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1.
It is demonstrated that the long term variation in cosmic ray intensity I(t) can be described by an integral equation, , which is derived from a generalization of Simpson's coasting solar wind model. A source function S(t?τ) is given by some appropriate solar activity index at a time t?τ(τ ? 0) and the characteristic functionf(τ)(?0 forτ ? 0) expresses the time dependence of the efficiency of the intensity depression due to solar disturbances represented by S(t ?τ) when the disturbances generated at the solar surface propagate through the modulating region with the solar wind. It is demonstrated further that the equation can be derived from the general diffusion-convection theory on some assumptions, and as a result, the source and characteristic functions can be related to diffusion coefficient and its transition in space. Assuming the sunspot number R (or two activity indices including R) as the source function, the characteristic function f(τ) [or f(τ)'s] is obtained with data of the cosmic ray intensity extended over several decades. Based on the theory, one can obtain from f(τ) the following physical quantities in space, such as the transition and life time of solar disturbances, the boundary of the modulating region, and the radial and time dependences of the diffusion coefficient, radial density gradient and modulated intensity of cosmic rays. Results deduced from the present analysis are consistent with those obtained directly or indirectly by space observations. 相似文献
2.
The problem of interaction between the interplanetary shock of 8 March, 1970 and the Earth's bow shock, magnetopause and plasmapause is considered. Estimates are made using existing models of the moments of initial impulsive interaction of interplanetary shocks with the bow shock and of the secondary interaction of the resulting split discontinuities with the magnetopause, plasmapause and a modified bow shock. Using computed data on the plasma's concentration jumps at discontinuities and on the latters' velocities, estimates have been carried out of remote sounding and the response signals' phase difference change rates Δf (which were found to be of the order of ～ 10?3?10?2Hz) appearing on the radio path with a non-coherent response near the subsolar region. It has been ascertained that the non-coherent response method permits, by using generators with a stability of , effective investigation (with a good time resolution) of the impulsive interaction of interplanetary shocks with the plasma discontinuities of the bow shockmagnetopause-plasmapause system. 相似文献
3.
E.M. Dubinin P.L. Israelevich N.S. Nikolaeva I. Kutiev I.M. Podgorny 《Planetary and Space Science》1985,33(6):597-606
An intense, localized auroral disturbance observed by Intercosmos-Bulgaria-1300 satellite in the morning sector at the altitude 850 km is analyzed in detail. The disturbance is characterized by strong “jumps” of electric and magnetic fields reaching ～ 80 mV/m and ～ 100 nT, fluctuations of ion density (Δn/n ～ 70%) and bursts of downward and upward energetic electron fluxes. Electric and magnetic disturbances display a distinct spatial-temporal relationship typical for the standing quasi-monochromatic wave (). The ratio of amplitudes of electric and magnetic fluctuations is equal to Alfvén velocity (ΔE/ΔB ～ vA/c). However, a strong parallel component of the electric field (～ 30 mV/m) and large ion density fluctuations indicate significant changes of plasma properties (the effects of anomalous resistivity are possible). 相似文献
4.
Eric M. Jones 《Icarus》1981,46(3):328-336
Monte Carlo calculations of the expansion of space-faring civilizations are presented for a wide range of values of the population growth coefficient (α) and emigration coefficient (γ). Even for the very low values proposed by Newman and Sagan (α = 10?4per year; γ = 10?8per year) the migration wavefront expands at 1.4 × 10?5 pc per year. Even with this low expansion velocity, such a civilization would fill the Galaxy in about 109 years. Filling times of the order of 60 million years seem probable. The wavefront velocity is approximated by , where is the average radial distance traveled, the average distance traveled, and υs the ship speed. This approximation was derived by Newman. 相似文献
5.
The paper gives the results of detailed studies of the frequency spectra of the chain of the wave packets Fs(t) of geomagnetic pulsations PC-1 recorded at the Novolazarevskaya station. The bulk of the energy of Fs(t) is concentrated in the vicinity of the central frequencies of spectra—the carrier frequencies of the signals. The velocity of the flux of protons generating these signals correspond to them. The spectra of the signals have oscillations—“satellites” irregularly distributed in frequency. These satellites, as the authors believe, testify to the presence of the individual groups of protons of low concentration whose velocities vary within 103–104 km s?1.Their energy is only of the order of 10?2–10?3 of the energy of the main proton flux. Clearly pronounced maxima on double and triple frequencies are detected. They show that the generation of pulsations PC-1 is accompanied by the generation on the overtones of wave packets called in this paper “two-fold” and “three-fold” pulsations PC-1. Intensive symmetrical satellites of a modulation character have been discovered on frequencies . Frequency differences correspond to them. The authors believe that the values of Δ?±sK are resonance frequencies of the magnetospheric cavity in which geomagnetic pulsations PC-1 are generated. It is established that the values of Δ?±sK coincide closely with the carrier frequencies of geomagnetic pulsations PC-3 and PC-4 generated in the magnetosphere. This leads to the conclusion that the resonance oscillations of the magnetospheric cavity are their source. Thus, the generation of geomagnetic pulsations of different types and resonance oscillations in the magnetosphere are integrated into a unified process. The importance of the results obtained and the necessity to check further their trustworthiness and universality, using experimental data gathered in different conditions, is stressed. 相似文献
6.
