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Measuring the Distance of VX Sagittarii with SiO Maser Proper Motions

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Chinese Journal of Astronomy and Astrophysics 2007年第4期7卷 531-538页

作者： Xi Chen zhi-qiang shen Ye Xu Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 Department of Earth Sciences National Taiwan Normal University 88 Sec. 4 Ting-Chou Rd. Taipei 116 Taiwan

We report on 43 GHz v=1, J=1-0 SiO maser proper motions in the circumstellar envelope of the M-type semi-regular variable star VX Sgr, observed by Very Long Baseline Array （VLBA） at 3 epochs during 1999 April-May. Applying the statistical parallax analysis to these proper motions, we estimated a distance of VX Sgr of 1.57±0.27kpc, which is consistent with that based on the proper motions of H20 masers, or on the assumption that VX Sgr belongs to the Sgr OB1 association. At this distance, VX Sgr can be classified as a red supergiant. Comparing the statistical parallax method with those of model fitting and annual parallax, we think that the statistical parallax method may be a good way of estimating SiO maser distances at present.

关键词： methods: statistical - masers -stars: individual (VX Sgr)- stars: distances

A Composite Model for GHz Peaked Spectra of Radio Sources

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Chinese Journal of Astronomy and Astrophysics 2005年第6期5卷 563-570页

作者： Jun Yang Xiang Liu zhi-qiang shen National Astronomical Observatories/Urumqi Observatory Chinese Academy of Sciences Urumqi 830011 Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 Graduate University of the Chinese Academy of Sciences Beijing 100049

GHz-Peaked Spectrum （GPS） radio sources are powerful and compact sources with convex spectra. With increasing observational findings, it has been realized that either Synchrotron Self-Absorption （SSA） alone or Free-Free Absorption （FFA） alone is not enough to account for all the spectral features. We present a model consisting of an SSA region partially covered by FFA plasma, and derive a composite spectral formula. By applying the model to a sample of 19 GPS sources having strong absorption, it is found that the external FFA process makes the SSA peak frequency linearly shift to a higher （observed） peak frequency. The shift indicates that the FFA does play a role at the frequency close to the observed peak frequency.

关键词： radio continuum: galaxies -- galaxies: active -- quasars: general

Preface: Key technologies for enhancing the performance of FAST

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Research in Astronomy and Astrophysics 2020年第5期20卷 63-64页

作者： Peng Jiang zhi-qiang shen Ren-Xin Xu CAS Key Laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Department of Radio Science and Technology Shanghai Astronomical ObservatoryShanghai 200030China School of Physics and Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing 100871China

The Five-hundred-meter Aperture Spherical radio Telescope(FAST)passed its national acceptance inspection on 2020 January *** special issue includes a total of 15 papers,which are selected to introduce the status of FAST’s performance and demonstrate the key technologies applied to *** presented performance parameters can provide an important reference for scientists to propose observations with *** key technologies presented in these papers include design and implementation in the measurement and control system,electromagnetic compatibility system,and receiver ***,scientific achievements obtained by FAST during the commissioning phase are also reported.

关键词： telescope techniques:radar astronomy methods:data analysis methods:observational techniques:interferometric

Deformation measurement by single spherical near-field intensity measurement for large reflector antenna

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Research in Astronomy and Astrophysics 2021年第10期21卷 175-186页

作者： Qian Ye Bo-Yang Wang qiang Yao Jin-Qing Wang Qing-Hui Liu zhi-qiang shen Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China School of Mechanical Engineering Shanghai Jiao Tong UnversityShanghai 200240China

This paper presents a new method to obtain the deformation distribution on the main reflector of an antenna only by measuring the electric intensity on a spherical surface with the focal point as the center of the sphere,regardless of *** the differential geometry theory with geometric optics method,this paper has derived a deformation-intensity equation to relate the surface deformation to the intensity distribution of a spherical near-field *** on the finite difference method(FDM)and GaussSeidel iteration,deformation has been calculated from intensity simulated by geometrical optics(GO)and physical optics(PO)methods,respectively,with relatively small errors,which prove the effectiveness of the equation proposed in this *** means of this method,it is possible to measure the deformation only by scanning the electric intensity of a single hemispherical near-field whose area is only about 1/15 of the *** measurement only needs a plane wave at any frequency as the incident wave,which means that both the signals from the outer space satellite and the far-field artificial beacon could be used as the *** scanning can be realized no matter what attitude and elevation angle the antenna is in because the size and angle of the hemisphere are changeable.

