共查询到20条相似文献，搜索用时 62 毫秒
1.
R. Grant Athay 《Solar physics》1988,116(2):223-237
An attempt is made in this paper to determine the coefficient a in a power-law relationship of the form V
~T
between the r.m.s. velocity fluctuation, V
for raster images with 3 resolution and the temperature, T of line formation using SMM solar data. For T between 8000 and 105 K, the data suggest a best fit with 3/4 < 1. It is argued, however, that unresolved fine structure tends to reduce the observed value of V
and that higher resolution data may yield different values for . Skylab data have shown that the non-thermal line broadening velocity, , is proportional to T
1/2. Also, for all temperatures less than 105 K, V
. This latter result, however, is again dependent on spatial resolution and may not be true in observations made with sufficient spatial resolution. The magnitudes of both V
and indicate that bulk motions play important roles in the structure of the solar atmosphere as well as in its energy and momentum balance. It is important, therefore, to identify the true nature of such motions with better accuracy than is possible with currently available data.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
2.
Robert J. Gould 《Astrophysics and Space Science》1971,10(2):265-279
Theoretical distributions of pulsar dispersion measures (times sinb
II) are computed for various assumed pulsar spatial distributions above (and below) the galactic plane, assuming a distribution for the ionized gas. The statistics on the twelve high-latitude pulsars lead to the conclusion that the pulsar distribution inz is at least as broad as the distribution of the ionized gas. The value derived for the local mean interstellar electron density in the galactic plane is 0.12 cm–3 and is interpreted to be due to a uniform ionized intercloud medium.Interstellar absorption of radio waves at low frequencies and cosmic X-rays at low energies are considered with regard to irregularities in the distribution of ionized gas. It is shown that if the obervations are made with a wide angle receiver the effective absorption optical deph is –2/2 where is the mean value and is the dispersion in . This relation assumes is much larger than . Analysis of recent low-frequency radio measurements from a satellite-borne receiver, however, leads to the conclusion that effects of irregulatirities are large. 相似文献
3.
V. N. Fedorenko 《Astrophysics and Space Science》1990,163(2):187-200
I give an interpretation of a result of Simpsonet al. (1988) on the variation with kinetic energyT
i
of the mean pathlengthX
m
(T
i
) of the galactic cosmic rays (CGRs) in the range 0.1T
i
10.0 GeV nucl–1. I argue that the data onX
m
(T
i
) may be interpreted in terms of a model of GCR diffusion on the one-dimensional Alfvén-wave turbulence, having a cutoff in the spectrum at frequencies
h
, where
h
is the proton gyrofrequency. The cutoff results in changing of the character of variation of the GCR diffusion coefficientD(T
i
)T
a
in the rangeT
i
1 GeV nucl–1 towards some more complicated variation at 0.1T
i
1.0 GeV nucl–1 due to the peculiarities of the pitch-angle scattering at 900. 相似文献
4.
John P. Vinti 《Celestial Mechanics and Dynamical Astronomy》1971,4(3-4):348-367
The paper represents the Earth's gravitational potentialV, outside a sphere bounding the Earth, by means of its difference V from the author's spheroidal potential. The difference V is in turn represented as arising from a surface density on the sphere bounding the Earth. Because of the slow decrease with ordern of the normalized coefficients in the spherical harmonic expansion ofV, the density anomalies from which the higher coefficients arise must occur in regions close to the Earth's surface. The surface density is thus an idealization of the product of the density anomaly and the crustal thicknessb. Values of are computed from potential coefficients obtained from two sources, Rapp and the Smithsonian Astrophysical Observatory. The two sources give qualitative agreement for the values of and for its contour map. The numerical values obtained for are compatible with the idea that the responsible density anomalies are reasonably small, i.e., less than 0.05 g/cm3, and occur in the crust alone.This paper was prepared under the sponsorship of the Electronics Research Center of the National Aeronautics and Space Administration through NASA Grant NGR 22-009-311. 相似文献
5.
Raj Bali 《Astrophysics and Space Science》1985,116(1):81-88
The object of this paper is to investigate the behavior of a magnetic field in a viscous fluid cosmological model. It has been assumed that the expansion () is proportional to the eigenvalue
1
of the shear tensor
i
j
and the coefficient of shearing viscosity is proportional to the scalar of expansion. The paper also discusses the behavior of the model when the magnetic field tends to zero and comments on some other physical properties. 相似文献
6.
Analytic structure of high-density steady isothermal spheres is discussed using the TOV equation of hydrostatic equilibrium which satisfies an equation of state of the kind:P = K
g
, =
g
c
2.Approximate analytical solutions to the Tolman-Oppenheimer-Volkoff (TOV) equations of hydrostatic equilibrium in (, ), (,U) and (u, v) phase planes in concise and simple form useful for short computer programmes or on small calculator, have been given. In Figures 1, 2, and 3, respectively, we display the qualitative behaviours of the ratio of gas density
g
to the central density
gc
,
g
/
gc
; pressureP to the
gc
,P/
gc
; and the metric componente
–, for three representative general relativistic (GR) isothermal configurations =0.1, 0.2, and 0.3. Figure 4 shows the solution curve (, ) for =0.1, 0.2, and 0.3 (=0 represents the classical (Newtonian) curve). Numerical values of physical quantitiesv (=4r
2
P
*(r)), in steps ofu (=M(r)/r)=0.03, and the mass functionU, in steps of =0.2 (dimensionless radial distance), are given, respectively, in Tables I and II. Other interesting features of the configurations, such as ratio of gravitational radius 2GM/c
2 to the coordinate radiusR, mass distributionM(r)/M, pressure (or density) distributionP/P
c
, binding energy (B.E.), etc., have also been incorporated in the text. It has further been shown that velocity of sound inside the configurations is always less than the velocity of light.Part of the work done at Azerbaijan State University, Baku, U.S.S.R., and Mosul University, Mosul, Iraq, 1985-1986 相似文献
7.
