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Spectroscopic study of globular clusters in the halo of M31 with the Xinglong 2.16 m telescope

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Research in astronomy and Astrophysics 2011年第11期11卷 1298-1310页

作者： Zhou Fan1,2.Ya-Fang Huang1,2.Jin-Zeng Li1,2.Xu Zhou1,2.jun ma1,2.Hong Wu1,2.Tian-Meng Zhang1,2.and Yong-Heng Zhao1,2.1 {2. astronomical Observatories,chinese academy of sciences.beijing 100012.china 2.key laboratory of optical astronomy,{2. astronomical Observatories,chinese academy of sciences.beijing 100012.china national astronomical Observatories Chinese Academy of Sciences Beijing 100012 China key laboratory of {2. astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China

We present spectroscopic observations for 11 confirmed globular clusters(GCs) of M31 with the OMR spectrograph on the 2.16 m telescope at the Xinglong site of national astronomical Observatories,{2. academy of *** of our sample clusters are located in the halo of M31 and the most remote one is out to a projected radius of 78.75 kpc from the galactic *** all our sample clusters,we measured the Lick absorption-line indices and radial *** is noted that most GCs in our sample are distinct from the HI rotation curve of galaxy M31,especially for B514,MCGC5,H12.and B517,suggesting that most of our sample clusters do not have a kinematic association with the star-forming young disk of the *** separately fitted the absorption line indices from the updated stellar population model of Thomas et *** two different tracks of Cassisi and Padova,by applying the χ2.minimization *** fitting results show that all our sample clusters are older than 10 Gyr,and metal-poor(2.38 ≤ [Fe/H] ≤ 0.91 dex).After merging the spectroscopic metallicity of our work with the previously published ones,we extended the cluster sample out to a projected radius of 117 kpc from the galaxy's *** found the metallicity gradient exists for all the confirmed clusters with a slope of 0.02. ± 0.001 dex kpc ***,the slope turns out to be 0.018 ± 0.001 dex kpc 1 for all the halo clusters,which is much *** we only consider the outer halo clusters with rp > 2. kpc,the slope becomes 0.010 ± 0.002.dex kpc 1 and if one cluster G001 is excluded from the outer halo sample,the slope is 0.004 ± 0.002.dex kpc ***,we conclude that the metallicity gradient for M31's outer halo clusters is not significant,which agrees well with previous findings.

关键词： galaxies individual(M31) — galaxies star clusters — globular clusters general — star clusters general

Can Asymmetry of Solar Activity be Extended into Extended Cycle?

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chinese Journal of astronomy and Astrophysics 2002年第1期2卷 66-70页

作者： Ke－junLi Jing－XiuWang 等 YunnanObservatory ChineseAcademyofSciencesKunming650011 nationalastronomicalObservatories ChineseAcademyofSciencesBeijing100012

With the use of the Royal Greenwich Observatory data set of sunspot groups, an attempt is made to examine the north-south asymmetry of solar activity in the 'extended' solar cycles. It is inferred that the asymmetry e... 详细信息

关键词： Sun: sunspot - Sun: active cycle - Sun: activity

An experimental indoor phasing system based on active optics using dispersed Hartmann sensing technology in the visible waveband

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Research in astronomy and Astrophysics 2011年第9期11卷 1111-1122页

作者： Yong Zhang Gen-Rong Liu Yue-Fei Wang Ye-Ping Li Ya-jun Zhang Liang Zhang Yi-Zhong Zeng Jie Zhang national astronomical Observatories / Nanjing Institute of astronomical Optics ＆ Technology Chinese Academy of Sciences Nanjing 210042 China key laboratory of {2. Optics ＆ Technology Nanjing Institute of Astronomical Optics ＆ Technology Chinese Academy of Sciences Nanjing 210042 China Graduate University of chinese academy of {2. Beijing 100049 China

