Об устойчивости лагранжевых решений пространственной эллиптической задачи трех тел

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Stability of the librational triangular points of the three-dimensional elliptic restricted three-body problem is studied. The problem is solved in the non-linear statement at the small values of eccentricity.For all values ofe, , besides ones which correspond to the resonances of the third and the fourth order the librational points are stable taking into account the terms up to the fourth order in the normal form of the Hamiltonian function of the perturbed motion.At sufficiently smalle and the non-stability in sense of Liapunov has been proved. The approximate equations of the boundary of the stability area in the planee, has been obtained. The cause of the non-stability is an equality of the rotational period of the principal attracting masses in the elliptic orbit and the period of oscillation of indefinitely small mass along the direction perpendicular to the plane of their motion.

     

Возможный механизм радиоизлучения пульсаров

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О колебаниях хвоста магнитосферы в приБлижении квазигидро динамики

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The nature of quiescent solar prominences

Quiescent prominences occur as long-lasting cool sheets of matter in the surrounding hot corona at the base of coronal streamers. Seen on the disk they appear as dark filaments dividing regions of opposite magnetic polarity.In this paper a theoretical model is presented, which describes the general appearance of quiescent prominences.It is shown that the neutral sheet between two regions of oppositely directed magnetic fields is thermally unstable. This gives rise to compression and cooling of coronal material to prominence material in a characteristic time of the order of one day for a field strength of 0.5 gauss in the lower corona.It is assumed that due to the finite electrical resistivity of the plasma, filamentary structures are formed by the tearing-mode resistive plasma instability. These structures are thermally insulated from the hot surroundings by the newly formed closed azimuthal magnetic field configuration.It has been shown that for fine structures with a diameter of 300 km the growth rate of the tearing-mode instability is of the same order as the cooling time. The occurrence of fine structures within the prominence is of vital importance for their origin.On leave from the Observatory Sonnenborgh at Utrecht, The Netherlands.     

Сопоставление модели карлсона с моделью сплошной среды

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Effect of self-gravitation or finite ion mass on the stability of anisotropic plasma

The problem of stability of an unbounded anisotropic plasma characterized by different temperatures along and transverse to the magnetic field is investigated for an arbitrary direction of propagation. Chewet al (1956) equations modified to incorporate self-gravitation, finite ion Larmor radius (FLR) and Hall current are used. Uniform rotation (of an order of interest in astrophysics) is also considered. Extensive numerical treatment of the dispersion relation leads to several interesting results.Inclusion of FLR, or Hall current or both together introduces pulsational instability for prepagation parallel to the magnetic field. The aperiodic growth rate of the mirror instability is only slightly altered due to FLR or Hall current effects. In the absence of rotation, self-gravitation, FLR and Hall current, the growth rate decreases for the mirror region as the direction of propagation approaches the field direction, while the fire hose instability persists for arbitrary propagation, even in the limiting case (the mirror limit) where the propagation is nearly transverse to the magnetic field. Uniform rotation altogether stabilizes the fire hose instability for a sufficiently strong pressure (or temperature) anisotropy. Pulsational instability is introduced when both ratation and self-gravitation effects are present. Either FLR or Hall current depresses the growth rate of the fire hose instability and introduces pulsational instability for the general case of arbitrary propagation. When FLR and Hall current effects are present simultaneously, the interaction terms due to these effects may be strongly destabilizing in nature for arbitrary propagation.     

Pitch angle scattering of solar particles: Comparison of ‘particle’ and ‘field’ approach

In the quasi-linear theory of pitch angle scattering the power spectrum of magnetic field fluctuations is related to the shape of the pitch angle diffusion coefficient D(), the absolute value of the mean free path , and the rigidity dependence of the mean free path (R). We discuss these relations in detail during the solar particle event of 11 April, 1978 which was observed on HELIOS-2 at a distance of 0.49 AU from the Sun. Magnetic field measurements obtained during the time of the event are used as a basis for the layer model in which the method of particle trajectories in an actually measured field is used to simulate pitch angle diffusion. The values of D() and based on the trajectory simulation for 100 MeV protons (field approach) are compared with results obtained from solar proton data (particle approach) and with predictions from quasi-linear theory based on the additional assumption of the slab model for magnetic field fluctuations (QLT approach). The time of the event is characterized by a high level of field fluctuations, the observed mean free path of about 0.03 AU for 100 MeV protons is smaller than the average value near 1 AU. Results from the field and particle approaches agree surprisingly well. The remaining difference in the mean free path of about a factor of 2 could be due to tangential discontinuities which are measured by the magnetometer, but not seen by the real particles traveling along the average field. The results from the field and QLT approaches based on the same set of magnetic field measurements differ by about a factor of 4. One of the reasons for this discrepancy is that the conditions for resonance scattering are only marginally valid. In addition, the wave vectors representing Alfvén-type fluctuations may not be totally field aligned. This deviation from the slab model would cause an increase of the theoretically predicted mean free path and lead to better agreement with the other two approaches.     

