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A new class of symmetric periodic solutions of the spatial elliptic restricted three-body problem

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Science china(Physics,Mechanics & Astronomy) 2009年第9期52卷 1404-1413页

作者： XU XingBo1,2.& FU YanNing1 1 Purple mountain {2., chinese Academy of sciences, nanjing 2.0008, china 2.Graduate University of chinese Academy of sciences, Beijing 100039, china Purple mountain {2. Chinese Academy of Sciences Nanjing China Graduate University of chinese Academy of sciences Beijing China

We show that there exists a new class of symmetric periodic solutions of the spatial elliptic restricted three-body problem. In such a solution, the infinitesimal body is confined to the vicinity of a primary and moves on a nearly circular orbit. This orbit is almost perpendicular to the orbital plane of the primaries, where the line of symmetry of the orbit lies. The existence is shown by applying a corollary of Arenstorf's fixed point theorem to a periodicity equation system of the problem. And this existence doesn't require any restriction on the mass ratio of the primaries, nor on the eccentricity of their relative elliptic orbit. Potential relevance of this new class of periodic solutions to real celestial body systems and the follow-up studies in this respect are also discussed.

关键词： periodic orbits spatial restricted three-body problem symmetric orbits averaging

Effects of various solar indices on accuracy of Earth’s thermospheric neutral density models

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Science china(Physics,Mechanics & Astronomy) 2009年第7期52卷 1120-1128页

作者： WANG HongBo1,2.& ZHAO ChangYin1 1 Purple mountain {2., chinese Academy of sciences, nanjing 2.0008, china 2.Graduate University of chinese Academy of sciences, Beijing 100049, china Purple mountain {2. Chinese Academy of Sciences Nanjing China Graduate University of chinese Academy of sciences Beijing China

Four kinds of solar indices F10.7, E10.7, S10, Mg10 and four thermospheric neutral density models, i.e., CIRA72. DTM94, NRLMSISE00 and JB2.06, are discussed. The CHAMP accelerometer data are used to calculate thermospheric total mass density. Based on the comparison of the model densities with CHAMP observations, the effects of various indices on the model accuracy are detected. It is found that under quiet and moderate solar conditions (F10.72.0) the error’s standard deviation using E10.7 increases quickly and causes the models’ accuracy to fall down. With regard to S10, Mg10, their effects under quiet solar conditions are inconspicuous. If under active solar conditions, they can reduce the model error’s standard deviation by 5%-10%, implying that S10, Mg10 make the model error more stable. The JB2.06 model, which was constructed by multi-solar-index (F10.7, S10, Mg10), is compared with DTM94 and NRLMSISE00 based on single-solar-index. It is found that JB2.06’s accuracy is better than DTM94’s, and is close to NRLMSISE00 under the quiet solar condition. During the solar burst occurring on October 2., 2.03, JB2.06 has been in best agreement with CHAMP observations. All in all, the new indices may improve thermospheric density models’ accuracy under some special conditions. Concretely, E10.7 may reduce the average error of models and S10, Mg10 may prevent the error’s divergence.

关键词： solar radiation index CHAMP accelerometer data neutrals density model

The approximate state transition matrix based on non-orthogonal decomposition and its application in orbit determination

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Science china(Physics,Mechanics & Astronomy) 2010年第3期53卷 555-561页

作者： CHEN WuShen1,2. MA JingYuan2. ZHANG Jing2.& LU BenKui2.1 nanjing University of Technology, nanjing 2.0009, {2. 2.Purple mountain observatory, chinese Academy of sciences, nanjing 2.0008, {2. nanjing University of Technology Nanjing China Purple mountain {2. Chinese Academy of Sciences Nanjing China

The Unit Vector Method (UVM) is an orbit determination method extensively applied. In this paper, the UVM and classical Differential Orbit Improvement (DOI) are compared, and a fusion method is given for the orbit determination with different kind data. Based on non-orthogonal decomposition of position and velocity vectors, an approximation scheme is constructed to calculate the state transition matrix. This method simplifies the calculation of the approximate state transition matrix, analyzes the convergence mechanism of the UVM, and makes clear the defect of weight strategy in UVM. Results of orbit the determination with simulating and real data show that this method has good numerical stability and rational weight distribution.

