太阳质量损失对地球轨道改变的长期影响的估计

研究了太阳质量损失对地球轨道２的长期影响。太阳质量损失包括太阳因光于辐射和太阳风流失两方面产生的质量损失。利用二体问题的中心体变质量的Ｊｅａｎｓ理论估计了太阳目前在主序阶段和将来后主序（红巨星＿阶段由于上述两种机制造成的质量损失对地球轨道改变的长期效应。计算结果表明：太阳质量损失在主序阶段对地球轨道改变的影响较小,但在后主序阶段对地球轨道改变的影响甚大,且此估计只是一种理论预测。     

太阳质量损失对流星群轨道改变的长期影响

将作者在变质量天体力学所得理论结果应用于太阳质量损失对流星群轨道根数变化的长期效应上。太阳质量损失包括光子辐射和太阳风造成的质量损失。利用G—M型变质量天体轨道根数变化方程的一阶和二阶解对15个流星群轨道半长轴、近日点距离、轨道周期和近日点经度因太阳质量损失造成的每世纪的长期改变效应做了数值计算,并得出计算结果。其计算结果表明,太阳质量损失使流星群轨道半长轴每世纪的改变效应较明显,它们同太阳距离的扩大影响值得关注,但对轨道周期的拉长每世纪的影响甚小,对近日点经度只有量级变化小到可以略而不计。     

太阳质量损失对高阶行星轨道的长期影响

在文[1]研究的基础上给出了太阳质量损失对三阶行星轨道的影响解,并计算了二、三阶解的长期效应的数值结果。理论结果表明,在三阶解中对于质量变化模型k=3的情形,太阳质量损失对轨道半长轴继续产生长期项、混合项和周期项,但对轨道偏心率和近点角距只产生周期项,三阶解的效应值虽小,但有定性意义。     

太阳质量损失对高阶行星轨道的长期影响

在文[1]研究的基础上给出了太阳质量损失对三阶行星轨道的影响解，并计算了二、三阶解的长期效应的数值结果。理论结果表明，在三阶解中对于质量变化模型κ=3的情形，太阳质量损失对轨道半长轴继续产生长期项、混合项和周期项，但对轨道偏心率和近点角距只产生周期项，三阶解的效应值虽小，但有定性意义。     

磁制动作用下太阳在主序阶段质量流失对自转角速度减速的影响

研究了磁制动作用下太阳在主序阶段质量流失对自转角速度在主序前半程和后半程随时间的演变的影响.根据推导给出了理论结果.理论结果表明:磁制动作用对自转角速度的影响在主序前半程比后半程影响更大.计算了在主序前半程(1×10~9–5×10~9yr)和后半程(5×10~9–10×10~9yr)内角速度演变的数值.数值结果表明:无论在主序前半程还是在后半程自转角速度随时间逐渐减慢.最后详细讨论了给出的理论和数值结果.     

天体自转因素导致的相对论性效应

本文在PPN框架中得到了太用系内自转因素产生的瞬时轨道根数改正的一阶封闭分析解.轨道半长径和偏心率不受长期效应的影响,只受周期效应的影响;轨道倾角、升交点经度、近星点角距,平近点角既受长期效应又受周期效应的影响.我们用两种引力理论分别计算了太阳自转对地内大行星及—些小行星轨道,行星自转对自然卫星轨道,地球自转对人造卫星轨道所产生的各相对论性效应.     

太阳质量变化对小行星轨道根数的影响

利用变质量天体力学方法研究了太阳质量变化对小行星轨道根数的影响,质量变化包括因光子辐射和太阳造成的质量损失以及因太阳吸积周围星际物质造成的质量增加两个联合因素,利用Gylden-Meshcherskii(G-M)型变质量天体轨道根数变化方程的一阶和二阶解对7颗小行星轨根数的长期和周期性的影响作了数值计算,在一阶解中太阳质量流失对小行星轨道半长轴,轨道偏心率和近点辐角的变化率产生增大作用,而质量吸积起减小作用,在二阶解中两者起到增大作用,不过质量流失不大于质量吸积的作用,故总的趋势是使半长轴,偏心率和近点辐角的变化率增大。     