Effect of perturbations on the stability of triangular points. In the restricted problem of three bodies with variable mass

The effect of small perturbations and in the coriolis and the centrifugal forces respectively on the stability of the triangular points in the restricted problem of three bodies with variable mass has been studied. It is found that the range of stability of triangular points increases or decreases depending upon whether the perturbation point (, ) lies in one or the other of the two parts in which the (, ) plane is divided by the line J₈–J₉=0 where J₈ and J₉ depend upon , the constant due to the variation in mass governed by Jeans' law.     

ОJ 287: Поляризационное и фотометрическое поведение В 1971–1976 гг

J 287 1972–1976. , . . J ( ), () . (₀=80°) . J 287 ¶ . p=42.8%, ₀=101°. (50%).     

The orientation of magnetic fields in quiescent prominences

We have measured the longitudinal component, B, of the magnetic field in quiescent prominences and obtained a relationship between B and , where is the angle between the long axis of the prominence and the north-south direction on the sun. From this relationship we deduce a distribution function for the magnetic field vector in quiescent prominences in terms of the angle between the field and the long axis of the prominence. The mean angle, , for our data is small, - 15°, indicating that the magnetic field traverses quiescent prominences under a small, but finite angle.On leave from Max-Planck Institut für Physik und Astrophysik, München.The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

The solar wind and the temperature-density structure of the solar corona

The influence of the solar wind on large-scale temperature and density distributions in the lower corona is studied. This influence is most profoundly felt through its effect upon the geometry of coronal magnetic fields since the presence of expansion divides the corona into magnetically open and closed regions. Each of these regions is governed by entirely different energy transport processes. This results in significant temperature differences since only the open field regions suffer outward conductive heat losses. Because the temperature influences the density in an exponential manner, large density inhomogeneities are to be expected.An approximate method for calculating the temperature and density distribution in a known magnetic field geometry is outlined and numerical estimates are carried out for representative coronal conditions. These estimates show that temperature differences of a factor of about two and density differences of ten can be expected in the lower corona even for uniform base conditions. As a result, we do not regard the so-called coronal holes necessairly as locations of reduced mechanical heating. Alternatively, we suggest that they are regions of open magnetic field lines being continuously drained of energy contert by the solar wind expansion and outward thermal conduction.The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

Scanner observations of the Be starsν Gem,κ Ori,β Mon andω CMa

The photoelectric spectrophotometric scans of the Be stars Gem, Ori, Mon and CMa have been analyzed to find out few stellar parameters. The absolute energy distributions of these stars in the wavelength range 350–750 nm have been given. Their effective temperatures and gravities have been estimated from comparisons with non-LTE model atmospheres. The stars Gem and Mon have been found to have Balmer discontinuities in emission. The excess emission in the region 620–750 nm has been observed for Mon and CMa. The evolutionary aspects of these stars are discussed and their masses have been estimated.     

Close Binary System Go Cygnus: Standard Ubv Observations and Light Curve Analysis

Standard UBV light curves of eclipsing binary star GO CYGNUS havebeen presented. These light curves indicate a Lyrae typevariations with circular orbit. The Light curve analysis have beencarried out on three colours U, B and V. The results obtained fromthese analysis represent an occultation solution with r r =1.24.     

General-relativistic hierarchical cosmology: An exact model

An exact solution of Einstein's equation is stated in which the density (), pressure (p), scale factorS and metric coefficients are functions of only one dimensionless self-similar variable,ct/R, wheret is cosmic time andR is a co-moving radial coordinate. The solution represents a cosmology that begins as a static sphere having R ^–2 and evolves into an expanding model which is pressure-free and has a hierarchical type of density law ( R ^–, approximately, with =a number, 02). It is suggested that this model should supersede the previous models of Wesson and other workers, since it appears to be the simplest cosmology for a hierarchy.     

Stability of the libration points of a rotating triaxial ellipsoid

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.

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Some fundamental elements of universe mechanics

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.

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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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A new microwave/X-ray diagnostic for the thermal phase of solar flares

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).     

εлектроны космических лучей радиогало галактики

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The development and production of new,non-standard methods of observations with the radio telescope RATAN-600

The recent modernization of the RATAN-600 radio telescope at the Special Astrophysical Observatory has provided an opportunity to develop new procedures, called relay and zoned relay, for utilizing the new cone-surface secondary reflector. The geometric area, the horizontal beamwidth spatial resolution, and the permissible radiometer bandwidth are discussed. We are also able to estimate the changes in the sensitivities of the radio telescope-radiometer systems. The new procedures, called relay and zoned relay, allow us to obtain two-dimensional images of radio objects and to track the development of rapidly varying sources in any azimuth.Presented at the CESRA-Workshop on Coronal Magnetic Energy Release at Caputh near Potsdam in May 1994.     

Determination of constant α force-free solar magnetic fields from magnetograph data

At first it is shown that a magnetic field being force-free, i.e. satisfying × B = B, with = constant ( 0) in the whole exterior of the Sun cannot have a finite energy content and cannot be determined uniquely from only one magnetic field component given at the photosphere. Then the boundary value problem for a semi-infinite column of arbitrary cross section is solved by a Green's function method.