Prediction of Space Weather Using an Asymmetric Cone Model for Halo CMEs

Halo coronal mass ejections (HCMEs) are responsible of the most severe geomagnetic storms. A prediction of their geoeffectiveness and travel time to Earth’s vicinity is crucial to forecast space weather. Unfortunately, coronagraphic observations are subjected to projection effects and do not provide true characteristics of CMEs. Recently, Michalek (Solar Phys. 237, 101, 2006) developed an asymmetric cone model to obtain the space speed, width, and source location of HCMEs. We applied this technique to obtain the parameters of all front-sided HCMEs observed by the SOHO/LASCO experiment during a period from the beginning of 2001 until the end of 2002 (solar cycle 23). These parameters were applied for space weather forecasting. Our study finds that the space speeds are strongly correlated with the travel times of HCMEs to Earth’s vicinity and with the magnitudes related to geomagnetic disturbances.     

边缘耀斑中HeI 10830的加宽计算

讨论了 ＨｅＩ １０８３０Ａ的 Ｄｏｐｐｌｅｒ和 Ｓｔａｒｋ加宽机制以及各种加宽参数的计算，并 得到以下一些结论：辐射阻尼对 ＨｅＩ １０８３０ Ａ的加宽作用与 Ｄｏｐｐｌｅｒ效应相比可以忽略； 在公认的耀斑电子密度（Ｎｅ＝３．２ ×１０１３ｃｍ－３）的情况下，所有阻尼项均不可能产生可以 觉察的加宽；直到 Ｎｅ＝１０１５ｃｍ－３，各种阻尼对线心半宽的增加都不起作用，其值最多 在１０－３的量级，因此；线心都可以看作是Ｄｏｐｐｌｅｒ加宽；当 Ｎｅ＞１０１４ ｃｍ－３时，Ｓｔａｒｋ 加宽，特别是电子碰撞的 Ｓｔａｒｋ加宽将在 ＨｅＩ １０８３０ Ａ的加宽中起主要作用；如要 Ｓｔａｒｋ 加宽谱线的线翼比纯Ｄｏｐｐｌｅｒ加宽大１－２倍，则阻尼加宽半宽与。可以相比拟；如果 用 Ｓｔａｒｋ加宽来解释 １９８９年边缘耀斑的观测轮廓，则电子密度将达１０～（１７）ｃｍ－３，与氦 原子的碰撞阻尼（γ３）造成的加宽对Ｉ１２和Ｉ３两分量明显不同，它们对Ｉ１２的影响比对Ｉ３ 的影响大近一个量级，我们的观测显示Ｉ１２和Ｉ３线翼的延伸基本一样，因而我们的观测 轮廓不可能是γ３造成的     

红外波段太阳观测技术方法研究

1m红外太阳塔是我国未来重点发展的地面太阳观测设备 ,本文的所有工作均围绕着与此相关的红外波段太阳观测技术方法展开。1 .针对望远镜实验平台—云台太阳光谱仪 ,建立了光谱仪分光流量模型 ,并用多种实验手段验证了其可靠性。利用该模型计算了FeⅠ 1 .56μm红外太阳光谱的分光流量 ,分析了实验观测的可行性及改进方案。2 .针对探测器实验平台—PtSi红外焦平面阵列相机 ,建立了FeⅠ 1 .56μm光谱观测信噪比模型 ,模拟了各种噪声对观测的影响。在此基础上 ,在国内首次成功进行了FeⅠ1 .56μm红外太阳光谱的面阵观测实验。3 .在红外观测实验所处的高背景低对比度条件下 ,讨论了红外太阳光谱观测的图像处理方法 ,分析了观测中出现的干涉条纹的来源及解决办法 ,初步建立起了一整套红外太阳光谱与成像的定标方法和图像处理方法。4 .首次利用PVA材料 ,设计研制了一套FeⅠ 1 .56μm近红外Stokes参量偏振仪 ,并将该偏振仪安装在美国国立天文台McMath望远镜上进行了观测实验。针对一太阳黑子 ,通过扫描进行了二维的Stokes参量观测。同时建立了一套从Stokes参量反演磁矢量场的方法 ,并将反演的结果与怀柔太阳磁场望远镜的观测结果进行了比对。5.针对 1m红外太阳塔的太阳光谱仪系统 ,给出了垂直多波段光谱仪和红外     

On the acceleration of solar-flare charged particles in a collapsing magnetic trap with an electric potential

We consider the kinetic problem of charged-particle acceleration in a magnetic trap with converging magnetic mirrors. We show that for a positive electrostatic potential of the trap plasma relative to the mirrors, the efficiency of confinement and acceleration increases for electrons and decreases for ions.     

