欧空局"火星登陆器"和"火星电离层和测地实验"计划

该文全面介绍了欧洲空间局的“火星登陆器(NetLander)”及其“火星电离层和测地实验(NEIGE)”项目。具体叙述了项目的科学目标与内容、实现途径、组织机构、工程技术方面的框架,以及目前最新的进展状况。希望借此能为我国开展相关工作提供参考与借鉴．     

"十五"期间天体测量优先发展领域

阐明了现代天体测量学科的发展趋势和前沿课题。回顾了在国家自然科学基金委员会的支持下“八五”、“九五”期间我国天体测量学的发展和取得的成果,并对国家自然科学基金委员会在“十五”期间继续支持我国天体测量优先发展领域和前沿课题提出了若干建议。     

太阳中微子"亏缺"与非标准太阳模型

系统阐述了太阳中微子“亏缺”问题出现的背景,包括介绍标准太阳模型,太阳内部的相聚变反应,太阳中微子能谱和流量的理论估算,以及太阳中微子探测实验和结果。讨论了为解释太阳中微子“亏缺”而提出的各种非标准太阳模型以及近年来愈益受到重视的中微子振动问题。     

利用VLBI数据确定"探测一号"卫星的轨道

双星计划的“探测一号”是中国首颗真正严格意义上的科学实验卫星,其运行轨道为中国迄今所发射的卫星中距地球最远,远地点地心距达7．8万公里．采用射电天文的VLBI技术可以对“探测一号”以及更远的深空目标,如探月飞行器实现跟踪．为了验证VLBI技术在我国探月计划中的作用,上海天文台组织了国内目前仅有的上海、乌鲁木齐和昆明3个台站对“探测一号”进行试跟踪,利用对“探测一号”约两天的VLBI观测数据,确定“探测一号”卫星的轨道,对VLBI的定轨能力做初步的探讨．按照测控部门提供的初轨 (其精度仅保证跟踪)推算的轨道与VLBI时延的拟合误差平均约2 km,时延率的拟合误差平均约15 cm／s．而利用VLBI数据定轨后的拟合程度相对于初轨有了很大的改善,结果表明,单独利用VLBI时延定轨,时延的拟合精度约5．5 m,作为外部检核的VLBI时延率的拟合精度在2 cm／s左右．单独利用VLBI时延率定轨,时延率的拟合精度约为1．3 cm／s,作为外部检核的VLBI时延的拟合精度约为29 m．而若将时延和时延率数据联合定轨,采用其内符精度加权,VLBI时延和时延率的残差分别为5．5 m和 2 cm／s．为了合理地评估VLBI定轨的真实精度,利用模拟数据进行误差协方差分析,结果表明VLBI定轨精度受动力学模型误差的影响较大,由于"探测一号”卫星的动力学模型难以精确确定,所以利用两天弧段的VLBI数据确定“探测一号”卫星轨道的位置误差为km量级,而速度误差可达cm／s量级．模拟计算还表明, VLBI和USB数据联合定轨可以大大提高定轨精度．     

早型星系中"黑洞/核球"质量线性关系的解析估计

在“等级式成团”（hierarchical clustering)宇宙学演化框架下,早型星系（E／SO）的形成和演化不是如经典的“整体塌缩”（monolithic collapse)演化模式所描述的是由高红移处的短时间剧烈恒星形成过程一次性完成的;相反,它们可能是在大尺度结构形成过程中由盘星系间的相互合并演化而来,特别是对于质量相当的盘星系间的剧烈合并过程。目前的数值模拟和高分辨成像观测都已证实了这种可能性,而且红移巡天的结果也更多地支持这种演化模式。在此提出一个星系合并过程中核区星暴和中心黑洞共生演化的模型,来解释由空间望远镜（HST）和地面CCD高分辨测光所得的早型星系“黑洞／核球”统计线性相关,也即中心黑洞质量约为其核球体质量的0．6％;同时,该演化模型还可以进一步合理地解释在类星体的近红外成像观测中统计得出的相似的线性相关性,即类星体中心亮度与其母星系质量成正比。并给出此模型计算的极限情况和模型的解析估计。     

