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本文概述了太阳射电天文学的历史,从早期的失败到1942年Hey对太阳射电波的偶然发现为止.文中讨论了太阳射电研究在米波-十米波、千米-百米波和厘米波所取得的主要进展。同时讨论了与射电爆发共生的耀斑的观测以及用等离子体辐射和回旋同步加速辐射对这些观测所作的解释。从空间对与Ⅲ型爆发有关的等离子振荡和一维电子速度分布的测量,业已证实了用等离子体辐射对观测所作的解释。Ⅲ型爆发的米波-十米波射电日像仪测量和千米-百米波的飞船测量表明,Ⅲ型电子束流是沿着浓密的日冕流和沿着阿基米德螺旋轨道运动的。在厘米波段利用角秒分辨率的大天线阵对活动区和射电爆发所作的高空间分辨率观测,表明了它在观测日冕磁场、了解冕环的物理性质、测量耀斑附近磁场结构,从而在研究太阳耀斑起源方面有着巨大的威力. 相似文献
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利用国家天文台(北京和昆明)的射电频谱仪(频段为0.65~7.6 GHz)和相关的NoRH/17GHz射电以及TRACE/171 EUV和Yohkoh/SXT的观测资料,分析了2001/04/10和10/19的2个共生精细时间结构的稀有事件,这2个事件的射电爆发时间轮廓和观测特征相似,通过这2个事件的微波(17GHz)偏振观测资料的比较,发现这2个射电爆发均由包含多重(4极)磁结构的复杂活动区引起,特别指出这2个耀斑最后都导致了耀斑后相的分米波射电爆发(第二次触发耀斑),这可能是后环引起的射电爆发。它们都分别对应于双极磁位形,表明这两次触发耀斑是由相似的耀斑模型产生。2个分米波爆发可能是相似(homologous)耀斑的射电表现,可以推测这两次耀斑的驱动器可能皆是磁流浮现或对消(因为源区有新的单或双极出现或消失),而它们的触发器皆是由双极反向Y型位形(具有一个双极拱的单磁流系统)的磁重联,耀斑后环的演化是导致耀斑后相分米波射电爆发的必要条件。我们认为,这双带耀斑对应的宽带射电爆发辐射机制是回旋同步加速辐射过程,而耀斑后相的窄带分米波爆发的辐射机制是等离子体辐射过程。 相似文献
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基于我国的太阳射电宽带频谱仪(0．625～7．600GHz)在2003年10月22日～11月3日观测到8个伴生日冕物质抛射(CME)的太阳射电爆发,结合Nobeyama Radio Polarimeter(NORP)的单频观测、Nobeyama Radioheliograph (NORH)、Siberian Solar Radio Telescope(SSRT)的成像观测以及Culgoora和WAVE／WIND的低频射电频谱观测,对8个射电爆发的射电辐射特征进行了初步分析．试图从中寻找与CME伴生的射电爆发的特征。 相似文献
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通过对2．6～3．8GHz射电频谱仪观测数据的检索。挑选出73个孤立的特征寿命为20s的Ⅲ型爆发进行统计分析。得到了太阳射电Ⅲ型爆发在2600—3800MHz间的辐射寿命的统计分布；并用相应的数据检验了在米波和分米波辐射存在的经验关系，结果显示在2．6-3．8GHz的射电波段上，Ⅲ型爆发的寿命和频率之间仍然成反比的关系，但是系数不同于米波和分米波对应的系数。 相似文献
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利用综合孔径射电望远镜在 ２３２ ＭＨｚ观测太阳,具有 ３·８’的空间分辨率、 ２０ ｍｓ 的时间分辨率和高灵敏度及很好的抗干扰能力．１９９９年共观测到１２次大爆发,其中８次与日冕物质抛射相关．可以利用米波射电爆发预报ＣＭＥ事件． 相似文献
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本介绍了云南天台四波段（１．４２,２．１３,２．８４和４．２６ＧＨｚ）太阳射电高时间分辨率同步观测得到的五个微波ＩＩＩ爆发事件,它们具有宽频带,长和短寿命,内向和外向快速频漂等特征,观测事例表明,非热电子束引起的等离子体辐射和电子回旋脉泽辐射两种机制都可能发生,这些观测特征即可不完全同于米波－分米波ＩＩＩ型爆发,也不完全同于微波高频段ＩＩＩ型爆发,说明在微波低频段可能存在二重性或过渡现象。 相似文献
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在本文中,我们对米波太阳射电爆发的观测和研究（Ｓｐｉｋｅｓ以及各类爆发）进行了较全面的总结,对Ｓｐｉｋｅｓ、米波射电爆发及基和太阳耀斑、ＣＭＥ（日冕物质抛射）的相互关系也给出了比较详细的讨论关加以概括;针对米波射电的未来观测和研究、米波Ｓｐｉｋｅｓ与广泛的其它太阳耀斑现象的米波射电爆发才耀斑及ＣＭＥ的关系和米波射电辐射的理论问题,在理论和观测两方面提出了未来工作的设想和建议。主要观战和结论有： 相似文献
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232MHz太阳爆发与日冕物质抛射 总被引：1，自引：0，他引：1
利用综合孔径射电望远镜的２３２ＭＨｚ观测太阳,具有３．８’的空间分辨率,２０ｍｓ的时间分辨率和高灵敏度及很好的抗干扰能力。１９９９年共观测到１２次大爆发,其中８次与日冕物质抛射相关,可以利用米波射电爆发预报ＣＭＥ事件。 相似文献
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Magnetic reconnection is commonly accepted to play a key role in flare energy release, but only poor information about the
main characteristics of this process is available so far. An intrinsic feature of reconnection is plasma density enhancement
in current sheets. A unique method to detect this effect is provided by analysis of drifting bursts, whose emission frequency
is close to the local Langmuir frequency or its harmonics. With this purpose, we analyze a series of several tens of drifting
microwave bursts during the 30 March 2001 flare. The burst drift rates range from −10 to 20 GHz s−1. Using one-dimensional scans recorded with the SSRT interferometer at two different frequencies near 5.7 GHz, we have measured
relative positions of burst sources and their velocities along a flare loop revealed from soft X-ray and extreme-ultraviolet
images. It is argued that the contribution of the increasing density effect into the observed frequency drift rates is about
6 GHz s−1, which is shown to be consistent with theoretical models of magnetic reconnection with reasonable boundary conditions. 相似文献
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Min Wang Rui-Xiang Xie Chun Xu Shuo-Biao Shi Yi-Hua Yan National Astronomical Observatories Yunnan Observatory Chinese Academy of Sciences Kunming National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2005,5(5):508-518
