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CO observations of massive star forming regions at different evolutionary phases

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Science china(Physics,Mechanics & Astronomy) 2006年第5期49卷 626-640页

作者： CHEN Xi1,2, XU Ye1,3, SHEN Zhiqiang1,3 & LI Jingjing1,2 1. shanghai astronomical observatory, chinese academy of sciences, shanghai 200030, china 2. Graduate School of the chinese academy of sciences, Beijing 100034, china 3. Joint Institute for Galaxy and Cosmology, shanghai astronomical observatory and the University of Science and Technology of china, shanghai 200030, china shanghai astronomical observatory Chinese Academy of Sciences Shanghai 200030 China Graduate School of the chinese academy of sciences Beijing 100034 China Joint Institute for Galaxy Cosmology Shanghai Astronomical Observatory the University of Science Technology of china Shanghai 200030 China

The 12CO (J=1-0), 13CO (J=1-0) and C18O (J=1-0) emissions in 9 massive star forming regions, which are believed to be at different stages of massive star formation, were mapped with the 13.7 m millimeter wave telescope at Qinghai Station of Purple Mountain observatory. Of the observed 9 sources, 13CO cores were detected in seven of them, and C18O cores in five of them. And only two sources associated with C18O cores and H2O masers showed the extended structures and strong outflows. This is the first detection of outflow associated with IRAS 22566+5828 in the observing field of S152/S153. The physical parameters of cores and outflows for these sources, derived from Local Thermal Equilibrium (LTE) analysis, are presented. These observing results suggest that the C18O cores will only appear when the gas density is high enough and the probability to have an outflow is very high when the clumps show the C18O and H2O maser simulta- neously.

关键词： star formation cloud core outflow H2O maser

Orbit determination for geostationary satellites with the combination of transfer ranging and pseudorange data

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Science china(Physics,Mechanics & Astronomy) 2010年第9期53卷 1746-1754页

作者： GUO Rui1,2,3,4,HU XiaoGong2,4,LIU Li1,WU XiaoLi1,HUANG Yong2,4 & HE Feng1 1 Beijing Global Information Application and Development Center,Beijing 100094,china 2 shanghai astronomical observatory,chinese academy of sciences,shanghai 200030,china 3 Graduate University of chinese academy of sciences,Beijing 100049,china 4 Space Navigation and Positioning Technology,Laboratory of shanghai Municipal,shanghai 200030,china 1. Beijing Global Information Application and Development Center Beijing 100094 China2. Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 China3. Graduate University of Chinese Academy of Sciences Beijing 100049 China4. Space Navigation and Positioning Technology Laboratory of Shanghai Municipal Shanghai 200030 China

Geostationary satellites(GEOs) play a significant role in the regional satellite navigation *** experiments show that the clock corrections could be mitigated through a single strategy or double differencing strategies for a navigation constellation,but for the mode of individual GEO orbit determination,high precision orbit and clock correction could not be obtained in the orbit determination based on the pseudorange data.A new GEO combined precise orbit determination(POD) strategy is studied in this paper,which combines pseudorange data and C-band transfer ranging *** strategy overcomes the deficiency of C-band transfer ranging caused by limited stations and tracking time *** the combination of transfer ranging and pseudorange data,clock corrections between the GEO and the stations can be estimated simultaneously along with orbital parameters,maintaining self-consistency between the satellite ephemeris and clock correction *** error covariance analysis is conducted to illuminate the contributions from the transfer ranging data and the psudoranging *** data collected for a chinese GEO satellite with 3 C-band transfer ranging stations and 4 L-band pseudorange tracking stations,POD experiments indicate that a meter-level accuracy is *** root-mean-square(RMS) of the post-fit C-band ranging data is about 0.203 m,and the RMS of the post-fit pseudorange is 0.408 *** component errors of the POD experiments are independently evaluated with the satellite laser ranging(SLR) data from a station in Beijing,with the residual RMS of 0.076 *** SLR evaluation also suggests that for 2-h orbital predication,the predicted radial error is about 0.404 m,and the clock correction error is about 1.38 *** for the combination of one C-band transfer ranging station and 4 pseudorange stations,POD is able to achieve a reasonable accuracy with the radial error of 0.280 m and the 2-h predicted radial error of 0.888 *** syn

关键词： satellite navigation precise orbit determination pseudorange equipment ranging delay GEO SLR

The Channel Maps and the Position-Velocity Diagrams of Multi-core Structure of Cepheus C

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天文研究与技术 1999年第S1期 218-221页

作者： Yu Zhi yao 1,2 , Jiang Dong rong 1,2 1 (shanghai astronomical observatory, The chinese academy of sciences, shanghai 200030, china) 2 (National astronomical Observatories, The chinese academy of sciences, china E mail: zyyu@center. shao. ac.