关键词： telescopes waves line:profiles scattering

Seven-frequency VLBI Observations of the GHz-Peaked-Spectrum Source OQ 208

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Chinese Journal of Astronomy and Astrophysics 2007年第5期7卷 611-619页

作者： Wen-Feng Luo Jun Yang Lang Cui Xiang Liu zhi-qiang shen National Astronomical Observatories / Urumqi Observatory Chinese Academy of Sciences Urumqi 830011 Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai 200030 Graduate School of Chinese Academy of Sciences Beijing 100049 Joint Institute for Galaxy and Cosmology SHAO and USTC

We present quasi-simultaneous VLBI images of the GHz-Peaked-Spectrum radio source OQ 208 obtained with the Very Long Baseline Array at 1.4, 1.7, 2.3, 5.0, 8.4, 15.4 GHz and the European VLBI Network at 6.7 GHz. The low frequency （1.4, 1.7 and 2.3 GHz） observations reveal a weak and extended steep-spectrum component at about 30 mas away at position angle - 110°, which may be a remnant emission. The radio structure of OQ 208 consists of two mini-lobes at 5.0, 6.7, 8.4 and 15.4 GHz. Our spectral analysis further confirms that the southwest lobe undergoes free-free absorption and finds that the free-free absorption is stronger in the inner region. By fitting the 8.4 GHz images from 1994 to 2005, we obtain a separation speed of 0.0314-0.006 mas yr^-1 between the two mini-lobes. This indicates a jet proper motion of 0.1054-0.020 c and a kinematic age of 219±42 yr for the radio source.

关键词： galaxies individual (OQ 208) -- radio continuum galaxies

Observational characteristics of SiO masers around VX Sgr

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Research in Astronomy and Astrophysics 2020年第12期20卷 196-204页

作者： Jiang-Bo Su zhi-qiang shen Xi Chen Jing Liu Yan Wang Yi-Bin Zhao Department of Physics and Electronics Yuncheng UniversityYuncheng 044000China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China Center for Astrophysics Guangzhou UniversityGuangzhou 510006China

SiO maser VLBA observations toward VX Sgr are performed at five epochs, and lots of maser spots are obtained. We make a statistical analysis on these spots. It is shown that the apparent sizes and the fluxes of maser spots decrease with increasing the distance from the central star. In addition, the similarity between the v = 1,2(J =1–0) spectrums increases with epochs, consistent with the full width at half maximum(FWHM), while the total fluxes increase. The results may be related to the changeable pumping mechanisms.

关键词： masers stars:individual(VX Sgr) techniques:interferometric turbulence

Rapid Deformation Calculation for Large Reflector Antennas:A Surrogate Model Method

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Research in Astronomy and Astrophysics 2023年第1期23卷 4-17页

作者： Zi-Han Zhang Qian Ye Li Fu Jin-Qing Wang Meng Guo-Xiang zhi-qiang shen School of Mechanical Engineering Shanghai Jiao Tong UniversityShanghai 200240China Shanghai Astronomical Observatory Chinese Academy of SciencesShanghai 200030China