We present a, large complex radio burst and its associated fast tune structures observed on 2001 April 10 in the frequency range of 0.65-7.6 GHz. The NoRH radio image observation shows very complex radio source structures which include preexisting, newly emerging, submerging/cancelling polarities and a bipolar, a tripolar (a 'bipolar + remote unipolar'), and a quadrupolar structure. This suggests that the radio burst is generated from a very complicated loop structure. According to the spectral and image observations, we assume that the beginning of this flare was caused by a single bipolar loop configuration with a 'Y-type' re-connection structure. A composite of radio continuum and fast time structures is contained in this flare. The various fast radio emission phenomena include normal and reverse drifting type III bursts, and slowly drifting and no-drift structures. The tripolar configurations may form a double-loop with a 'three-legged' structure, which is an important source of the various types of fast time structures. The two-loop reconnection model can lead simultaneously to electron acceleration and corona heating. We have also analyzed the behaviors of coronal magnetic polarities and the emission processes of different types radio emission qualitatively. Interactions of a bipolar or multi-polar loop are consistent with our observational results. Our observations favor the magnetic reconnection configurations of the 'inverted Y-type' (bipolar) and the 'three-legged' structures (tripolar or quadrupolar). 相似文献
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Evidence that Synchrotron Emission from Nonthermal Electrons Produces the Increasing Submillimeter Spectral Component in Solar Flares 总被引：1，自引：0，他引：1
Adriana V. R. Silva G. H. Share R. J. Murphy J. E. R. Costa C. G. Giménez de Castro J.-P. Raulin P. Kaufmann 《Solar physics》2007,245(2):311-326
We investigate the origin of the increasing spectra observed at submillimeter wavelengths detected in the flare on 2 November
2003 starting at 17:17 UT. This flare, classified as an X8.3 and 2B event, was simultaneously detected by RHESSI and the Solar
Submillimeter Telescope (SST) at 212 and 405 GHz. Comparison of the time profiles at various wavelengths shows that the submillimeter
emission resembles that of the high-energy X rays observed by RHESSI whereas the microwaves observed by the Owens Valley Solar
Array (OVSA) resemble that of ∼50 keV X rays. Moreover, the centroid position of the submillimeter radiation is seen to originate
within the same flaring loops of the ultraviolet and X-ray sources. Nevertheless, the submillimeter spectra are distinct from
the usual microwave spectra, appearing to be a distinct spectral component with peak frequency in the THz range. Three possibilities
to explain this increasing radio spectra are discussed: (1) gyrosynchrotron radiation from accelerated electrons, (2) bremsstrahlung
from thermal electrons, and (3) gyrosynchrotron emission from the positrons produced by pion or radioactive decay after nuclear
interactions. The latter possibility is ruled out on the grounds that to explain the submillimeter observations requires 3000
to 2×105 more positrons than what is inferred from X-ray and γ-ray observations. It is possible to model the emission as thermal; however, such sources would produce too much flux in the
ultraviolet and soft X-ray wavelengths. Nevertheless we are able to explain both spectral components at microwave and submillimeter
wavelengths by gyrosynchrotron emission from the same population of accelerated electrons that emit hard X rays and γ rays. We find that the same 5×1035 electrons inferred from RHESSI observations are responsible for the compact submillimeter source (0.5 arcsec in radius) in
a region of 4500 G low in the atmosphere, and for the traditional microwave spectral component by a more extended source (50
arcsec) in a 480 G magnetic field located higher up in the loops. The extreme values in magnetic field and source size required
to account for the submillimeter emission can be relaxed if anisotropy and transport of the electrons are taken into account. 相似文献
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Qi-Jun Fu Yi-Hua Yan Yu-Ying Liu Min Wang Shu-Juan WangNational Astronomical Observatories Chinese Academy of Sciences Beijing fuqijun@sohu.com 《中国天文和天体物理学报》2004,4(2):176-188
