太阳射电米波爆发与日冕物质喷射

利用云南天文台声光频谱仪观测到的一次特殊的太阳射电米波爆发，与对应的光学活动及相关事件，我们探讨了1991年6月7日的日冕物质喷射 过程。     

一个复杂太阳射电爆发及其微波源区特征的初步研究

我国“太阳射电宽带频谱仪(0．7～7．6GHz)”于2001年10月19日观测到的复杂太阳射电大爆发，呈现许多有趣的特征。本文结合NoRH的高空分辨率成像观测资料，分析了该爆发的微波射电源区的演化特征及与射电辐射特征的关系。还发现微波源的缓慢运动，这可能与爆发所伴随的CME的形成有关。     

1998年9月23 日复杂太阳爆发射电联合观测的初步分析

利用北京天文台1998.09.23日1-2GHz和2.6-3.8GHz频谱仪观测到的一个Ⅲ-Ⅳ型复杂大爆发，结合俄罗斯SSRT和德国分米-米波动态频谱仪的观测资料，进行了初步的比对分析，拓展了关于日冕电子加速和日冕磁结构方面的一些研究内容，简单地注释了一些可研究的现象和运动Ⅳ型爆发及多重脉动的辐射机制。     

太阳AR7646,7647活动区黑子磁场和新的射电微耀斑爆发

１９９４年１月５日日面上产生的１次１Ｎ／Ｍ１．０耀斑爆发，射电１．４２ＧＨｚ高时间分辨率观测也同时接收到，在小爆发过程里瘵有５３个脉冲信号叠加在连志辐射背景上，是很罕见的现象。在ＡＲ７６４６的黑子前导区域，５日有２处新浮的小黑子对，磁场分别的现象。     

太阳射电爆发的起因：耀斑或／和日冕物质抛射

本文分析了近二十年来的地面和空间太阳有关观测资料,得出太阳射电爆发的起因为耀斑和／ 或日冕物质抛射（ＣＭＥ） 而不仅仅是耀斑,这将有利于更深刻地了解太阳射电爆发和共生高能现象的物理过程     

太阳射电米波Ⅲ型爆发的观测分析

统计分析了云南天文台在２２周峰年期间观测到的米波Ⅲ型射电爆发与光学活动的关系,发现在２３０￣３００ＭＨｚ频率范围的米波Ⅲ型爆发与Ｈα耀斑的关系是密切的,Ⅲ型爆发的产生与双极磁结构和复杂型黑子活动区也密切相关。并对统计结果作了讨论。     

太阳白光耀斑的射电辐射特征：运动Ⅳ型爆发和与耀斑后环共生的短周期脉动

通过１９９１年６月６日一个复杂的太阳活动事件（包括宽带射电运动Ⅳ型爆发、脉冲相伴生的白光耀斑、耀斑后环及其伴生的射电多重短周期（约１－４劝现象等）的分析,探讨了白光耀斑产生的射电辐射特征,根据太阳白光耀斑和射电运动Ⅳ型爆发产生的物理过程,着重讨论了射电运动Ⅳ型爆发、耀斑后环和短周期脉动现象,并认为它们可能是白光耀斑的对应物。     

太阳白光耀斑的射电辐射特征:运动Ⅳ型爆发和与耀斑后环共生的短周期脉动现象

通过１９９１ 年６ 月６ 日一个复杂的太阳活动事件（ 包括宽带射电运动Ⅳ型爆发、脉冲相伴生的白光耀斑、耀斑后环及其伴生的射电多重短周期（ 约１ － ４ 秒） 脉动现象等） 的分析,探讨了白光耀斑产生的射电辐射特征,根据太阳白光耀斑和射电运动Ⅳ型爆发产生的物理过程,着重讨论了射电运动Ⅳ型爆发、耀斑后环和短周期脉动现象,并认为它们可能是白光耀斑的对应物     

由多频射电爆发探讨太阳白光耀斑的起源问题

从射电运动Ⅳ型爆发的特征和多频射电爆发开始时序的分析可以看出这个伴生的白光耀斑（ Ｗ Ｌ Ｆ） 和射电爆发同是由低日冕的加速电子激活,可能通过非热电子沉降能量于色球层, 产生了色球层压缩波, 又经二步能量传输过程在上光球层导致 Ｗ Ｌ Ｆ。通过对共生事件的分析, 并与已知的二类 Ｗ Ｌ Ｆ的观测特征作了比较, 提出该 Ｗ Ｌ Ｆ 可能属于二类的混合型, 并提出 Ｗ Ｌ Ｆ 可能存在射电辐射的必要条件     

微波爆发区的日冕磁场研究

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。     

Are Homologous Radio Bursts Driven by Solar Post-Flare Loops？

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.     

