A new mechanism for pulsar gamma-ray emission

Gamma-ray emission in pulsar magnetospheres is attributed to synchrotron radiation, which tends to decrease the pitch angle of the particle, being balanced by plasma processes tending to increase the pitch angle. The plasma processes are non-resonant instabilities that drive non-resonant quasilinear diffusion (NQD), thereby pumping energy from waves and the parallel motion of the particle into the perpendicular motion of the particle. It is shown that NQD can maintain the pitch angles for particles near the light-cylinder such that they radiate synchrotron radiation at MeV energies. Compared to conventional emission mechanisms (such as polar cap or outer gap models), the resulting spectrum has a relatively low upper cut-off from about a few to 100 MeV. Possible observational consequences of this mechanism are discussed.     

Relative motion of near orbiting satellites

The relative motion of two particles on adjacent orbits about the same primary has been investigated under the condition that both motions have the same period. The geometrical properties of the relative displacement and velocity traces, on representative planes, are studied. A complete state of the motion is given; and, the range and range-rate variations, over one or more orbits, are described.It has been found that cusps appear on some of the traces provided that a proper relationship exists between the eccentricity and inclination. (Here, one particle moves on a circular path while the second moves on an ellipse.) The conditions for which cusps appear are given, and typical traces are shown.     

Electrostatic charging and motion of dust near the surface of an asteroid

The electrostatic charging and motion of dust near the surface of an asteroid is analyzed. It is shown that, despite the weak gravity, strong electric fields are needed to lift charged dust particles from the surface. The mechanism of generation of such fields, and the results of calculations of the motion of particles with various diameters in the electric fields near the dark side of the asteroid surface, is discussed. It is noted that the dust particle motion should be the most pronounced, as happens in the case of the Moon, in a certain neighborhood of the terminator.     

Motion of a charged particle around a black hole permeated by magnetic field and its chaotic characters

Motion of a charged particle around a black hole immersed in magnetic field is calculated. It is shown that this motion has a chaotic property depending on initial parameters.     

On the formation of pulsar radiation diagrmas

A model of pulsars is discussed in which formation of a polar diagram of the radiation is influenced by the motion of the source around a neutron star with a velocity close to that of light. For a power-law frequency-spectrum of the radiation and isotropy of the diagram in a system of coordinates rotating with the source, the width of the observed pulse is shown to be independent of frequency.The proposed explanation of the second period characteristics of type CP 1919 pulsars is based on the effect of relativistic motion of the radiation source. The positions are established (relative to the axis of rotation of the star) of the local sources of radiation in the optical and in the radio ranges for the pulsar NP 0532. It is shown how the polarization characteristics of the optical radiation of this pulsar may be connected with the effects of relativistic orbiting of the source of radiation about the star.     

Interplanetary dust particles and solar electromagnetic radiation

The action of the solar electromagnetic radiation on the motion of interplanetary dust particle of the plane mirror form is investigated. It is shown that for rapidly rotating plane mirror the speed of inspiralling toward the Sun is about a factor of 4 lower than that for spherical mirror of the same cross-sectional area. In principle, it is also possible that the plane mirror can be expelled from the inner part of the Solar System. Presented derivation is a little more general - it is considered that some parts of the incident radiation can be also absorbed or transmitted, not only reflected.Obtained results show that the Poynting-Robertson effect is strongly model-dependent. It is suggested that for real irregular porous particles the speed of inspiralling toward the Sun can be smaller than that for perfectly absorbing sphere. Orbital plane can change in time.     

The motion of charged particles in a strong electromagnetic field and curvature radiation

The features of the relativistic charge particle motion and emission due to the radiative slamping in the strong electromagnetic fields are investigated. It is shown that the radiative force responsible for curvature radiation is associated with the particle drift in an inhomogeneous magnetic field. The adiabatic trajectory is obtained for the relativistic particle, moving in a strong static electron-magnetic field, particle energy being determined by the balance of the work of the electric field and the energy losses through curvature radiation.     

