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1.
介绍使用１０ｍ天线上２１ｃｍ波段ｍｓ级连续快速记录系统,观测到分米波太阳射电快速活动的几种形态,特征,尖峰辐射及其共生现象。 相似文献
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对１９８８年６月２９日云南天文台高时间分辨率射电望远镜观测到的微波超快速吸收现象进行了分析研究。在世界时０７ｈ３８ｍ５０ｓ至０７ｈ３８ｍ５８ｓ超快速吸收现象出现在太阳活动区ＮＯＡＡ／ＵＳＡＦ５０６０上空的４００ＧＨｚ上,而在２８４ＧＨｚ和１４２ＧＨｚ上空出现的是ｓｐｉｋｅ辐射。当时,该活动区呈现出极其活跃的双极磁场位形。在世界时０７ｈ３８ｍ至０８ｈ４７ｍ先后产生了３Ｂ级和２Ｂ级的Ｈα耀斑,并出现了Ｍ６５Ｘ射线爆发。根据电子回旋脉泽谐波吸收峰的特性,我们计算了三个波段的二次、三次谐波的磁场强度,并采用偶极磁场模型进行分析。对于４００ＧＨｚ上出现的超快速吸收现象,可能是产生的三次谐波脉泽辐射,在穿过吸收区时被吸收掉了。 相似文献
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一个太阳微波射电爆发中的快速脉动现象 总被引：1，自引：0，他引：1
１９９０年７月３０日观测到一个射电大爆发,其中在２８４０ＭＨｚ射电爆发的峰值附近,发现了周期约为３０ｍｓ的快速脉动现象,脉动是窄带的,调制度约为５０％。 相似文献
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一个太阳射波射电爆发中的快速脉动现象 总被引：1，自引：1，他引：0
１９９０年７月３０日观测到一个射电大爆发,其中在２８４０ＭＨｚ射电爆发的峰值附近,发现了周期约为３０ｍｓ的快速脉动现象,脉动是窄带的,调制度约为５０％。 相似文献
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本文分析类星体０９１７＋６２在波长６ｃｍ和１１ｃｍ上快速变化（时标１天）的结构函数．讨论在什么条件下，这种快速变化可用星际折射闪烁来解释．结果表明，折射闪烁解释对星际介质和射电源结构提出了相当明确的限制：散射介质应为连续介质，其有效距离应０．４ｋｐｃ；射电源应包含０．０５—０．１ｍａｓ的致密结构．对快变射电源方向上脉冲星的测量以确定星际介质特性和用ＶＬＢＩ测量快变射电源中的小角径成分，将是检验星际折射闪烁解释的必要途径． 相似文献
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本研究了寻常波和非常波在线性传播条件下，对快速毫秒级ｓｐｉｋｅ的时延、频漂和偏振逆转的影响。计算表明，在（２０－４０）×Ｂａｕｍｂａｃｈ－Ａｌｌｅｎ的电子密度分布下，由于传播产生的时延，偏振逆转等约为３０－３００ｍｓ，这与观测结果在量级上是一致的。这说明在快速活动中传播效应是一个重要的因素。 相似文献
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位于活动区磁中性线上方的暗条,随着活动区光球物质运动和磁结构演化,其上升运动规律呈多样性。根据暗条上升运动的特征,一般将其分为两类：第一类为缓慢上升（速度为Ｋｍ．ｓ＾－１量级）,在暗条上升过程中,亚电场中速是子能量为几十～１００ＬｅＶ量级（Ｅ〈ＥＤ,Ｅ为暗条表面电场强度,ＥＤ为经典Ｄｕｅｃｉｅｒ场）;第二类为快速上升（速度为几十～几百Ｋｍ．ｓ＾－１量级）因暗条快速上升在其下方形成Ｘ型中性点,暗条加 相似文献
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不同频段上极移,日长变化与大气角动量变化激发结果的比较 总被引：1，自引：0，他引：1
本文用ＪＭＡ大气角动量序列计算了对极移和日长变化的激发量（ｍ＇１、ｍ＇２和ｍ＇３），并分三个频段与天文观测得到的地球自转参数序列（ｍ１、ｍ２和ｍ３）进行了比较．结果表明：在钱德勒和季节性频段上，大气运动确实是固体地球自转变化的主要激发源． 相似文献
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蒋达西 《紫金山天文台台刊》1995,14(4):274-282
本对１９８４年４月－１９８５年４月在南京紫金山山上大人卫测点，用积分多普勒观测的二维单点定位资料进行了分析。并根据卫星来自ＳＥ、ＳＷ、ＮＥ、ＮＷ四个象限获取的资料，分别进行了归算和处理，结果精度如下：σφ（ＳＥ）＝３．７ｍ，σφ（ＳＷ）＝４．２ｍ σφ（ＮＥ）５．１ｍ，σφ（ＮＷ）＝６．５ｍ σλ（ＳＥ）＝４．９ｍ，σλ（ＳＷ）＝５．６ｍ σλ（ＮＥ）３．３ｍ，σλ（ＮＷ）＝４．０ｍ上述表达式中 相似文献
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The nonlinear excitation of fast magnetosonic waves by phase mixing Alfvén waves in a cold plasma with a smooth inhomogeneity of density across a uniform magnetic field is considered. If initially fast waves are absent from the system, then nonlinearity leads to their excitation by transversal gradients in the Alfvén wave. The efficiency of the nonlinear Alfvén–fast magnetosonic wave coupling is strongly increased by the inhomogeneity of the medium. The fast waves, permanently generated by Alfvén wave phase mixing, are refracted from the region with transversal gradients of the Alfvén speed. This nonlinear process suggests a mechanism of indirect plasma heating by phase mixing through the excitation of obliquely propagating fast waves. 相似文献
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本文利用10米天线上21cmms级连续无间隙快速记录系统,在第22周太阳峰年期间观测到大量的分米波段的太阳射电尖峰辐射的快速活动资料,对这些资料进行分析、比对发现尖峰辐射的快速活动至少包括：毛刺型、缓变型、缓变脉冲型、脉冲型、开关型．同时也对太阳射电尖峰辐射与其它共生现象进行分析,并对尖峰辐射的形态进行了简单的讨论． 相似文献
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K. Murawski 《Solar physics》1992,139(2):279-297
The nonlinear propagation of the Alfvén and magnetosonic waves in the solar corona is investigated in terms of model equations. Due to viscous effects taken into account the propagation of the fast wave itself is governed by Burgers type equations possessing both expansion and compression shock solutions. Numerical simulations show that both parallely and perpendicularly propagating fast waves can steepen into shocks if their amplitudes are in excess of some sizeable fraction of the Alfvén velocity. However, if the magnetic field changes linearly in the perpendicular direction, then formation of perpendicular shocks can be hindered. The Alfvén waves exhibit a tendency to drive both the slow and fast magnetosonic waves whose propagation is described by linearized Boussinesq type equations with ponderomotive terms due to the Alfvén wave. The limits of the slow and fast waves are investigated. 相似文献