太阳系角动量分布的说明

本文对今天太阳系角动量的特殊分布提出一种说明:太阳在进入主序以前,在引力收缩阶段内曾经大量抛射物质,通过沙兹曼机制而损失了绝大部分角动量;但太阳当时抛出的物质绝大部分不进入星云盘,行星物质已有足够的角动量,不需要太阳把角动量转移给它。结合对角动量特殊分布的说明,本文对太阳系形成过程的早期阶段进行了一些量的估算。     

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。     

磁感应阻力对导体卫星在圆形轨道上的摄动影响

用功能转换原理和摄动理论的两种方法重点研究了导体卫星在地球磁场和有电导率介质空间飞行时磁感应阻力对圆形轨道半径的摄动影响。理论研究表明：导体卫星在圆形轨道上受磁感应阻力后轨道半径有随时间变化的长期摄动效应外还有周期性变化。此外，文中还讨论了磁感应阻力对圆形轨道的其它要素的摄动影响概况。     

Impact of the Quadrupole Moment of the Sun on the Dynamics of the Earth-Moon System

Range of values of the Sun's mass quadrupole moment of coefficient J₂ arising both from experimental and theoretical determinations enlarge across literature on two orders of magnitude, from around 10^-7 until to 10^-5. The accurate knowledge of the Moon's physical librations, for which the Lunar Laser Ranging data reach an outstanding precision level, prove to be appropriate to reduce the interval of J₂ values by giving an upper bound of J₂. A solar quadrupole moment as high as 1.1 10^-5 given either from the upper bounds of the error bars of the observations, or from the Roche's theory, is not compatible with the knowledge of the lunar librations accurately modeled and observed with the LLR experiment. The suitable values of J₂ have to be smaller than 3.0 10^-6. As a consequence, this upper bound of 3.0 10^-6 is accepted to study the impact of the Sun's quadrupole moment of mass on the dynamics of the Earth-Moon system. Such as effect (with J₂ = 5.5±1.3 × 10^-6) has been already tested in 1983 by Campbell & Moffat using analytical approximate equations, and thus for the orbits of Mercury, Venus, the Earth and Icarus. The approximate equations are no longer sufficient compared with present observational data and exact equations are required. As if to compute the effect on the lunar librations, we have used our BJV relativistic model of solar system integration including the spin-orbit coupled motion of the Moon. The model is solved by numerical integration. The BJV model stems from general relativity by using the DSX formalism for purposes of celestial mechanics when it is about to deal with a system of n extended, weakly self-gravitating, rotating and deformable bodies in mutual interactions. The resulting effects on the orbital elements of the Earth have been computed and plotted over 160 and 1600 years. The impact of the quadrupole moment of the Sun on the Earth's orbital motion is mainly characterized by variations of , , and . As a consequence, the Sun's quadrupole moment of mass could play a sensible role over long time periods of integration of solar system models. This revised version was published online in July 2006 with corrections to the Cover Date.     

On the role of the motion of the photospheric footpoints of the magnetic field lines

By means of a simple relation between the velocity v of the fluid particle and the velocity v_f of the photospheric footpoint of the magnetic field line v_z and B_z being respectively the components of v and the magnetic field B normal to the photospheric surface, it is shown formally that through the phtospheric surface the transport of all the quantities attributed to the magnetic field, such as the magnetic flux, the magnetic energy and the helicity, is independent of v_z, and v_f is the only kinematical quantity on which the transport depends. In addition, in the neighborhood of the neutral line the velocity v_l of the moving curve of constant B_z is found to be equal approximately to the component of v or v_f in the direction of v_l. Since v_l can be measured or extimated, so can the components of v and v_f near the neutral line.     

