日本的十年尺度波动分析和核幔电磁耦合

分析了１８００－１９９５年的日长年均值（△ＬＯＤＹ）观测资料表明：日长（△ＬＯＤＹ）的十年波动明显大于观测噪声水平。用小波变换方法分析了△ＬＯＤＹ观测资料,表明△ＬＯＤＹ的十年尺度的周期为６０ａ（年）和３０ａ（年）,所对应的振幅 １ｍｓ和０．５ｍｓ左右。文中采用国际地球自转服务中心提供的（ＥＯＰＣ０４９７）的日长（△ＬＯＤＣ０４９７）序列以及美国国家环境预测中心和美国国家大气研究中心（ＮＣＥＰ／Ｎ     

地球自转日长变化(LOD)和大气角动量(AAM)所对应的动力系统

利用一个多分维的分形地应的一维映射可以用子波变换反演出来,对地自转日长（ＬＯＤ）资料和大气角动量（ＡＡＭ）资料进行子波变换说明,在２０年尺度上、周年尺度和２－３２年尺度上,ＬＯＤ和ＡＡＭ的突变时间基本一致,所反演出的不同层次上分岔时间的分段映射动力系统也极其相似。     

大气对地球自转参数（ERP）的高频激发

本文采用１９８３—１９９２年期间由空间大地测量技术观测和归算的地球自转参数（ＥＲＰ）序列，以及由全球气象资料归算的大气角动量（ＡＡＭ）序列，分析和研究了大气对地球自转参数的日长变化（ＬＯＤ）和极移（ｘ和ｙ）在一个月时间尺度以内的高频激发作用，得到的主要结果如下：１大气对ＬＯＤ分量高频潮汐的估计值存在着影响，但是，潮汐形变参数ｋ／ｃ随时间和频率的变化却是受非大气因素的扰动引起的．２．大气可以解释３０天以下ＬＯＤ非潮汐的大部分变化．３．极移分量３０天以内的高频变化也主要由大气激发．ｘ分量与大气的相关性要强于ｙ分量，而且更为稳定，主要表现为平均时间尺度约为２７天的波动，大气对这个波动的贡献可达７０％．     

日长年际变化的主要激发源

将年际时间尺度上的△ＬＯＤ序列（１９５８．０－１９９８．０）与大气角动量变化（纬向风）风的激发和ＳＯＩ等作比较,表明大气动力学过程是年际时间尺度△ＬＯＤ变化的重要激发源,在实测△ＬＯＤ、纬向风激发和ＳＯＩ中存在的一些相近的频率分量,但是,在实测△ＬＯＤ中有若干很强的信号（如平均周期约６．３年,平均振幅约０．１３ｍｓ的主要分量,以及平均周期约９．０年,平均振幅约０．０７ｍｓ的分量）在纬向风激发和ＳＯ     

激变变星及相关天体的Hα与近红外电离钙三重线的光谱分析

给出了１９９７年４月１５日至１７日在北京天台用２．１６ｍ望远镜卡焦光谱仪观测获得的６颗激变变星（ＡＢ Ｂｏｏ,ＵＸ ＵＭａ,Ｔ ＣｒＢ,ＡＨ Ｈｅｒ,Ｚ Ｃａｍ和Ｖ４２６ Ｏｐｈ）及３颗相关天体（ＵＭａ３,ＥＧ ＵＭａ和Ｌｅｏ３）的ＣＣＤ光谱,并同时拍摄了５颗晚型星（３Ｄｒａ,ｖ Ｖｉｒ,ψＬｅｏ,３４Ｂｏｏ和３６Ｃｏｍ）的ＣＣＤ光谱,作为晚型星参考谱,测量了观测样本星的Ｈα和近红外ＣａⅡ的三重     

Starlette卫星精密定轨中大气模型效度的比较

为满足大气模型比较的需要，把ＣＩＲＡ－１９８６大气模式（简称ＣＩＲＡ８６）引入大气阻力选择模块，对上海天文台人造卫星精密定轨软件ＳＨＯＲＤＥ进行大气模式的扩充。利用多种大气模式分别对Ｓｔａｒｌｅｔｔｅ卫星的观测资料进行解算，结果表明：ＳＨＯＲＤＥ中指数大气模式更适合对Ｓｔａｒｌｅｔｔｅ卫星进行精密定轨研究。     

Starlete卫星精密定轨中大气模型效度的比较

为满足大气模型比较的需要，把ＣＩＲＡ－１９８６大气模式（简称ＣＩＲＡ８６）引入大气阻力选择模块，对上海天文台人造卫星精密定轨软件ＳＨＯＲＤＥ［１］进行大气模式的扩充。利用多种大气模式分别对Ｓｔａｒｌｅｔｅ卫星的观测资料进行解算，结果表明：ＳＨＯＲＤＥ中指数大气模式更适合对Ｓｔａｒｌｅｔｅ卫星进行精密定轨研究     

