共查询到19条相似文献，搜索用时 140 毫秒
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纪树臣 《紫金山天文台台刊》1999,(2)
基于云南天文台射电频谱仪的频率设置,第２３ 周太阳峰年期,我们作了下列观测研究选题：（１） 质子耀斑的初始能量释放过程及粒子加速研究。（２） 通过微波———分米波运动Ⅳ型爆发观测,开展日冕物质抛射研究。（３） 射电快速精细结构及微耀斑研究。（４） 通过频谱观测发展日冕磁场的诊断方法、反演磁场的拓朴结构。（５） 开展太阳灾变事件中的射电先兆研究,为日地空间环境警报提供射电观测依据 相似文献
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纪树臣 《紫金山天文台台刊》1999,18(2):169-172
基于云南天文台射频谱仪的频率设置,第２３周太阳峰年期,我们作了下列观测研究选题;（１）质子耀斑的初始能量释放过程及粒子加速研究。（２）通过微波－分米波运动Ⅳ型爆发观测,开展日冕物质抛射研究。（３）射电快速精细结构及微耀斑研究。（４）通过频谱观测发展日冕磁场的诊断方法、反演磁场的拓扑结构。（５）开展太阳突变事件中的射电先兆研究,为日地空间环境警报提供射电观测依据。 相似文献
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国家天文台分米波太阳射电频谱仪用新的观测模式获得太阳射电频谱的一些新的观测现象。新的观测模式频率在1．1—1．34GHz范围，时间分辨率是1．25ms；正常的观测模式下频率在1．1—2．06GHz范围，时间分辨率是5ms。在两种模式下频率分辨率为4MHz。发现窄带Ⅲ型爆发（“blips”）斑马纹（Zebra）和纤维结构（Fiber）中的超精细结构和一些新的精细结构。这些新的结果有助于深入理解在太阳耀斑期间低日冕中能量的释放和转移，也为拟建中的太阳射电频谱日像仪提出了新的要求。 相似文献
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统计分析了太阳活动周下降段(2003～2005年)发生的76个共生CME的射电爆发事件.射电爆发资料来自国家天文台和Culgoora的微波和米波频谱仪.在76个事件中有50个快速CME和26个慢速CME.从中发现,快速CME和慢速CME的产率分别随着太阳活动周的降低而下降和上升,这可能说明CME的产率与太阳活动周中日冕磁结构的位形和位置变化有关.同时也发现,射电爆发的类型和寿命有一个变化规律,即随着频率的降低射电爆发的寿命变长,此特征支持了伴生CME的Ⅱ型爆发统一模型的思想.另外还发现在厘米一分米波范围,CME开始前后,容易发生射电Ⅲ型爆发或快速精细结构.这说明射电辐射的精细结构可能是CME的前兆现象或CME早期发展阶段由于磁重联引发的低日冕小尺度磁扰动的结果. 相似文献
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本采用荷兰Ｄｗｉｎｇｌｏｏ射电天台的多通道频谱仪（４－８ＧＨｚ）所观测到的一种典型的精细结构事例（Ｔｙｐｅ Ｈａｎｄ）来证实源区存在小尺度磁场结构以及电子的短时标加速过程。进一步根据实测和理论分析估算电子的平均速度大约为光速的十分之一，微磁流管直径大约为６００ｋｍ。以及在短时标（０．１ｓ）加速过程中电子能量密度的演化。由此可见，在射电精细结构的动态频谱中含有极其丰富的物理信息，对太阳耀斑机制的 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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太阳米波射电爆发是活动区上空日冕中的现象,与太阳耀斑有密切关系。近些年来,高空间分辨率的动态频谱仪获得了大量观测资料。在资料分析、理论模型和综合评述等备方面发表了许多文章。在日冕质量抛射和太阳周围磁场相互关系的研究中也取得了很大进展。 相似文献
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Fiber – or intermediate drift – bursts are a continuum fine structure in some complex solar radio events. We present the analysis of such bursts in the X17 flare on 28 Oct. 2003. Based on the whistler wave model of fiber bursts we derive the 3D magnetic field structures that carry the radio sources in different stages of the event and obtain insight into the energy release evolution in the main flare phase, the related paths of nonthermal particle propagation in the corona, and the involved magnetic field structures. Additionally, we test the whistler wave model of fiber bursts for the meter and the decimeter wave range. Radio spectral data (Astrophysikalisches Institut Potsdam, Astronomical Observatory Ond?ejov) show a continuum with fibers for ≈?6 min during the main flare phase. Radio imaging data (Nançay Radio Heliograph) yield source centroid positions of the fibers at three frequencies in the spectrometer band. We compare the radio positions with the potential coronal magnetic field extrapolated from SOHO/MDI data. Given the detected source site configuration and evolution, and the change of the fiber burst frequency range with time, we can also extract those coronal flux tubes where the high-frequency fiber bursts are situated even without decimeter imaging data. To this aim we use a kinetic simulation of whistler wave growth in sample flux tubes modeled by selected potential field lines and a barometric density model. The whistler wave model of fiber bursts accurately explains the observations on 28 Oct. 2003. A laterally extended system of low coronal loops is found to guide the whistler waves. It connects several neighboring active regions including the flaring AR 10486. For varying source sites the fiber bursts are emitted at the fundamental mode of the plasma frequency over the whole range (1200?