在后牛顿引力理论(PPN形式)中引力常数变化对地球自转产生的效应

介绍和论述了在后牛顿引力理论(PPN形式)中在优越参考系和非优越参考系中经过参数化后引力常数变化对地球自转产生的效应,其中特别重点介绍了年周期变化的效应。此外也将理论结果同观测结果相对比。     

On the theory of the oblateness of the Sun

In this paper we first emphasize why it is important to know the successive zonal harmonics of the Sun's figure with high accuracy: mainly fundamental astrometry, helioseismology, planetary motions and relativistic effects. Then we briefly comment why the Sun appears oblate, going back to primitive definitions in order to underline some discrepancies in theories and to emphasize again the relevant hypotheses. We propose a new theoretical approach entirely based on an expansion in terms of Legendre's functions, including the differential rotation of the Sun at the surface. This permits linking the two first spherical harmonic coefficients (J ₂ and J ₄) with the geometric parameters that can be measured on the Sun (equatorial and polar radii). We emphasize the difficulties in inferring gravitational oblateness from visual measurements of the geometric oblateness, and more generally a dynamical flattening. Results are given for different observed rotational laws. It is shown that the surface oblateness is surely upper bounded by 11 milliarcsecond. As a consequence of the observed surface and sub-surface differential rotation laws, we deduce a measure of the two first gravitational harmonics, the quadrupole and the octopole moment of the Sun: J ₂=−(6.13±2.52)×10⁻⁷ if all observed data are taken into account, and respectively, J ₂=−(6.84±3.75)×10⁻⁷ if only sunspot data are considered, and J ₂=−(3.49±1.86)×10⁻⁷ in the case of helioseismic data alone. The value deduced from all available data for the octopole is: J ₄=(2.8±2.1)×10⁻¹². These values are compared to some others found in the literature. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1005238718479     

Accounting for the viscosity of the fluid core in the problem of the physical libration of the moon

A two-component theoretical model of the physical libration of the Moon in longitude is constructed with account taken of the viscosity of the core. In the new version, a hydrodynamic problem of motion of a fluid filling a solid rotating shell is solved. It is found that surfaces of equal angular velocity are spherical, and a velocity field of the fluid core of the Moon is described by elementary functions. A distribution of the internal pressure in the core is found. An angular momentum exchange between the fluid core and solid mantle is described by a third-order differential equation with a right-hand side. The roots of a characteristic equation are studied and the stability of rotation is proved. A libration angle as a function of time is found using the derived solution of the differential equation. Limiting cases of infinitely large and infinitely small viscosity are considered and an effect of lag of a libration phase from a phase of action of an external moment of forces is ascertained. This makes it possible to estimate the viscosity and sizes of the lunar fluid core from data of observations.     

Third Integral and the Dynamics of the Galaxy in the Neighborhood of the Sun

Observational data on the dynamics of stars in the neighborhood of the sun indicate the existence of a third integral besides the integrals of the angular momentum and energy. The Poincaré integral is proposed as a third integral. The consequences of this assumption are derived and compared with available astrophysical data.     

射电日像仪灵敏度测量

灵敏度是射电望远镜的一个重要性能指标,它反映了望远镜监测弱信号的能力。基于明安图射电频谱日像仪(Mingantu Ultrawide Spectral Radioheliograph,MUSER)的调试观测,给出了日像仪灵敏度的测量方法,对天线系统以及整个阵列的灵敏度进行测量分析,得到了日像仪系统整体的灵敏度性能参数。测量同时给出了天线系统的效率以及接收机系统的增益,这将为下一步日像仪展开常规的科学观测提供参考。     

Calculation of the global system of the field-aligned currents on the dayside of the magnetosphere

Using the well-known equation for the normal component of the current which exist near the tangential discontinuity in the plasma in the case of the frozen-in magnetic field, and supposing that the current closes in the ionosphere in the auroral oval in the region 1, one calculates and compares with the data of observations the dependence of the density of the field-aligned current at the level of the ionosphere on the local time.     

Dynamical determination of the mass of the Kuiper Belt from motions of the inner planets of the Solar system

In this paper we determine dynamically the mass of the Kuiper Belt Objects by exploiting the latest least-squares determinations of the extra rates of perihelia of the inner planets of the Solar system. By modelling classical Kuiper Belt Objects as an ecliptic ring of finite thickness, we obtain 0.033 ± 0.115 in units of terrestrial masses. For resonant Kuiper Belt Objects, a two-ring model yields 0.018 ± 0.063. These values are consistent with recent determinations obtained using ground- and space-based optical techniques. Some implications for precise tests of Einsteinian and post-Einsteinian gravity are briefly discussed.