Eruption of a helically twisted prominence

In this paper we analyze the eruption of a prominence, characterized by a helical-like structure and by a non-linear rising motion. We approximated the prominence as a cylindrical curved flux tube and estimated the behaviour of several geometrical parameters during the activation and the eruption phases. We determined that, at the onset of the activation, the number N of turns of a magnetic field line over the whole length of the prominence was 5.0, while the value of the ratio P/r ₀ between the pitch of the magnetic field lines and the prominence width was 0.45. These values are in good agreement with those predicted by the kink-mode instability. Moreover, we found a decrease of the total twist of one helical thread from 10 to 2 during the prominence eruption, indicating a relaxation of the magnetic field towards a less twisted configuration. We conclude that the prominence was initially destabilized by the kink-mode instability and, not succeeding in finding a new equilibrium configuration, it erupted.     

Sobolev's Φ-function of radiative transfer in planar and spherical scattering media

In recent years Sobolev's -function of radiative transfer has been discussed in connection with the resolvent of Milne's integral equation such that it plays an important role in the determination of the radiation field in semi-infinite (or finite) atmospheres with internal sources (cf. Sobolev, 1963). In the present paper, the part of Sobolev's -function in plane-parallel and spherical, isotropically scattering, atmospheres with internal source distribution is investigated from analytical and numerical aspects. With the aid of invariant imbedding (cf. Bellmanet al., 1968), we computed Sobolev's -function of Milne's integral equation for the planar case by solving the Cauchy system for the auxiliary function and Chandrasekhar'sX- andY-functions. The corresponding -function for the spherical case is readily obtained from the for the planar case.Investigation supported by the National Science Foundation under Grant No. GP 29049, the Atomic Energy Commission, Division of Research under Contract No. AT(04-3)-113, Project 19, and the National Institutes of Health under Grant No. 16197-05.     

A relation in families of periodic solutions

We show the existence of a general relation between the parameters of periodic solutions in dynamical systems with ignorable coordinates. In particular, for time-independent systems with an axis of symmetry, the relation takes the form T/A=–/E, whereT is the period,A is the angular momentum, is the angle through which the system has rotated after one period, andE is the energy.     

On a Babcock-Leighton dynamo model with a deep-seated generating layer for the toroidal magnetic field, II

In a previous paper (Paper I), we studied a dynamo model of the Babcock-Leighton type (i.e., the surface eruptions of toroidal magnetic field are the source for the poloidal field) that included a thin, deep seated, generating layer (GL) for the toroidal field, B. Meridional motions (of the order of 12 m s^–1 at the surface), rising at the equator and sinking at the poles were essential for the dynamo action. The induction equation was solved by approximating the latitudinal dependence of the fields by Legendre polynomials. No solutions were found with _p = _f where _p and _f are the fluxes for the preceding and following spot, respectively. The solutions presented in Paper I, had _p = –0.5 _f , were oscillatory in time, and large radial fields, B, were present at the surface.Here, we resume the study of Paper I with a different numerical approach allowing for a much higher resolution in , the polar angle. The time dependent partial differential equations for the toroidal and poloidal field are solved with the help of a second order, time and space centered, finite difference scheme. Oscillatory solutions with _p = _f are found for various values of the meridional motions and diffusivity coefficients. The surface values of B, while considerably smaller than those of Paper I, are still unacceptably large, specially at the poles. The reason can be traced to the eruption of toroidal field at high latitudes. It appears that in order to obtain small values for the radial field in the polar regions, high latitude sources ( smaller than /4, say), must reach their maximum below the surface. Weaker meridional motions near the poles than in the equatorial region are also suggested.     

On a Babcock-Leighton dynamo model with a deep-seated generating layer for the toroidal magnetic field

A dynamo model of the Babcock-Leighton type having the following features is studied. The toroidal fieldB is generated in a thin layer (the GL), located at the lower solar convection zone, by a shear in the angular velocity acting on the poloidal fieldB _p (= × [0, 0,A ].) If, in this layer, and for a certain value of the polar angle,, |B _Ø | exceeds a critical field,B _cr , then the eruption of a flux tube occurs. This flux tube, which is assumed to rise radially, generates, when reaching the surface, a bipolar magnetic region (BMR) with fluxes _p and _f for the preceding and following spot respectively. For the purpose of the numerical calculations this BMR is replaced by its equivalent axisymmetrical magnetic ring doublet. The ensemble of these eruptions acts as the source term for the poloidal field. This field, generated in the surface layers, reaches the lower solar convection by transport due to meridional motions and by diffusion. The meridional motions are the superpositions of a one-cell velocity field that rises at the equator and sinks at the poles and of a two-cell circulation that rises at the equator and poles and sinks at mid latitudes. The toroidal field andA _Ø were expanded in Legendre polynomials, and the coupled partial differential equations (int andr; time and radial coordinate) satisfied by the coefficients in these expansions were solved by a finite difference method. In the expansions, Legendre polynomials up to order thirty were included.In spite of an exhaustive search no solutions were found with _p = – _f . The solutions presented in this paper were obtained with _p = –0.5 _f . In this case, the northern and southern hemisphere are not entirely decoupled since lines of force join both hemispheres. Most of the solutions found were periodic. For the one-cell meridional flow described above and for a purely radial shear in the GL (the angular velocity increasing inwards) the dynamo wave propagates from the pole towards the equator. The new cycle starts at the poles while the old cycle is still present in the equatorial regions.     

