用周期图谱分析方法计算Blazar天体的光变周期

对适用于等间隔时间序列的周期图谱分析方法进行了研究,用模拟信号进行了检验,证实了它适用于有噪声的时间序列.并把这种方法应用到类星体3C 279、3C 345,BL Lac天体OJ 287、ON 231的光变周期分析中,得到它们的光变周期分别为7.14年、10.00年、11.76年、6.80年.结果表明用周期图谱分析方法得到的结论和其他文献用Jurkevich方法得到的结论一致.获得的周期对进一步研究Blazar天体的物理机制很有帮助.还分析了窗函数的影响,指出它们的优缺点,便于在实际工作中做出正确选择.     

On the Use of Inflatable Decelerators in the Design of Spacecraft Intended for the Study of Venus

Solar System Research - The article presents aspects of the use of inflatable decelerators in the design of spacecraft (SC) intended for the study of the atmosphere of Venus. The results of the...     

Measurement of Solar Neutrons on 05 March 2012, Using a Fiber-Type Neutron Monitor Onboard the Attached Payload to the ISS

The solar neutron detector Space Environment Data Acquisition Equipment – Attached Payload (SEDA-FIB) onboard the International Space Station (ISS) detected several events from the solar direction associated with three large solar flares observed on 05 (X1.1), 07 (X5.4), and 09 (M6.3) March 2012. In this study, we focus on the interesting event of 05 March, present the temporal profiles of the neutrons, and discuss the physics that may be related to a possible acceleration scenario for ions above the solar surface. We compare our data with images of the flares obtained by the ultraviolet telescope Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO).     

A Method for Estimating the Direction of Gravitational Acceleration in the Active Phase of a Spacecraft Landing on the Martian Surface

We know the spacecraft orientation before its touchdown on the Martian surface with an accuracy of 3–4°. The spacecraft control can result in a significant horizontal velocity at altitudes lower than 15 meters at the instant when the landing legs contact the surface when data from the radar location system terminates. An independent method for determining the gravity acceleration vector is presented in the paper. This method is implemented using information obtained from the gyro-inertial and radar instrumentation.     

On the Formation of a Nonequilibrium Chemical Composition in the Shells of Neutron Stars

Astrophysics - The chemical composition of the shell of a neutron star (SNS) at high temperatures and densities is discussed in this paper. A model for nucleosynthesis is proposed based on the...     

基于Keck方法的大型拼接镜面共面方法的研究

LAMOST是我国也是世界上唯一的同时应用薄镜面主动光学和拼接镜面主动光学的望远镜,但望远镜目前的设计要求还只是共焦,还没有很好地开展共面技术的研究和应用.Keck望远镜的共相方法已经得到了成功的应用.在红外波段得到了10m镜的衍射像.参照Keck的算法,开发了一套用于检测拼接子镜前后有一定平移误差时的模拟软件,在LAMOST及以后各大型望远镜的拼接镜面实验装置上应用.结果表明,这个方法是现实可行的.     

Study of the Structure of the Coma Cluster Based on a Hierarchical Force Clustering Method

Six subclusters in the Coma cluster have been selected on the basis of a hierarchical clustering method that takes the gravitational interaction among galaxies into account. Of these, 3 central subclusters around the galaxies NGC 4889, NGC 4874, and NGC 4839 have been singled out. We have used the objective statistical criterion applied by Vennik and Anosova in studies of close groups of galaxies to evaluate each member included in a subcluster with a high probability. Galaxies with a significant deficit of hydrogen HI, including objects from the Bravo-Alfaro list, have been identified with members of the subclusters, with the greatest number of them in the subclusters around NGC 4874 and NGC 4839. A quantitative estimate of the hydrogen deficit using the HI index in the RCG3 catalog reveals a statistically significant excess value for those galaxies that are members of the subclusters compared to galaxies with a hydrogen deficit in the overall Coma cluster field. A substantial number of the spiral galaxies with a hydrogen deficit in the subclusters turned out to be radio galaxies as well. __________ Translated from Astrofizika, Vol. 48, No. 4, pp. 515–528 (November 2005).     

类星体吸收线红移系统证认方法的进一步探讨

本文对崔振兴和陈建生等人所提出的类星体吸收线红移系统证认方法作了进一步探讨。指出了方法的局限性及改进的办法;也指出了有待于今后继续研究的问题;并将改进后的方法应用于类星体PKS 0528-250的光谱分析中,得到了它的吸收线红移系统有:Z_a=2.8110,2.8130,2.5375,2.1410。这和Morton等(1980)所得的A_1,A_2,B,C红移系统一致。另外,我们又得到的新系统是Z_a=0.0345,0.0065。Chen和Morton(1984)所得到的D_1,D_2,E,F,G系统,我们未发现。讨论了产生这种差别的原因。     

A Study on the Abundance Distribution of Heavy Elements in Metal-poor Stars by the Parameterization Method

Based on a large amount of observed data of element abundances in metal-poor stars, taking the abundance distribution of heavy elements in the solar system as a standard, and selecting Sr, Ba and Eu as the typical elements of the three nucleosynthetic processes in metal-poor stars, namely the weak sprocess, main s-process and r-process, we have studied the contributions of the three kinds of neutron-capture processes to the abundance distribution of heavy elements in metal-poor stars, with the parameterization method. It is found that the higher the metal abundance, the greater the contributions of the weak s-process and the chief s-process to the abundances of lighter neutron-capture elements. The heavier neutron-capture elements are mainly produced by the r-process and the chief s-process; and that at low metallicity, the abundances of heavy neutron-capture elements are mainly produced by the r-process. In the early Galaxy, the weak s-process has almost no contribution to the element abundance.     

