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本文对太阳射电精细结构这一领域进行了较为详尽深入的调研 ,发现由于观测仪器技术指标 (时间、频率、频率覆盖、偏振、灵敏度等 )相对不高 ,有很多的精细结构 ,在时间上、在频率上并没有被完全分解开来 ,或是没有被检测到。对FFS的研究 ,还处于发现 -认识 -逐步深化的阶段。观测资料还很单薄。在微波高端 (厘米波段 ) ,精细结构的观测资料更是很少。另外 ,对FFS也只是有一个侧重频谱形态的分类。本文利用我国的“太阳射电宽带快速频谱仪”的观测资料 ,几年来 ,对微波频段的射电快速精细结构进行了较为深入的研究。主要研究结果有 :发现了弱偏振微波尖峰辐射中两个偏振分量之间的时间延迟和偏振反转现象 ;首次发现了微波 (短分米波段 )高偏振U型爆发并给出解释 ;首次发现了厘米波N型和M型爆发并给出解释 ;首次发现了高偏振微波斑点并给出解释 ;首次利用甚高频率分辨率频谱仪 ,通过对大样本的分米波尖峰辐射的统计 ,给出了更为可靠的、更小的相对带宽的下限 ;结合高空间分辨率的观测资料 ,对运动Ⅳ型爆发及其伴生的精细结构作了探讨 ;对双向电子束的起源及其加速位置进行了研究 相似文献
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本文对太阳射电精细结构这一领域进行了较为详尽深入的调研，发现由于观测仪器技术指标（时间、频率、频率覆盖、偏振、灵敏度等）相对不高，有很多的精细结构，在时间上、在频率上并没有被完全分解开来，或是没有被检测到。对FFS的研究，还处于发现－认识－逐步深化的阶段。观测资料还很单薄。在微波高端（厘米波段），精细结构的观测资料更是很少。另外，对FFS也只是有一个侧重频谱形态的分类。本文利用我国的“太阳射电宽带快速频谱仪”的观测资料，几年来，对微波频段的射电快速精细结构进行了较为深入的研究。主要研究结果有：发现了弱偏振微波尖峰辐射中两个偏振分量之间的时间延迟和偏振反转现象；首次发现了微波（短分米波段）高偏振U型爆发并给出解释；首次发现了厘米波N型和M型爆发并给出解释；首次发现了高偏振微波斑点并给出解释；首次利用甚高频率分辨率频谱仪，通过对大样本的分米波尖峰辐射的统计，给出了更为可靠的、更小的相对带宽的下限；结合高空间分辨率的观测资料，对运动Ⅳ型爆发及其伴生的精细结构作了探讨；对双向电子束的起源及其加速位置进行了研究。 相似文献
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射电观测是太阳物理和日地空间科学的重要探测手段,尤其是对于太阳爆发过程中的太阳非热粒子加速、发射和传播等过程.迄今,世界各地研制建成了上百台太阳射电望远镜,包括射电流量计、射电动态频谱仪和射电日像仪等.基于技术进步和新的科学设想,人们还在不断提出新的太阳射电望远镜计划.研制新的太阳射电望远镜时,需要考虑观测频率、带宽、时间分辨率、频率分辨率、空间分辨率、偏振精度等设计参数.事实上,过度追求高参数往往会无法实现期望的科学目标.如何合理地选择太阳射电望远镜的参数呢?长期的观测研究发现太阳射电爆发常常可分成一系列从长到短不同时标的爆发过程,其中,尖峰爆发是最小时间尺度的爆发现象,同时也是太阳上目前发现的最小空间尺度上的爆发过程,可看成一种元爆发过程,可能对应于单一的磁场重联和磁能释放.根据太阳射电天文学研究,识别尖峰爆发是对新一代太阳射电望远镜的基本要求.尖峰爆发的时间尺度和空间尺度又是随频率而变化的.从分析不同频段太阳射电尖峰爆发的时间和带宽的标度律来说明如何为新一代望远镜的设计选择合理的参数指标,并提出谱-像结合观测模式,最大程度地保证望远镜科学目标的实现.这种观测模式或将成为未来太阳射电观测的主要方式,对揭示太阳爆发现象中的非热过程的物理本质具有非常重要的意义. 相似文献
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太阳射电尖峰辐射(spike)的窄频带是一个具有特征性的参数,不但可从它计算出Spike辐射源区的小尺度结构,而且观测结果与Spike辐射理论可相互验证.我们利用云南天文台0.5 MHz频率分辨率的射电频谱观测资料,作出了230—300MHz频段上单个Spike带宽分布,并由此给出一群Spike源区的最可几尺度为151km,最大源区尺度为830km. 相似文献
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本文介绍用“三波段太阳射电高时间分辨率同步观测系统”所观测到的1988年12月16日三波段(1420MHz、2840MHz、4000MHz)太阳射电大爆发中毫秒级精细结构的观测特征,指出太阳射电快速活动在射电爆发的不同阶段具有不同的特征,首先在爆发的上升沿出现2840MHz的毫秒尖峰辐射群,继而在1420MHz上出现毫秒级尖峰辐射群,并且还在以后的几个爆发次峰上陆续出现,在长达两小时的大爆发过程中,在4000MHz上始终未产生毫秒级尖峰辐射,这也反应了射电尖峰辐射现象存在着一定的带宽。特别引起注意的是毫秒级尖峰辐射群均出现在射电爆发的峰值附近,在其它时间的记录中尚未发现毫秒尖峰辐射。 三波段的秒级射电爆发曲线如图1所示。毫秒级精细结构如图2所示。由图2可见,单个尖峰辐射的持续随频率的减小而增加,2840MHz多为10—20ms,1420MHz多为30—170ms;所产生的尖峰辐射群强度不大,而且很少有孤立的尖峰;2840MHz尖峰辐射的强度一般为450—900sfu,1420MHz一般为500—1770sfu(1sfu=10~(-22)WM~(-2)Hz~(-1));还特别引起注意的是在2840MHz上当所出现的尖峰辐射群结束时,往往出现持续时间为100ms的流量下降现象,(此种现象在以往的观测中未曾见过),详见图2b和2c;关于事件尖峰辐射的丰度,仅对几个尖峰辐射群作了统计如下: 在1420M 相似文献
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本文论述了在太阳射电尖峰爆中研究观测量之间统计关系的重要性。并在非线性参量稳定性模型的基础上，给出尖峰爆中尖峰出现重复率Ｒ与爆发流量密度ｓ及尖峰的调制幅度△ｓ与ｓ之间统计关系的理论预期。Ｒ－Ｓ统计关系的理论预期与观测结果符合得很好。 相似文献