The limits of possible values of inclination of Mercury's equator

The method of estimation of the limits, containing the equator inclination of a celestial body, had been developed. In this method it is necessary to know the orbital elements and the mass of a celestial body. Another condition is that the axial rotation of a body should be in the resonance with its orbital motion. It has been found that the equator inclinations should have the values between 1 .7 and 2 .6 for Mercury and between 1 .0 and 1 .8 for the Moon. It also has been found that largest harmonics in Mercury's physical libration are the harmonics sin( – 3g), cos( – 3g), sin g and sin 2.     

Isotropization in Brans-Dicke-Bianchi type-V

In this paper we find that from the exact solution for Bianchi type-V in the Brans-Dicke theory with =0 the Hubble parameters are the same for , so that the Universe will be isotropized.     

Параметрические неустойчивости в рельтивистской плазме

. , ( ₀²) , , . - , , . .     

Linear current instability in loop prominences

By use of the dispersion equation given by Song, Wu, and Dryer (1987) for a cylinder plasma with mass motion and gravity included, we investigate the linear current instabilities developed in loop prominences. The results indicate that the mode of linear instability depends mainly on whetherv _s ² > or not, wherev _s is the sonic velocity at heightz, =GM/(R +z) is the gravity potential,G the gravitational constant,M andR the mass and the radius of the Sun respectively. Ifv _s ² > , then the sausage instability will be dominant. Otherwise, the kink instability will be more important. A possible explanation of knot structure, which appears sometimes in solar loop prominences has been given.     

The solution of Jacobi's virial equation for nonconservative systems and analysis of its dependence on parameters

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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, - , . . ., , , , , n . , , . .

     

Rotational dynamics of deformable celestial bodies

1.40M . C¹²+C¹²Mg²⁴+. Bruenn (1972) . , ( ), . , URCA . ( , ) . .     

Le développement du potentiel dans le cas d'une densité lisse

The potential of a body of revolution is expanded in a series of spherical functions. It is proved that for a body of smooth structure the coefficients of expansion decrease in a power law.

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. , .

     

турбулентноштб в космологии

=qr, I II (Marochniket al., 1975 a, b), . , II; , . , , ye , . . t _g.     

Комптоновское рассеяние в источниках с синхротронной реабсорбцией

, ( ). n =3–5, T _e =4T _b (1 + ), - ( ) ,T _b - . , . , . W _H , ,n =3, =1. n =3–5(E), (E) , , = 1 – (), |()| < 1, |(E)| < 1. 3 273.     

High velocity neutron stars and γ-ray bursts

The observations of the BATSE instrument on the Compton Gamma-Ray Observatory show that the spatial distribution of -ray burst sources is isotropic but radially non-uniform. As is well known, the spectral features, the time histories and the X-ray tails present in some -ray bursts suggest that they may arise from galactic neutron stars. But, low velocity neutron stars born in the Galactic disk would concentrate toward the galactic plane and center, and could not fit the BATSE results. However, the high velocity neutron stars with velocity 1000 km s^–1 may escape from the Galactic gravitational field and form a nearly isotropic distribution. Here we calculate the three statistical values of V/V _max, sin² b and cos as functions of the intensitiesC _max/C _min and find that they could be fitted by the distribution of high velocity neutron stars under the assumption that the high velocity neutron stars should turn on as -ray burst sources only after some time (perhaps after they have ceased to be radio pulsars). Our calculation shows that the statistical value of cos is more sensitive than sin² b to the angular distribution of high velocity neutron stars, i.e. the deviation of cos from 0 is more readily detected than the deviation of sin² b from 1/3, so we expect that with the increasing sensitivity of instrument and the more exact value of cos , it is possible to determine whether this high velocity neutron star model is correct. Some results are discussed in the text.     

Волна охлаждения в оьолочках сверхновых звëзд

, . , , . II (m ₀20M ). ( II ) .     

Набλюдатрльльй подхои к ранним ста диям эволюции звезд

. . u . . . ]qi . , , . . (, , , , -). . , . , . FU ) - ).     

Энтропийны и АдиАъатические возмущения плотноти Маслого масщтаща — антивещество во вслэнной

, , , , . . . , . , . . ( , 1970) . , .     

Структура Области Взаимодействия Солнечного Ветра С Межзвездной Средой и Ее Влияние На Проникновение Атомов Н в Солнечный Ветер

( , , , ), et al. (1970). , . , , , , (Weaveret al., 1977), (Dyson, 1975), ( , 1976) .. , , , (Wallis, 1975). , L -.     

Образобание изотопа11В В углеродном слое зведьы под деиствием нейтрино

, , , ¹¹ , . , , . ¹¹, , , 5×10^–6–5×10^–4 ( (2.5–5)×10^–7). , ¹¹ . , .