大气角动量资料源的变化对研究日长变化激发的贡献

本文采用1979—1995年间由空间大地测量技术观测和归算的日长变化（△LOD）序列,以及由美国国家气象中心（NMC）和美国国家环境预测中心与美国国家大气研究中心（NCEP／NCAR）利用全球气象资料各自归算的大气角动量（AAM）序列,重新分析、研究和估计了大气对△LOD的激发作用,比较了上述各个大气角动量序列对△LOD激发贡献,得到的主要结果如下：1．NCEP／NCAR用同化后的全球气象资料重新归算的AAM序列比原来NMC的序列具有系统均匀化、噪声小和分辨率高的特点,以及和日长变化的符合度更好．2．采用NCEP／NCAR重新归算的AAM来研究大气在从亚季节性到年际时间尺度上对非潮汐△LOD的激发贡献,得到进一步改善的结果,尤其是在准两年时间尺度上．但是大气仍不能解释全部△LOD化,可能存在其它激发源．3．大气对△LOD高频潮汐项的估计值影响较小,并从△LOD中解算出周年和半年潮汐参数估计的初步结果．     

LAMOST工程中天体测量要求的探讨

作者认为,有五种误差会影响ＬＡＭＯＳＴ工程光纤定位：（１）光纤的机械定位误差;（２）输入星表与导星星表的误差;（３）焦面坐标系与理想坐标系的转换误差;（４）较差大气折射对观测目标的影响;（５）导星的跟踪误差。并提出在ＬＡＭＯＳＴ工程中有关天体测量的三个研究课题：（１）星表系统差的研究,以提供适合ＬＡＭＯＳＴ使用的导星星表和输入星表;（２）望远镜光学系统畸变的研究以及焦面坐标与理想坐标间关系的确定,提出用国内外观测资料,建立５°×５°的几个标准天区;（３）从现有的光学图象和测光资料中给出ＬＡＭＯＳＴ输入星表中星象的类别,如双星、聚星、变星、星系等。建议ＬＡＭＯＳＴ工程中采用ＧＳＣ－Ⅱ作为导星星表,而输入星表的精度应好于０．５４”。     

大气对地球自转季节性变化的贡献

采用１９７９－１９９５年期间新的大气角动量资料,研究了大气在季节性时间尺度上对日长变化和极移的贡献。结果表明,考虑了风和大气压的贡献后,大气在周年和半年时间尺度上对日长变化的贡献分别可达９５％和８８％。同时还给出了大气对极移激发的定量结果,其中,大气的周年尺度上对极移Ｘ分同的贡献为１６％,对Ｙ分量的贡献为４３％;在半年尺度上海洋的贡献,才能进上步解决地球自转激发的问题。     

A survey of orbits of co-orbitals of Mars

Many asteroids with a semimajor axis close to that of Mars have been discovered in the last several years. Potentially some of these could be in 1:1 resonance with Mars, much as are the classic Trojan asteroids with Jupiter, and its lesser-known horseshoe companions with Earth. In the 1990s, two Trojan companions of Mars, 5261 Eureka and 1998 VF₃₁, were discovered, librating about the L₅ Lagrange point, 60° behind Mars in its orbit. Although several other potential Mars Trojans have been identified, our orbital calculations show only one other known asteroid, 1999 UJ₇, to be a Trojan, associated with the L₄ Lagrange point, 60° ahead of Mars in its orbit. We further find that asteroid 36017 (1999 ND₄₃) is a horseshoe librator, alternating with periods of Trojan motion. This asteroid makes repeated close approaches to Earth and has a chaotic orbit whose behavior can be confidently predicted for less than 3000 years. We identify two objects, 2001 HW₁₅ and 2000 TG₂, within the resonant region capable of undergoing what we designate “circulation transition”, in which objects can pass between circulation outside the orbit of Mars and circulation inside it, or vice versa. The eccentricity of the orbit of Mars appears to play an important role in circulation transition and in horseshoe motion. Based on the orbits and on spectroscopic data, the Trojan asteroids of Mars may be primordial bodies, while some co-orbital bodies may be in a temporary state of motion.     

Equation of state and anisotropy of pressure of magnetars

Magnetars are the neutron stars with the highest magnetic fields up to 10¹⁵–10¹⁶ G. It has been proposed that they are also responsible for a variety of extra-galactic phenomena, ranging from giant flares in nearby galaxies to fast radio bursts. Utilizing a relativistic mean field model and a variable magnetic field configuration, we investigate the effects of strong magnetic fields on the equation of state and anisotropy of pressure of magnetars. It is found that the mass and radius of low-mass magnetars are weakly enhanced under the action of the strong magnetic field, and the anisotropy of pressure can be ignored. Unlike other previous investigations, the magnetic field is unable to violate the mass limit of the neutron stars.     

