确定太阳横向磁场方位角的综合方法

本分析了现有几种常用的确定太阳磁场横向分量方位角的方法，如势场法，Ｋｒａｌｌ法，吴－艾法和“方位角连续”法，作认为这些方法各有不同的适用范围，其中任何一种方法都不能单独确定太阳横向磁场。在此分析的基础上，提出了确定太阳横向磁场方位角的综合方法。该法的要点是：用势场法和Ｋｒａｌｌ法分别处理同一磁场观测资料，比较这两种方法所得到的横场分布图，找出它们的相同区域和有差别区域，从相同区域出发，利用“无     

解决太阳横向磁场方向测定中180°不确定性的一个方法

本文提出了一种解决太阳横向磁场方向测定中１８０°不确定性的方法。该方法首先将Ｇａｒｙ等提出的方法定量化，客观地确定每一点的横场方向；然后由独立的Ｈ＿α观测或磁场演化历史，分析和确定磁力线的拓扑联接性，对客观确定的横场方向做经验修正。对活动区的应用表明，该方法是一个可供选择的解决横场方向不确定性的有效方法。     

解决太阳横向磁场方向测定中180°不确定性的一个方法

本提出了一种解决太阳横向磁场方向测定中１８０°不确定性的方法。该方法首先将Ｇａｒｙ等提出的方法定量化，客观地确定每一点的横场方向；然后由独立的Ｈα观测或磁场演化历史，分析和确定磁力线的扑联接性，对客观确定的横场方向做经验修正，对活动区的应用表明，该方法是一个可供选择的解决横场方向不确定性的有效方法。     

太阳黑子磁场方位角随深度的变化

为了建立三维的太阳黑子磁场模型，必须确定横向磁场的方位角（x)及其随深度的可能变化。本文提出一种探测x随深度变化的方法，即对黑子的一定点依次用磁敏谱线的不同部分测量代表线偏振的两个斯托克斯参数Q和U，然后按由牧田提出并经我们改进的方法，给出磁场方位角图。如果x随深度呈现出扭曲结构，则方位角图上的曲线含有圆圈形，否则可是类似抛物线的较为简单的曲线。在测量仪器的灵敏度足够的情况下，本方法对黑子外面的日面弱磁场区域也可以使用。     

太阳黑子矢量磁场的综合测定法

本文利用太阳活动区强磁场的扫描照像资料计算出总磁场和纵向磁场强度,再推出横场强度值,结合黑子半影的形态定出横场的方向,从而推算黑子区域的矢量磁场。这种综合测定法的优点是只需要简单的观测设备,使用计算机归算资料,就能很容易地得到矢量磁图。这种方法的缺点是所得的矢量磁场仅限于黑子区域。但是由于多数的太阳耀斑的触发点都发生在结构复杂的黑子区域内,因此用本方法得到的矢量磁图仍然是很有意义的。作为一个例子,我们对Hale No.17906(YN No.81547)黑子群的矢量磁场进行了详细的计算。     

太阳NOAA6891活动区磁中性线的分析

太阳活动高产区NOAA6891是一个岛型δ黑子，它有5条中性线，表现出不同的性质．其中第3条的横场比较弱，但是由于有剪切，所以有耀斑活动．而第2条中性线的横场较大，剪切得非常厉害，所以在这个区域产生了大量的耀斑，包括2个白光耀斑．正因为如此，所以要对磁场作三维分析，其中用磁场拓扑界面来分析是一种好的途径．     

太原NOAA6891活动区磁中性线的分析

太阳活动高产ＮＯＡＡ６８９１是一个岛型δ黑子，它有５条中性线，表现出不同的性质。其中第３条的横场比较弱，但是由于有剪切，所以有耀斑活动。而第２条中性线的横场较大，剪切得非常厉害。所以在这个区域产生了大量的耀斑，包括２个白光耀斑。所以要对磁场作三维分析，其中用磁场拓扑界硕来分析是一种好的途径。     

磁塌缩不稳定与自生间歇磁流

太阳和天体物理吸积盘中的场是一种空间间歇的磁流。在整个太阳上都可发现这种间歇磁流片，其中光球上90%以上的磁流呈现为强场形态，其强度为0.1-0.2T，大小为50-300km；在吸积盘中，已知脉动磁场比宏观磁场强几个数量级。磁场的重联湮灭，导致在薄电流片区形成小尺度的磁环胞以及同涨的横等离激元。磁流和等离激元之间的非线性相互作用引起自类似塌缩，形成更为空间间歇的塌缩的磁环元胞。而横等离激元诱发的自生磁场具有调制不稳定性，导致磁场塌缩，形成高度间歇的磁流。分别在磁流力学和等离子体动力论两种情况下，分析了这种磁塌缩不稳定性，并用于解释太阳上的间歇磁流以及寻求天体物理吸积盘中的反常粘滞。     

太阳耀斑区磁场和电流研究的一些新进展

在太阳耀斑区磁场和电流研究方面，文中将着重介绍太阳横向磁场方位的确定，太阳活动区磁场的非热性表示、太阳耀斑前后的活动区磁场变化、以及耀斑核块与活动区纵向电流密度极大点位置的关系等几个重要问题的研究现状。     

与耀斑相关的磁场演化

本文利用紫金山天文台太阳光谱仪缝前附属Ｄａｙｓｔａｒ滤光器拍摄的，发生在ＮＯＡＡ５３９５活动区中的三个耀斑的Ｈα单色光资料，对比北京天文台怀柔观测站取得的光球磁场资料，研究耀斑产生位置与光球磁场演化的关系，结果表明：（１）在所研究的５０个耀斑亮核中，有３８个位于新浮磁流区附近，另有少数亮核出现在磁对消区；（２）耀斑亮核多集中在横场方向交叉，剪切角大的复杂磁区，耀斑后多数区域磁场结构简化；（３）耀斑     

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.     

Born–Infeld type phantom model in the ω–ω′ plane

In this paper, we investigate the dynamics of Born–Infeld (B–I) phantom model in the ω–ω′ plane, which is defined by the equation of state parameter for the dark energy and its derivative with respect to N (the logarithm of the scale factor a). We find the scalar field equation of motion in ω–ω′ plane, and show mathematically the property of attractor solutions which correspond to ω _φ ∼−1, Ω _φ =1, which avoid the “Big rip” problem and meets the current observations well.      

A Comparison of Several Image Locating Algorithms in Astronomical Instruments

In astronomical observations at optical wavelengths, a fast image tracking system can be adopted to reduce the effects of the atmospheric seeing and telescopic tracking error, and therefore improve the observing efficiency. Aiming at the need of astronomical observations, totally 5 kinds of algorithms in two categories were selected to make a comparative study on their accuracies and stabilities under different noise conditions by both numerical experiment and laboratory test. The results indicate that the normalized cross-correlation method and barycenter method have not only a higher accuracy but also a better reliability against interferences, they will be applied to the high-resolution spectrograph of the Xinglong 2.16 m telescope and the scienti?c instruments of the SONG (Stellar Observations Network Group) project, respectively.     

Shear and vorticity in a combined Einstein-Cartan-Brans-Dicke inflationary lambda-Universe

A combined BCDE (Brans-Dicke and Einstein-Cartan) theory with lambda-term is developed through Raychaudhuri’s equation, for inflationary scenario. It involves a variable cosmological constant, which decreases with time, jointly with energy density, cosmic pressure, shear, vorticity, and Hubble’s parameter, while the scale factor, total spin and scalar field increase exponentially. The post-inflationary fluid resembles a perfect one, though total spin grows, but the angular speed does not (Astrophys. Space Sci. 312: 275, 2007d).