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631.
The detection of X-rays from Nova Muscae 1983 (discovered on January 18, 1983) constitutes the first detection of X-rays from a classical nova during outburst. X-ray observations were carried out on 1984 April 20 and July 14 when Nova Mus had entered the nebular stage. During both observations no significant flux was observed with the medium energy detectors (2–50 keV). The source was detected with the low energy detector (.04–2 keV) using 3000 Å Lexan and Parlene- N-Aluminium filters; counting rates of (3.4 ± 1.2) × 103 and (3.7 ± 1.2 × 10-3 counts/sec were measured with the respective filters. The source was detected again on July 14 with about the same intensity. Either a shocked shell of circumstellar gas emitting 107 thermal bremsstrahlung at 1035 erg/sec intensity or a white dwarf remnant emitting 3.5 × 105 blackbody radiation at 1037 erg/sec luminosity are compatible with the measurements.Spectra taken in the visual spectral range show strong forbidden coronal emission lines of [FeVII] 6085, [FeX] 6374, and as never observed before in such a strength, [FeXIV] 5303 requiring excitation temperatures of 2 × 106 °K. 相似文献
632.
L.A. Fisk M.A. Lee 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(3):93-96
A simple shock model for the acceleration of energetic particles in corotating interaction regions (CIR) in the solar wind is presented. Particles are accelerated at the forward and reverse shocks which bound the CIR by being compressed between the shock fronts and magnetic irregularities upstream from the shocks, or by being compressed between upstream irregularities and those downstream from the shocks. Particles also suffer adiabatic deceleration in the expanding solar wind, an effect not included in previous shock models for acceleration in CIR's. The model is able to account for the observed exponential spectra at earth, the observed behavior of the spectra with radial distance, the observed radial gradients in the intensity, and the observed differences in the intensity and spectra at the forward and reverse shocks. 相似文献
633.
G. M. Malacinski A. W. Neff 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1986,6(12):29-36
Developing systems provide unique opportunities for analyzing the effects of microgravity on animals. Several unusual types of cells as well as various extraordinary cellular behavior patterns characterize the embryos of most animals. Those features have been exploited as test systems for space flight. The data from previous experiments are reviewed, and considerations for the design of future experiments are presented. 相似文献
634.
J.M. Dlugach E.G. Yanovitskij 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1981,1(8):167-170
This work is devoted to the derivation of the optical properties of the Venus atmosphere from “Venera-10” optical measurements. Within the framework of a two-layer model of Venus atmosphere it is found that in the spectral interval 0.52 – 0.85 μm the optical thickness of the upper cloud layer is ≈ 50 and the optical parameters of the lower layer are similar to the Rayleigh ones. Comparison is made between the measurements of radiation field within the atmosphere and the results of strict calculations. A preliminary conclusion is suggested that there are considerable numbers of aerosol particles with a radius ? 0.03 μm in the lower layer. The results of the upper boundary of the cloud layer is estimated to be ≈ 70 km. 相似文献
635.
M. Gogoshev N. Petkov A. Kuzmin Ts. Gogosheva St. Spassov Iv. Kostadinov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(7):115-120
This paper shows the possibilities of the optical scanning imager for investigation of the structure of the auroral, SAR and tropical arcs and in this way to study the particle precipitation, neutral winds across the magnetic equator, drifts, electric fields and the current systems in the ionosphere. 相似文献
636.
J.M. Russell E.E. Remsberg L.L. Gordley J.C. Gille P.L. Bailey 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1982,2(10):169-172
The LIMS experiment was launched on the Nimbus 7 satellite for the purpose of sounding the vertical structure of temperature and key upper atmosphere trace gases on a global scale. The technique of thermal infrared limb sounding was used to obtain measurements of O3, H2O, NO2, and HNO3. LIMS collected data almost continuously from late October to late May over the latitude range from 64°S to 84°N. Two of the gases, NO2 and HNO3, are important elements in the NOx chain of chemical reactions leading to ozone destruction. We will describe results for these gases in terms of zonal mean profiles and latitudinal distributions. The period selected for study is January–May 1979, when a major stratospheric warming occurred. 相似文献
637.
Analytical and experimental considerations of the large-signal transient responses of the buck-type switching regulator are described. The dynamic behavior under the large-signal condition is different from the small-signal operation because of the saturation characteristics of the pulsewidth modulator feedback controller. The effect of this nonlinearity is analyzed by dividing its operation into three modes. As a result the peak values of the inrush current and output voltage are obtained analytically both for the start-up and for the step change of the load condition. 相似文献
638.
M.B. Vasilyev A.S. Vyshlov M.A. Kolosov A.P. Mesterton N.A. Savich V.A. Samovol L.N. Samoznaev A.I. Sidorenko 《Acta Astronautica》1980,7(3):335-340
The experiment with two-frequency radio occultation measurements of the Venusian nightside ionosphere using the Venera-9 and 10 orbiters is described. The experiment is the first of a kind in which the radio link to one of the spacecraft is used to probe the ionosphere, while the other is measuring the variations in the integral electron number density along the path of radio ray propagation. The experiment has been designed to achieve the maximum possible accuracies in determining the parameters of the probed ionosphere using the bistatic two-frequency radio occultation method. 相似文献
639.
640.
Thermal springs in evaporitic environments provide a unique biological laboratory in which to study natural selection and evolutionary diversification. These isolated systems may be an analogue for conditions in early Earth or Mars history. One modern example of such a system can be found in the Chihuahuan Desert of north-central Mexico. The Cuatro Cienegas basin hosts a series of thermal springs that form a complex of aquatic ecosystems under a range of environmental conditions. Using landmark-based morphometric techniques, we have quantified an unusually high level of morphological variability in the endemic gastropod Mexipyrgus from Cuatro Cienegas. The differentiation is seen both within and between hydrological systems. Our results suggest that this type of environmental system is capable of producing and maintaining a high level of morphological diversity on small spatial scales, and thus should be a target for future astrobiological research. 相似文献