–?300 MHz). The present event can be understood without assuming two different generation mechanisms for meter and decimeter wave fiber bursts. It gives new insight into particle acceleration and propagation in the low flare and post-CME corona. 相似文献
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太阳大气磁场的研究对于太阳大气物理及太阳活动研究是十分重要的。目前探测光球以外的日够以球，过渡区磁场的几乎唯一办法，是在紧密联系其他频说段取得的信息基础上使用射电观测。根据在微波，米波段有关辐射机制和传播过程，介绍了推导磁场讯息的基本射电方法。 相似文献
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一个太阳耀斑约含数千个微耀斑［１］，每个微耀斑以热的，低频波和加速粒子的形式释放能量。耀斑期间大部分能量的释放是通过电子加速转移的结果，然而电子加速是在耀斑前相开始，并在整个耀斑持续期间继续保持。在耀斑发展的不同相期间伴有各种各样的射电辐射现象（及其它波段共生现象），多波段射电观测和比较可以给出有关电子加速过程和耀斑自身发展的重要信息，尤其可检测加速开始的时间和频率部位（目前仍为太阳物理的前沿）。微耀斑能量的瞬时释放可能是引起不同类型快速精细结构的原因，射电毫秒级尖峰辐射是起因于连续能量释放的证据，其辐射源位于或靠近能量释放区［２］，公认射电辐射的快速结构是日冕电子束的特征信号［３，４］，所以今后使用高时间和高频率分辨率的宽带频谱仪同时观测可详细地探测加速过程，从而对预耀斑的加热和初始能量释放，耀斑的逐步建立和演化都具有重要意义。本文介绍几个典型事件，包括射电尖峰脉冲辐射，类尖峰辐射和短时标漂移结构 相似文献
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太阳米波和分米波的射电观测是对太阳爆发过程中耀斑和日冕物质抛射现象研究的重要观测手段。米波和分米波的太阳射电暴以相干等离子体辐射为主导,表现出在时域和频域的多样性和复杂性。其中Ⅱ型射电暴是激波在日冕中运动引起电磁波辐射的结果。在Ⅱ型射电暴方面,首先对米波Ⅱ型射电暴的激波起源问题和米波Ⅱ型射电暴与行星际Ⅱ型射电暴的关系问题进行了讨论;其次,结合Lin-Forbes太阳爆发理论模型对Ⅱ型射电暴的开始时间和起始频率进行讨论:最后,对Ⅱ型射电暴信号中包含的两种射电精细结构,Herringbone结构(即鱼骨结构)和与激波相关的Ⅲ型射电暴也分别进行了讨论。Ⅲ型射电暴是高能电子束在日冕中运动产生电磁波辐射的结果。在Ⅲ型射电暴方面,首先介绍了利用Ⅲ型射电暴对日冕磁场位形和等离子体密度进行研究的具体方法;其次,对利用Ⅲ型射电暴测量日冕温度的最新理论进行介绍;最后,对Ⅲ型射电暴和Ⅱ型射电暴的时间关系、Ⅲ型射电暴和粒子加速以及Ⅲ型射电暴信号中包含的射电精细结构(例如斑马纹、纤维爆发及尖峰辐射)等问题进行讨论并介绍有关的最新研究进展。 相似文献
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Various topological features, for example magnetic null points and separators, have been inferred as likely sites of magnetic reconnection and particle acceleration in the solar atmosphere. In fact, magnetic reconnection is not constrained to solely take place at or near such topological features and may also take place in the absence of such features. Studies of particle acceleration using non-topological reconnection experiments embedded in the solar atmosphere are uncommon. We aim to investigate and characterise particle behaviour in a model of magnetic reconnection which causes an arcade of solar coronal magnetic field to twist and form an erupting flux rope, crucially in the absence of any common topological features where reconnection is often thought to occur. We use a numerical scheme that evolves the gyro-averaged orbit equations of single electrons and protons in time and space, and simulate the gyromotion of particles in a fully analytical global field model. We observe and discuss how the magnetic and electric fields of the model and the initial conditions of each orbit may lead to acceleration of protons and electrons up to 2 MeV in energy (depending on model parameters). We describe the morphology of time-dependent acceleration and impact sites for each particle species and compare our findings to those recovered by topologically based studies of three-dimensional (3D) reconnection and particle acceleration. We also broadly compare aspects of our findings to general observational features typically seen during two-ribbon flare events. 相似文献