对"文[1,2]"评论的答复

对“关于太阳线性无力场评注和快速傅氏分析法的应用的评论”一文,提出一些看法和补充,以增进对无力场计算太阳磁场问题的进一步的认识．     

古诗中的天地观念（一）：天地神话

在中国古代,“天”、“地”不仅是天文学中的基本概念,也是社会文化乃至日常生活中的重要概念。在现代教育氛围中长大的我们,常会觉得“天”、“地”很抽象,远不如“地球”、“太阳系”、“银河系”概念更直观亲切。但古人不这么看,我们的先民在未知宇宙深层奥秘的时候,只能“跟着感觉走”,先民创造“天”、“地”二词时,是把它们当作两个实体看待的,而且认为其形状就是他们看到的样子。     

关于"太阳线性无力场评注和快速傅氏分析法的应用"的评论

“太阳线性无力场评注和快速傅氏分析法的应用”一文对太阳线性无力场的工作做了一些评注,在此基础上对快速傅立叶方法的应用提出了改进的计算方法．该文的某些观点值得商榷,有必要对其中存在的问题予以澄清．另外,对该文关于快速傅氏分析法的工作从理论的角度提出看法．     

诗词歌赋中的星座世界（五）——北极星和紫微垣

这一讲,我们从北斗七星移到中国星空的最核心区域——北极星及其所在的紫微垣。 “紫微垣”是天上的三个“城堡”之一,这三个城堡统称“三垣”,“垣”即墙,每一垣有两道用星星联成的墙围出了一块近圆形的天区,这“三垣”都在北天球,以北极为中心的叫“紫微垣”,另外两个是“太微垣”和“天市垣”。     

吟词说天

二．题解与句注： ①太岁明星回头行正路：太岁明星。与木星相应的假想天体,在此句中指木星,目前运行在人马座,亮度约-2．4等。回头行正路,是指木星在9月由“逆行”到8日11时变为“留”,留后由“逆行”改为“顺行”。此句是说木星经过前一阶段的“逆行”,改为“顺行”即行正路了。     

90年代太阳模型和太阳震荡研究进展(I):太阳模型研究进展(英)

太阳模型的研究是了解太阳整体结构和性质的极为重要的手段。90年代以来太阳模型研究取得了进展。随着MHD及OPAL物态方程的引入,理论上的太阳振荡频率与观测值的差别已大为减小,而考虑湍流频谱分布的局域对流理论和三维流体动力学模拟结果可对太阳内部对流能量传输过程有更深刻的理解．以前所发现的理论模型与反演结果得到的初始氦丰度的差别已能由扩散过程加以解释,而太阳表面锂丰度亏损问题也可以由扩散过程或早期演化星风来加以解决,太阳中微子问题则似应由粒子物理而不是天体物理来解决。     

Night‐time science with large solar telescopes: The magnetic Sun through time

Today the Sun has a regular magnetic cycle driven by a dynamo action. But how did this regular cycle develop? How do basic parameters such as rotation rate, age, and differential rotation affect the generation of magnetic fields? Zeeman Doppler imaging (ZDI) is a technique that uses high‐resolution observations in circularly polarised light to map the surface magnetic topology on stars. Utilising the spectropolarimetric capabilities of future large solar telescopes it will be possible to study the evolution and morphology of the magnetic fields on a range of Sun‐like stars from solar twins through to rapidly‐rotating active young Suns and thus study the solar magnetic dynamo through time. In this article I discuss recent results from ZDI of Sun‐like stars and how we can use night‐time observations from future solar telescopes to solve unanswered questions about the origin and evolution of the Sun's magnetic dynamo (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

ChemiX: a Bragg crystal spectrometer for the <Emphasis Type="Italic">Interhelioprobe</Emphasis> interplanetary mission

Interhelioprobe (IHP), an analogue to the ESA Solar Orbiter, is the prospective Russian space solar observatory intended for in-situ and remote sensing investigations of the Sun and the inner heliosphere from a heliocentric orbit with the perihelion of about 60 solar radii. One of several instruments on board will be the Bragg crystal spectrometer ChemiX which will measure X-ray spectra from solar corona structures. Analysis of the spectra will allow the determination of the elemental composition of plasma in hot coronal sources like flares and active regions. ChemiX is under development at the Wroc?aw Solar Physics Division of the Polish Academy of Sciences Space Research Centre in collaboration with an international team (see the co-author list). This paper gives an overview of the ChemiX scientific goals and design preparatory to phase B of the instrument development.     