关键词： Unit Vector Method state transition matrix non-orthogonal decomposition

The simulation of GCRs at near earth interplanetary locations for radioprotection

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Science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1739-1745页

作者： BAO Gang Purple mountain {2.,chinese Academy of sciences,nanjing 2.0008,china Purple mountain {2. Chinese Academy of Sciences Nanjing China

The interplanetary radiation environment is detrimental to space missions,giving rise to cumulative damage to both astronauts and payloads and enhanced background levels in ***,there is a pressing need for a reliable simulation of these harmful effects for risk assessment and shielding optimization in manned space *** have modeled the interaction processes of the two most abundant galactic cosmic ray particle fluxes(protons and helium nuclei) using the Geant4 toolkit for a given space vehicle *** total energy deposited due to protons and helium nuclei is calculated in this work,and the energy deposited due to the secondary particles generated by this radiation is also estimated.

关键词： radioprotection simulation Geant4 cosmic rays

The red damping wing of Gunn-Peterson trough in the high redshift GRBs

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Science china(Physics,Mechanics & Astronomy) 2009年第9期52卷 1428-1433页

作者： XU Zhou1,2.& WEI DaMing1,3 1 Purple mountain {2., chinese Academy of sciences, nanjing 2.0008, china 2.Graduate University of chinese Academy of sciences, Beijing 100012. china 3 Joint Center for Particle Nuclear Physics and Cosmology of Purple mountain {2.-nanjing University, nanjing 2.0008, china Purple mountain {2. Chinese Academy of Sciences Nanjing China Graduate University of chinese Academy of sciences Beijing China Joint Center for Particle Nuclear Physics and Cosmology of Purple mountain {2.-nanjing University Nanjing China

We calculate the red damping wing of Gunn-Peterson trough taking the evolution of the neutral fraction into consideration and take a clear look at the ionized region around the ionizing sources. We get the result that the damping wing flux feature is mainly determined by the neutral hydrogen outside the ionized bubble and the cut off in the damping wing would be useful to get the size of the ionized bubble. We also fit the red damping wing of the recently discovered high redshift GRB080913 and find that the ionized bubble is too small to create apparent cut off in the spectrum of this burst.

关键词： cosmology theory intergalactic medium gamma ray burst

An Alternative Explanation for a Screw-like Meteoric Train Photographed by Double-Station Observations

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chinese Journal of Astronomy and Astrophysics 2007年第6期7卷 814-822页

作者： Guang-Jie Wu1,2.1 National Astronomical Observatories/Yunnan observatory,chinese Academy of {2.,Kunming 650011 2.Purple mountain observatory,chinese Academy of {2.,nanjing 2.0008 National Astronomical Observatories / Yunnan observatory Chinese Academy of Sciences Kunming 650011 Purple mountain {2. Chinese Academy of Sciences Nanjing 210008

Two-station observation of meteors, especially a meteor trains, provides an effective approach to the measurement of the physical parameters. We have collected four special groups of photographs of meteoric trains taken at two stations during Leonids 2.01. One representative group has been measured and analyzed in detail. An analysis has been reported in our first paper. In this paper, an alternative explanation for the screw-like meteoric train is suggested based on some physical calculations. The results reveal that this train has a screw-like structure and, apparently, spoke beams. The mother meteor of this train may be negatively charged and moves forward along a left-hand screw trajectory under the effect of the geomagnetic field. The spoke beams might be the visual effect of the long time exposure of many particles released from the disintegrated meteoroid.

