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1.
V. I. Ferronsky S. A. Denisk S. V. Ferronsky 《Celestial Mechanics and Dynamical Astronomy》1979,20(2):143-172
It is shown that the product of the form-factors and in expressions for potential energy and the moment of inertia runs to a constant value in the asymptotic time limit of simultaneous collision of all particles for nonconservative systems.The solution of Jacobi's virial equation for nonconservative systems is obtained. In deriving this result, we used the property of monotony and continuity of the total energy function for the intervals of the smooth evolution of the system.The solution of Jacobi's virial equation for nonconservative and conservative systems near discriminant lines where the moment of inertia is equal to zero is found to possess the same asymptotic behaviour as in the case of an arbitraryn particles system in the asymptotic time limit of simultaneous collision of alln particles.It follows from analysis of the solution of Jacobi's virial equation for nonconservative systems that the amplitude value of oscillations of the moment of inertia decrease to zero near the bifurcational point during the evolution of celestial bodies. Parameters of the bifurcational point and conditions of the system's birfurcation also are found.
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2.
We have observed 10 solar bursts during the thermal phase using the Haystack radio telescope at 22 GHz. We show that these high frequency flux observations, when compared with soft X-ray band fluxes, give useful information about the temperature profile in the flare loops. The microwave and X-ray band fluxes provide determinations of the maximum loop temperature, the total emission measure, and the index of the differential emission measure (q(T)/T = cT–1). The special case of an isothermal loop ( = ) has been considered previously by Thomas et al. (1985), and we confirm their diagnostic calculations for the GOES X-ray bands, but find that the flare loops we observed departed significantly from the isothermal regime. Our results ( = 1–3.5) imply that, during the late phases of flares, condensation cooling ( 3.5) competes with radiative cooling ( 1.5). Further, our results appear to be in good agreement with previous deductions from XUV rocket spectra ( 2–3). 相似文献
3.
The interaction between small-scale magnetic fields and horizontal photospheric flows has been studied from observations of high angular resolution
obtained with the Lockheed narrowband filter in the Swedish Vacuum Solar Telescope at La Palma. The measured magnetic flux density (B
) is in the range from a detection limit of 10 G to about 500 G, showing a good correspondence with the filigree. The magnetic flux elements take part in the local flows towards downdrafts at the supergranulation cell boundaries. The measured flux density, as well as the associated filigree intensity, decrease as the structures approach the downdrafts, presumably as a result of increased tilting and possibly submergence of flux into the downdrafts. 相似文献
4.
J. H. Piddington 《Astrophysics and Space Science》1978,55(2):401-425
The flux-rope theory of solar magnetic fields is reviewed briefly and, together with the dynamo theory, compared with various observational results. Dynamo and related theories are based on fields controlled by the plasma, and it is shown that such fields cannot account for the strong surface fields or even emerge without becoming tangled. Observations which appear uniquely explicable in terms of powerful (4000 G), helically twisted flux ropes and their many twisted flux fibres (3×1018 Mx) are listed as follows. (i) Emerging magnetic flux is seen first as pairs of small, closely spaced flux concentrations whose motions suggest magnetic control to provide bipolar regions of extent105 km. The associated system of arch filaments rotates on the disk as would a series of emerging flux fibres twisted into a rope. (ii) Sunspots form by the accretion of pores and magnetic knots of like polarity, sometimes moving along curved paths between stationary elements of opposite polarity. (iii) Fluxes of1022 Mx in large sunspots must have been concentrated to strengths of4000 G before emerging, and also strongly helically twisted to avoid the flute instability. (iv) The trumpet-shaped flux-rope-fibre sunspot model (Figure 6) accounts readily for the phenomena of the moat convection, the sunspot energy deficit, the complex Evershed flow, penumbral filaments (flux 3×1018 Mx) and temporary light bridges. (v) Asymmetries in sunspot groups (in spot size, lifetime and proper motion) show that the spot fields are extensions of two submerged magnetic structures comprising strong fields. (vi) Sunspots decay by the loss of magnetic knots with strong fields and flux 5×1018 Mx. These must be isolated flux tubes, twisted to account for their stability. (vii) Flux fibres leaving a spot are prone to the kink instability, thus accounting for their sudden appearance in pairs, the transport of total flux several times that of the spot and net flux equal to that of the spot. (viii) Ephemeral active regions and X-ray bright points are explained similarly without invoking improbably huge quantities of new flux. (ix) Atmospheric structures show a high prevalence of helical twists (force-free fields) and rotary motions on all scales from spicules to large prominences. It is difficult to account for these twists unless they are present in emerging flux. (x) In and above the photosphere the flux fibres (3×1018 Mx) fray into loose associations of flux threads (3×1017 Mx) to provide a simple, selfconsistent model of the solar filigree and the chromospheric rosette (bush) with its group of mottles (spicules). (xi) Global patterns of surface and coronal magnetic fields reveal puzzling features such as the migration of large unipolar regions and the freedom from differential rotation of some structures. Submerged flux ropes peeling out of the Sun provide a starting point for explaining these effects. These results provide a strong case for the flux-rope theory against the entrenched dynamo theory, and suggest that more observations should be made of the above ten phenomena. Where possible, simultaneous observations should be made of Zeeman effects and of plasma distributions and velocity field seen in white light and spectral lines. 相似文献
5.
