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1.
位于日冕微波区的微波Ⅲ型爆发界面频率的发现 总被引：3，自引：0，他引：3
在北京天台１．０－２．０ＧＨｚ射电频谱仪记录到的１９９４年１月５日爆发图上，首次发现一界面频率位于１２４０ＭＨｚ与１３４０ＭＨｚ之间的微波Ⅲ型爆发对，其频率漂率为－０．２２ＧＨｚ／ｓ和＋０．２３ＧＨｚ／ｓ由此推出电子加速区位于光球之上，３．７×１０＾４ｋｍ的高度，电子加速区及Ⅲ型爆发形成区的高度范围约为１０００公里，而电子束的速度相应为０．１０２ｃ及０．１０６ｃ。 相似文献
2.
我们用新的时间分辨率短至８ｍｓ 的２ ．６ ～３ ．８ＧＨｚ 微波动态频谱仪在１９９８ 年４ 月１５ 日爆发和１９９７ 年１１ 月３ 日爆发中发现了微Ｕ 型爆发。其顶部频率为３ ．２ ～３ ．４ＧＨｚ（ 相应的等离子体密度：基波：１ ．２ ×１０１１ － １ ．４ ×１０１１／ｃｍ ３ ,二次谐波：３ ．２ ×１０１０ － ３ ．５ ×１０１０／ｃｍ ３） ;根部频率为３ ．４ ～３ ．６ＧＨｚ;单个Ｕ 型爆发的频率范围为６０ ～２２０ ＭＨｚ ;上升段频漂率为７ ～２８ＧＨｚ／ｓ;上升段持续时间为８ ～２４ｍｓ;寿命为１６ ～４８ｍｓ;偏振度大于８０ ％ 。在活动区为偶极子磁场的假设下,估计源区高度约为１ ．３ ×１０４ 公里,单一环的高度为２５０ ～８００ 公里。由此得出结论：１ ．由于高频漂率和高偏振度,似乎发现的微Ｕ 型爆发不是Ⅲ型爆发形成,而是尖峰辐射（Ｓｐｉｋｅ） 形成。２ ．我们发现的是小尺度的微磁环,其尺度与Ｓｐｉｋｅ 辐射的寿命相当。我们在１９９７ 年１１ 月２ 日的爆发中发现平均周期为数十ｍｓ 的准周期振荡群。在高密度流管的磁声波ＭＨＤ 振荡条件下,可取得磁环半径约９０ 公里的结果。由此可以得到微磁环物理尺度的图象 相似文献
3.
分析了１９９３－１０－０２０７３９．５－０７４５．０ＵＴ在２．８４０ＧＨｚ－２．５４５ＧＨｚ观测到的一次太阳射电爆发事件，证认了这次爆发的一部分是微波类ＩＩ型爆发．计算结果表明，这次ＩＩ型爆发是由速度为１．０×１０８ｍ／ｓ的相对论性电子束所引起的，产生电子束的源区背景温度为Ｔ～３×１０７Ｋ，射电爆发亮温度Ｔｂ～１０１２Ｋ，爆发源区的尺度Ｌ～３．４×１０２ｋｍ． 相似文献
4.
分析了１９９３－１０－０２ ０７３９．５－０７４５．０ＵＴ在２．８４０ＧＨｚ－２．５４５ＧＨｚ观测到的一次太阳射射电爆发事件，证认了这次爆发的一部分是微波类Ⅲ型爆发。计算结果表明，这次Ⅲ型爆发是由速度为１．０×１０＾８ｍ／ｓ的相对论性电子束所引起的，产生电子束的源区背景温度为Ｔ－３×１０＾７Ｋ，射电爆发亮温度Ｔｂ＝１０６１２Ｋ，爆发源区的悄度Ｌ－３．４×１０＾２ｋｍ。 相似文献
5.