A. G. Gasanalizade 《Solar physics》1971,20(2):507-512
The Freundlich red shift of wavelengths in the solar spectrum is discussed. Born's approach on the photon-photon interaction is used in conjunction with Melvin's recalculation of Freundlich's universal constant in order to derive the cross-section for scattering in the solar atmosphere. The new cross-section appears to be = 1.58 × 10–18 cm2, which is about one thousand times Born's estimate for the effective cross-section. However, a modified value of the constant is in a good agreement with the one obtained by Ter Haar by scattering process methods, which leads to 10–18 cm2 for the photon-photon interaction cross-section of the solar atmosphere. A new expression for Freundlich's red shift formula is obtained. Some numerical examples are given and some interesting aspects of Freundlich's parameters are discussed. 相似文献
8.
Two peculiarities of the magnetic splitting of lines in sunspot spectra have been investigated. The first one consists of the fact that in a rather small region of the penumbra, near the umbrapenumbra boundary, the -component is absent in the spectra of one circular polarization while both -components are present. In the spectra of the opposite circular polarization, the -components are absent but the -component is present. By analogy with the magnetic stars, in whose spectra such an effect was observed by Babcock, this phenomenon was called by us the crossover effect in the sunspot spectra. Some properties of this effect in the different spectral lines were investigated. The nature of this effect is discussed.The second peculiarity consists of the anomalous splitting of the -component of Zeeman triplets which are of the same and opposite signs in comparison with splitting of the -components. The different possibilities of explanation are discussed. 相似文献
9.
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
10.
R. Mewe J. Heise E. H. B. M. Gronenschild A. C. Brinkman J. Schrijver A. J. F. den Boggende 《Astrophysics and Space Science》1976,42(1):217-222
With the soft X-ray detector (0.2–0.284 keV) aboard the Astronomical Netherlands Satellite (ANS) we have searched for X-ray emission from hot star coronae and peculiar stars. On Sirius ( CMa) and Capella ( Aur) X-ray emission has been measured at 6 and 5 level, respectively, above background. In all other cases the search revealed no evidence for soft X-ray emission. Upper limits to the luminosities of about 25 star coronae (main-sequence stars, (sub)giants, and supergiants) and of 4 peculiar stars ( Sco, Lyr, P Cyg, and Car) have been obtained.Paper presented at the COSPAR/IAU Symposium on Fast Transients in X-and Gamma-Rays, held at Varna, Bulgaria, 29–31 May, 1975. 相似文献
11.
In the theory of supergravity (N=1), the supersymmetric version of general relativity, and for the Kasner cosmological model (Bianchi type I) we find a non-trivial solution (for the metric and spinor-vector) under the most simple assumption =11 + 22; 12+21=0 and for a special choosed gaugeN=1,N
j=0, 0=0. This method could be also applied to other cosmological metrics and extended to enlarged Grassmann basis.O. Obregón was partially supported by the Alexander von Humboldt Stiftung. 相似文献
12.
An essential part in the mechanics under study is taking into consideration the effect of motions of the Universe objects upon that of an individual one surrounded by them including those infinitely far from it. Only macro-objects of the Universe are meant here.
Zusammenfassung Ein wesentlicher Bestandteil der Mechanik unter unserer Betrachtung ist die Berechnung des Einflusses auf die Bewegung eines individuellen Objektes von Bewegungen der Universum Objekte die es umringen einschließlich jene Objekte, die unendlich entfernt sind. Nur Makroobjekte des Weltalles sind in der Absicht dabei.
, . .相似文献
13.
14.
15.
-- () ., , , , , . , , . , . 相似文献
16.
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
17.
The tidal force effects of a spherical galaxy passing head-on through a disk galaxy have been studied for various orientations of the disk galaxy with respect to the direction of relative motion of the two galaxies. The density distribution of the spherical galaxy is taken to be that of a polytrope of indexn=4 and that of the disk galaxy is taken to be, (r)=ce–4r/R, where c is the central density andR the radius of the disk. It is found that the disruptive effects due to the tidal force are minimum when the plane of the disk lies along the direction of relative motion, but are maximum when the plane of the disk is slightly inclined to this direction (about 15°). The tidal force effects at the median radius have also been computed. The tadal force effects are much higher in the interior region of the disk. 相似文献
18.
A detailed study of classical polytropes in general relativity has been presented for O ((dP/dE)O) 1.0 and O((P/E
O)O. The behaviour of various structural parameters with O/O, O and O are the values ofP/E and dP/dE at the centre) has been studied. The most important result of this study is the fact the qualitative behaviour of all the structural parameters depends only on the value of µO for the various assigned O values. The maximum value of surface red shift occurs when µO=0.6 and for O=1.0 it equals 0.618. These structures are gravitationally bound for µO0.8 and most so for µO=0.4. The maximum value of binding coefficient comes out to be 0.181 when O=1.0. These structures have been used to model neutron stars. The maximum mass of neutron star based upon such a model comes out to be 2.55M
(for µO=0.4 and O=1.0) and maximum size comes out to be 15.0 km (for µO=0.2 and O=1.0). It is also seen that the structures are pulsationally stable for µ0.6. 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.
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