空间太阳望远镜科学卫星

“空间太阳望远镜”是一颗载有口径为1米的主光学望远镜、极紫外望远镜、Ha与白光望远镜和宽带光谱仪及射电频谱仪的科学卫星。它将在距地面730千米轨道的太阳同步轨道上运行,在摆脱了地球大气层影响后,对太阳进行广泛光谱范围和全连续的高空间分辨率高时间分辨率和高频率分辨率的科学探测,为太阳物理研究和空间天气预报提供重要实测数据。     

云南天文台太阳望远镜光学系统的光学传递函数检验

摘要：给出了太阳光谱望远镜光学系统成像质量的测定方法．以及给出了我们用星光作为目标来测定望远镜光学系统传递函数时必须考虑的条件和理论基础。实测结果给出望远镜空间分辨率的上限为0．6“，95％光能集中度在1．2“以内。     

太阳光谱望远镜的Stokes光谱测量

中国科学院云南天文台"太阳Stokes光谱观测与理论研究”团组自进入国家天文观测中心以来,经过一年多的努力,对50cm太阳光谱望远镜原偏振测量部分进行了彻底改造,由原来的D.C.调制改为A.C.调制,且增加了偏振测量校正系统.其机械,电控设计和加工于2000年2月完成,3月完成了光学调试,4月上旬完成了偏振解调和图像处理的软件编制.自2000年4月下旬以来,对23周峰年出现的部分活动区进行了较为成功的斯托克斯光谱测量,其偏振测量精度可达2×10-3,已接近国际水平,为该团组开展的课题研究打下了良好的基础.以此望远镜与怀柔观测基地太阳磁场望远镜相配合,将使我国太阳矢量磁场和速度场的研究更上一个台阶.给出了偏振测量的具体方法和部分测量结果.尽管取得了以上的成绩,但在近期内将对该偏振测量方式作进一步改进,用双光束分析代替单光束分析,使偏振测量精度提高到5×10-4,从而使之不仅能在活动区而且也能在宁静区得到矢量磁场的信息,不仅如此,还可对太阳第二光谱进行测量,提高我们依托该望远镜进行研究的广度和深度.     

构建实时三维太阳光谱望远镜的建议

提出了一种新型太阳光谱望远镜的建议，这种望远镜能够同时记录太阳日面观测区域的两维空间的色散（三维光谱），即一系列同步狭窄带通的光谱图像。借助该望远镜我们可以得到高时间分辨率的光谱图（10ms），进而能够做细致的光谱分析。该望远镜由一组子望远镜组成，每个子镜负责记录观测区域的一个事先设计好的透过带，所有透过带覆盖了所研究谱线的整个光谱波段，可以用来诊断不透明的低层大气物质流的三维速度场、重构太阳活动区（即太阳耀斑区）的三维结构。此外，若每个子镜都加栽上偏振仪时，则能够得到精确的矢量磁场，这种矢量磁场能够作为第二代视频磁场测量仪。此望远镜由一组紧密排列的子镜组成，文章分别给出了两种不同排列子镜的方式。描述了用来观测的每个子镜的透过带的样品光学表，并且提出了不同探测器的同时成像技术。最后，我们把该望远镜和ATST（Advanced Technology Solar Telescope）进行了比较。     

8m中国巨型太阳望远镜偏振光学设计

望远镜的仪器偏振是影响太阳磁场测量的重要因素,为了获得精确的太阳磁场信息,对大型太阳望远镜光学系统进行偏振优化设计非常必要.针对8 m中国巨型太阳望远镜(Chinese Giant Solar Telescope, CGST)的偏振设计需求,提出了基于四镜偏振补偿结构的望远镜折轴光学系统设计方案.基于偏振光线追迹方法,分析了该方案仪器偏振在望远镜光瞳和视场上的分布特性以及视场分布特性随望远镜运动和波长的变化.结果表明,在HeI 1.083μm和FeI 1.565μm磁敏谱线所在的近红外波段, CGST仪器偏振满足2×10^-4测量精度要求的“无偏振视场”为0.91′,而在可见光波段该“无偏振视场”为0.5′.     