A telescope with a larger primary mirror can collect much more light and resolve objects much better than one with a smaller mirror, and so the larger version is always pursued by astronomers and {2. technicians. Instead of using a monolithic primary mirror, more and more large telescopes, which are currently being planned or in construction, have adopted a segmented primary mirror design. Therefore, how to sense and phase such a primary mirror is a key issue for the future of extremely large optical/infrared telescopes. The Dispersed Fringe Sensor （DFS）, or Dispersed Hartmann Sensor （DHS）, is a non-contact method using broadband point light sources and it can estimate the piston by the two-directional spectrum formed by the transmissive grating＇s dispersion and lenslet array. Thus it can implement the combination of co-focusing by Shack-Hartmann technology and phasing by dispersed fringe sensing technologies such as the template-mapping method and the Hartmann method. We introduce the successful design, construction and alignment of our dis- persed Hartmann sensor together with its design principles and simulations. We also conduct many successful real phasing tests and phasing corrections in the visible waveband using our existing indoor segmented mirror optics platform. Finally, some conclusions are reached based on the test and correction of experimental results.

关键词： astronomical instrumentation -- methods and techniques -- instrumen- tation: active optics -- adaptive optics

Test observations that search for metal-poor stars with the Guoshoujing Telescope (LAMOST)

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Research in astronomy and Astrophysics 2010年第8期10卷 753-760页

作者： Hai-Ning Li Gang Zhao Norbert Christlieb A-Li Luo Jing-Kun Zhao Yong-Heng Zhao Jian-jun Chen Zhong-Rui Bai key laboratory of {2. astronomy National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Graduate University of chinese academy of {2. Beijing 100049 China Zentrum fur Astronomie der Universitat Heidelberg Landessternwarte Konigstuhl 12 69117 Heidelberg Germany

Metal-deficient stars are regarded as fossils of the early generation of stars and therefore make crucial observational targets related to stellar astrophysics. They provide fundamental information and insights on properties of the very early stage of the chemical history of the Galaxy and have been investigated for decades. The unique design of the Guoshoujing Telescope （LAMOST）, such as its large field and multi-object observational capability, enables it to be an excellent tool for searching for these metal-poor stars in the Milky Way. This work reports the result of test observations which search for metal-poor stars with LAMOST, during which nine candidate metal-poor stars with [Fe/H] ≤ - 1.0 were newly detected based on the low-resolution spectroscopic observations of the LAMOST commissioning data. The sample of stars demonstrates the efficiency of selecting from the input catalog, as well as the ability of LAMOST to enlarge the sample of metal-poor stars in the Milky Way. Furthermore, the sample of stars could be used for future calibrations of the LAMOST stellar pa- rameter pipeline.

关键词： Galaxy stellar content -- surveys -- stars Population Ⅱ

Development of a Front End Array for Broadband Phased Array Receiver

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Research in astronomy and Astrophysics 2024年第4期24卷 60-70页

作者： Kai Wang Liang Cao jun ma Xue-Feng Duan Hao Yan mao-Zheng Chen Yun-Wei Ning Xinjiang astronomical Observatory Chinese Academy of SciencesUrumqi 8300lChina University of the chinese academy of {2. Beijing 100049China Xinjiang key laboratory of Microwave Technology Urumqi 830011China

