A Research on the Imaging Strategy and Imaging Simulation of Toutatis in the Chang’e-2 Flyby Mission

For the Chang’e-2 extended mission of asteroid exploration, the illumination conditions for imaging the asteroid Toutatis are calculated in this paper according to the orbital parameters of both the Chang’e-2 detector and the asteroid, as well as the incident angles of sunlight. On this basis, it is suggested to take photographs after flyby, and the orientation of the camera's optical axis in the coordinate system deflned by Earth's mean equator and equinox at J2000.0 is proposed to be (118.02°, 22.03°). Based on the shape model of Toutatis determined by the foreign radar data, the orientation of the asteroid in the inertial space is calculated at the rendezvous time. Using the Oren-Nayar diffuse-reflection model and the relative positions among the sun, the asteroid, and the detector, together with the cameras orientation, the imaging simulations are performed on the starry sky background respectively at the distances of 300 km, 500 km, and 1000 km from the asteroid after flyby. The results of simulations are verified further by the optical images of Toutatis obtained in the mission.     

Tidal Evolution of the Kepler Candidate Two-planet Systems

The tidal evolution of ten Kepler candidate two-planet systems is investigated by using the general secular perturbation theory, and then a general picture of tidal evolution for these systems is described. Taking the KOI 1239 system as an example, the tidal effect of the system is studied in detail, the results indicate that the dissipative term of the tidal effect causes the attenuation of planets’ orbital eccentricities, and it plays a dominant role in the process of orbital evolution, however, the conservative term of the tidal effect and the relativistic effect may damp the excitation of the eccentricity of the inner planet under the secular perturbation of the outer planet. In addition, the process of tidal evolution is also affected by both the initial eccentricity of the outer planet and the planet's tidal dissipation coeffcient. At the same time, the numerical simulation on the tidal evolution of the KOI 1239 system is also made, and the numerical results are consistent with those of general secular perturbation theory.     

Active Region Coronal Rain Event Observed by the Fast Imaging Solar Spectrograph on the NST

The Fast Imaging Solar Spectrograph (FISS) is being operated on the New Solar Telescope of the Big Bear Solar Observatory. It simultaneously records spectra of Hα and Ca ii 8542 Å lines, and this dual-spectra measurement provides an estimate of the temperature and nonthermal speed components. We observed a loop structure in AR 11305 using the FISS, SDO/AIA, and STEREO/EUVI in 304 Å, and found plasma material falling along the loop from a coronal height into the umbra of a sunspot, which accelerated up to 80 km?s^?1. We also observed C2 and C7 flare events near the loop. The temperature of the downflows was in the range of 10?000?–?33?000 K, increasing toward the umbra. The temperature of the flow varied with time, and the temperature near the footpoint rose immediately after the C7 flare, but the temperature toward the umbra remained the same. There seemed to be a temporal correlation between the amount of downflow material and the observed C-class flares. The downflows decreased gradually soon after the flares and then increased after a few hours. These high-speed red-shift events occurred continuously during the observations. The flows observed on-disk in Hα and Ca ii 8542 Å appeared as fragmented, fuzzy condensed material falling from the coronal heights when seen off-limb with STEREO/EUVI at 304 Å. Based on these observations, we propose that these flows were an on-disk signature of coronal rain.     

Landau damping of longitudinal oscillation in ultra-relativistic plasmas by analytic function of nonextensive distribution

The analytic function of relativistic nonextensive distribution is given, and employed to solve the Landau damping of longitudinal oscillation in ultra-relativistic plasmas. The unified expression of Landau damping which reduces to the result in relativistic Maxwellian distributed plasmas in the extensive limit is obtained, and find that Landau damping is relevant to both the number and energy of resonant particles, which described by temperature and nonextensive parameters in relativistic nonextensive distribution.     

Isolation and biological characteristics of aerobic marine magnetotactic bacterium YSC-1

1 INTRODUCTION Magnetotactic bacteria are able to respond and orient along the direction of terrestrial or artificial magnetic field, a behavior referred to as magneto- taxis. In the majority of magnetotactic bacteria, the magnetosomes are 25–120 nm in d…     

国家1∶50000地形数据库的数据设计与建库

国家基础地理信息系统1∶50000数据库是构建数字中国空间地理框架的重要组成部分,1∶50000地形数据库作为1∶50000数据库的重要数据内容,是数据内容复杂、建设难度最大的数据库。本文介绍了数据库在数据精度、数据质量和数据结构等方面的设计要求,同时对数据库建设的关键技术环节进行了介绍。     

亚洲一号卫星共视法定轨及时刻同步

１９９３年中国科学院同步卫星观测网同步接收亚洲一号卫星的电视信号，进行了多台站时差法定轨及共视法时刻同步试验。试验表明：时差法定轨在经度、纬度方向精度较高，在卫星高度方向误差较大。不进行卫星位置修正时，时刻同步误差小于３μｓ；进行卫星位置修正时的时刻同步误差小于０．９μｓ，可应用于局部或大范围网络时刻同步及同步卫星轨道研究。     

地核能量的积累与释放

地核不仅具有巨量热能，而且有巨量旋转能，这是地球能量释放的内因；天文因素使地核产生周期性的南北振荡，是地球能量间歇性释放的外因。地质旋回与天文周期直接相关，可以根据天文周期预测未来的地质变化     

走向Internet网际

从１９９５年３月１３日开始，我们开始与中国科学院网络中心和昆明电信局通信处联系，准备建立云南天文台Ｅｍａｉｌ系统。到３月２１日本系统技术上已基本调试完成。本文介绍了这一系统的建立过程和通过这一系统可以得到的网络资源。     

空间数据自动化建库工具研究

空间数据库的建设速度和成本是影响GIS应用的重要因素。目前空间数据建库存在软件通用性差、建库过程操作复杂、人工干预多、建库效率低等问题。本文针对建库中存在的问题，研究并提出了基于可视化建模思想的空间数据库自动化建库技术，有助于大幅度降低建库复杂性及建库成本，提高效率。