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四频率太阳射电高时间分辨率观测特征：微耀斑能量释放的证据 总被引：1，自引：0，他引：1
作为微耀斑能量释放的证据，本文扼要介绍了云南天文台“四频率太阳射电高时间分辨率同步观测系统”（１．４２，２．１３，２．８４和４．２６ＧＨｚ）１９８９年１２月－１９９３年４月的观测事例，包含低强度的毫秒尖峰辐射（ｍｓｓｐｉｋｅ），类尖峰辐射（ｓｐｉｋｅ－ｌｉｋｅ），快速脉动现象，两种新的快速精细结构──微波Ⅲ型爆和微波类斑点结构．统计了快速精细结构的寿命，在统计基础上分别以实例描述了各类现象的观测特征． 相似文献
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太阳二十二周峰年云南天文台四波段射电同步观测结果 总被引：1，自引：1，他引：0
本文主要介绍云南天文台“四波段太阳射电高时间分辨率同步观测系统”１９８９年１２月至１９９３年４月观测事件的统计结果，对１０２个射电爆发进行了初步分析，着重揭示几个类别典型事件的时间轮廓，说明射电高时间分辨率观测的意义。 相似文献
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Arnold O. Benz Christian Monstein Michael Beverland Hansueli Meyer Bruno Stuber 《Solar physics》2009,260(2):375-388
A new multichannel spectrometer, Phoenix-3, is in operation having capabilities to observe solar flare radio emissions in the 0.1?–?5 GHz range at an unprecedented spectral resolution of 61.0 kHz with high sensitivity. The present setup for routine observations allows measuring circular polarization, but requires a data compression to 4096 frequency channels in the 1?–?5 GHz range and to a temporal resolution of 200 ms. First results are presented by means of a well observed event that included narrowband spikes at 350?–?850 MHz. Spike bandwidths are found to have a power?–?law distribution, dropping off below a value of 2 MHz for full width at half maximum (FWHM). The narrowest spikes have a FWHM bandwidth less than 0.3 MHz or 0.04% of the central frequency. The smallest half-power increase occurs within 0.104 MHz at 443.5 MHz, which is close to the predicted natural width of maser emission. The spectrum of spikes is found to be asymmetric, having an enhanced low-frequency tail. The distribution of the total spike flux is approximately an exponential. 相似文献
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G. D. Fleishman 《Astronomy Letters》2004,30(9):603-614
We studied the spectral properties of the electron cyclotron maser emission generated by anisotropic distributions of fast electrons with power-law magnitude distributions in solar flares. The natural bandwidth of the generated spectral line depends significantly on the angle between the direction of the wave emission and the direction of the magnetic field in the source. In addition, the line bandwidth depends on the parameters of the momentum and pitch-angle distribution functions for fast electrons. The typical spectral bandwidths are shown to lie within the range 0.1–0.4%, in agreement with the minimum observable bandwidths of millisecond solar radio spikes. 相似文献
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On the high-speed plasma streams,stormtime sudden commencements and cosmic-ray intensity: Relation amongst them during epoch 1978 to 1982 总被引：3，自引：0，他引：3