The receiver is a signal receiving device placed at the focus of the *** order to improve the observation efficiency,the concept of phased array receiver has been proposed in recent years,which places a small phased array at the focal plane of the reflector,and flexible pattern and beam scanning functions can be achieved through a beamforming *** combined with the element multiplexing,all beams within the entire field of view can be observed simultaneously to achieve continuous sky *** article focuses on the front-end array of phased array receiver at 0.7-1.8 GHz for QiTai Telescope,and designs a Vivaldi antenna array of PCB structure with dual line *** polarization antenna is designed to arrange in a rectangle manner by 11×*** on the simulation results of the focal field,32.18,and eight elements were selected to form one beam at 0.7,1.2.,and1.8 *** analog beamforming network was constructed,and the measured gains of axial beam under uniform weighting were 19.32.13.72.and 15.2. *** the beam scanning method of reflector antenna,the pattern test of different position element sets required for PAF beam scanning was carried out under independent *** pattern optimization at 1.2. GHz was carried out by weighting method of conjugate field *** with uniform weighting,the gain,sidelobe level,and main beam direction under conjugate field matching have been *** the above test and simulation results are slightly different,which is related to the passive array and laboratory testing condition,the relevant work has accumulated experience in the development of the front-end array for the phased array receiver,and has good guiding significance for future performance verification after the array is installed on the telescope.

关键词： telescopes instrumentation:detectors techniques:radar astronomy

Applying Hybrid Clustering in Pulsar Candidate Sifting with Multi-modality for FAST Survey

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Research in astronomy and Astrophysics 2024年第3期24卷 283-296页

作者： Zi-Yi You Yun-Rong Pan Zhi ma Li Zhang Shuo Xiao Dan-Dan Zhang Shi-jun Dang Ru-Shuang Zhao Pei Wang Ai-jun Dong Jia-Tao Jiang Ji-Bing Leng Wei-An Li Si-Yao Li School of Physics and Electronic Science Guizhou Normal UniversityGuiyang 550025China Guizhou Provincial key laboratory of Radio {2. and Data Processing Guizhou Normal UniversityGuiyang 550025China College of Big Data and Information Engineering Guizhou UniversityGuiyang 550025China CAS key laboratory of FAST National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China key laboratory of Infor{2.tion and Computing Guizhou Province Guizhou Normal UniversityGuiyang 550001China School of Big data and Computer Science Guizhou Normal UniversityGuiyang 550025China Guizhou Software Engineering Research Center Guiyang 550000China

Pulsar search is always the basis of pulsar navigation,gravitational wave detection and other research ***,the volume of pulsar candidates collected by the Five-hundred-meter Aperture Spherical radio Telescope(FAST)shows an explosive growth rate that has brought challenges for its pulsar candidate filtering ***,the multi-view heterogeneous data and class imbalance between true pulsars and non-pulsar candidates have negative effects on traditional single-modal supervised classification *** this study,a multi-modal and semi-supervised learning based on a pulsar candidate sifting algorithm is presented,which adopts a hybrid ensemble clustering scheme of density-based and partition-based methods combined with a feature-level fusion strategy for input data and a data partition strategy for *** on both High Time Resolution Universe SurveyⅡ(HTRU2.and actual FAST observation data demonstrate that the proposed algorithm could excellently identify pulsars:On HTRU2.the precision and recall rates of its parallel mode reach0.981 and 0.988 *** FAST data,those of its parallel mode reach 0.891 and 0.961,meanwhile,the running time also significantly decreases with the increment of parallel nodes within ***,we can conclude that our algorithm could be a feasible idea for large scale pulsar candidate sifting for FAST drift scan observation.

关键词： methods data analysis-surveys-methods numerical

Performance analysis of the mutual coupling effect on Phased Array Feeds

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astronomical Techniques and Instruments 2024年第4期1卷 211-217页

作者： Kai Wang maozheng Chen jun ma Hao Yan Liang Cao Xuefeng Duan Jiahui Li Xinjiang astronomical Observatory Chinese Academy of SciencesUrumqi 830011China University of chinese academy of {2. Beijing 100049China Xinjiang key laboratory of Microwave Technology Urumqi 830011China

A phased array feed(PAF)is a type of receiving array that places phased array antennas on the focal plane of a radio telescope to expand its field of view and improve observation *** to the mutual coupling effect between elements caused by a tightly arranged feed array,which changes the performance of a PAF,this paper presents a 7×7 rectangular feed array model for a 2. m reflector *** adjusting the element spacings,the performance of a PAF with different spacings is comprehensively analyzed with respect to the mutual coupling effect via performance statistics and *** research aims to provide a reference for the preliminary design of a related PAF.