利用甚长基线干涉仪，在１６６５ＭＨｚ频率上，观测超致密氢ＩＩ区Ｇ４５．０７＋０．１３的左右圆偏振羟基（ＯＨ）分子脉泽辐射．利用多条纹率成图方法，获得了这个区域２０ｍａｓ相对位置精度的脉泽结构图．除两个弱子源以外，所有脉泽子源都位于彗状结构氢ＩＩ区“彗头”的前沿．脉泽团离致密氢ＩＩ区中心投影距离为０＂．４．在完全饱和辐射的假设下，估计脉泽活动区具有氢分子数密度约为４．５×１０８（Ｈ２）ｃｍ－３．在脉泽源中，发现一对Ｚｅｅｍａｎ对，从它们的ＬＳＲ速度差，导出脉泽区的磁场约为３ｍＧ，方向为远离地球方向．在致密氢ＩＩ区Ｇ４５．０７＋０．１３彗头附近的脉泽团的直径为６×１０１６ｃｍ．这与Ｇ３４．０３＋０．２的观测结果很类似．这给解释彗状结构的氢ＩＩ区的各种模型提供了一个可靠的观测约束条件． 相似文献
6.
用于分子谱线观测的512路数字式自相关频谱仪 总被引：1，自引：0，他引：1
本文简要介绍了采用一比特自相关技术实现的５１２路数字式自相关频谱仪的工作原理及系统的硬件和软件构成。该频谱仪主要用于分米及ｃｍ波段分子谱线观测。频谱仪系统时钟可在６２５ＫＨｚ和２０ＭＨｚ之间按２的倍率选择，最大分析带宽为１０ＭＨｚ。最高频率分辨率为０．６１ＫＨｚ，相应于１８ｃｍ波段的速度分辨率为０．１ｋｍ／ｓ。文章最后给出了利用上海天文台２５ｍ射电望远镜观测ＯＨ脉泽源的结果。 相似文献
7.
云南天文台快速采样射电望远镜（１．４２ＧＨｚ，２．８４ＧＨｚ，４．００ＧＨｚ）于１９８８年１２月１６日观测到一次特大微波ＩＶ型爆发。爆发从世界时０８＾ｈ３１＾ｍ结束。在７０分钟的持续期内，爆发出现了五个主峰段，呈现出１２．５分钟的长周期振荡和１．２分钟的短周期振荡。其中两个频率上出现了丰富的快速精细结构。根据爆发源区的扭斜磁场位形，本文提出振荡是ＭＨＤ调制磁流管的磁场强度产生的，爆发是高能电子在磁 相似文献
8.
１９８８年１２月１６日世界时０８ｈ３１ｍｉｎ至０９ｈ４１ｍｉｎ，云南天文台ＰｈｏｅｎｉｘＩ日冕射电频谱仪（１．４２ＧＨｚ，２．８４ＧＨｚ，４．００ＧＨｚ）收到一个罕见的微波Ⅳ型大爆发，爆发从米波Ⅳ型一直延伸到微波Ⅳ型，持续时间长，爆发强度大，爆发型别复杂。前后出现了五个主峰段，呈现出１．２ｍｉｎ和１．２５ｍｉｎ的短周期和长周期振荡。在其中的两个频段上叠加有丰富的Ｓｐｉｋｅ辐射，根据爆发源区的扭斜磁场位形，我们采用磁俘获模型，计算了源区的有效温度，源区磁场随高度的变化，并算出了峰值频率在８．８９ＧＨｚ，其结果表明爆发是高能电子被磁场俘获，做回旋同步辐射所致 相似文献
9.
介绍一个专用甚高频频率合成器的设计方案和实施中的一些关键技术．该合成器输出频率范围为９９．３ＭＨｚ～１００．７ＭＨｚ；步距分粗（２０ｋＨｚ）细（１００Ｈｚ）两档；输出短期频率的稳定度为３×１０（－９）／２５ｍｓ和１×１０（－１０）／ｓ． 相似文献
10.