The surface accuracy of the large-aperture reflector antenna has a significant influence on the observation *** researchers have focused on using the finite element(FE)simulation to study the effect of gravity and heat on the deformation distribution of the main ***,the temperature distribution of the antenna is challenging to obtain,and it takes a long time for the FE simulation to carry out FE modeling and *** address these limitations,this study presents a surrogate model based on Extreme Gradient Boosting(XGBoost)and deep Convolutional Neural Network(CNN)to get the deformation distribution of the main reflector *** the design of the surrogate model,using the XGBoost algorithm and sparse sampling to solve the difficulty of obtaining the entire temperature distribution is first proposed,and then a deep CNN is developed for estimating *** on the effect of dynamic loads on the antenna structure,a diverse data set is generated to train and test the surrogate *** results show that the surrogate model reduces the calculating time dramatically and can obtain the indistinguishable deformation compared to the FE *** technique provides a valuable tool for temperature and deformation calculation of large-aperture antennas.

关键词： telescopes-methods analytical-methods numerical-methods data analysis

Roles of Nano-Domain Switching and Non-180° Domains in Enhancing Local Piezoelectric Responses of Highly （100）-Oriented Pb(Zr0.60Ti0.40)O3 Thin Films

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Chinese Physics Letters 2019年第10期36卷 86-89页

作者： Chen-Fei Jin Si-Qi Zhang zhi-qiang shen Wei-Li Li School of Physics Harbin Institute of TechnologyHarbin 150001 School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001

Ferroelectric Pb(Zr0.60Ti0.40)O3 thin films deposited on the niobium-doped SrTiO3 and Pt(111)/Ti/SiO2/Si substrates are fabricated by a sol-gel method.X-ray diffraction indicates that the films have a ’cube-on-cube’growth with highly(100)preferred orientation and good surface *** piezoelectric force microscopy,we investigate domain structures and butterfly amplitude loops of ferroelectric thin *** results indicate that the film deposited on Nb:SrTiO3 has both kinds of 180° polarizations perpendicular or parallel to the surface while the film deposited on Pt/Ti/SiO2/Si has irregular phase *** piezoelectric polarization are observed in the films on niobium-doped SrTiO3 with local d33* values around 45 pm/V three times more than that of the films around 13 pm/V deposited on Pt(111)/Ti/SiO2/Si. Our findings emphasize that nanodomain switching ability and non-180° domains will contribute significantly to enhance piezoelectric responses of ferroelectric thin films.

关键词： method. piezoelectric ferroelectric

One large glitch in PSR B1737-30 detected with the TMRT

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Research in Astronomy and Astrophysics 2019年第5期19卷 113-122页

作者： Jie Liu Zhen Yan Jian-Ping Yuan Ru-Shuang Zhao zhi-Peng Huang Xin-Ji Wu Na Wang zhi-qiang shen Shanghai Astronomical Observatory Chinese Academy of Sciences School of Physical Science and Technology ShanghaiTech University University of Chinese Academy of Sciences Key Laboratory of Radio Astronomy Chinese Academy of Sciences Xinjiang Astronomical Observatory Chinese Academy of Sciences School of Physics Peking University

One large glitch was detected in PSR B1737-30 using data spanning from MJD 57999 to 58406 obtained with the newly built Shanghai Tian Ma Radio Telescope(TMRT). The glitch took place at the time around MJD 58232.4 when the pulsar underwent an increase in the rotation frequency of △v about 1.38 × 10^(-6) Hz, corresponding to a fractional step change of △v/v～ 8.39 × 10^(-7). Post-glitch v gradually decreased to the pre-glitch value. The frequency derivative was observed to undergo a step change of about-9×10^(-16) s^(-2). Since July 1987, there have been 36 glitches already reported in PSR B1737-30 including this one. According to our analysis, the glitch size distribution is well described by a power law with an index of 1.13. The distribution of the interval between two adjacent glitches(waiting time △T) follows a Poisson probability density function. For PSR B1737-30, the interval is prone to be long after a large glitch. However, no correlation is found between glitch size and the interval since the previous glitch.

关键词： stars:neutron pulsars:general pulsars:individual:B1737-30