太阳Stokes光谱望远镜的结构及其数据处理方法

云南天文台的太阳Stokes光谱望远镜是一台通过测量磁敏谱线的Stokes参数I,Q,U和V的轮廓来研究太阳磁场精细结构的光谱型矢量磁场测量仪。它利用4个完整的Stokes轮廓所蕴含的丰富信息,完全确定辐射的偏振状态,从而精确地测定太阳黑子区的矢量磁场。文章首先介绍了该望远镜的结构,进而详细地介绍了该望远镜所测量的偏振光谱资料的处理方法。     

云南天文台太阳光谱望远镜偏振分析器检验

介绍了利用云南天文台水平式太阳光谱仪对太阳光谱望远镜偏振分析器进行检验的情况。检验得到的太阳黑子Ｉ、Ｑ、Ｕ、Ｖ四个斯托克斯轮廓与理论轮廓的特征相近,表明该偏振分析器达到了设计要求,用它可以获得太阳黑子的所有斯托克斯参量。     

云南天文台太阳光谱望远镜偏振分析器检验

介绍了利用云南天文台水平式太阳光谱仪对太阳光谱望远镜偏振分析器进行检验的情况。检验得到的太阳黑子Ｉ,Ｑ,Ｕ,Ｖ四个斯托克斯轮廓与理论轮廓的特征相近,表明该偏振分析器达到了设计要求,用它可以获得太阳黑子的所有斯托克斯参量。     

NVST偏振观测系统的运动控制实现

中国科学院云南天文台1 m新真空太阳望远镜(New Vacuum Solar Telescope,NVST)是我国在太阳物理和空间科学对太阳进行光学和近红外观测的主力设备,主要科学目标是高精度、高时空分辨率的太阳磁场测量。1 m新真空太阳望远镜采用机械扫描偏振观测方式,由于光学系统的结构特性导致望远镜在跟踪太阳的过程中不可避免地引入了随时间变化的偏振效应,因此在进行偏振观测时需要进行系统定标,整个系统由定标单元、分析单元和探测器组成,其间涉及的多个运动部件均有复杂精密的运动要求。针对偏振定标过程和偏振观测过程中各光学器件的运动需求,给出了定标单元和分析单元的控制要求,实现了不同观测模式下各部件的运动要求。基于TCP/IP协议的远程控制方案,集成了采用串口通讯的各商用驱动控制器,开发了一套在.NET架构下的定标单元控制软件和相应的用户界面,并预留了观测控制系统接口。性能测试表明,系统符合观测要求,现已投入使用,为后续的偏振观测奠定了基础。     

太阳物理光学仪器的新进展

对过去三年来（１９９０．９－１９９３．８），太阳物理光学仪器的进展作了简要的综述。它主要包括高空间分辨率设备，磁像仪和偏振器，两维光谱仪，大型望远镜和大型观测网，以及空间系统等五个方面。这些进展表明，太阳物理的观测技术和方法正外在具有历史意义的重大转变之中，即运用并推动现代光学，现代接收与处理系统，以及空间技术的重大发展的历史阶段。     

Instructions for authors

正Research in Astronomy and Astrophysics publishes original research papers and reviews 011 all liranchcs of astronoiriy and astrophysics.Reviews arc by invitation only.Important new results that require rapid publication can be submitted as a Letter(Letters must be restricted in length     

