关于有挠时空理论中的宇宙模型

本文阐明了引力规范理论的自治性.以简单的R+Q~2理论为例讨论了宇宙模型.挠率的存在并不改变标准宇宙模型的结果.     

脉冲星“晃荡”所产生的引力辐射

本文得出了含有自引力、内应力和内部运动项的脉冲星“晃荡”的多极引力辐射公式,并用该公式估算了脉冲星Crab和Vela的引力辐射功率,最后讨论了该公式的理论意义。     

自引力辐射体系的熵与引力坍缩

本利用李立新和刘辽导出的黑洞视界附近的辐射态方程，计算了约束在一个球形盒子中的自引力辐射体系的熵（不含中心黑洞和含有中心黑洞两种情况）。与Ｓｏｒｋｉｎ等人的计算比较，本的结果不会出现发散困难，而且体系的总熵（包括中心黑洞的熵）的上限正好等于坍缩后形成的同质量的黑洞熵。作认为，自引力辐射体系坍缩的合理模式是先形成中心黑洞，然后中心黑洞逐渐长大直至整个体系全部坍缩为黑洞。在坍缩过程中，任一中间态     

Bianchi I型宇宙中矢量暴涨理论相关问题的研究

通过矢量暴涨理论,研究了与之相关的问题,特别是粒子生成对慢滚过程、相图以及各向异性的影响.计算结果表明,粒子生成对标量场的影响使得相图上出现一个峰,峰的方向不受初始条件和质量改变的影响.而对于矢量场,情况则不同,粒子生成对应的峰其方向会改变,这与质量的变化有关.相应地,体系的各向异性也会随之增强或减弱.各向异性的程度不仅决定于慢滚过程,还决定于慢滚后的粒子生成过程.粒子生成可以成为宇宙各向同性化的原因.     

粒子在标量张量理论的二阶后闵可夫斯基近似弱引力场中的引力偏转

标量张量理论是目前为止最成功的相对论性引力理论之一,经受住了已有实验和观测的检验.随着实验和观测精度的提高,理论将得到进一步的检验.为此将该理论的可观测效应计算到二阶后牛顿近似非常必要.标量张量理论的二阶后牛顿近似结果已经由Xie等人给出.为得到有质量粒子在弱引力场中的偏转情况,利用二阶后闵可夫斯基近似下的度规解得到了粒子的测地线方程,并通过迭代的方法求得在非束缚条件下,粒子在弱引力场中的轨迹的解析解.进一步利用此结果计算了粒子在弱引力场中的偏转角(与光线的偏转角不同)并与前人的结果进行了比较.     

ISW效应对Yukawa引力势的检验

该文利用Integrated Sachs-Wolfe(ISW)效应探测宇宙大尺度引力势随时间的变化速率,从而能够在宇宙学尺度上检验引力的性质.以Yukawa引力势为例,探讨了利用ISW效应检验引力性质的能力.计算表明,ISW效应对引力的性质很敏感,通过与宇宙微波背景辐射实验WMAP五年的观测结果相比较,发现相对于牛顿常数,等效牛顿常数在宇宙学尺度上最多只有约2%的改变.     

卫星轨道偏心率的变化特征及其对轨道寿命的影响

轨道偏心率的变化极其重要,它是制约各类(不同高度)空间飞行体轨道寿命的关键因素之一.对于地球低轨卫星,主要受大气耗散作用的影响,而对环月(或环火星)低轨卫星,主要受非球形引力位中奇次带谐项的影响,会出现变幅较大的长周期变化,从而导致近星点高度hp在一段时间内有明显的下降趋势.对大偏心率轨道和高轨道,第三体的引力作用也会使e出现变幅较大的长周期变化,近星点高度hp也会有明显下降的现象,这都会影响卫星的轨道寿命,但这一动力学机制与大气耗散机制和非球形引力机制都不相同.即对轨道偏心率的变化特征及其对轨道寿命的影响作一综述.     

类星体的厚吸积盘与自引力吸积盘模型

本文对类星体的各种厚吸积盘模型,紫外超现象的吸积盘模型及自引力吸积盘模型作了简扼评述.     

Spectral Observations of BIG Objects. III

Results of spectral observations of 66 objects from the BIG (Byurakan IRAS Galaxies) sample made with the 1.93 m telescope at the Observatoire de Haute Provence (OHP, France) are presented. Emission lines are observed from 64 of the galaxies. The red shifts are determined, the radial velocities, distances, and absolute stellar magnitudes are calculated, the spectrum line parameters are determined, diagnostic diagrams are constructed, the objects are classified according to activity type, and their IR and far-IR luminosities are calculated. Of the 66 objects (corresponding to 61 IRAS sources), 6 are Sy2, 2 are LINERs, 8 are AGN (Sy2 or LINER), 10 are composite, 34 are HII, and 4 are Em of undetermined type. It is calculated that IRAS 07479+7832= BIG d141a is a ultraluminous IR galaxy (ULIG), and 21 are LIG. Spectra of several of the galaxies being studied are presented.     