An approximate form of the Boltzmann equation has been used to obtain local ionization rates due to the absorption of galactic cosmic rays in the Jovian atmosphere. It is shown that the muon flux component of the cosmic ray-induced cascade may be especially importannt in ionizing the atmosphere at levels where the total number density exceeds 1019 cm?3 (well below the ionospheric layers produced by solar euv). A model containing both positive and negative ion reactions has been employed to compute equilibrium electron and ion number densities. Peak electron number densities on the order of 103 cm?3 may be expected even at relatively low magnetic latitudes. The dominant positive ions are NH4+ and CnHm+ cluster ions, with n ? 2; it is suggested that the absorption of galactic cosmic ray energy at such relatively high pressures in the Jovian atmosphere and the subsequent chemical reactions may be instrumental in the local formation of complex hydrocarbons. 相似文献
7.
The Stokes parameters of resonance radiation scattered by a Na atom with the angular momentum F aligned by directed unpolarized radiation in a magnetic field H ～ 10?5?10?1 Oe are presented. An influence of the orientation of the magnetic field on these parameters are studied; the intensity ratio changes within ±5%, and the polarization degree P(D2) within ±25%. Measurements of and P(D2), if the geometry of scattering is known, may give information on the direction of the magnetic field in the sodium atmospheres of comets, as well as Io's sodium cloud or man-made cosmic clouds. 相似文献
8.
The horizontal electric field has been measured with balloons over the Pacific Ocean near the Sanriku Coast in Japan. By comparing the electric-field data obtained during magnetically disturbed periods, 16–17 October 1973, 6–7 October 1975 and 3–4 October 1977, with IMF Bz, auroral zone AU and AL, equatorial Dst and , mid-latitude magnetic fields (H, D, Z at Kakioka), and the ionospheric electron density (?0F2 at Kokubunji), it is found that the observed electric fields of about 9 mVm?1 made the clockwise rotation during the growth and recovery stages of the magnetospheric substorms. Relations between high and middle latitude ionospheres and between the magnetosphere and the ionosphere are discussed in relation to the origin and propagation of these electric fields. 相似文献
9.
The space erosion of stony meteorites has been determined to be 650μm 106y?1, while that of iron meteorites has been determined to be 22 μm 106y?1. The erosion rates are based on flux and size distributions of small particles in the solar system, meteoroid orbitals and the relation, determined by laboratory experiments, between excavated volume due to a collision and the size and velocity of the impacting small particle. Neither multiple collision or space erosion can explain the difference in cosmic ray exposure ages based on and those based on . It is concluded that there is a long term cosmic ray variation. 相似文献
10.
An extensive study of the IMP-6 and IMP-8 plasma and radio wave data has been performed to try to find electron plasma oscillations associated with type III radio noise bursts and low-energy solar electrons. This study shows that electron plasma oscillations are seldom observed in association with solar electron events and type III radio bursts at 1.0 AU. In nearly four years of observations only one event was found in which electron plasma oscillations are clearly associated with solar electrons. For this event the plasma oscillations appeared coincident with the development of a secondary maximum in the electron velocity distribution functions due to solar electrons streaming outwards from the Sun. Numerous cases were found in which no electron plasma oscillations with field strengths greater than 1 μV m?1 could be detected even though electrons from the solar flare were clearly detected at the spacecraft. For the one case in which electron plasma oscillations are definitely produced by the electrons ejected by the solar flare the electric field strength is relatively small, only about 100 μV m?1. This field strength is about a factor of ten smaller than the amplitude of electron plasma oscillations generated by electrons streaming into the solar wind from the bow shock. Electromagnetic radiation, believed to be similar to the type III radio emission, is also observed coming from the region of the more intense electron plasma oscillations upstream of the bow shock. Quantitative calculations of the rate of conversion of the plasma oscillation energy to electromagnetic radiation are presented for plasma oscillations excited by both solar electrons and electrons from the bow shock. These calculations show that neither the type III radio emissions nor the radiation from upstream of the bow shock can be adequately explained by a current theory for the coupling of electron plasma oscillations to electromagnetic radiation. Possible ways of resolving these difficulties are discussed. 相似文献
11.
