检验行星潮汐对太阳耀斑的影响

第１９太阳周内６．５年中的１１１９个≥２＾－级太阳耀斑，相对于木星和金星的日面经度观测分布为Ｐｊ（Ｌ）和Ｐｖ（Ｌ）。五种理论分布假设为：（１）均匀随机分布；（２）均匀随机＋横向潮汐力分布；（３）均匀随机＋竖向潮汐力分布；（４）均匀随机＋潮汐力模量分布；（５）均匀随机＋横向潮汐力和竖向潮汐力分布。观测和理论分布的χ＾２拟合优度检验表明：在较严格的显性水平上（α〈０．０１），五种理论分布假设都能接受     

太阳耀斑的分类

太阳耀斑分类工作的进展反映了太阳耀斑观测研究与理论研究的进展。本文首先综述耀斑的分类，对近年提出的种种分类作评述，讨论这些分类的观测基础。然后，基于最近两个太阳周的观测工作，提出一种新的多能段太阳耀斑分类方法。按照耀斑在光学，Ｘ射线以及射电波段的观测表象，把耀斑较完整地分为８类。     

太阳耀斑爆发对京津冀地区云——地闪电活动的影响

太阳活动能否影响地球天气气候是一个全球关心的问题［１,２］．目前大多数研究者认为,太阳活动影响短期天气变化最可能的途径是通过调制大气电环境来实现的［３－５］,太阳耀斑爆发及其伴随事件均可对地球电环境产生明显的影响［１－５］,并通过磁层－电离层－中性大气层的耦合作用影响大气电场,再通过云中电性质的改变影响云的微物理结构［６,７］,并直接产生动力作用［８－１０］,从而影响雷雨云的发展,造成短期天气变化．２０多年来已有大量有关太阳耀斑与地球雷暴间的相关统计工作［３－５］．Ｍａｒｋｓｏｎ［１１］、Ｂｏｓ…     

太阳耀斑研究的新进展

近年来对太阳耀斑的研究取得了重要的进展，一些新的发 现主要来自高分辨率的观测，特别是来自“阳光”卫星的结果，综合的范围包括太阳耀斑中磁重联的新证据、硬Ｘ射线源的分类、Ｘ射线喷流的发现、环－环相互作用的证据以及对耀斑大气动力学过程的新认识等。     

太阳耀斑的近红外光谱诊断

本文简要介绍了太阳耀斑近红外光谱的观测和研究,指出太阳近红外光谱的确能对耀斑的运动、电子密度和加热机制等提供诊断信息,有些方面比Ｈα还灵敏。最后还对２３ 周峰年观测选题提出了一些建议     

关于太阳白光耀斑连续发射起源的讨论

白光耀斑研究近年来获得较大进展，对其连续发射起源机制目前流行三种解释．一是耀斑形成过程中所产生的色球凝聚[1-3]，二是非热粒子注入大气致氢原子非热激发和电离[4-6]，三是色球强加热所引起的对大气深层的辐射反加热[7]．这三类解释具有一个共性，即除了自身直接对连续谱     

太阳黑子运动引起的耀斑与活动区的耦合

利用紫台赣榆站太阳精细结构望远镜拍摄的色球和光球照片，研究了1990年11月6日至13日NOAA6361活动区的磁位形演化和耀斑产生区域，发现该活动区的活动主要集中在11日和12日两天还观测到新老活动区的碰撞耦合及耦合界面处小纤维（fibril）的快速变化，这些现象是由于前导黑子之一的p1黑子的连续几天的运动造成的．所有的活动也主要集中在P1黑子的周围．     

耀斑色球压缩区的传播与谱线的不对称性

色球压缩区是耀斑大气动力学过程的一个基本特征，是产生色球谱线红不对称性的基础。本文基于压缩区从大气高层向低层传播的理论公式，在二种不同情况下，计算得到了压缩区内物质运动速度随高度和时间的变化．结果表明，色球蒸发区压力增量Δｐ为常数时压缩区之寿命比压缩区波阵面后的压力ｐ２为常数时要长得多，这就大大缓解了以往谱线不对称性的延续时间的理论值比观测值小的矛盾。形成高度不同的谱线具有不同程度的不对称性这一观测现象也同色球压缩区的传播特性相一致。     