Variable stars in the globular cluster NGC 6362

We report the results of a CCD search for short-period variables in the field of a southern globular cluster NGC 6362. We identified 19 new candidate variables, five of which are cluster RR Lyraes, four are probable SX Phe-type stars and eight are eclipsing binaries. Of the discovered binaries, three are EA-type systems, two of which are located on the cluster CMD in the turn-off region and the third 1 mag above the turn-off point, in the yellow straggler region. Five other systems are of W UMa type, three of which are foreground objects and two are likely cluster members. The remaining two candidates exhibit a modulation of the brightness level with an amplitude of 0.1–0.2 mag; further observations are needed to reveal the nature of their variability. Phased VI light curves for 20 variables (18 RR Lyrae stars and two blue stragglers) located in the central region of the cluster are presented.     

The features of infra-red emission of planetary nebulae in the inner galaxy

414 galactic PN with measured infra-red luminosities (302 of which are located within the sector of galactic longitudes from 345° to 15°) are investigated. All nebulae are subdivided into four mass classes and different distance scales for each class are used. Planetary nebulae located in the inner Galaxy are selected. The galactic radial gradients of infra-red luminosities and excesses are obtained for each nebula mass class. Possible explanations of the effect are discussed.     

Ccd Photometry and Modeling of the Overcontact Binary Systems Nn Vir and Yy CrB

New ground-based BV RI CCD observations of the eclipsing binary systems NN Vir and YY CrB are analyzed and illustrated. New times of minima are given and new ephemerides are proposed. The light curves are analyzed with the Wilson-Devinney light curve synthesis code and new geometric and photometric elements are derived. These elements are used together with the available spectroscopic data to compute absolute elements. The evolutionary status of each system is studied by means of mass-radius diagrams. The systems NN Vir and YY CrB are found to be A-type and W-type W UMa systems, respectively.     

Electrostatic solitons in multispecies electron-positron plasmas

Acoustic solitons are investigated in electron-positron plasmas containing equal hot and cool components of both species. The hot components are isothermal Boltzmann distributed, the cool constituents are modelled by adiabatic fluids. The equations are integrated exactly in terms of a Sagdeev potential. Solitons are shown to be possible, but no double layers, due to the symmetry in the model. Bearing in mind the constraints imposed by the Boltzmann assumption, small amplitude solitons only are found. Such findings are relevant for different kinds of astrophysical plasmas, as well as for other types of similar acoustic solitons.     

Connections between jet physics and the properties of radio-loud and radio-quiet galaxies

Relationships between jet physics and the evolutionary phases of radio galaxies are discussed. This includes the connection between the properties of relativistic jets and the Fanaroff–Riley classes of radio galaxies and the interaction of jets with the interstellar medium in Gigahertz Peak Spectrum and Compact Steep Spectrum Radio Sources. Jets in Seyfert galaxies are compared with those in classical radio galaxies and recent work suggesting that there are major differences between the two types of jets is summarized. The proposed major differences are principally that Seyfert jets are thermally dominated with subrelativistic speeds whereas Radio Galaxy jets are relativistic electron/positron flows. Hence, the production of jets in Seyferts and radio galaxies are fundamentally different.     

The temperature of interstellar porous grains

Free-space equilibrium temperatures for porous interstellar grains are computed for different dust sizes and are compared to those expected for homogeneous normal grains for two material candidates: graphite and a lunar silicate. Relevant differences are found with the former, but are essentially negligible with the latter. The results are discussed in terms of the different optical properties produced by the porosity of the grains. The possible astrophysical implications of these findings are also mentioned.     

The identification and interaction of network,intranetwork, and ephemeral-region magnetic fields

Network magnetic fields, ephemeral active regions, and intranetwork magnetic fields are illustrated and discussed in several contexts. First, they are presented in relation to the appearance and disappearance of magnetic flux. Second, their properties in common with all solar magnetic features are discussed. Third, their distinguishing characteristics are emphasized. Lastly, their interactions are illustrated.Network magnetic fields are no longer considered to be just the aged remnants of active regions. The network is the dynamic product of the merging and cancelling of intranetwork fields, ephemeral regions, and the remnants of active regions. Intranetwork fields are magnetic fields of mixed polarity that appear to originate continuously from localized source sites in between the network. The intranetwork magnetic fields are characterized by flow of successive fragments in approximately radial patterns away from their apparent source sites and by the relative weakness of their magnetic fields. Ephemeral active regions are small, new bipoles that grow as a unit or a succession of bipolar units and whose poles move in opposite directions from their apparent site of origin. Large ephemeral regions are not distinguishable from small active regions.Solar Cycle Workshop Paper.     

Generalizations of the Jacobian integral

The restricted problem of three bodies is generalized to the restricted problem of 2+n bodies. Instead of one body of small mass and two primaries, the system is modified so that there are several gravitationally interacting bodies with small masses. Their motions are influenced by the primaries but they do not influence the motions of the primaries. Several variations of the classical problem are discussed. The separate Jacobian integrals of the minor bodies are lost but a conservative (time-independent) Hamiltonian of the system is obtained. For the case of two minor bodies, the five Lagrangian points of the classical problem are generalized and fourteen equilibrium solutions are established. The four linearly stable equilibrium solutions which are the generalizations of the triangular Lagrangian points are once again stable but only for considerably smaller values of the mass parameter of the primaries than in the classical problem.     

Flows in clumpy planetary nebulae

The dynamics of clumps observed in planetary nebulae are considered. The possibility that SiO maser spots in evolved stars and the planetary nebula clumps are formed by the Parker instability behind shocks in pulsating stars' atmospheres is raised. Molecular observations of the clumps are suggested. The effects of the ablation of clumps on the global flow structure of a more tenuous plasma in which they are embedded are reviewed.