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V. I. Krasovskii 《Planetary and Space Science》1961,8(3-4):125-136
A general review is given of the results of the airglow and auroral investigations during I.G.Y and I.G.C. in the Institute for Atmospheric Physics of the Academy of Sciences of the U.S.S.R. A strong helium emission at 10830 Å has been discovered in sunlit aurorae and in the ordinary twilight airglow. It is now observed regularly. A detailed theory of this fluorescent emission has been developed. Extensive observations on the hydroxyl bands between 5000 and 12,000 Å have been carried out at a number of stations. Marked seasonal and geographical variations have been found in them. During intense aurorae the line-width of the 6300 Å emission from great altitudes increases. The effect has been studied using Fabry-Perot interferometers. Contributions have been made to knowledge on auroral morphology. The interpretation of some of the results which are described in the review are discussed. 相似文献
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A brief history of C.T.R. Wilson’s invention of the cloud chamber is presented. Initially, the research programme concerned the origin of the atmospheric phenomena he had experienced as a temporary meteorological observer on Ben Nevis. As his understanding of the physical conditions under which the condensation of water droplets took place from supersaturated water vapour developed, he realised that the technique provided the first way of imaging the tracks of the charged particles released by X-rays, in radioactive decays and in nuclear interactions. 相似文献
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Verne R. OBERBECK 《Meteoritics & planetary science》2008,43(4):815-817
Abstract— Any permanent presence on the Moon will require use of materials from the lunar regolith, the surface soil layer on the Moon. Thus, knowledge of the thickness of the lunar regolith is essential. It has been proposed that crater counts obtained from high Sun angle photography give larger estimates of impact crater equilibrium diameters than for low Sun angle photography, and thus deeper estimates of lunar surface regolith than were previously made using crater morphology, size of blocky rimmed craters, and equilibrium diameters determined on low Sun angle images. The purpose of this comment is to evaluate this result as a means of resolving this important question before planning for future lunar missions is undertaken 相似文献
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Using a spherically symmetric model of the Virgo flow the global Hubble parameter has been estimated from the observed radial velocities and the photometrically measured distances of nearby galaxies. Adopting the observed recession velocity of the Virgo Cluster to about 1000 km s−1 and the infall velocity of the Local Group to 350 km s−1 the global Hubble constant results to 73 ± 10 km s−1 Mpc−1. This value corresponds with the distance of the Virgo Cluster of 18 ± 2 Mpc. The cosmic dispersion of the galaxies around the Hubble relation is of order of 35 km s−1. 相似文献
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The Earth’s atmosphere is an integral part of the detector in ground-based imaging atmospheric Cherenkov telescope (IACT) experiments and has to be taken into account in the calibration. Atmospheric and hardware-related deviations from simulated conditions can result in the mis-reconstruction of primary particle energies and therefore of source spectra. During the eight years of observations with the High Energy Stereoscopic System (H.E.S.S.) in Namibia, the overall yield in Cherenkov photons has varied strongly with time due to gradual hardware aging, together with adjustments of the hardware components, and natural, as well as anthropogenic, variations of the atmospheric transparency. Here we present robust data selection criteria that minimize these effects over the full data set of the H.E.S.S. experiment and introduce the Cherenkov transparency coefficient as a new atmospheric monitoring quantity. The influence of atmospheric transparency, as quantified by this coefficient, on energy reconstruction and spectral parameters is examined and its correlation with the aerosol optical depth (AOD) of independent MISR satellite measurements and local measurements of atmospheric clarity is investigated. 相似文献
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The ejection of energetic electrons and
protons,and γ-ray burst are revealed by solar space observations,which have confirmed
some related theories of solar radio emission and uncovered the nuclear reaction in
flares.The difference and relationship between CME and plasma cloud in flares are shown by
space observations.The hot and cold regions of flares are known.The theory of nonlinear
magnetohydrodynamics is developed by solar and heliospheric magnetic field observations. 相似文献
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Recent spectroscopic observations of atmospheric emissions in the u.v. region of the spectrum have been analyzed using laboratory-measured excitation cross-sections, models and observations of energetic electron fluxes and models of atmospheric composition. In both the airglow and the aurora, self-consistent pictures of the excitation processes and atmospheric composition have been obtained. These analyses have shown that photoelectron fluxes measured from the Atmospheric Explorer satellite are in good agreement with the photoelectron-excited dayglow and that a large number of recent laboratory-measured excitation processes are able to reproduce the u.v. spectra in both the dayglow and aurora. In this paper we show that accurate quantitative determinations of thermospheric parameters can now be made from u.v. spectral observations. In particular, we show that the composition and temperature can be obtained from altitude profiles of the emissions alone, without reliance on the absolute photoelectron flux. 相似文献
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The dissociation of N2 by electron impact and by e.u.v. photo-absorption is studied, and it is shown that the forbidden predissociation of the numerous 1Πu and 1Σu+ valence and Rydberg states of N2 in the 11–24eV energy range is the dominant mechanism for N atom production. By measuring the absolute emission cross sections for the e.u.v. singlet bands of N2 and by using the generalized oscillator strength data of Lassettre (1974), it has been possible to construct a detailed model of the total N2 dissociation cross section which is in good agreement with the measurements of Winters (1966) and Niehaus (1967) and provides some insights into the maximum possible yield from dissociative excitation. The total cross section for exciting N2 e.u.v. radiation in the 800Å–1100Å wavelength range has been measured and found to have a value of 3.4 ×10?17 cm2 at 100 eV under optically thin conditions. Although this result implies that large fluxes of e.u.v. photons should be excited in auroral substorms and in the airglow, they are not observed, and we show that this development is a consequence of radiation entrapment and predissociation. The total cross section for dissociating N2 by electron impact is given for optically thin and thick media. And some questions concerning the energy budget of a magnetospheric storm which are raised by these results, are discussed. 相似文献
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太阳空间观测为揭示太阳新的观测现象与研究开拓了新的途径。空间观测具有全波段、全时段、全方位以及无大气抖动和大气散射光等观测优点。本文着重探讨了太阳空间长波射电观测、Ｘ射线观测、紫外线观测的成就与研究结果。这些波段（包括光学）的爆发均起因于太阳大气中被加速的荷能电子与太阳等离子体、磁场相互作用而产生的电磁辐射,其能量约占太阳耀斑总量的１／４,即１０２５Ｊ。 相似文献
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Donald E. Billings 《Solar physics》1975,41(2):367-369
Observational line width evidence for a possible discrepancy between ion and electron temperature in the corona is reviewed for comparison with the conclusions of Knight et al. We note that the high line-width temperatures extend much higher in the corona than the high ion temperatures computed by Knight et al., and suggest that a significant ion-electron temperature difference should be expected only near a steep temperature gradient, as in the transition region. 相似文献
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The depletion of an initially uniform distribution of asteroids extending form Mars to Saturn, caused by the gravitational perturbations of Jupiter and Saturn, is calculated by numerical integration of the asteroid orbits. Almost all (about 85%) the asteroids between Jupiter and Saturn are ejected in the first 6000 years Most of the asteroids between the Jupiter resonance (4.0 A.U.) and Jupiter are ejected in the first 2400 years with the exception of the stable librators (e.g., the Hilda group). Interior to the resonance the depletion was small, and interior to the resonance (3.3 A.U.) no asteroids were ejected in the first 2400 years. 相似文献
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