A new spectrometer has been put into operation that registers solar flare radio emission in the 0.1 to 3 GHz band. It is a frequency-agile system which can be fully programmed to measure both senses of circular polarization at any frequency within that range at selectable bandwidth. The time resolution has to be compromized with the number of frequency channels and can be in the range of 0.5 ms to 250 ms for 1 to 500 channels. First results mainly from the 1–3 GHz band are presented, a spectral region that has never been observed with high-resolution spectrometers. Most noteworthy are the frequent appearances of myriads of narrowband, fast-drifting bursts (microwave type III), diffuse patches of continuum emission, and broad clusters of millisecond spikes sometimes extending from 0.3 to 3 GHz. 相似文献
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On 13 December 2006, some unusual radio bursts in the range 2.6?–?3.8 GHz were observed during an X3.4 flare/CME event from 02:30 to 04:30 UT in active region NOAA 10930 (S06W27) with the digital spectrometers of the National Astronomical Observatories of China (NAOC). During this event many spikes were detected with the high temporal resolution of 8 ms and high frequency resolution of 10 MHz. Many of them were found to have complex structures associated with other radio burst types. The new observational features may reflect certain emission signatures of the electron acceleration site. In this paper, we present the results of the analysis of the new observational features of the complex spikes. According to the observed properties of the spikes, we identify five classes. Their observational parameters, such as duration, bandwidth, and relative bandwidth, were determined. Most spikes had negative polarization, but spikes with positive polarization were observed during a short time interval and were identified as a separate class. Based on the analysis of observations with Hinode/SOT (Solar Optical Telescope) we suggest that the sources of the spikes with opposite polarizations were different. Combined observations of spikes and fiber bursts are used to estimate the magnetic field strength in the source. 相似文献
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The study of the minor constituents of the planetary atmospheres from the analysis of the scattered light properties requires
the knowledge of the absolute incident solar irradiance at high resolution. The data were obtained from the UVSP experiment
on board the Solar Maximum Mission satellite in the 184.5–232.5 nm spectral range. We have reconstituted the solar spectrum
measured in three different regions of the solar disk with a spectral resolution of 0.01 nm and a spatial resolution of 3 arc sec.