Estimation of the Time Scale of Merging of the Components of Contact Binaries of the W UMa Type

Time scales of the transition from contact binary systems of the W UMa type to single stars of the blue straggler type are estimated. A model of one-way mass transfer from the primary component to the companion inside a common envelope (Eggen et al.) and a model of a contact binary lying on the zero-age main sequence with a companion that is losing mass (F. van't Veer) are used to calculate these scales. The merging times of components were calculated for 304 contact systems of the W UMa type from the Catalog of Approximate Photometric and Absolute Elements of Eclipsing Variable Stars on a scale of loss of mass and orbital angular momentum due to magnetic braking, under the assumption of synchronization of the axial rotation and orbital revolution. On the basis of the resulting statistics, the characteristic merging scales are 0.4-0.6 and 0.5-0.7 Gyr, respectively, for the above two models. The results of a comparison with the work of other authors are discussed.     

淮河洪水的可公度性分析

分析了上两个世纪发生在淮河的洪水事件的可公度性，根据其可公度值及其黄金分割点指出1991年与2003年淮河洪水的不可避免，最后讨论了可公度性的局限及淮河洪水可公度值的可能机制。     

Modeling of lightcurves of binary asteroids

We present a numerical method for inverting long-period components of lightcurves of asynchronous binary asteroids. Data of five near-Earth binary asteroids, (175706) 1996 FG₃, (65803) Didymos, (66391) 1999 KW₄, (185851) 2000 DP₁₀₇ and (66063) 1998 RO₁, for two of them from more than one apparition, were inverted. Their mutual orbits' poles and Keplerian elements, size ratios, and ellipsoidal shape axial ratios were estimated via this inversion. The pole solutions and size ratios for 1999 KW₄ and 2000 DP₁₀₇ are in a good agreement with independent estimates from radar measurements. We show that uncertainties of estimates of bulk densities of binary systems can be large, especially when observed on short arcs.     

Influence of Neutron Star Parameters on Evolutions of Different Types of Pulsar

Influences of the mass, moment of inertia, rotation, absence of stability in the atmosphere and some other parameters of neutron stars on the evolution of pulsars are examined. It is shown that the locations and evolutions of soft gamma repeaters, anomalous X-ray pulsars and other types of pulsar on the period versus period derivative diagram can be explained adopting values of B < 10¹⁴ G for these objects if they have smaller mass (e.g. about 0.5 Solar mass) compared to the conventionally adopted values of mass. This approach gives the possibility to explain many properties of different types of pulsar.     

Investigation of Times of Minima of Selected Early-Type Eclipsing Binaries

New precise times of minimum light for several early-type eclipsing binaries were obtained at three observatories. The changes of period of the following measured binaries are discussed: V1182 Aql, LY Aur, SZ Cam, FZ CMa, QZ Car, LZ Cen, V606 Cen, AH Cep and TU~Mus.     

Flattening of galaxies of different morphological types in subclusters of Coma

This paper deals with the observed variation in the flattening of galaxies with the density of galaxies in the subclusters of Coma surrounding NGC 4889, NGC 4874, and NGC 4839 based on data from the Abastumani Combined Catalog of Galaxies. The mean values of the observed ratios of the diameters of the galaxies, as well as histograms of their distributions, indicate that in the central, dense regions of the subclusters within a volume of 0.5h ₇₅ ⁻¹ Mpc³, E and S0 type galaxies are close to spheroidal. A significant reduction in the mean values of the diameters of the galaxies in the subclusters is noted, regardless of their morphology relative to the galaxies in the halo of the Coma cluster. In the subclusters, spiral galaxies are found with a hydrogen deficit that is more than 5 times the hydrogen deficit in spirals within the halo of the cluster. According to their 3-D coordinates, most of the galaxies with a hydrogen deficit are located closer to the south-east edge of the subcluster surrounding NGC 4874 near an extended gas filament in the x-ray region. This may indicate that the subcluster is moving toward a central condensation of faint galaxies in the Coma cluster and a possible merger with it. __________ Translated from Astrofizika, Vol. 50, No. 3, pp. 355–368 (August 2007).     

On the application of optimization methods to the determination of members of families of periodic solutions

The techniques used for the numerical computation of families of periodic orbits of dynamical systems rely on predictor-corrector algorithms. These algorithms usually depend on the solution of systems of approximate equations constructed from the periodicity conditions of these orbits. In this contribution we transform the root finding procedure to an optimization one which is applied on an objective function based on the exact periodicity conditions. Thus, the determination of periodic solutions and families of such orbits can be accomplished through unconstrained optimization. In this paper we apply and compare some well-known minimization methods for the solution of this problem. The obtained results are promising. This revised version was published online in July 2006 with corrections to the Cover Date.