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The phenomena observed at the Sun have a variety of unique radio signatures that can be used to diagnose the processes in the solar atmosphere. The insights provided by radio observations are further enhanced when they are combined with observations from space-based telescopes. This Topical collection demonstrates the power of combination methodology at work and provides new results on i) type I solar radio bursts and thermal emission to study active regions; ii) type II and IV bursts to better understand the structure of coronal mass ejections; and iii) non-thermal gyro-synchrotron and/or type III bursts to improve the characterisation of particle acceleration in solar flares. The ongoing improvements in time, frequency, and spatial resolutions of ground-based telescopes reveal new levels in the complexity of solar phenomena and pose new questions. 相似文献
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A plot of frequency separation in fine structure in solar continuum radio bursts against emission frequency indicates that the frequency structure cannot represent local proton plasma frequency modulation. However, the observations are consistent with the interpretation of the frequency structure as harmonics of the local electron cyclotron frequency and lead to reasonable estimates of the ratio between magnetic and kinetic pressures in stable coronal magnetic field configurations producing continuum radio sources. 相似文献
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本文采用荷兰Ｄｗｉｎｇｌｏｏ射电天文台的多通道频谱仪（４－８ＧＨｚ）所观测到的一种典型的精细结构事例（ＴｙｐｅＨａｎｄ）来证实源区存在小尺度磁场结构以及电子的短时标加速过程．进一步根据实测和理论分析估算电子的平均速度大约为光速的十分之一，微磁流管直径大约为６００ｋｍ．以及在短时标（０．１ｓ）加速过程中电子能量密度的演化．由此可见，在射电精细结构的动态频谱中含有极其丰富的物理信息，对太阳耀斑机制的理解具有重要意义． 相似文献
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G. P. Chernov 《Solar System Research》2008,42(5):434-447
Several recent phenomena with zebra patterns (ZPs) and fiber bursts on the dynamic spectra of solar type IV radio bursts have been complexly analyzed using all available ground-based and satellite data (SOHO, TRACE, RHESSI). ZPs and fiber bursts were observed at frequencies of 50–3800 MHz. The main relative spectral parameters and the degree of circular polarization of ZPs and fiber bursts are almost identical. The fine structure was observed in powerful and weak phenomena (and was more impressive in weak phenomena) during impulsive and decline phases at instants of recurring continuum bursts. The shape of the fine structure depends on that of the magnetic loops in a radio source, the type of fast particle acceleration (impulsive or prolonged), and the presence of shock waves and coronal mass ejections. Several new effects of the interaction between zebra stripes and fiber bursts have been detected. Specifically, up to 40 fiber bursts with different frequency ranges were simultaneously observed in the frequency range 1–2 GHz against a background of sudden absorptions. It has been indicated that different effects in the ZP stripe behavior can be explained within the scope of the model with whistlers, if the quasi-linear diffusion of fast particles on whistlers (which deforms the particle velocity distribution function) is taken into account. 相似文献