Astrophysical constraints on the gravitational constant

We study the astrophysical bounds on the change of the gravitational constant with time. We found that |/G|<10^–12yr^–1 is the condition that has to be satisfied in order not to cause a conflict with the observations. We find the condition to be in accord with the lower limits, the superstring theory predicts.     

Nonlinear analytic solution for perturbed relative motion using differential equinoctial elements

This paper develops a nonlinear analytic solution for satellite relative motion in J₂-perturbed elliptic orbits by using the geometric method that can avoid directly solving the complex differential equations. The differential equinoctial elements (DEEs) are used to remove any singularities for zero-eccentricity or zero-inclination orbits. Based on the relationship between the relative states and the DEEs, state transition tensors (STTs) for transforming the osculating DEEs and propagating the mean DEEs have been derived. The formulation of these STTs has been split into a set of vector and matrix operations, which avoids directly expanding the complex second-order terms, and thus, the obtained STTs could be easy-to-understand and easy-to-code. Numerical results show that the proposed nonlinear solution is valid for zero-eccentricity and zero-inclination reference orbit and is more accurate than the previous linear or nonlinear methods for the long-term prediction of satellite relative motion.     

冕流与日冕物质抛射的关系

本文研究了卡林顿自转周１５９１ － １５９２ 中冕流偏振亮度的变化。冕流带偏振亮度的分布是不均匀的,不均匀度为１０ ％ － ５０ ％ 。无日冕物质抛射影响存在时,沿冕流带冕流的分布可持续稳定存在近两个太阳自转周。当一个日冕物质抛射伴随冕流产生时,冕流的经向角大小若大于２７°,可导致冕流尖角区顶部上升速度大于２ｋｍ／ｓ。     

太阳射电望远镜远程控制系统

本文简要介绍了云南天文台１０ 米口径的太阳射电望远镜天线的远程控制系统中局域网控制和通过电话线控制的实现方案     

乌鲁木齐天文站25m天线18cm脉冲星脉冲到达时间观测系统

脉冲星脉冲到达时间观测系统建立在２５ｍ射电天线的１８ｃｍ波段上,消色散采用了２ｘ１２８ｘ２．５ＭＨｚ多通过滤波器和数字化器,数据采集系统由ＰＣ机完成．１９９９年５月至６月间建立了基于常温接收机的到达时间观测系统．观测到的最弱源的平均流量密度为４ｍＪｙ．     

Flare-induced signals in polarization measurements during the X2.6 flare on 2005 January 15

Flare-induced signals in polarization measurements which were manifested as apparent polarity reversal in magnetograms have been reported since 1981. We are motivated to further quantify the phenomenon by asking two questions: can we distinguish the flare-induced signals from real magnetic changes during flares, and what we can learn about flare energy release from the flare-induced signals? We select the X2.6 flare that occurred on 2005 January 15, for further study. The flare took place in NOAA active re-gion (AR) 10720 at approximately the central meridian, which makes the interpretation of the vector magnetograms less ambiguous. We have identified that flare-induced signals during this flare appeared in six zones. The zones are located within an average distance of 5 Mm from their weight center to the main magnetic neutral line, have an average size of (0.6±0.4)×1017 cm2, duration of 13±4 min, and flux density change of 181±125 G in the area of reversed polarity. The following new facts have been revealed by this study: (1) the flare-induced signal is also seen in the transverse magnetograms but with smaller magnitude, e.g., about 50 G; (2) the flare-induced signal mainly manifests itself as apparent polarity reversal, but the signal starts and ends as a weakening of flux density; (3) The flare-induced signals appear in phase with the peaks of hard X-ray emission as observed by the Ramaty High Energy Solar Spectroscopic lmager (RHESSI), and mostly trace the position of RHESSI hard X-ray footpoint sources. (4) in four zones, it takes place cotemporally with real magnetic changes which persist after the flare. Only for the other two zones does the flux density recover to the pre-flare level immediately after the flare.The physical implications of the flare-induced signal are discussed in view of its relevance to the non-thermal electron precipitation and primary energy release in the flare.     

An unusual timing and spectral state of a black hole microquasar XTE J1550-564

An unusual timing and spectral state of a black hole microquasar XTE J1550-564 observed with RXTE is analyzed. Millisecond variabilities are found, which are significantly shorter than the minimum possible time scale in the light curves of black hole binaries, as suggested by Sunyaev & Revnivtsev (2000). The X-ray spectral fitting result indicates that there is an unusual soft component in the spectrum, which may be responsible for the millisecond variabilities. The millisecond variabilities as well as the unusual soft spectral component should be produced from some small, but independent active regions in the accretion disk.     

On the determination of the earth''s rotation using the McDonald lunar laser ranging data of 1971.6 – 1979.0

Using 1658 normal points of the McDonald lunar ranging data in the period 1971.6–1979.0, I calculated the Earth's rotation curve, and found an offset of −330 × 10⁻¹⁰ for UT₁ – UTC. The difference between the UT₁ values given by the lunar data and BIH is 3.6 ms. This difference and the standard error of single determinations increase with increasing interval length used in the data reduction. This is shown to be due to the neglect of the secular term in UT₁-UTC. It appears that an interval length of 2 days is suitable when calculating the Earth's rotation.     

喀左盆地九佛堂组露头高分辨率层序地层划分

在实测106 km剖面和对喀左盆地九佛堂组沉积特征及演化进行详细研究的基础上,依据相序关系,并结合碳酸钙、油页岩的成因意义,将九佛堂组划分了 1个长期基准面旋回和7个中期基准面旋回。在长期基准面旋回内,上升期的中期基准面旋回发育以上升半旋回为主的不完全对称型中期基准面旋回,上升与下降过渡期的中期基准面旋回,则发育近完全对称的中期基准面旋回,下降期的中期基准面旋回,则发育以下降半旋回为主的不完全对称型中期基准面旋回。经过对中期基准面旋回和短期基准面旋回发育特点和形成原因的详细研究,对代表剖面进行了中期基准面旋回对比。     

The Faraday rotation of sunspots

In this paper the numerical solutions of the Unno-Beckers's equations for the magneto-sensitive line Fei 5250.216 are used to demonstrate the importance and role of Faraday rotation in sunspot magnetic fields and to study the influence of this effect on the measurements of the azimuth of the transverse field. We propose a method to determine the intrinsic direction of the transverse field with the observed azimuthal angle of the plane of linear polarization.