Alexander I. Ershkovich 《Planetary and Space Science》1979,27(10):1239-1245
Helical waves in the tail of Comet Morehouse are studied in the WKB approximation with the plasma non-uniformity along the tail taken into account. A comet tail boundary is considered as a transition layer of thickness d, with the linear velocity profile within it. This approach enables us to set the limits of applicability of the tangential discontinuity model: for wavelengths λ which satisfy the condition both models are practically coincident. The thickness d of the tail boundary is derived from the observations of the increase of the wave amplitude along the tail axis: d ≈ (15–20) × 103 km. With such a thickness stability conditions turn out to be marginal. This could explain why helical waves in type-1 comet tails are seen only occasionally and not at all times. 相似文献
12.
Louis A. Capone John Dubach Robert C. Whitten Sheo S. Prasad Krishnamurthy Santhanam 《Icarus》1980,44(1):72-84
We have studied the possible synthesis of organic molecules by the absorption of galactic cosmic rays in an N2CH4H2 Titan model atmosphere. The cosmic-ray-induced ionization results in peak electron densities of 2 × 103 cm?3, with NH4+, C3H9+, and C4H9+ being among the important positive ions. Details of the ion and neutral chemistry relevant to the production of organic molecules are discussed. The potential importance of reactions with CH4 and H2 is also demonstrated. Although the integrated production rate of organic matter due to the absorption of the cosmic ray cascade is much less than that by solar ultraviolet radiation, the production of nitrogen-bearing organic molecules by cosmic rays may be greater. 相似文献
13.
A.T.Y. Lui C.-I. Meng L.A. Frank K.L. Ackerson S.-I. Akasofu 《Planetary and Space Science》1981,29(8):837-842
The temperature and density of the plasma in the Earth's distant plasma sheet at the downstream distances of about 20–25 Re are examined during a high geomagnetic disturbance period. It is shown that the plasma sheet cools when magnetospheric substorm expansion is indicated by the AE index. During cooling, the plasma sheet temperature, T, and the number density, N, are related by (adiabatic process) in some instances, while by T ∝ N?1 (isobaric process) in other cases. The total plasma and magnetic pressure decreases when and increases when T ∝ N?1. Observation also indicates that the dawn-dusk component of plasma flow is frequently large and comparable to the sunward-tailward flow component near the central plasma sheet during substorms. 相似文献
14.
J.S. Reid 《Planetary and Space Science》1976,24(7):705-710
Cosmic noise absorption pulsation events observed with fast response riometers at Macquarie Island in the southern auroral zone have almost always been accompanied by Pi 1 micropulsations. A cross-spectral analysis of fast response riometer data and vertical component induction magnetometer data for one such event showed that, after the low frequency components are removed, the absorption A(t) is better correlated with the absolute value of the field Z(t) than with the recorded quantity . The peaks in Z(t) lag those in A(t) by one second while A(t) lags by abou second. Furthermore, many of the pulsations in Z(t) show a similar time asymmetry to that commonly observed in c.n.a. pulsations, viz. a more rapid onset time than decay time.These results are taken as evidence that the Pi 1 micropulsations observed from the ground during the recovery phase of an auroral substorm are brought about by fluctuations in the ionospheric currents which give rise to the magnetic bay, these fluctuations being due to conductivity changes resulting from particle precipitation. The lag between A(t) and Z > (t) is attributed to the self-inductance of the electrojet. 相似文献
15.
From published ground-base, spacecraft, and rocket photometry and polarimetry of the zodiacal light, a number of optical and physical parameters have been derived. It was assumed that the number density, mean particle size, and albedo vary with heliocentric distance, and shown that average individual interplanetary particles have a small but definite opposition effect, a mean single-scattering albedo in the V band at 1-AU heliocentric distance of 0.09 ± 0.01, and a zero-phase geometric albedo of 0.04. Modeled by a power law, both albedos decrease with increasing heliocentric distance as r?0.54. The corresponding exponents for changes in mean particle size and number density are related in a simple way. The median orbital inclination of zodiacal light particles with respect to the ecliptic is 12°, close to the observed median value for faint asteroids and short-period comets. Furthermore, the color of dust particles and its variation with solar phase angle closely resemble those of C asteroids. These findings are, at least, consistent with the zodiacal cloud originating primarily from collisions among asteroids. Finally, a value of ?1018?ErmE g was derived for the mass of the zodiacal cloud, where ?E is the mean particle radius (in micrometers) at 1-AU-heliocentric distance. For extinction in the ecliptic, was obtained, where ? is the solar elongation in degrees. 相似文献
16.
《Chinese Astronomy and Astrophysics》1983,7(1):18-24
Based on four previous studies with standard-candle quasars and using the correct formula for the luminosity distance, we obtain an improved determination of the deceleration parameter, q0 = +2.07. From the new catalog of quasars, we find the statistical relation and hence the mean quasar luminosity or and its rates of change and . Finally, we discuss the question whether there is a Malmquist effect in our sample and the question of the dichotomy of published q0-values. 相似文献
17.