本文作者用上海天文台的２５米天线和１２．２ＧＨｚ的接收系统，对银道面附近的一个ＨＩＩ区复合体Ｇ１８．２—０．３进行了射电连续谱观测．采用沿源运动轨迹，对观测曲线进行多子源模型拟合的方法，将该复合体中的６个子源从延展的ＨＩＩ区辐射中分离了出来，并导出了每个子源在１２．２ＧＨｚ频率上的流量和角大小．结合外台站在２６９５ＭＨｚ，４７５０ＭＨｚ和１０．５５ＧＨｚ上的流量还得到了这些子源的辐射频谱．分析表明它们具有热辐射性质．对具有射电复合线（Ｈ７６α）资料和角尺度的４个子源导出了它们的电子密度在（１—３）×１０２ｃｍ－３间．此外通过对Ｇ１８．２—０．３复合体子源ＩＲＡＳ资料的分析和模型拟合还得到了每个子源周围冷尘埃的等效黑体温度．其中４个子源并具有ＩＲＡＳ－ＬＲＳ资料．分析它们得到了与该ＨＩＩ区成协尘埃的性质．根据５个子源的ＩＲＡＳ流量、频带以及色改正因子又求出了这些子源在１—５００μｍ间的总红外光度在２×１０４—１０５Ｌ间．它表明与Ｇ１８．２—０．３中各子源成协的新形成星是一些大质量的ＯＢ型星，它们在同一个延展ＨＩＩ区中如此密集证明了大质量星“致密—堆积”形成模式的合理性． 相似文献
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12.
本文介绍了北京天文台观测到的太阳射电10厘米波段的毫秒级快速精细结构(FFS)中一类有长持续时间的尖峰(我们称毫秒时标记录上陡升陡降图形为“尖峰”,称秒级时标的记录上的陡升陡降图形为“脉冲”)群事件。这一类微波毫秒尖峰群(MMS)事件具有一系列显著的特点: 1)它在秒级时间常数的慢速记录上常常对应一8S型(持续时间小于1分钟的脉冲)的爆发。因而利用脉冲的频谱特性,对这一类微波爆发中的毫秒精细结构的特征及可能的机制进行探讨,以弥补目前只能在一个波段上观测FFS事件的缺陷。 2)这一类脉冲爆发具有从低频向高频的频漂(正的频漂),而且频漂的速率随频率带增加而增加。 3)脉冲的幅度在波长8—10厘米间受到强烈的衰减。 4)脉冲群中的每一脉冲的极大频率及起始频率从高频逐渐移向低频,意昧着激发源逐渐上升。估计上升速度约为50公里/秒。 5)这类脉冲常常出现在有δ型磁结构、最大磁场强度大于2500高斯的复杂活动区中,可能有不同级别的耀斑与之对应。 6)这类脉冲与硬X线爆发事件、分米波段快速频漂事件及“BLIPS”事件见文[7]有密切的关系。 7)这一类微波快速尖峰群事件可以解释为来自耀斑-爆发事件中形成的电子加速中心的快速非热电子流向下运动穿入一耀斑环激起的电子迴旋脉泽辐射。 相似文献
13.
We analyze the dynamics of the broadband frequency spectrum of 338 microwave bursts observed in the years 2001?–?2002 with the Owens Valley Solar Array. A subset of 38 strong microwave bursts that show a single spectral maximum are studied in detail. Our main goal is to study changes in spectral peak frequency ν pk with time. We show that, for a majority of these simple bursts, the peak frequency shows a high positive correlation with flux density – it increases on the rise phase in ≈83% of 24 bursts where it could be cleanly measured, and decreases immediately after the peak time in ≈62% of 34 bursts. This behavior is in qualitative agreement with theoretical expectations based on gyrosynchrotron self-absorption. However, for a significant number of events (≈30?–?36%) the peak frequency variation is much smaller than expected from self-absorption, or may be entirely absent. The observed temporal behavior of ν pk is compared with a simple model of gyrosynchrotron radio emission. We show that the anomalous behavior is well accounted for by the effects of Razin suppression, and further show how an analysis of the temporal evolution of ν pk can be used to uniquely determine the relative importance of self-absorption and Razin suppression in a given burst. The analysis technique provides a new, quantitative diagnostic for the gyrosynchrotron component of solar microwave bursts. Applying this analysis technique to our sample of bursts, we find that in most of the bursts (60%) the spectral dynamics of ν pk around the time of peak flux density is caused by self-absorption. On the other hand, for a significant number of events (≈70%), the Razin effect may play the dominant role in defining the spectral peak and dynamics of ν pk, especially on the early rise phase and late decay phase of the bursts. 相似文献
14.