The equation for the two-particles cosmic-ray distribution function is derived by means of the Boltzmann kinetic equation averaging. This equation is valid for arbitrary ratio of regular and random parts of the magnetic field. For small energy particles the guiding-center approximation is used. On the basis of the derived equation the dependence between power spectra of cosmic-ray intensity and random magnetic field is obtained. If power spectra are degree functions for high energy particles ( 10 GeV nucleon–1), then the spectral exponent of magnetic field lies between and –2, where is the spectral exponent of cosmic-ray power spectra. The experimental data concerning moderate energy particles are in accordance with =, which demonstrates that the magnetic fluctuations are isotropic or cosmic-ray space gradient is small near the Earth orbit. 相似文献
6.
The emission spectra and their time variations of gyro-synchrotron emission from an ensemble of energetic electrons are computed for some initial power-law distributions of the electron energies N()d=
–
with =2 or 4. The spectra and decay curves of the emission are compared with solar microwave bursts in order to separately estimate the magnetic field H and . From a limited number of observations, we have 3 and H 103 gauss for the microwave impulsive bursts, and 2 and H (500–1000) gauss for the microwave type-IV bursts. 相似文献
7.
The stability of magnetic flux tubes embedded vertically in a convection zone is investigated. For thin tubes, the dominant instability is of the convective type, i.e. it is driven by buoyancy forces associated with displacements along the tube. The stability is determined by = 8P/B
2; if
c
the tube is convectively stable, otherwise it is unstable, where the critical value
c
depends on the stratification of the convection zone. For a solar convection zone model,
c
= 1.83, corresponding to a magnetic field strength of 1350 G at the surface of the Sun. It is concluded that the flux tubes making up the small scale field of the Sun are probably hydrodynamically stable.In tubes with >
c, the instability is expected to transform the tube either into a state of vanishing surface field strength (in the case of an upward flow), or one with a field strength higher than the original value (if the instability sets in as a downward flow). Following Parker, we suggest that this effect is related to the concentrated nature of the observed solar fields.The National Center for Atmospheric Research is sponsored by the National Science Foundation. 相似文献
8.
P. C. Ram 《Astrophysics and Space Science》1984,100(1-2):107-116
Hall effects on the flow of electrically conducting rarefied gas due to combined buoyant effects of thermal and mass diffusion past an infinite porous plate with constant suction in the presence of strong transverse magnetic field have been investigated. The equations governing the flow poblem have been solved for primary, secondary velocities and temperature. The effects of Hall current, magnetic field and the effect of rarefication have been discussed graphically followed by a discussion.Nomenclature
x,y
coordinate system
-
u
velocity inx direction
-
v
0
suction velocity
-
w
velocity inz direction
- E
Eckert number
- G, G*
Grashof numbers
-
h
1
velocity slip coefficient
-
h
2
temperature jump coefficient
-
h
3
concentration jump coefficient
-
M, m
magnetic field parameter, Hall parameter
- Pr
Prandtl number
- Sc
Schmidt number
-
T, T
w, T
temperature in flow regime, plate temperature, temperature outside the boundary layer very away from the plate
-
C, C
w, C
concentration of the gas in flow, concentration at the plate, concentration far away from the plate
-
thermal conductivity
-
D
coefficient of chemical molecular diffusion
-
coefficient of kinematic viscosity
-
coefficient of viscosity
-
electrical conductivity
-
C
p
specific heat of gas at constant pressure density 相似文献
9.