Hα coronagraph observations of a flare spray,March 1, 1969

An H solar prominence with the characteristics of a spray was ejected in association with a bright limb flare. Knots of material were observed to a distance of more than one solar radius above the west limb of the Sun. The optical event was followed by 80 MHz emission from a type IV source which was observed moving out through several solar radii.Coronagraph observations have been used to determine the trajectories and velocities of the knots in directions perpendicular to the line of sight. After some early deceleration velocities increase to 300–500 km/sec and slowly decline with variations depending on the initial direction of outflow. We suggest that the magnetic field over the spot group is deformed by the energy of the mass motions of material fragments, some of which then continue to move outward from the Sun.     

Laboratory simulation of cometary erosion by space plasma

A laboratory experiment has been made where a plasma stream collides with targets made of different materials of cosmic interest. The experiment can be viewed as a process simulation of the solar wind particle interaction with solid surfaces in space — e.g., cometary dust. Special interest is given to sputtering of OH and Na.It is also shown that the erosion of solid particles in interplanetary space at large heliocentric distances is most likely dominated by sputtering and by sublimation near the Sun. The heliocentric distance of the limit between the two regions is determined mainly by the material properties of the eroded surface, e.g., heat of sublimation and sputtering yield, a typical distance being 0.5 AU.It is concluded that the observations of Na in comets at large solar distances, in some cases also near the Sun, is most likely to be explained by solar wind sputtering. OH emission in space could be of importance also from dry, water-free, matter by means of molecule sputtering. The observed OH production rates in comets are however too large to be explained in this way and are certainly the results of sublimation and dissociation of H₂O from an icy nucleus.     

太阳辐照的观测研究进展

太阳总辐照是指在地球大气层顶接收到的太阳总辐射照度,也叫"太阳常数",但它实际上并非常数。太阳总辐照随波长的分布即为太阳分光辐照。太阳辐照变化的研究,对理解太阳表面及内部活动的物理过程、机制,研究地球大气、日地关系,解决人类面临的全球气候变暖的挑战等,都具有重要意义。首先简单介绍了太阳辐照,回顾了太阳辐照的空间观测;接着介绍了观测数据的并合,以及对合成数据的一些研究;然后讨论了太阳辐照变化的原因,简述了太阳总辐照的重构及其在气候研究上的一些应用,并进行必要的评论;最后对未来的研究方向提出了一些看法。     

Mass loss rate of the zodiacal dust cloud

The mass loss rate of the zodiacal dust cloud near the Sun has been estimated on the basis of the orbital behaviour of circumsolar dust grains suffering sublimation. It is found that the solar dust ring located at 4 solar radii from the Sun, which consists of grains whose inward spiraling due to the Poynting-Robertson effect is stopped by the influence of sublimation, loses its mass at a rate of 3.50.35 tons per second.     

Le nouvel astrolabe de l'Observatoire de Paris

The new polyvalent astrolabe of the Paris Observatory is described. After some optical modifications this new instrument is able to observ the stars, some planets and the Sun with, a internal error less than 04 in the last case. Some new modifications are in progress to obtain better results and stability in the solar observations. This instrument will be able to give a valuable contribution in the solar system studies and in the comparisons of some celestial reference systems particularly during the Hipparcos satellite mission.     

Inverting helioseismic data

Methods by which the observed frequencies of solar oscillations can be, and in some cases have been used to infer the internal structure of the Sun are discussed. Attention is confined to so-called inverse methods that identify and extract the information that is actually contained in the data. Because only a finite quantity of data can ever be acquired, the functions describing the interior stratification of the Sun can never be established completely without the acceptance of certain assumptions. Nevertheless, the assumptions that are required are simple to understand, and the results do not depend on the complicated and uncertain theory of stellar evolution which has traditionally been used to construct solar models. First results of the inversions have given us an estimate of the sound speed and the angular velocity throughout much of the solar interior. These estimates have already stimulated speculation which hopefully will encourage further theoretical and observational research that will improve our understanding of the Sun.     

Solar Rotation And Cycle Length

A positive correlation is suggested between solar rotation rate and solar cycle length for cycles 12 to 20. This result seems to be opposite to recent observations in solar-type stars and the Sun and yields inverse correlations between cycle lengths and chromospheric activity, but it agrees with previous work with solar-type stars and the Sun suggesting a positive correlation between cycle length and rotation rate. Estimates of solar cycle length for the Maunder minimum suggest a length 17 yr.