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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 83.011) (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 time lag spectrum of Cir X-1 on its normal branch

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 60-63页

作者： QU JinLu1,LU Yu1,2,DING GuoQiang3,ZHANG Fan1,LEI YaJuan1 & LI ZhiBing1 1 Key Laboratory for Particle Astrophysics,Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,china 2 Graduate University of Chinese Academy of Sciences,Beijing 100049,china 3.urumqi observatory,naoc urumqi 83.011,china Key Laboratory for Particle Astrophysics Institute of High Energy Physics Chinese Academy of Sciences Beijing China Graduate University of Chinese Academy of Sciences Beijing China urumqi observatory NAOC Urumqi China

In the radiation-hydrodynamics model,the time lag and fractional root-mean-squared(rms) amplitude as a function of emitted photon energy should show a minimum on the normal branch *** has been seen in the Z-sources Cyg X-2 and GX ***,using the observations from the Rossi X-ray Timing Explorer(RXTE),we study the energy dependence of normal branch QPOs in the peculiar Z-source Cir *** discuss the results in the context of radiation-hydrodynamics and the Comptonization model.

关键词： Cir X-1 temporal variability QPO time lag

A mathematical method for the de-dispersion of the pulsar profile

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 228-230页

作者： YUAN JianPing1,2,WANG Na1,WU XinJi3 & ESAMDIN Ali1 1 urumqi observatory,National Astronomical Obsevatories,urumqi 83.011,china 2 Graduate University of the Chinese Academy of Sciences,Beijing 100049,china 3 Department of Astronomy,Peking University,Beijing 100871,china urumqi observatory National Astronomical Obsevatories Urumqi China Graduate University of the Chinese Academy of Sciences Beijing China Department of Astronomy Peking University Beijing China

This paper presents a mathematical method for de-dispersion of average pulsar *** applied this method to four dispersed pulsar *** results revealed that this method significantly removed the dispersion broadening and ... 详细信息

关键词： pulsar dispersion measure interstellar medium

Strong pulses from pulsar PSR J0034-0721

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Research in Astronomy and Astrophysics 2011年第8期11卷 974-980页

作者： Adili Tuoheti Ali Esamdin Hui-Dong Hu Guo-Liang Lv Na Wang Mamat Abliz Department of Physics Xinjiang University Urumqi 830046 China Xinjiang Astronomical observatory Chinese Academy of Sciences Urumqi 830011 China Xinjiang University-National Astronomical Observatories Joint Center For Astrophysics Urumqi 830046 China

We present an analysis of strong single pulses from PSR J0034-0721. Our observations were made using the urumqi 25-m radio telescope at a radio frequency of 1.54 GHz. A total of 353 strong pulses were detected during eight hours of observing, The signal-to-noise ratios of the detected pulses range from 5 to 11.5. The peak fluxes of those pulses are 17 to 39 times that of the average pulse peak. The cumulative distribution of the signal-to-noise ratios of these strong pulses has a rough power-law distribution with a slope of 4.4 q- 0.5. Ten of the strong pulses arrived approximately 23 to 40 ms earlier than the average profile peak. This suggests the possibility that there are two strong pulse-emitting regions.

关键词： pulsars: PSR J0034-0721 individual pulses: strong pulses

Statistical study of the pulse width distribution for radio pulsars

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 220-223页

作者： CHEN JianLing1,2,WANG Na1,YUAN JianPing1,2,WANG HongGuang3,YAN WenMing1,2 & LIU ZhiYong1 1 urumqi observatory,National Astronomical Obsevatories,Chinese Academy of Sciences,urumqi 83.011,china 2 Graduate University of the Chinese Academy of Sciences,Beijing 100049,china 3 Center for Astrophysics,Guangzhou University,Guangzhou 510006,china urumqi observatory National Astronomical Obsevatories Chinese Academy of Sciences Urumqi China Graduate University of the Chinese Academy of Sciences Beijing China Center for Astrophysics Guangzhou University Guangzhou China

Pulse widths of standard pulse profiles for 262 pulsars were measured by using the urumqi 25 m radio telescope at 1.54 *** the simplest case of circular emission beam,we applied Monte Carlo simulations to the pulse width *** density functions of magnetic inclination angle α and observer angle ξ were *** Kolmogorov-Smirnov tests,we derived the most probable distribution for α and ξ.

关键词： pulsar pulse width emission beam random distribution

The emission positions of kHz QPOs and Kerr spacetime influence

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Science china(Physics,Mechanics & Astronomy) 2010年第S1期53卷 114-116页

作者： ZHANG ChengMin1,WEI YingChun1,YIN HongXing1,ZHAO YongHeng1,LEI YaJuan2,SONG LiMing2,ZHANG Fan2 & YAN Yan3 1 National Astronomical Observatories,Chinese Academy of Sciences,Beijing 100012,china 2 Institute of High Energy Physics,Chinese Academy of Sciences,19B Yuquan Road,Beijing 100049,china 3.urumqi observatory,National Astronomical Observatories,CAS,urumqi 83.011,china National Astronomical Observatories Chinese Academy of Sciences Beijing China Institute of High Energy Physics Chinese Academy of Sciences Beijing China urumqi observatory National Astronomical Observatories CAS Urumqi China

Based the Alfven wave oscillation model(AWOM) and relativistic precession model(RPM) for twin kHz QPOs,we estimate the emission positions of most detected kHz QPOs to be at r=18+/-3 km(R/15 km),except Cir X-1 at r-30+/-5 km(R/15 km).For the proposed Keplerian frequency as an upper limit to kHz QPO,the spin effects in Kerr Spacetime are discussed,which have about a 5%(2%) modification for that of the Schwarzchild case for the spin frequency of 1000(400) *** application to the four typical QPO sources,Cir X-1,Sco X-1,SAX J1808.4-3658 and XTE 1807-294,is mentioned.

关键词： kHz QPO neutron star low-mass X-ray binaries

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 observatory, Chinese Academy of Sciences, Nanjing 210008, china 2 Graduate University of Chinese Academy of Sciences, Beijing 100012, china 3 Joint Center for Particle Nuclear Physics and Cosmology of Purple Mountain observatory-Nanjing University, Nanjing 210008, china Purple Mountain observatory 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 observatory-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

Scintillation Dynamic Spectra and Transverse Velocities ofSeven Pulsars

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Chinese Journal of Astronomy and Astrophysics 2001年第5期1卷 421-432页

作者： NaWang Xin－JiWu 等 urumqiAstronomicalobservatory NAO－CASUrumqi830011 DepartmentofAstronomy PekingUniversityBeijing1008

Using a pulsar timing system developed at urumqi Astronomical observatory's 25-m telescope, we observed scintillation dynamic spectra for seven pulsars at the relatively high frequency of 1540 MHz over a wide frequency band of 320 MHz. Averaging observations at different epochs, we obtain time scales and decorrelation bandwidths for diffractive scintillation and show that these imply a power-law index for the electron density fluctuation close to 4.0. Assuming this value and that the scattering disk is approximately midway between the pulsar and the earth, we compute transverse velocities for the seven pulsars. These values are generally in good agreement with the proper motion velocities.

关键词： pulsars: general ISM: general

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 China Graduate School of the Chinese Academy of Sciences Beijing China Joint Institute for Galaxy and Cosmology Shanghai Astronomical Observatory and the University of Science and Technology of China Shanghai 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