Quasiintegrals of the photogravitational eccentric restricted three-body problem with Poynting–Robertson drag

A restricted three-body problem for a dust particle, in presence of a spherical cometary nucleus in an eccentric (elliptic, parabolic or hyperbolic) orbit about the Sun, is considered. The force of radiation pressure and the Poynting– Robertson effect are taken into account. The differential equations of the particle’s non-inertial spatial motion are investigated both analytically and numerically. With the help of a complex representation, a new single equation of the motion is obtained. Conversion of the equations of motion system into a single equation allows the derivation of simple expressions similar to the integral of energy and integrals of areas. The derived expressions are named quasiintegrals. Relative values of terms of the energy quasiintegral for a smallest, largest, and a mean comet are calculated. We have found that in a number of cases the quasiintegrals are related to the regular integrals of motion, and discuss how the quasiintegrals may be applied to find some significant constraints on the motion of a body of infinitesimal mass.     

Dust in jupiter''s magnetosphere: Physical processes

The physical processes acting on charged microscopic dust grains in the Jovian magnetosphere are examined. Such small dust grains are believed to be injected continuously into the magnetosphere via volcanic activity on Io. It is shown that electromagnetic forces dominate the dust particle dynamics, and that these particles behave adiabatically, in the sense that the guiding centre approximation to their motion applies. Based on this fact, the diffusion across field lines, caused by random charge fluctuations of the dust grains, can be determined. This diffusion is the major cross field transport mechanism and determines the dispersion of dust grains from Io throughout the inner Jovian magnetosphere. Other physical processes (radiation pressure drag, Coulomb drag, sputtering) are also examined regarding their importance for particle transport.     

Electric and magnetic drift of non-adiabatic ions in the Earth's geomagnetic tail current sheet

It has been shown recently that non-adiabatic particles in the Earth's magnetotail drift across the tail roughly as predicted for adiabatic particles with 90° pitch angles. In this paper we show that this result implies the existence of an approximate invariant of the motion. Adding the effect of convection associated electric fields, we can then obtain the approximate bounce averaged motion of non-adiabatic particles in the magnetotail. Thus the particle motion and energization due to combined magnetic and electric drifts in the magnetotail are easily predicted.     

The rectilinear restricted problem of three bodies

In this paper we discuss some aspects of the isosceles case of the rectilinear restricted problem of three bodies, where two primaries of equal mass move on rectilinear ellipses, and the particle is confined to the symmetry axis of the system. In particular, the behaviour near a collision of the primaries and also near a collision of all three bodies is investigated. It is shown that this latter singularity is a triple collision in the sense of Siegel's theory. Furthermore, asymptotic expansions for the particle's motion during a parabolic and a hyperbolic escape are derived.Presented at the Conference on Celestial Mechanics, Oberwolfach, Germany, August 27–September 2, 1972.     

The formal integrals of the restricted planar problem of the three bodies

The first integrals of motion of the restricted planar circular problem of three bodies are constructed as the formal power series in r^1/2, r being the distance of a moving particle from the primary. It is shown that the coefficients of these series are trigonometric polynomials of an angular variable. Some particular solutions have been found in a closed form. The proposed method for constructing the formal integrals can be generalized to a spatial problem of three bodies.     

On the stability of dust orbits in mean-motion resonances perturbed by from an interstellar wind

Circumstellar dust particles can be captured in a mean-motion resonance (MMR) with a planet and simultaneously be affected by non-gravitational effects. It is possible to describe the secular variations of a particle orbit in the MMR analytically using averaged resonant equations. We derive the averaged resonant equations from the equations of motion in near-canonical form. The secular variations of the particle orbit depending on the orientation of the orbit in space are taken into account. The averaged resonant equations can be derived/confirmed also from Lagrange’s planetary equations. We apply the derived theory to the case when the non-gravitational effects are the Poynting–Robertson effect, the radial stellar wind, and an interstellar wind. The analytical and numerical results obtained are in excellent agreement. We found that the types of orbits correspond to libration centers of the conservative problem. The averaged resonant equations can lead to a system of equations which holds for stationary points in a subset of resonant variables. Using this system we show analytically that for the considered non-gravitational effects, all stationary points should correspond to orbits which are stationary in interplanetary space after an averaging over a synodic period. In an exact resonance, the stationary orbits are stable. The stability is achieved by a periodic repetition of the evolution during the synodic period. Numerical solutions of this system show that there are no stationary orbits for either the exact or non-exact resonances.     