关键词： Reflector antenna Focal field Phased array Beamforming Mutual coupling

Structure and Inclination Angle of the Spiral Galaxy M31

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chinese Physics Letters 2001年第10期18卷 1420-1422页

作者： ma jun national astronomical Observatories Chinese Academy of SciencesBeijing 100012 Joint laboratory of optical {2. Chinese Academy of SciencesBeijing 100012

The mathematical form, the symmetry of the spiral structure, and the projection of the galactic disc on the image of the spiral galaxy M31 have been directly studied. It is found that M31 has two symmetric arms, i.e. the pitch angles of the two arms are nearly equal;these are 7.7° and 8.0°, respectively. Using the method proposed in this letter, the inclination angle of the galactic disc ofM31 is also obtained, which is 77.5° and is in good agreement with previously published results.

关键词： M31 galactic galaxy

Intermediate-mass black holes in Green pea galaxies(IMBH-GP)I:A candidate sample from LAMOST and SDSS

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Science china(Physics,Mechanics & astronomy) 2024年第10期67卷 147-161页

作者： Ruqiu Lin Zhen-Ya Zheng Fang-Ting Yuan jun-Xian Wang Chunyan Jiang Ning Jiang Lingzhi Wang Linhua Jiang Xiang Ji Shuairu Zhu Xiaodan Fu key laboratory for Research in Galaxies and Cosmology Shanghai Astronomical ObservatoryChinese Academy of SciencesShanghai 200030China School of astronomy and Space sciences University of Chinese Academy of SciencesBeijing 100049China CAS key laboratory for Research in Galaxies and Cosmology Department of AstronomyUniversity of Science and Technology of ChinaHefei 230026China chinese academy of {2. South America Center for astronomy(CASSACA) National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China CAS key laboratory of {2. astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Kavli Institute for astronomy and Astrophysics Peking UniversityBeijing 100871China Department of astronomy School of PhysicsPeking UniversityBeijing 100871China

The scaling relation of central massive black holes(M_(BH)s)and their host galaxies is well-studied for supermassive BHs(SM_(BH)s,M_(BH)≥10^(6)M_(⊙)).However,this relation has large uncertainties in the mass range of the intermediate-mass BHs(IM_(BH)s,M_(BH)~10^(3)-10^(6)M_(⊙)).Since Green pea(GP)galaxies are luminous compact dwarf galaxies,which may be likely to host less massive SM_(BH)s or even IM_(BH)s,we systematically search for M_(BH)s in a large sample of 2.90 GP galaxies at zmass of 108.83±0.11M_(⊙)and hosts M_(BH)s with single-epoch virial masses ranging from M_(BH)~10^(4.7)to 10^(8.5)M_(⊙)(median 105.85±0.64M_(⊙)).Among the 59 M_(BH) candidates,36 have black hole masses M_(BH)≤10^(6)M_(⊙)(IM_(BH) candidates),one of which even has M_(BH)■10^(5)M_(⊙).We find that the M_(BH)-M_(*)relation of our M_(BH) sample is consistent with the M_(BH)-M_(bulge)relation for SM_(BH)s,while is above the M_(BH)-M_(*)relation for M_(BH)s in dwarf galaxies in the same mass ***,we show that 2. M_(BH) candidates,including 4 IM_(BH) candidates,have additional evidence of black hole activities,assessed through various methods such as the broad-line width,BPT diagram,mid-infrared color,X-ray luminosity,and radio *** studies show that it is very promising to find IM_(BH)s in GP galaxies,and the BH sample so obtained enables us to probe the connection between the M_(BH)s and compact dwarf galaxies in the low-redshift Universe.

关键词： SMBHs IMBHs Green pea galaxies compact dwarf galaxies