A thermodynamic model of high temperature lava vaporization on Io

We modified the MAGMA chemical equilibrium code developed by Fegley and Cameron (1987, Earth Planet. Sci. Lett. 82, 207-222) and used it to model vaporization of high temperature silicate lavas on Io. The MAGMA code computes chemical equilibria in a melt, between melt and its equilibrium vapor, and in the gas phase. The good agreement of MAGMA code results with experimental data and with other computer codes is demonstrated. The temperature-dependent pressure and composition of vapor in equilibrium with lava is calculated from 1700 to 2400 K for 109 different silicate lavas in the ONaKFeSiMgCaAlTi system. Results for five lavas (tholeiitic basalt, alkali basalt, Barberton komatiite, dunite, and a molten type B1 Ca, Al-rich inclusion) are discussed in detail. The effects of continuous fractional vaporization on chemistry of these lavas and their equilibrium vapor are presented. The predicted abundances (relative to Na) of K, Fe, Si, Al, Ca, and Ti in the vapor equilibrated with lavas at 1900 K are lower than published upper limits for Io's atmosphere (which do not include Mg). We predict evaporative loss of alkalis, Fe, and Si during volcanic eruptions. Sodium is more volatile than K, and the Na/K ratio in the gas is decreased by fractional vaporization. This process can match Io's atmospheric Na/K ratio of 10±3 reported by Brown (2001, Icarus 151, 190-195). Silicon monoxide is an abundant species in the vapor above lavas. Spectroscopic searches are recommended for SiO at IR and mm wavelengths. Reactions of metallic vapors with S- and Cl-bearing volcanic gases may form other unusual gases including MgCl₂, MgS, MgCl, FeCl₂, FeS, FeCl, and SiS.     

Instructions for authors

正Research in Astronomy and Astrophysics publishes original research papers and reviews on all branches of astronomy and astrophysics.Reviews are by invitation only.Important new results that require rapid publication can be submitted as a Letter(Letters must be restricted in length to 6 printed pages).Authors who submit a paper are expected to be able to certify that the paper is original work,     

Research in Astronomy and Astrophysics CONTENTS

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Alkali and halogen chemistry in volcanic gases on Io

We use chemical equilibrium calculations to model the speciation of alkalis and halogens in volcanic gases emitted on Io. The calculations cover wide temperature (500-2000 K) and pressure (10⁻⁶ to 10⁺¹ bars) ranges, which overlap the nominal conditions at Pele (T=1760 K, P=0.01 bars). About 230 compounds of 11 elements (O, S, Li, Na, K, Rb, Cs, F, Cl, Br, I) are considered. The elemental abundances for O, S, Na, K, and Cl are based upon observations. CI chondritic elemental abundances relative to sulfur are used for the other alkalis and halogens (as yet unobserved on Io). We predict the major alkali species in Pele-like volcanic gases and the percentage distribution of each alkali are LiCl (73%), LiF (27%); NaCl (81%), Na (16%), NaF (3%); KCl (91%), K (5%), KF (4%); RbCl (93%), Rb (4%), RbF (3%); CsCl (92%), CsF (6%), Cs (2%). Likewise the major halogen species and the percentage distribution of each halogen are NaF (88%), KF (10%), LiF (2%); NaCl (89%), KCl (11%); NaBr (89%), KBr (10%), Br (1%); NaI (61%), I (30%), KI (9%). We predict the major halogen condensates and their condensation temperatures at P=0.01 bar are NaF (1115 K), LiF (970 K); NaCl (1050 K), KCl (950 K); KBr (750 K), RbBr (730 K), CsBr (645 K); and solid I₂ (200 K). We also model disequilibrium chemistry of the alkalis and halogens in the volcanic plume. Based on this work and our prior modeling for Na, K, and Cl in a volcanic plume, we predict the major loss processes for the alkali halide gases are photolysis and/or condensation onto grains. Their estimated photochemical lifetimes range from a few minutes for alkali iodides to a few hours for alkali fluorides. Condensation is apparently the only loss process for elemental iodine. On the basis of elemental abundances and photochemical lifetimes, we recommend searching for gaseous KCl, NaF, LiF, LiCl, RbF, RbCl, CsF, and CsCl around volcanic vents during eruptions. Based on abundance considerations and observations of brown dwarfs we also recommend a search of Io's extended atmosphere and the Io plasma torus for neutral and ionized Li, Cs, Rb, and F.     