Scaling-laws of Radio Spike Bursts and Their Constraints on New Solar Radio Telescopestwo

Radio observation is one of important methods in solar physics and space science. Sometimes, it is almost the sole approach to observe the physical processes such as the acceleration, emission, and propagation of non-thermal energetic particles, etc. So far, more than 100 solar radio telescopes have been built in the world, including solar radiometers, dynamic spectrometers, and radioheliographs. Some of them have been closed after the fulfillment of their primary scientific objectives, or for their malfunctions, and thus replaced by other advanced instruments. At the same time, based on some new technologies and scientific ideas, various kinds of new and much more complicated solar radio telescopes are being constructed by solar radio astronomers and space scientists, such as the American E-OVSA and the solar radio observing system under the framework of Chinese Meridian Project II, etc. When we plan to develop a new solar radio telescope, it is crucial to design the most suitable technical parameters, e.g., the observing frequency range and bandwidth, temporal resolution, frequency resolution, spatial resolution, polarization degree, and dynamic range. Then, how do we select a rational set of these parameters? The long-term observation and study revealed that a large strong solar radio burst is frequently composed of a series of small bursts with different time scales. Among them, the radio spike burst is the smallest one with the shortest lifetime, the narrowest bandwidth, and the smallest source region. Solar radio spikes are considered to be related to a single magnetic energy release process, and can be regarded as an elementary burst in solar flares. It is a basic requirement for the new solar radio telescope to observe and discriminate these solar radio spike bursts, even though the temporal and spatial scales of radio spike bursts actually vary with the observing frequency. This paper presents the scaling laws of the lifetime and bandwidth of solar radio spike bursts with respect to the observing frequency, which provide some constraints for the new solar radio telescopes, and help us to select the rational telescope parameters. Besides, we propose a spectrum-image combination mode as the best observation mode for the next-generation solar radio telescopes with high temporal, spectral, and spatial resolutions, which may have an important significance for revealing the physical essence of the various non-thermal processes in violent solar eruptions.     

Propagation of the Slow Magnetoacoustic Waves in Coronal Loops Above Sunspots

The observations from the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) have revealed the weak dis- turbances (WDs) propagating in the fan-like coronal loops of the active region (AR 11092) at 171 ?A, 193 ?A, and 211 ?A. These WDs seem to be a common phenomenon in this part of the active region. The disturbances originate from the bright loop foot, and propagate along the loops. The observed propagation speed decreases with the increasing temperature, and varies between 40 km/s and 121 km/s, close to and less than the sound speed in coronal loops. Consid- ering the projection effect and the different angles of the loops with respect to the line of sight, this is exactly what the slow-wave model expects. The wavelet analysis shows that the periods of the WDs observed in different wavebands have no signi?cant difference, the two distinct periods, 3 min and more than 10 min, are all detected in the three EUV wavebands. Not only the coronal loops but also the sunspot region in the chromosphere exhibit intensity oscillations with a period of the order of 3 min. This result suggests that the sunspot oscillations can propagate into the corona through the chromosphere and transition region.     

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.     

日冕分米波射电甚短周期脉动的观测证据

利用国家天文台云南天文台“分米波(700—1500MHz)射电频谱仪”和“四波段太阳射电高时间分辨率同步观测系统”分别于2001年6月24日和1990年7月30日观测到了两个稀少事件，前者是一个小射电爆发，其上升相伴随有短周期(约29、40和100毫秒)的脉动，后者是一个射电大爆发，在2840MHz上产生了周期约30毫秒的射电脉动，还着重讨论其甚短周期(如29—40毫秒)的脉动现象，甚短周期脉动可能是归因于起源在日冕深处不稳定区域的哨声波束周期链对射电辐射的调制，或沉降电子束驱动的静电高混杂波，经由波-波非线性相互作用导致甚短周期的射电脉动。     

Absorption in Burst Emission

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.     

Damped Oscillations of Coronal Loops

A mechanism of damped oscillations of a coronal loop is investigated. The loop is treated as a thin toroidal flux rope with two stationary photospheric footpoints, carrying both toroidal and poloidal currents. The forces and the flux-rope dynamics are described within the framework of ideal magnetohydrodynamics (MHD). The main features of the theory are the following: i) Oscillatory motions are determined by the Lorentz force that acts on curved current-carrying plasma structures and ii) damping is caused by drag that provides the momentum coupling between the flux rope and the ambient coronal plasma. The oscillation is restricted to the vertical plane of the flux rope. The initial equilibrium flux rope is set into oscillation by a pulse of upflow of the ambient plasma. The theory is applied to two events of oscillating loops observed by the Transition Region and Coronal Explorer (TRACE). It is shown that the Lorentz force and drag with a reasonable value of the coupling coefficient (c _d ) and without anomalous dissipation are able to accurately account for the observed damped oscillations. The analysis shows that the variations in the observed intensity can be explained by the minor radial expansion and contraction. For the two events, the values of the drag coefficient consistent with the observed damping times are in the range c _d ≈2 – 5, with specific values being dependent on parameters such as the loop density, ambient magnetic field, and the loop geometry. This range is consistent with a previous MHD simulation study and with values used to reproduce the observed trajectories of coronal mass ejections (CMEs).