The 2.6-3.8 GHz, 4.5-7.5 GHz, 5.2-7.6 GHz and 0.7-1.5 GHz component spectrometers of Solar Broadband Radio Spectrometer (SBRS) started routine observations, respectively, in late August 1996, August 1999, August 1999, and June 2000. They just managed to catch the coming 23rd solar active maximum. Consequently, a large amount of microwave burst data with high temporal and high spectral resolution and high sensitivity were obtained. A variety of fine structures (FS) superimposed on microwave bursts have been found. Some of them are known, such as microwave type Ⅲ bursts, microwave spike emission, but these were observed with more detail; some are new. Reported for the first time here are microwave type U bursts with similar spectral morphology to those in decimetric and metric wavelengths, and with outstanding characteristics such as very short durations (tens to hundreds ms), narrow bandwidths, higher frequency drift rates and higher degrees of polarization. Type N and type M bursts were also observed. Detailed zebra pattern and fiber bursts at the high frequency were found. Drifting pulsation structure (DPS) phenomena closely associated with CME are considered to manifest the initial phase of the CME, and quasi-periodic pulsation with periods of tens ms have been recorded. Microwave “patches”, unlike those reported previously, were observed with very short durations (about 300ms), very high flux densities (up to 1000 sfu), very high polarization (about 100% RCP), extremely narrow bandwidths (about 5%), and very high spectral indexes. These cannot be interpreted with the gyrosynchrotron process. A superfine structure in the form of microwave FS (ZPS,type U), consisting of microwave millisecond spike emission (MMS), was also found. 相似文献
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Min Wang Rui-Xiang Xie Yi-Hua Yan Yu-Ying Liu 《中国天文和天体物理学报》2007,7(4):477-486
Three particularly complex radio bursts (2001 October 19, 2001 April 10 and 2003 October 26) obtained with the spectrometers (0.65-7.6GHz) at the National Astronomical Observatories, Chinese Academy of Sciences (NAOC, Beijing and Yunnan) and other in- struments (NoRH, TRACE and SXT) are presented. They each have two groups of peaks occurring in different frequency ranges (broad-band microwave and narrow-band decimeter wavelengths). We stress that the second group of burst peaks that occurred in the late phase of the flares and associated with post-flare loops may be homologous radio bursts. We think that they are driven by the post-flare loops. In contrast to the time profiles of the radio bursts and the images of coronal magnetic polarities, we are able to find that the three events are caused by the active regions including main single-bipole magnetic structures, which are associated with multipole magnetic structures during the flare evolutions. In particular, we point out that the later decimetric radio bursts are possibly the radio counterparts of the homologous flares (called "homologous radio bursts" by us), which are also driven by the single-bipole mag- netic structures. By examining the evolutions of the magnetic polarities of sources (17GHz), we could presume that the drivers of the homologous radio bursts are new and/or recurring appearances/disappearances of the magnetic polarities of radio sources, and that the triggers are the magnetic reconnections of single-bipole configurations. 相似文献
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Anisotropic Beam Model for the Spectral Observations of Radio Burst Fine Structures on 1998 April 15
A fine structure consisting of three almost equidistant frequency bands was observed in the high frequency part of a solar burst on 1998 April 15 by the spectrometer of Beijing Astronomical Observatory in the range 2.6-3.8GHz. A model for this event based on beam-anisotropic instability in the solar corona is presented. Longitudinal plasma waves are excited at cyclotron resonance and then transformed into radio emission at their second harmonic.The model is in accordance with the observations if we suppose a magnetic field strength in the region of emission generation of about 200G. 相似文献