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IMP-6 spacecraft observations of low frequency radio emission, fast electrons, and solar wind plasma are used to examine the dynamics of the fast electron streams which generate solar type-III radio bursts. Of twenty solar electron events observed between April, 1971 and August, 1972, four were found to be amenable to detailed analysis. Observations of the direction of arrival of the radio emission at different frequencies were combined with the solar wind density and velocity measurements at 1 AU to define an Archimedean spiral trajectory for the radio burst exciter. The propagation characteristics of the exciter and of the fast electrons observed at 1 AU were then conpared. We find that: (1) the fast electrons excite the radio emission at the second harmonic; (2) the total distance travelled by the electrons was between 30 and 70% longer than the length of the smooth spiral defined by the radio observations; (3) this additional distance travelled is the result of scattering of the electrons in the interplanetary medium; (4) the observations are consistent with negligible true energy loss by the fast electrons. 相似文献
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The thermal inertia values of Saturn’s main rings (the A, B, and C rings and the Cassini division) are derived by applying our thermal model to azimuthally scanned spectra taken by the Cassini Composite Infrared Spectrometer (CIRS). Model fits show the thermal inertia of ring particles to be 16, 13, 20, and 11 J m−2 K−1 s−1/2 for the A, B, and C rings, and the Cassini division, respectively. However, there are systematic deviations between modeled and observed temperatures in Saturn’s shadow depending on solar phase angle, and these deviations indicate that the apparent thermal inertia increases with solar phase angle. This dependence is likely to be explained if large slowly spinning particles have lower thermal inertia values than those for small fast spinning particles because the thermal emission of slow rotators is relatively stronger than that of fast rotators at low phase and vise versa. Additional parameter fits, which assume that slow and fast rotators have different thermal inertia values, show the derived thermal inertia values of slow (fast) rotators to be 8 (77), 8 (27), 9 (34), 5 (55) J m−2 K−1 s−1/2 for the A, B, and C rings, and the Cassini division, respectively. The values for fast rotators are still much smaller than those for solid ice with no porosity. Thus, fast rotators are likely to have surface regolith layers, but these may not be as fluffy as those for slow rotators, probably because the capability of holding regolith particles is limited for fast rotators due to the strong centrifugal force on surfaces of fast rotators. Other additional parameter fits, in which radii of fast rotators are varied, indicate that particles less than ∼1 cm should not occupy more than roughly a half of the cross section for the A, B, and C rings. 相似文献
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We consider the magnetohydrodynamic (MHD) interactions of solar coronal fast shock waves of flare and/or nonflare origin with the boundaries of coronal streamers and coronal holes. Boundaries are treated as MHD tangential discontinuities (TD). Different parameters of the observed corona are used in the investigation. The general case of the oblique interaction is studied.It is shown that a solar fast shock wave must be refracted usually as a fast shock wave inside the coronal streamer. For the special case of the velocity shear across TD, a slow shock wave is generated. On the contrary, the shock wave refracted inside the coronal hole is indeed a slow shock wave.The significance of different effects due to the interaction of fast and slow shock waves on the coronal magnetic field is noticed, especially at the time of a coronal mass ejection (CME). It is also shown, that an oblique fast MHD coronal shock wave may trigger an instability at the boundary of a streamer considered as a TD. It might have a relation with the observed process of abrupt disappearance of the streamer's boundary in the solar corona.On leave from the Academy of Sciences, Central Astronomical Observatory Pulkovo, 196140, St. Petersburg, Russia. 相似文献
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A resume of the main results obtained in the framework of fast electron hypothesis is presented. The fast electrons are possessed by strong constant properties, that is, nearly monoenergetic in spectrum and with the energy of 3. Fast electrons appear spontaneously in all kinds of cool dwarfs, young and old, and stimulate the generation of all types of flares, faint and powerful, in all ranges of electromagnetic waves — optical, ultraviolet, radio, X-ray. The general flare mechanisms are inverse Compton effect at the faint and moderate flares and nonthermal bremsstrahlung at powerfulness. This hypothesis explains an enormous number of observational facts and relationships — all these are