The warm current sheet model, and its implications on the temporal behaviour of the geomagnetic tail

A simple model current sheet is studied numerically. Consistent fields and particle trajectories, and their dependence on electron and proton temperature, convection velocity and normal field, B_z, linking through the current sheet, are presented and discussed. It is shown that the protons, which are the major current carriers, largely retain the decoupling of the motion in the x-y plane from the normal oscillations as in the ‘cold’ current sheet. The positive potential of the current sheet is shown to be sufficient to trap some energetic electrons, the motion of which enables the predominance of energetic electrons towards the dawn side of the tail to be understood. Semi-empirical relationships for the thickness and the potential of the current sheet are obtained.

The consequences of such a current sheet on the behaviour of the geomagnetic tail are investigated. Using Faraday's law and the consistent cross tail electric field it is shown that the effect of a southward turning of the interplanetary field is to lead to a decrease in B_z,an increase of the current sheet conductivity, and a growth of stored field energy, i.e. the current sheet blocks merging. The decrease of the resistance of the current sheet is limited by the finite width of the tail. Finally, it is pointed out that if the conditions which bring about the growth of field energy persist, then the collapse of the field lines characteristic of substorms may occur.     

The thermospheric heating efficiency under electron precipitation conditions

A time-dependent model calculation of the interaction between energetic electrons and the thermosphere is performed to evaluate the heating efficiency. All energy channels which contribute to the neutral heating of the atmosphere are considered in detail. Neutral chemical reactions and deactivation of metastables are found to be the major heat sources. It is shown that, below 150km, the heating efficiency is on the order of 60% and nearly independent of altitude. At higher altitude, its value decreases in a manner depending on the atmosphere density and composition. It is concluded that, in the dayside polar cusp, particle heating may be an important source of thermospheric motion.     

A note on a Lagrangian formulation for motion about the collinear points

A lagrangian formulation for the three-dimensional motion of a satellite in the vicinity of the collinear points of the circular-restricted problem is reconsidered. It is shown that the influence of the primaries can be expressed in the form of two third-body disturbing functions. By use of this approach, the equations for the Lagrangian and for the motion itself are readily developed into highly compact expressions. All orders of the non-linear developments are shown to be easily obtainable using well-known recursive relationships. The resulting forms for these equations are well suited for use in the initial phase of canonical or non-canonical investigations.     

The Influence of Ion-Acoustic Turbulence on the Electron Acceleration in the Reconnecting Current Sheet

Through solving the single electron equation of motion and the Fokker-Planck equation including the terms of electric field strength and ion-acoustic turbulence, we study the influence of the ion-acoustic wave on the electron acceleration in turbulent reconnecting current sheets. It is shown that the ion-acoustic turbulence which causes plasma heating rather than particle acceleration should be considered. With typical parameter values, the acceleration time scale is around the order of 10^-6 s, the accelerated electrons may have approximately a power-law distribution in the energy range 20 ～100 keV and the spectral index is about 3～10, which is basically consistent with the observed hard X-ray spectra in solar flares.     

耀斑氦线的观测和研究

介绍了耀斑各波区（从ＥＵＶ到红外）氦线观测的进展，从中阐明氦线观测和研究在提供太阳耀斑物理参数，了解耀斑动力学过程，电场，能量平衡及高能粒子产生和传输方面的特殊意义，并分析了这个领域目前已经取犁研究结果和今后研究中在观测技术和理论分析两个方面尚需解决的关键问题。