关键词： meteors meteoroids -- magnetic fields

Development of superconducting mixers for THz astronomy

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Science china(Information sciences) 2012年第1期55卷 120-126页

作者： SHI ShengCai1,2.1Purple mountain {2.,chinese Academy of sciences,nanjing 2.0008,china 2.ey Laboratory of Radio Astronomy,chinese Academy of sciences,nanjing 2.0008,china Purple mountain {2. Chinese Academy of Sciences Nanjing China Key Laboratory of Radio Astronomy Chinese Academy of Sciences Nanjing China

The terahertz(THz)regime,loosely defined as 0.1-10 THz,is the last frequency window to be fully explored in *** particular,it is a regime in which there are rich molecular rotation lines and atomic fine structure *** are very important tracers for studying the dynamics of astronomical objects such as stars and planetary *** those spectral lines usually makes use of coherent detectors(i.e.,heterodyne mixers).With sensitivity approaching the quantum limit,superconducting mixers have become the coherent detector of choice in THz *** this paper we mainly introduce the superconducting mixers developed at Purple mountain {2. and those for international collaborative projects.

关键词： terahertz detection superconducting mixer quantum limit

“Double dawn”eclipse and the rotational variation of the earth

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chinese Science Bulletin 2000年第11期45卷 988-991页

作者： ZHANG Peiyu & HAN Yanben1. Purple mountain {2., chinese Academy of sciences, nanjing 2.0008, china 2. Beijing Astronomical {2., chinese Academy of sciences, Beijing 100012. National Astronomical {2., chinese Academy of sciences, Beijing 100012. china Purple mountain {2. Chinese Academy of Sciences Nanjing China Beijing Astronomical observatory Chinese Academy of Sciences Beijing National Astronomical observatory Chinese Academy of Sciences Beijing China

A record of 'double dawn' at State Zheng in the first year of the reign of King Yi in Western Zhou Dynasty in the chronicle 'Bamboo Annals' (Zhushu Jinian) is discussed. We think that it may be a record of an annular solar eclipse happening in 899 BC. The record and the AT, which describes the secular variation of the earth’s rotation, are analyzed and discussed.

关键词： solar eclipse earth’s rotation.

Simulations for terrestrial planets formation

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Science china(Physics,Mechanics & Astronomy) 2009年第5期52卷 794-803页

作者： ZHANG Niu 1,2.&JI JiangHui 2.3 1Graduate University of chinese Academy of sciences,Beijing 100049,{2. 2.urple mountain observatory,chinese Academy of sciences,nanjing 2.0008,{2. 3 National Astronomical Observatories,chinese Academy of sciences,Beijing 100012.{2. Graduate University of chinese Academy of sciences Beijing China Purple mountain {2. Chinese Academy of Sciences Nanjing China National Astronomical Observatories Chinese Academy of Sciences Beijing China

In this paper,the formation of terrestrial planets in the late stage of planetary formation is investigated using the two-planet *** that time,the protostar formed for about 3 Ma and the gas disk *** the model,the perturbations from Jupiter and Saturn are *** of the mass of outer planet,and the initial eccentricities and inclinations of embryos and planetesimals are also *** results show that,terrestrial planets are formed in 50 Ma,and the accretion rate is about 60%-80%.In each simulation,3-4 terrestrial planets are formed inside"Jupiter"with masses of 0.15 -3.6M⊕.In the 0.5-4 AU,when the eccentricities of planetesimals are excited,planetesimals are able to accrete material from wide radial *** plenty of water material of the terrestrial planet in the Habitable Zone may be transferred from the farther places by this *** could also happen a few times between two major planets only if the outer planet has a moderate mass and the small terrestrial planet could survive at some resonances over time scale of 10 8 *** one of our simulations,commensurability of the orbital periods of planets is very ***,a librating-circulating 3:2.configuration of mean motion resonance is found.

关键词： astrophysics exoplanet planetary formation n-body simulation