The first important problem in the star forming process is the formation of proto star core in star forming regions of molecular cloud. The multi core structure in star forming regions is related to the forming of proto star core. The molecular radiation of C 18 O( J = 1-0) in Cepheus C has been observed. The C 18 O( J = 1-0) observations form the basis for an interesting study on the cloud cores and star formation activity in the cores of the Cepheus C. In order to study the multi core structure of C 18 O( J = 1-0) in the Cepheus C the channel maps and the position velocity diagrams of C 18 O( J = 1-0) will be shown. From the maps it is found that the contour level and distribution size of the three cores in Cepheus C are related to the channel velocity very much. The channel velocity of C 18 O( J = 1-0) molecules in core b, which distributed in all the channels velocity, is different with one in core a and core c very much. The C 18 O( J = 1-0) molecules in core a and core c of the Cepheus C mostly distributed in the blue shifted channel velocity relating to peak velocity, and only in -10.0 ～ -9.5 km/s, which is the red shifted channel velocity relating to peak velocity. And the contour level of C 18 O( J = 1-0) in -10.0 ～ -9.5 km/s is small and the distrbution size in the channel map is small. According to the position velocity diagrams the asymmetry of the distribution both blue shifted and red shifted components should reflect the asymmetry of the profile. From the diagrams it also is found that the contour level and the distribution size of the three cores are different from each other. Both results from the maps and diagrams are coincident with each other.

关键词： Maps The Channel Maps and the Position-Velocity core Diagrams of Multi-core Structure of Cepheus C

Seasonal Variations Analysis of the Origin and Scale of International Terrestrial Reference Frame

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Seasonal Variations Analysis of the Origin and Scale of Inte...

Application of Compass Ionospheric Model in GNSS Positioning

第三届中国卫星导航学术年会

作者： LI Yan-yan1, SONG Shu-li2, ZHU Wen-yao2, ZHAO Juan11Department of Astronomy of Beijing Normal University, Beijing 100875, china*shanghai astronomical observatory, 80 Nandan Road, shanghai 200030, china 2shanghai astronomical observatory, chinese academy of sciences, shanghai 200030, china

Based on the time series of station coordinates provided by international SLR service （ILRS） over 1993-2011 using a set of global 92 ILRSA fiducial stations and by international VLBI service （IVS） over 1980-2009 using a set of global 113 VLBI fiducial stations, we generated a time series of the geocenter motion （GCM） and scale factor variations in terms of the network shift approach, which has been the longest and highest accurate one until now. Fourier analysis and wavelet analysis were employed to analyze the nonlinear variations of GCM and scale factor time series. The results indicate that the variations of GCM and scale are dominated by annual and semiannual motions, and show certain long periodic variations. The amplitude and phase of the annual and semiannual motions has certain changes in different years.

关键词： international terrestrial reference frame geocenter motion scale network shift approach

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Application of Compass Ionospheric Model in GNSS Positioning

第三届中国卫星导航学术年会

作者： Wu XiaoLi1Hu XiaoGong2 .Wang Gang1*Zhong HuiJuan3&Tang ChengPan21. Beijing Global Information Center of Application and Exploration, Beijing 100094, china 2. shanghai astronomical observatory, chinese academy of sciences, shanghai 200030, china 3. china Defense Science Technology Information Center, Beijing 100142, china

As an important component of a GNSS navigation message, ionospheric delay model parameters are broadcasted for single-frequency users to improve their positioning accuracy. GPS provides daily Klobuchar ionospheric model parameters based on geomagnetic reference frame, while the regional satellite navigation system of Compass broadcasts an eight-parameter ionospheric model generated by processing real data from continuous monitoring stations, which is updated every 2 hours. To evaluate model performance, model predictions are compared against real ionosphere measurements, along with positioning accuracy comparisons. Real data analysis indicates that the Compass ionospheric model provides higher correction precision in middle-latitude regions, but relatively lower correction precision for low-latitude regions where ionosphere possesses much more variability. Thanks to the constellation design of Compass, ionospheric model errors for some receivers manifest a common bias for in-coming GNSS signals from different satellites. Consequently, ionospheric model errors are somehow translated into the receivers’ clock error estimation, while have less influence on the positioning. Given that the chinese global navigation system will still rely on a domestic continuous monitoring network to provide global ionosphere correction service, the applicability of the ionospheric model in regions beyond china’s mainland is studied by applying the regional model to single-frequency positioning experiments of GPS. Real data analysis shows that in the northern hemisphere areas including Asia, Europe and North America, compared with the GPS single-frequency positioning using Klobuchar model for ionospheric delay corrections, the three-dimension position accuracy is improved by 7.8% 35.3% by using the Compass model. But the positioning accuracy in the southern hemisphere is degraded by 9.5%3.5% due to the lack of monitoring stations there.

