes from the poles to midlatitudes. In particular, a general flow profile of the form sin
p
cos
q
which peaks near the equator (q p) will correspond to a cos
n
magnetic field at high latitudes only if p = 1 and
m = n /R. Recent measurements of n 8 and 600 km2 s–1 would then give
m 7 m s–1. 相似文献
19.
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
20.