The wavelength scale was determined with a standard deviation of 0.0025 nm. The comparison of the relative intensities in
three locations of the solar disk with those obtained by other authors allowed us to determine these positions accurately
and to derive the integrated spectrum of the whole disk. Finally, the resulting spectrum has been expressed in absolute units
using the spectral irradiance by the SOLSPEC and SUSIM spectrometers, respectively operated with the ATLAS 1 mission and from
the Upper Atmosphere Research Satellite. We obtained the absolute solar irradiance with an accuracy of 10% in the 184.5–232.5 nm
spectral range with a spectral resolution of 0.01 nm for the first time using data from space observations.
Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1017976515168 相似文献
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The simultaneous high resolution recordings of dynamic spectra in the range 93–220 MHz and polarization at 204 MHz of a complex type II–IV event which started at 08:33 UT on 3 May 1973 shown a sporadic zebra pattern. In contrast with the unpolarized type II burst, the stripes in the emission and absorption of the zebra pattern were fully polarized and most likely corresponded to the ordinary wave. As to spectral and polarization characteristics, the fiber bursts with intermediate frequency drift did not differ from the stripes of the zebra pattern. The microstructure of the type II burst was characterised by a lot of spikes with variable frequency drift, duration 0.1 s and instantaneous bandwidth ≈1 MHz. 相似文献
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We present the results of the analysis of thirteen events consisting of dm-spikes observed in Toruń between 15 March 2000
and 30 October 2001. The events were obtained with a very high time resolution (80 microseconds) radio spectrograph in the
1352 – 1490 MHz range. These data were complemented with observations from the radio spectrograph at Ondřejov in the 0.8 – 2.0 GHz
band. We evaluated the basic characteristics of the individual spikes (duration, spectral width, and frequency drifts), as
well as their groups and chains, the location of their emission sources, and the temporal correlations of the emissions with
various phases of the associated solar flares. We found that the mean duration and spectral width of the radio spikes are
equal to 0.036 s and 9.96 MHz, respectively. Distributions of the duration and spectral widths of the spikes have positive
skewness for all investigated events. Each spike shows positive or negative frequency drift. The mean negative and positive
drifts of the investigated spikes are equal to −776 MHz s−1 and 1608 MHz s−1, respectively. The emission sources of the dm-spikes are located mainly at disk center. We have noticed two kinds of chains,
with and without frequency drifts. The mean durations of the chains vary between 0.067 s and 0.509 s, while their spectral
widths vary between 7.2 MHz and 17.25 MHz. The mean duration of an individual spike observed in a chain was equal to 0.03 s.
While we found some agreement between the global characteristics of the groups of spikes recorded with the two instruments
located in Toruń and Ondřejov, we did not find any one-to-one relation between individual spikes. 相似文献
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We present an atlas of the Zeeman spectral line polarisation throughout the visible spectrum of the cool F0p star β CrB based on MuSiCoS spectropolarimetry. Stokes I, V, Q and U spectra covering the full 4500–6600 Å MuSiCoS intermediate bandpass are shown at sufficient display resolution so as to be suitable for the identification of individual spectral features. This is foreseen as being useful, for example, in the planning of very high resolution spectropolarimetric studies of Ap star Zeeman signatures using high-dispersion instruments likely to have significantly smaller spectral bandwidth. 相似文献
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The Solar–Stellar Irradiance Comparison Experiment (SOLSTICE) measures the solar spectral irradiance from 115 to 320 nm with
a resolution of 0.1 nm. The Sun and stars are both observed with the same optics and detector, changing only the apertures
and integration times. Pre-launch calibration at SURF allows us to measure both with an absolute accuracy of 5%. The in-flight
sensitivity degradation is measured relative to a set of stable, early-type stars. The ensemble of stars form a calibration
reference standard that is stable to better than 1% over timescales of centuries. The stellar irradiances are repeatedly observed
on a grid of wavelengths and our goal is to measure changes in the absolute sensitivity of the instrument at the 0.5% per
year level. This paper describes the details of the observing technique and discusses the level of success in achieving design
goals. 相似文献