关键词： ionospheric model regional satellite navigation system model error positioning error

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基于DSP的氢钟高精度控制系统

数据采集与处理 2009年第B10期24卷 323-327页

作者：曲豹创陈从颜刘铁新邱实东南大学空间科学技术研究院南京210096 中国科学院上海天文台上海200030

介绍了基于数字信号处理器(DSP)应用于被动型氢钟中的伺服控制系统,针对晶振控制电压精度高和控制范围大的特点,设计了高精度电压输出和高速误差采集电路,并在硬件的基础上完成了软件驱动程序、主程序开发和数字式PID控制算法设计。硬... 详细信息

介绍了基于数字信号处理器(DSP)应用于被动型氢钟中的伺服控制系统,针对晶振控制电压精度高和控制范围大的特点,设计了高精度电压输出和高速误差采集电路,并在硬件的基础上完成了软件驱动程序、主程序开发和数字式PID控制算法设计。硬件测试的结果显示该控制系统满足了锁定过程控制要求,并取得了预期的控制效果。

关键词：氢钟控制系统晶振频率数字信号处理器

A Possible Origin of 6.7 GHz Linear Methanol Maser Sources

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chinese Journal of Astronomy and Astrophysics 2001年第5期1卷 389-394页

作者： Ye Xu (shanghai astronomical observatory, chinese academy of sciences, shanghai 200030) (Urumqi astronomical observatory, chinese academy of sciences, Urumqi 830011) (National astronomical Observatories, chinese academy of sciences, Beijing 100012) E-mail shanghai astronomical observatory Chinese Academy of Sciences Shanghai 200030 []Urumqi Astronomical Observatory Chinese Academy of Sciences Urumqi 830011 []National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

We present a model which explains the observed multi-linear spatial structures with different velocity gradients of the 50-61A+ methanol line at 6.7 GHz. We consider this and other hypotheses and conclude that the met... 详细信息

关键词： masers - stars: circumstellar matter - stars: formation

The Kiloparsec-scale Structure of 3C 286

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chinese Journal of Astronomy and Astrophysics 2004年第1期4卷 28-36页

作者： Tao An, Xiao-Yu Hong and Wei-Hua Wangshanghai astronomical observatory, chinese academy of sciences, shanghai 200030 National astronomical Observatories, chinese academy of sciences, Beijing 100012 shanghai astronomical observatory Chinese Academy of Sciences Shanghai 200030 []National Astronomical Observatories Chinese Academy of Sciences Beijing 100012

We present radio images of the compact steep spectrum (CSS) quasar 3C 286 acquired with the Very Large Array (VLA) at 8.4 and 22.5 GHz. The source exhibits a two-sided core-jet structure with a bright central component and two extended components one to the east (P.A. 100°) and another to the southwest (P.A. - 116°). From the compact core, an extension runs towards the southwest component up to - 0.7 arcsecond. The emission between the primary central component and the southwest component exhibits a knotty structure. A gradual change of the jet position angles from -135° to -120° in the inner southwest jet suggests a local bend. The position angle changes of the major eastern components E2 and El suggest that the eastern jet likely follows a curved trace. The bends in the jet trace may be associated with a relativistic precession or some interaction between the jet and the ambient matter. A mean spectral index of a22.58.4- 0.76 (Xv Va) is estimated for the core component. Steep spectra are also obtained for the extended southwest component (2.6', P.A. -116°) and eastern component (0.8', P.A. 100°), with a22.58.4-0.88 and a22.58.4-1.79, respectively. The radio morphologies and spectral index distributions suggest that the core seen in our images is likely to be the beamed inner jet while the real nucleus is dimmed by it beaming away from us.

关键词： galaxy: quasar: individual - radio continuum: VLA

Decomposition of the X-ray waveform of soft gamma-ray repeaters during giant flares

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 249-251页

作者： XING Yi & YU WenFei shanghai astronomical observatory,chinese academy of sciences,shanghai 200030,china chinese Acad Sci Shanghai Astron Observ Shanghai 200030 Peoples R China

We have analyzed the observations of SGR 1806-20 and SGR 1900+14 during giant flares made with the Rossi X-ray Timing *** have studied the pulsating tail after the initial spike and decomposed the pulse waveform into separate components of *** found evidence for phase shifts of those *** is probably due to rapid geometrical changes in the magnetic field of the neutron star during giant *** phase shifts could be used to constrain the geometry of the magnetic field.

关键词： soft gamma-repeaters giant flare waveform decomposition