太阳耀斑引起的磁扰的多因子回归分析

利用多元逐步回归方法分析了太阳耀斑的日面经纬度、面积,持续时间、地球的日面纬度、地磁轴与日地连线的夹角和地磁扰动的关系。结果表明这6个因子对磁扰均有不同程度的影响,由太阳耀斑引起的地磁扰动除与耀斑的特征有关外,还受地球空间位置的影响。     

Evidence that Synchrotron Emission from Nonthermal Electrons Produces the Increasing Submillimeter Spectral Component in Solar Flares

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.     

On the Positronium Continuum and 0.511 MeV Line in Solar Flares

We have studied the influence of the density of the annihilation region on the positronium continuum. A relation between the ratio 3γ/2γ and the densityis explicitly given, with which one can derive directly from the observed 3γ/2γ the density where the annihilation occurs. A unique solution may be found from the observed width of the 0.511MeV line. We applied the method to three flares observed by GRS/SMM. It is shown that due to the measuring uncertainties in the 0.511 MeV line width, we cannot distinguish a chromospheric source from a coronal source, though both accurately localized. To improve the measuring accuracy of the 0.511MeV line and the ratio 3γ/2γ will be an important step for a better understanding of the annihilation process in solar flares.     

耀斑日冕硬X射线源观测研究

对于足点被日面边缘遮挡住的耀斑的观测研究是诊断日冕硬X射线辐射的一个重要方法.通过统计分析RHESSI (Reuven Ramaty High-Energy Solar Spectroscopic Imager)卫星观测到的71个此类耀斑硬X射线源发现,前人提出的两类源,即日冕X射线辐射中热辐射与非热辐射源区空间分离较小的源和分离较大的源,在能谱、成像、光变曲线以及GOES持续时间等方面都没有显著的区别,其中辐射区的面积、耀斑总热能以及GOES持续时间与分离距离之间有很好的相关性.这些结果支持近年来提出的一些耀斑统一模型.同时也表明Masuda耀斑只是一类非常特殊的事件,不具有日冕硬X射线辐射的一般特征.     

Latitudinal Distribution of Solar Flares and Their Association with Coronal Mass Ejections

Major solar flare events have been utilised to study the latitudinal frequency distribution of solar flares in northern and southern hemispheres for the period of 1986 to 2003. A statistical analysis has been performed to obtain the correlation between Coronal Mass Ejections (CMEs) and Forbush decrease (Fds) of cosmic ray intensity. Almost the same flares distribution in both hemispheres is found in association with CMEs. In a further analysis, it is noted that a larger number of CME-associated solar flares located in the northern hemisphere are found to be more effective in producing Forbush decreases.     

On the Lower Energy Cutoff of Nonthermal Electrons in Solar Flares

1 INTRODUCTIONThe lower energy cutoff of nonthermal electron beams is an important quantity. Not only isit related to the acceleration mechanism, but it also determines the total number of acceleratedelectrons and the energy they carry. The power-law of electron beams cannot extend to lowerenergies indefinitely for if it did, it would imply an indeflnite1y large nuInber of electrons.A lower energy cutoff (E.), therefore, must exist, to keep the number of electrons within areasonable rang…     

On the Evolution of the Lower Energy Cutoff of Nonthermal Electrons in Solar Flares

1 INTRODUCTION Gan, Li and Chang (2001a) proposed a quantitative method to obtain the lower energycutoff (Er) of power-law electrons from the observed broken-down double power-law hard Xray spectrum. Most recently Can et al. (2002) improved the method and let it be moreself-consistent. They applied their improved method to the 54 hard X-ray events observed withBATSE/CGRO and acquired more general results in comparison with those obtained by Canet al. (2001b). Despite the data is rel…