The Shadow of Comet Hale–Bopp in Lyman-Alpha

For a few months around perihelion, thecentral part of the Hale–Bopp hydrogencloud has been optically thick to thesolar Lyα radiation, and hassignificantly reduced the solar flux availablefor the resonance glow of interstellarhydrogen beyond the comet. This shadowing effecton the interstellar gas is the first everobserved comet shadow. It is modeled andcompared with SWAN observations. Shadowmodelling will help to constrain the cometwater production and radiative transfer effectsin the interstellar ionisation cavity.     

Optical Response of the Atmosphere During the Caribbean Total Solar Eclipses of 26 February 1998 and of 3 February 1916 at Falcón state,Venezuela

An investigation of the optical response of the atmosphere before, during, and afterthe total solar eclipse of 26 February 1998 at the Caribbean Peninsula of Paraguaná (Falcón State) in Venezuela, was made by measuring photometrically the intensity of the sky brightness in three strategic directions: zenith, horizon anti-parallel or opposite the umbra path, and horizon perpendicular to this path. From these measurements, and by applying in an inverse way an empirical photometric model, very rough estimations of theextinction coefficient, and also of the average optical depth, were obtained in one of these particular directions. However based on meteorological measurements such as those of relative humidity and temperature, and applying a different model, a better estimation in the visual of the total global extinction coefficient of the sky (except the horizon), were made considering the contribution of each component: atmospheric aerosol, water vapour, ozone and Rayleigh scattering. It is shown that this global coefficient is mostly dependent upon aerosol extinction. In spite of the strong reduction of sky brightness photometrically observed during the totality, the results show that the sky was not dark. This is confirmed by the results obtained for the total global extinction coefficient. Additionally it is estimated that the total solar eclipse that took place also in Falcón State, Venezuela, at the beginning of the last century on 3 February 1916, was 30% darker that the 1998 eclipse, and that atmospheric aerosol played a relevant and similar role in the scattering of sunlight during the totality as it was for 1998's. Visual observations made during each event, which show that at length only one or two bright stars could be seen in the sky, support the results obtained for both eclipses.     

中国古代常规日食记录的整理分析

收集并分析了公元前8世纪到公元15世纪的中国古代密集、简略而公式化的日食记录。基于这些记录整理成一个包括938条日食记录的计算机可读形式的“常规日食记录表”。该表给出每次记录的原日期、公历日期、当时首都、所属朝代以及一部分记录所载的进一步详情。对该表的构成作了介绍,并对这些历史记录进行了初步的分析和归纳。     

虚拟太阳天文台及其发展

伴随着太阳物理研究的深入、观测仪器的发展、观测数据的积累,促使人们去思考这样一个问题:如何使研究者能够方便地检索、分析和使用在不同时间、不同地点、不同波段上观测得到的大量与太阳有关的数据,从而能探索更多悬而未决的科学谜题。这就是虚拟太阳天文台(VSO)项目被提出后得到有关天文台、研究所和大学积极响应并迅速投入运作的原因所在。介绍了虚拟太阳天文台的由来、作用、采用的技术和发展状况等。     

实时相关跟踪图像处理系统

文章介绍了怀柔太阳观测基地最近完成的一套实时高分辨太阳磁场观测系统。系统采用局部相关跟踪算法来提高磁场观测数据的空间分辨率，同时对相关跟踪算法的实现程序进行了优化以满足常规太阳磁场观测的要求。通过对试观测和常规观测数据的分析，我们发现：1）该系统能够大大提高单色像、磁场数据的对比度和空间分辨率；2）对相关跟踪算法的优化大大提高了系统的时间分辨率，系统可以投入常规观测使用。     

Location and parameters of a microwave millisecond spike event

A typical microwave millisecond spike event on November 2, 1997 was observed by the radio spectrograph of National Astronomical Observatories (NAOs) at 2.6–3.8 GHz with high time and frequency resolution. This event was also recorded by Nobeyama Radio Polarimeters (NoRP) at 1–35 GHz and Radio Heliograph (NoRH) at 17 GHz. The source at 17 GHz is located in one foot-point of a small bright coronal loop of YOHKOH SXT and SOHO EIT images with strong photospheric magnetic field in SOHO MDI magnetograph. It is assumed that the electron cyclotron maser instability and gyro-resonance absorption dominate, respectively, the rising and decay phase of the spike event. For different harmonic number of gyro-frequency or magnetic field strength, a fitting program with free plasma parameters is used to minimize the difference between the observational and theoretical values of the exponential growth and decay rates for a given spike. The plasma parameters at third harmonic number are more comparable to their typical values in solar corona. Hence, it is able to provide a diagnosis for the source parameters (magnetic field, density, and temperature), the properties of radiations (wave vector and propagation angle), and the properties of non-thermal electrons (density, pitch angle, and energy). The results are also comparable with the diagnosis of the gyro-synchrotron radiation model, the frequency drift rates and a dipole magnetic field model, as well as the YOHKOH SXT and SOHO MDI data. This study is supported by the NFSC project nos. 10333030 and 10273025, and “973” program with no. G2000078403.