Electrons accelerated during solar flares are revealed by their electromagnetic radiation in different spectral ranges, emitted at different heights in the solar atmosphere. The observational analysis points to a common and continuous injection of particles. Based on this result, a quantitative investigation of the hard X-ray and microwave emissions observed during the 29 June, 1980 flare at 11: 40 UT has been performed. This is the first modelisation that takes into account both the inhomogeneity of the microwave source region and the dynamical evolution of the electron population. First results of our model computations demonstrate that during the most energetic phase of the event both hard X-rays and microwaves are described by electron populations resulting from the same injection function, and that the total numbers of electrons required for both emissions are compatible. Account for the inhomogeneity of the microwave source is shown to be a necessary condition for the interpretation of observed spectra.Proceedings of the Workshop on Radio Continua during Solar Flares, held at Duino (Trieste), Italy, 27–31 May, 1985. 相似文献
15.
Previous models of microwave limb brightening have omitted the alignment of spicules along supergranule boundaries, have neglected the high temperature sheath around spicules, and have assumed an interspicular medium which was averaged over chromospheric network and non-network regions. We present a model which includes these factors. By constraining the model to conform to results from earlier UV and optical studies we are effectively left with two free parameters: the temperature at the core of the spicules, T
core, and (at solar minimum), the interspicular chromospheric network density model of the lower transition zone. The absence of limb brightening at the short millimeter wavelengths implies T
core 6000 k. Differences between the model and certain deconvolved observations near 9 mm are expected as a consequence of an extension of emission beyond the optical limb, predicted by the model, which affects the accuracy of the deconvolution technique. Unlike models which assume homogeneous spicules in a random distribution, ours does not require an abnormally high spicule area. 相似文献
16.
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
17.
回顾了日冕磁的研究历史，介绍了我们首镒提出的日冕磁场的微波诊断方法及其应用的带来的启迪，提出进一步开展日冕磁场及其相关研究的建议。 相似文献
18.
We report on the statistical properties of the microwave enhancement (brightness temperature, area, fine structure, life time
and magnetic field strength) in coronal holes observed over a period of several solar rotations. 相似文献
19.
We perform a frequentist analysis of the bispectrum of the Wilkinson Microwave Anisotropy Probe first-year data. We find clear signal domination up to ℓ≈ 200 , with overall consistency with Gaussianity, except for the following features. There is a flat patch (i.e. a low χ2 region) in the same-ℓ components of the bispectrum spanning the range ℓ= 32–62 ; this may be interpreted as ruling out Gaussianity at the 99.6 per cent confidence level. There is also an asymmetry between the north and south inter-ℓ bispectrum components at the 99 per cent confidence level. The preferred asymmetry axis correlates well with the (ℓ, b ) = (57, 10) direction quoted in the literature for asymmetries in the power spectrum and three-point correlation function. However, our analysis of the quadrupole (its bispectrum and principal axes) fails to make contact with previously claimed anomalies. 相似文献
20.
Two microwave type-U bursts observed with the 2.6–3.8 GHz spectrometer of Beijing Astronomical Observatory (BAO) are described and analysed in this paper. The microwave type-U bursts have very short durations (about 200 ms), narrow bandwidth, high-frequency drift rates of the ascending and descending branches, and a high degree of circular polarization (80%). The sense of polarization remains the same from the ascending to the descending branch. 相似文献