Patrick C. Crane 《Solar physics》1998,177(1-2):243-253
Fourier analysis (DFT/CLEAN) of the international sunspot number (R) series since 1932 has revealed two long (250–500 days) and distinct episodes of solar activity exhibiting persistent 13 -day variations. The first episode lasts 500 days near the maximum of solar cycle 20, and the second, 250 days near the end of the current solar cycle 22. The solar radio flux density (F
10_7cm) series since 1947 has also been analyzed. During the first episode both solar indices exhibit distinct 27- and 13-day variations (the first report of 13-day variations in F
10_7cm). During the second episode neither index exhibits distinct 27-day variations and only R exhibits 13-day variations. Conditions affecting the appearance of 13-day variations in F
10_7cm are discussed. 相似文献
10.
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.
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11.
12.
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13.
Observations of linear and circular polarization in five colour bands during a highly active state of VV Puppis in January-86 are reported. A strong linear polarization pulse with the maximum in the blue, PB22 %, is observed at the end of the bright phase when the active pole is at the limb and a weaker secondary pulse, PB7 %, is seen in the beginning of the bright phase, when the active pole reappears. Strong positive circular polarization is also observed in the blue and the ultraviolet, PUPB18 %, PV10 % during the bright phase. The circular polarization reverses the sign in the B and V bands during the faint phase and a negative polarization hump is seen when the active pole crosses the limb. The circular polarization in the V band reaches the value PV–10% at the hump, after which it remains near PV–5% during the faint phase. This is probably due to radiation coming from the second, less active pole and accretion thus takes place onto both poles. The wavelength dependences of the positive and negative parts of the circular polarization curve are different and no polarization reversal is seen in the U band. The position angle of the linear polarization is well determined during a large portion of the cycle, especially in the V band, thanks to the activity from both poles. A best fit to the position angle curve, taking into account also the duration of the positive circular polarization phase interval =0.40 (in the V band), yields the values of orbital inclination i=78°±2° and the colatitude of the active magnetic pole =146°±2°. The relatively good fit to the position angle data indicates that the simple dipole model is nearly correct in the case of VV Puppis. Some wavelength dependence is, however, seen in the position angle curves, especially in the I band where the slope / at the main pulse is considerably smaller than in the other bands. The shape of the position angle curves changes also in the blue and the ultraviolet around the middle of the bright phase. This is probably due to optical thickness effects as the side of the accretion column which is toward the observer changes near this phase.Based on observations made at the European Southern Observatory, La Silla, Chile.Paper presented at the IAU Colloquium No. 93 on Cataclysmic Variables. Recent Multi-Frequency Observations and Theoretical Developments, held at Dr. Remeis-Sternwarte Bamberg, F.R.G., 16–19 June, 1986.On leave from University of Helsinki Observatory 相似文献
14.
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.
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15.
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
16.
17.
Л. С. Бисноватыйколан В. С. ИмШенник Д. К. Надежин В. М. Чечеткин 《Astrophysics and Space Science》1975,35(1):3-21
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
18.
19.
The electrical conductivity of the lunar interior has been determined from magnetic field step transients measured on the lunar dark side. The simplest model which best fits the data is a spherically symmetric three layer model having a nonconducting outer crust of radial thickness 0.03R
moon; an intermediate layer of thicknessR0.37R
moon, with electrical conductivity
1 3.5 × 10–4 mhos/m; and an inner core of radiusR
2 0.6R
m
with conductivity
2 10–2 mhos/m. Temperatures calculated from these conductivities in the three regions for an example of an olivine Moon are as follows: crust, < 440 K; intermediate layer, 890 K; and core, 1240 K. The whole-moon relative permeability has been calculated from the measurements to be/
0 = 1.03 ± 0.13. Remanent magnetic fields at the landing sites are 38 ± 3 at Apollo 12, 43 ± 6 and 103 ± 5 at two Apollo 14 sites separated by 1.1 km, and 6 ± 4 at the Apollo 15 site. Measurements show that the 38 remanent field at the Apollo 12 site is compressed to 54 by a solar wind pressure increase of 7 × 10–8 dynes/cm2.National Research Council Postdoctoral Associate. 相似文献
20.
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