illustrated by two tree-like diagrams in Figures 1 and 2.In the second part, the problem of the spontaneous appearance of fast electrons above the stellar atmosphere is discussed. The nature of the fast electrons in universal and is independent of the physical conditions of the star or its atmosphere. Their origin have nothing in common also with the well known acceleration processes, including the magnetic and hydrodynamic nature, in stellar atmospheres. At present nuclear decay processes seem to be most probable for the appearance of fast electrons in outer regions of stellar atmospheres. Some decay processes are examined with various probability of their realization. Creation of the radioactive nucleus13N as a result of capture of H by12C and its consequent decay with the escape of a positron seems most probable; as this fast positron will act just like a fast electron. It is outlined the high effectivity of this process in binary systems. 相似文献
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We present our new model for the thermal infrared emission of Saturn's rings based on a multilayer approximation. In our model, (1) the equation of classical radiative transfer is solved directly for both visible and infrared light, (2) the vertical heterogeneity of spin frequencies of ring particles is taken into account, and (3) the heat transport due to particles motion in the vertical and azimuthal directions is taken into account. We adopt a bimodal size distribution, in which rapidly spinning small particles (whose spin periods are shorter than the thermal relaxation time) with large orbital inclinations have spherically symmetric temperatures, whereas non-spinning large particles (conventionally called slow rotators) with small orbital inclinations are heated up only on their illuminated sides. The most important physical parameters, which control ring temperatures, are the albedo in visible light, the fraction of fast rotators (ffast) in the optical depth, and the thermal inertia. In the present paper, we apply the model to Earth-based observations. Our model can well reproduce the observed temperature for all the main rings (A, B, and C rings), although we cannot determine exact values of the physical parameters due to degeneracy among them. Nevertheless, the range of the estimated albedo is limited to 0-0.52±0.05, 0.55±0.07-0.74±0.03, and 0.51±0.07-0.74±0.06 for the C, B, and A rings, respectively. These lower and upper limits are obtained assuming all ring particles to be either fast and slow rotators, respectively. For the C ring, at least some fraction of slow rotators is necessary (ffast?0.9) in order for the fitted albedo to be positive. For the A and B rings, non-zero fraction of fast rotators (ffast?0.1-0.2) is favorable, since the increase of the brightness temperature with increasing solar elevation angle is enhanced with some fraction of fast rotators. 相似文献
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The propagation of waves in a magnetic slab embedded in a magnetic environment is investigated. The possible modes of propagation are examined from the general dispersion relation, both analytically and numerically, for disturbances which are evanescent in the environment. Approximate dispersion relations governing propagation in a slender slab of field are derived both from the general dispersion relation and from an application of the slender flux tube approximation.Several different situations, representative of both photospheric and coronal conditions, are considered. In general, the structures are found to support both fast and slow, body and surface, waves. Under coronal conditions, for two dimensional propagation, disturbances propagate as fast and slow body waves. The fast body waves are analogous to the ducted shear waves of seismology (Love waves). 相似文献
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As evidence for energy release in microflares, high time resolution observations of solar radio emission obtained with our “synchronous observation system of solar radio radiation with high time resolution at four frequencies (1.42, 2.13, 2.84 and 4.26 GHz)” from December 1989 to April 1993 are presented in this paper. The observed events include weak ms spikes, “spike-likes”, fast pulsations as well as two kinds of newly discovered fast fine structures, i.e., microwave type III bursts and microwave patch-like structures. A statistical study of the duration of fast fine structures has been made and on its basis the various types of phenomena are illustrated with actual examples. 相似文献