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A. A. Konovalenko A. A. Stanislavsky E. P. Abranin V. V. Dorovsky V. N. Mel’nik M. L. Kaiser A. Lecacheux H. O. Rucker 《Solar physics》2007,245(2):345-354
Here we report a radio burst in absorption at 9?–?30 MHz observed with the UTR-2 telescope. This event occurred on 19 August 2003 about 11:16?–?11:26 UT, against solar type IV/II emission background. It is the first event where absorption was observed below 30 MHz. The absorption region, comparable with the solar radius size, traveled a long distance into the upper corona from the Sun. We show that the burst minimum corresponds to the almost full absorption of the solar radio emission up to a background level of the quiescent Sun. This supports the interpretation of the phenomenon as an absorption. The result is examined independently with the Nançay Decameter Array measurements and the Wind WAVES instrument records. 相似文献
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Properties, including the time duration, polarization, quasi-periodical oscillations and so on, of the microwave spike emissions observed at 2.5 GHz and 2.6 GHz during the solar flare of 1991 May 16 are analyzed statistically. The left-handed and right-handed circular polarizations of the spike emissions at 2.5, 2.6 and 3.1 GHz are reported in detail. At these 3 frequencies, most of the spikes are superposed on both the rising (and maximum) and the descending phase of the burst. It is noteworthy that spikes also appeared superposed on the small bursts that appeared after the main burst. The spike emission lasted 17 minutes. Polarization reversals on different timescales appearing in the spike emissions at 2.5 and 2.6 GHZ are described. Our statistical analysis indicates that the polarization reversals at 2.5 and 2.6 GHz differ in characters on average, the polarization reversal at 2.5 GHz is earlier than that of 2.6 GHz by about 1.5 minutes, and polarization reversal of the spike emission is more frequent at 2.5 GHZ. 相似文献
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太阳射电爆发(Solar Radio Burst, SRB)是太阳高能电子与背景等离子体相互作用产生的感应辐射现象,其多样的动力学谱类型及其复杂的精细结构反映了辐射源区磁等离子体结构状态丰富的物理信息,而相关辐射机制则是解读相关物理信息的关键工具.长期以来,在SRB辐射机制的研究中一直存在着争议不决的两种主要机制,即等离子体辐射机制和电子回旋脉泽(Electron Cyclotron Maser, ECM)辐射机制.近年来,针对传统的ECM辐射机制应用到SRB现象时遇到的一些主要困难,发展了由幂律谱电子低能截止驱动和包含快电子束自生阿尔文波效应的新型ECM驱动模型,并成功应用于解释各类不同SRB动力学谱的形成机制.基于这些新型的ECM辐射模型,系统地总结了ECM辐射机制在各种不同类型SRB现象中的应用,并对它们不同动力学谱结构的形成给出了一致统一的物理解释. 相似文献
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Ya-Yuan Wen Jing-Xiu Wang Yu-Zong Zhang National Astronomical Observatories Chinese Academy of Sciences Beijing 《中国天文和天体物理学报》2007,7(2):265-280
Using Nancay Radioheliograph (NRH) imaging observations, combined with SOHO/Michelson Doppler Imager (MDI) magnetogram observations and coronal magnetic field extrapolation, we studied the magnetic nature of metric noise storms that are associated with coronal mass ejections (CMEs). Four events are selected: the events of 2000 July 14, 2001 April 26, 2002 August 16 and 2001 March 28. The identified noise storm sources cover or partially cover the active regions (ARs), but the centers of storm sources are offset from the ARs. Using extrapolated magnetic field lines, we find that the noise storm sources trace the boundary between the open and closed field lines. We demonstrate that the disappearance of noise storm source is followed by the appearance of the burst source. The burst sources spread on the solar disk and their distributions correspond to the extent of the CME in LASCO C2 field of view. All the SOHO/Extreme Ultraviolet Imaging Telescope (EIT) dimmings associ- ated with noise storm sources are located at the periphery of noise storms where the magnetic lines of force were previously closed and low-lying. When the closed field becomes partially or fully open, the basic configurations of noise storm sources are changed, then the noise storm sources are no longer observed. These observations provide the information that the variations of noise storms manifest the restructuring or reconfiguring of the coronal magnetic field. 相似文献