Study on the Stressed Mirror Polishing with a Continuous Polishing Machine for Large Aperture Off-axis Aspheric Mirrors

A special stressed annular polishing technique is proposed to mill the off-axis aspheric sub-mirrors of a large segmented mirror with an annular polishing machine. Based on the basic principle of stressed annular polishing technique, a set of special stressing mechanisms are designed to convert milling the aspheric surfaces of sub-mirrors with different off-axis distances into milling the spherical surfaces with identical radii of curvature, so that they can be pol- ished simultaneously on a continuous polishing machine. It took about contin- uous 40 hours to polish a scaled-down mirror of the planning Chinese Future Giant Telescope (CFGT) using this technique. This mirror has the 330 mm di- ameter, 3.6 m off-axis distance, and the 21.6 m radius of curvature, and its max- imum asphericity is 16 micron. The experiment shows that this method has a high effciency, suits batch manufacturing, especially the batch manufacturing of aspheric sub-mirrors of the segmented primary mirror of an extremely large aperture telescope.     

The climatic and physiographic controls of the eastern Mediterranean over the late Pleistocene climates in the southern Levant and its neighboring deserts

Modern-day synoptic-scale eastern Mediterranean climatology provides a useful context to synthesize the diverse late Pleistocene (60–12 ka) paleohydrologic and paleoenvironmental indicators of past climatic conditions in the Levant and the deserts to its south and east. We first critically evaluate, extract, and summarize paleoenvironmental and paleohydrologic records. Then, we propose a framework of eastern Mediterranean atmospheric circulation features interacting with the morphology and location of the southeast Mediterranean coast. Together they strongly control the spatial distribution of rainfall and wind pattern. This cyclone–physiography interaction enforces the observed rainfall patterns by hampering rainfall generation south and southeast of the latitude of the north Sinai coast, currently at 31°15′.The proposed framework explains the much-increased rains in Lebanon and northern Israel and Jordan as deduced from pollen, rise and maintenance of Lake Lisan, and speleothem formation in areas currently arid and semiarid. The proposed framework also accounts for the southward and eastward transition into semiarid, arid, and hyperarid deserts as expressed in thick loess accumulation at the deserts' margins, dune migration from west to east in the Sinai and the western Negev, and the formation of hyperarid (< 80 mm yr^− 1) gypsic–salic soils in the southern Negev and Sinai. Our climatic synthesis explains the hyperarid condition in the southern Negev, located only 200–250 km south of the much-increased rains in the north, probably reflecting a steeper rainfall gradient than the present-day gradient from the wetter Levant into its bordering southern and eastern deserts.At present, the rainiest winter seasons in Lebanon and northern and central Israel are associated with more frequent (+ 20%), deeper Cyprus Lows traversing the eastern Mediterranean at approximately the latitude of southern Turkey. Even these wettest years in northern Israel do not yield above average annual rainfall amounts in the hyperarid southern Negev. This region is mainly influenced by the Active Red Sea Troughs that produce only localized rains. The eastern Mediterranean Cyprus Lows also produce more dust storms and transport higher amounts of suspended dust to the loess area than any other atmospheric pattern. Concurrent rainfall and dust are essential to the late Pleistocene formation of the elongated thick loess zone along the desert northern margin. Even with existing dust storms, the lack of rain and very sparse vegetation account for the absence of late Pleistocene loess sequences from the southern Negev and the formation of hyperarid soils.When the north Sinai coast shifted 30–70 km northwest due to last glacial global sea level lowering, the newly exposed coastal areas supplied the sand and dust to these active eastern Mediterranean cyclones. This enforced the latitude of the northern boundary of the loess zone to be directly due east of the LGM shoreline. This shift of coast to the northwest inhibited rainfall in the southern Levant deserts and maintained their hyperaridity. Concurrently, frequent deep eastern Mediterranean Cyprus Lows were funneled along the northern Mediterranean increasing (probably doubling) the rains in central and northern Israel, Lebanon, southwestern Syria and northern Jordan. These storms and rains formed lakes, forests, and speleothems only a short distance north of the deserts in the southern Levant.     

Active hot star shells

Interferometry in the visible provides milliarcsecond spatial resolution and thus has been used for studying the circumstellar environment of active hot stars. In this paper I will illustrate how the visibility modulus and phase can be used to better constrain the physics of Be disks through results from the VLA, the MkII and the GI2T interferometers. I will insist on the importance and the potential of coupling high angular resolution with high spectral resolution to the study of Be shells. Finally I will present a possible study of the circumstellar disk of Be stars using the VLTI. This revised version was published online in July 2006 with corrections to the Cover Date.