一种新型轻量化反射镜结构及其在空间望远镜相关跟踪摆镜上的应用研究

本文提出一种新的反射镜轻量化方案。此方案在结构特征和减重比例上接近蜂窝结构,减重效果比背面开孔的镜子和拱形镜要好得多;同时又可避免蜂窝镜的制造难度。另外,本文还就此方案在空间太阳望远镜(SST)的相关跟踪摆镜上的应用进行探讨,给出了主要结构参数和镜面变形分析结果,其结果表明,此轻量化平面镜能满足SST的使用要求。     

Reconstruction of Magnetic Activity of the Sun and Changes in Its Irradiance on a Millennium Timescale Using Neurocomputing

Relations between basic indices of the Sun and the cosmogenic isotope ¹⁴C and ¹⁰Be records were derived using the Artificial Neural Network (ANN) technique. A reconstruction of the sunspot indices and changes in Total Solar Irradiance (TSI) was carried out. Long-term changes in TSI appear in the amplitude modulation of its 11-year cyclic variation as well as in its lower envelope describing variability of the background irradiance of the Sun. According to the reconstruction the irradiance has increased about 2.5 W m⁻² since 1441.     

On the Influence of a Large-scale Magnetic Field on Turbulent Motions in an Electrically Conducting Medium

This paper deals with turbulent motions in a homogeneous incompressible electrically conducting medium in the presence of a magnetic field which is on average homogeneous and stationary. Using a model in which the turbulence is produced by a stochastic body force, and supposing a weak interaction between motion and magnetic field, a method is developed for calculating the pair correlation tensor of the velocity field from that occuring in a zero magnetic field. As an example, the pair-correlation tensor for a homogeneous stationary turbulence, which is isotropic and mirror-symmetric for zero magnetic field, is determined. With obvious assumptions on the correlation for zero field, two results are obtained. Firstly, the turbulent velocity is reduced by the magnetic field, the component parallel to the field, however, less than those perpendicular to it. Secondly, the correlation length parallel to the field turns out to be greater than the one perpendicular to it, indicating a tendency towards two-dimensional motion. Finally, the possibility of special situations is briefly discussed in which the turbulent velocity is enhanced by the magnetic field, and the anisotropies of the velocity components and the correlation lengths are opposite to those above.     

Numerical Study of Physical and Chemical Processes in the Shock Layer on the Trajectory of a Return Vehicle in the Atmosphere

Solar System Research - The paper presents the methods and results of the calculation of flow around a return vehicle accounting for the physical and chemical processes in the flow field during...     

大气对532nm激光影响在漫反射激光测距中的应用

激光光束在大气中的传输是与大气特征有关的,如大气湍流、大气散射与吸收,而且激光测距的回波除了与距离有关外,其回波数及精度也与大气特征相关。漫反射激光测距的目标是低轨空间碎片,在一定反射截面的条件下,应用一定功率的激光进行地面靶板漫反射测距试验,以确定多少功率的激光器可实现空间碎片的漫反射测距,这时地面靶的距离选取应该具有代表性,它代表了在一定斜程下穿过整个大气层的效应。通过对大气湍流和大气衰减对激光传输的影响进行分析,理论上计算出在低轨目标为400km时,漫反射激光测距试验地面靶的水平距离该取多远时才能代表在一定斜程下穿过400km大气层的效应,从而为漫反射激光测距试验地面靶距离的选取提供参考依据。     

On the possibility of the development of longitudinal wave instabilities on the background of the small-scale Bernstein turbulence in preflare chromosphere of a solar active region

The process of origination and development of instabilities of the longitudinal waves of two types, namely, low-frequency ion-acoustic and high-frequency (“electronic”) Langmuir waves, in the preflare atmosphere of an active solar region are studied. The area under study is located at the chromospheric part of the flare loop near its footpoint. A weak large-scale electric field of flaring loop is the main source of these instabilities. The velocity of an electronic flow in the preflare plasma is supposed to be much lower than thermal electron velocity. Instability development is considered against the background of small-scale Bernstein wave turbulence, which exists in the preflare plasma and has an extremely low threshold of excitation. The necessary conditions for the instability origination and development, as well as the boundary values of the main plasma and wave perturbation parameters, are calculated.