Zeng-yuan Yue 《Chinese Astronomy and Astrophysics》1983,7(3):186-194
It is shown that the asymptotic σ1(r) and ψ1(r) relations can be derived very simply by using the method of double series expansion, where σ1, ψ1(r,0) and ψ1 are the surface density perturbation, the gravitational potential perturbation at the symmetric plane Z=0 and the average potential perturbation respectively. The results are accurate to the order of both m2(kr)?2 and k〈∣z∣〉, where m is the number of spiral arms, k is the radial wave number, r is the distance from the centre of the galaxy, and 〈∣z∣〉 is the average vertical distance of a star from the Symmetrie plane Z=0. Such an accuracy is usually sufficient for the discussion of spiral modes in a spiral galaxy of small but finite disk thickness. It is pointed out that ψ1(r,0)～(σ1(r) relation can be expressed in a unified form for different vertical density profiles if 〈∣z∣〉 is adopted as the thickness scale, and that ψ1(r,0)～(σ1(r) can be expressed in a unified form for different vertical density profiles if 〈∣z?z∣〉 the average vertical separation between two stars, is adopted as the thickness scale. Only the value of the ratio is a functional of the vertical density profile. However, for the usual physically meaningful profiles, these values are very close to each other: It is for the Gaussian profile, for the profile, and 1.5 for the profile. 相似文献
18.
The quenching rate kN2 of by N2 and the specific recombination rate α1D of O2+ leading to are re-examined in light of available laboratory and satellite data. Use of recent experimental values for the transition probabilities in a re-analysis of AE-C satellite 6300 Å airglow data results in a value for kN2 of 2.3 × 10?11 cm3s?1 at thermospheric temperatures, in excellent agreement with the laboratory measurements. This implies a value of JO2 = 1.5 × 10?6s?1 for the O2 photodissociation rate in the Schumann-Runge continuum. The specific recombination coefficient α1D = 2.1 × 10?7cm3s?1 is also in agreement with the laboratory value. Implications for the suggested reaction are discussed. 相似文献
19.
The rates and altitudes for the dissociation of atmospheric constituents of Titan are calculated for solar UV, solar wind protons, interplanetary electrons, Saturn magnetospheric particles, and cosmic rays. The resulting integrated synthesis rates of organic products range from 102–103 g cm?2 over 4.5 × 109 years for high-energy particle sources to 1.3 × 104 g cm?2 for UV at , and to 5.0 × 105 g cm?2 if (acting primarily on C2H2, C2H4, and C4H2) is included. The production rate curves show no localized maxima corresponding to observed altitudes of Titan's hazes and clouds. For simple to moderately complex organic gases in the Titanian atmosphere, condensation occurs below the top of the main cloud deck at 2825 km. Such condensates comprise the principal cloud mass, with molecules of greater complexity condensing at higher altitudes. The scattering optical depths of the condensates of molecules produced in the Titanian mesosphere are as great as ～ 102/(particulate radius, μm) if column densities of condensed and gas phases are comparable. Visible condensation hazes of more complex organic compounds may occur at altitudes up to ～ 3060 km provided only that the abundance of organic products declines with molecular mass no faster than laboratory experiments indicate. Typical organics condensing at 2900 km have molecular masses = 100–150 Da. At current rates of production the integrated depth of precipitated organic liquids, ices, and tholins produced over 4.5 × 109 years ranges from a minimum ～ 100 m to kilometers if UV at is important. The organic nitrogen content of this layer is expected to be ～ 10?1?10?3 by mass. 相似文献
20.
A ring current model has been obtained which permits calculations ofDst variations on the Earth's surface during magnetic storms. The changes in Dst are described by the equation where ; p = mnv2 is solar wind pressure; F(EM) is the function, controlled by the electromagnetic parameters of interplanetary medium, of injection into ring current ; τ is the constant of ring current decay. , where C is the level of the Dst-variation field measurements; ? is the injection function characterizing the quasisteady-state injection of energy into the ring-current region. The constant Ç is determined from the condition that the change of the ring current energy from magnetic storm commencement to end should equal the difference between the injected and dissipated energy throughout the storm. The values of the factors b and τ were found by the method of minimizing the sum of the quadratic deviations of the calculated Dst from the values observed throughout the storm : b = 0.23 nT/(eV cm?3), τ = 8.2 h at Dst? ? 55 nT and τ = 5.8 h at -120 ? Dst ? — 55 nT. The injection function F(EM) is of the form F(EM) = d(Ey? A) at the values of the azimuthal component of the solar wind electric field Ey ? A, and F(EM) =0 at A?Ey.d = ? 1.2 × 10?3 Ts?1 (mV/m)?1 and A = ? 0.9 mV m?1 . Thus, the injection to ring current is possible at the northward Bz component of the IMF. 相似文献