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51.
地磁场对1999年9月空间天气大事件的响应 总被引:1,自引:0,他引:1
王文 《地震地磁观测与研究》2001,22(6):13-17
1999年9月22-25日发生一个大磁暴(Dst=-164nT).磁暴主相开始的头1小时伴随有丰富的Pc型地磁脉动,包括Pc2,Pc3,Pc4等。在行星际磁场Bz由北向转向南向后,磁暴主相开始,南向分量达到最大值后大约2小时,地磁H分量达到最小值,恢复相开始,并且,这次磁暴与太阳风各参数以及星际电场也存在一定的对应关系。 相似文献
52.
本文分析了1988年12月和1989年1月在长春、北京、兰州3个台站上观测的地磁脉动资料,研究了3个台站同时记录到的Pi2地磁脉动的频谱特征和偏振特性,进而对低纬Pi2地磁脉动的产生和传播机制做了理论研究. 相似文献
53.
We investigate the parameter space of a Parker dynamo with a simple alpha quenching nonlinearity, taking as governing parameters the dynamo number D (D<0) and the ratio of diffusion times in the radial and latitudinal directions in the convective zone. The latter parameter, μ, is connected with the aspect ratio (dimensionless thickness) of the convective zone. We isolate two asymptotic configuration of the dynamo waves excited by the Parker dynamo in the limiting case of strong generation. Apart from the standard case with the solar type dynamo wave travelling from mid-latitudes to the equator, we describe a form of dynamo activity which is basically an anharmonic standing wave. The first situation occurs when μ increases with |D|. With μ fixed and |D| increasing, the second asymptotic configuration occurs. We discuss possibilities of identifying these asymptotic configurations with various types of stellar activity as traced by stellar CaII data. 相似文献
54.
Vikram V. Dwarkadas 《Astrophysics and Space Science》2007,307(1-3):153-158
Core-Collapse supernovae arise from stars greater than 8 M⊙. These stars lose a considerable amount of mass during their lifetime, which accumulates around the star forming wind-blown
bubbles. Upon the death of the star in a spectacular explosion, the resulting SN shock wave will interact with this modified
medium. We study the evolution of the shock wave, and investigate the properties of this interaction. We concentrate on the
evolution of the SN shock wave in the medium around a 35 solar mass star. We discuss the hydrodynamics of the resulting interaction,
the formation and growth of instabilities, and deviations from sphericity. 相似文献
55.
蒋志 《矿物岩石地球化学通报》2001,20(3):165-171
本文讨论了地球内部长寿期放射性同位素衰变能的存量 ,给出地球脉动频率和频数公式 ,并据以重新建立了理论地质年表 ,解释了地球自转变化、地磁场倒转和黄赤交角变化等。 相似文献
56.
西北地区戈壁砂砾石场地的脉动特征 总被引:1,自引:0,他引:1
阐述了我国西北部戈壁砂砾石层的划分及其时代确定等问题,以近几年西北地区地震小区划和重大工程建设项目中的实际观测资料为依据,对西北戈壁滩砂砾石场地的脉动特征进行了分析和总结,在此基础上探讨了场地脉动频谱特性与场地有关参数的关系,同时还就地脉动测试在工程中的推广应用等问题提出了几点看法。 相似文献
57.
58.
Based on published estimates of areal extent, thickness and dating of igneous rocks related to formation of the North Atlantic
Volcanic Province, we calculate the magmatic production since the first reported magmatism at 70 Ma until present. We relate
the magmatism to the Icelandic Plume and estimate the total volumetric production to 22.1 × 106 km3. The magmatic production varied significantly with time, with a clear maximum of 55.5 m3/s around continental break-up at ca. 54 Ma. The lowest production is estimated at 4 m3/s, increasing to 7 m3/s at ca. 23 Ma. Two other pulses with increased activity are found around 40 Ma and in the late Miocene (10–5 Ma). The variations
in productivity are consistent with a plume pulsing with a periodicity of ca. 15 million years. The same periodicity and relative
timing is found for the Hawaiian Plume. If confirmed, these observations suggest that both plumes originate within the thin
boundary layer near the Core-Mantle Boundary. This hypothesis may imply periodic heating of the earth’s core with subsequent
heat-release to the mantle and increased global plume activity. 相似文献
59.
Pulsation of the Sun with a period of P0 ≈ 160 min discovered about two decades ago, is still waiting explanation. In view of the hypothesis about its cosmological origin, and attempting to find signature of this P0 periodicity among other (short-period variable) stars, the pulsation frequencies of δ Sct stars are subjected to specific analysis. With a confidence level ≈ 3.8σ it is found that the frequency v0 = P0−1 ≈ 104 m̈Hz, within the error limits, appears indeed to be the most “resonant” one for the total sample of 318 pulsating stars of δ Sct type (the most commensurable, or “synchronizing”, period for all these stars occurs to be 162 ± 4 min). We conjecture that a) the P0 oscillation might be connected with periodic fluctuations of gravity field (metrics), and b) the primary excitation mechanism of pulsations of δ Sct stars, reffected by this “ubiquitous” P0 resonance, must be attributed perhaps to superfast rotation of their inner cores (their rates tend to be in near-resonance with the “universal” v0 frequency). The arguments are given favouring a cosmoogical nature of the P0 oscillation. 相似文献
60.
To be able to simulate the interaction of extrasolar planets with the stellar wind, a number of planetary parameters are required. Some of these (like planetary mass and radius) can be obtained directly from observational data. Other properties are not known very precisely. For example, up to now, there is no observation providing information on the strength of planetary magnetic moments. However, there is good reason to expect only very small magnetic moments for planets in very close orbits around their stars (like HD 209458 b and OGLE-TR-56 b). Thus, as a first step towards a more complete treatment, it seems reasonable to treat the interaction of the stellar wind with an unmagnetized planet. Calculations were performed for a nonconducting as well as for a weakly conducting planet. The interaction with the stellar wind and the resulting induced magnetosphere was simulated using a three dimensional hybrid code as well as in the drift-kinetic approximation. The effect of a interplanetary magnetic field oriented perpendicular to the incoming stellar wind was included. In the case of a weakly conducting body an asymmetrical Mach cone is formed, whereas for a nonconducting body no Mach cone is observed. These investigations will serve as the first step in the search for particular effects occurring at extrasolar planets, which could possibly lead to observable effects, e.g. radio emission. The results are also relevant for plasma structures near weakly conducting, unmagnetized bodies like the Earth's moon. 相似文献