检索结果-南通市图书馆

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

在线全文

学校读者我要写书评

暂无评论

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.,Chinese Academy of Sciences,Beijing 100012.China 2.key {2. of optical astronomy,{2.,Chinese Academy of Sciences,Beijing 100012.China national astronomical observatories Chinese Academy of Sciences Beijing 100012 China key laboratory of {2. {2. 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,Chinese 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

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

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

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 Sciences 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

Can Asymmetry of Solar Activity be Extended into Extended Cycle?

在线全文

学校读者我要写书评

暂无评论

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 nationalastronomical{2. 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

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

在线全文

学校读者我要写书评

暂无评论

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. {2. National Astronomical Observatories Chinese Academy of Sciences Beijing 100012 China Graduate University of Chinese Academy of Sciences 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

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

在线全文

学校读者我要写书评

暂无评论

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

Structure and Inclination Angle of the Spiral Galaxy M31

在线全文

学校读者我要写书评

暂无评论

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

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

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 Sciences South America Center for astronomy(CASSACA) National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China CAS key laboratory of {2. {2. 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

The dusty and extremely red progenitor of the typeⅡsupernova 2.2.ixf in Messier 101

在线全文

学校读者我要写书评

暂无评论

Science China(Physics,Mechanics & astronomy) 2024年第1期67卷 160-172页

作者： Danfeng Xiang jun Mo Lingzhi Wang Xiaofeng Wang Jujia Zhang Han Lin Lifan Wang Department of Physics Tsinghua UniversityBeijing 100084China South America Center for astronomy National Astronomical ObservatoriesChinese Academy of SciencesBeijing 100101China Beijing Planetarium Beijing Academy of Sciences and TechnologyBeijing 100044China Yunnan observatories Chinese Academy of SciencesKunming 650216China key laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of SciencesKunming 650216China International Centre of Supernovae Yunnan Key LaboratoryKunming 650216China Mitchell Institute for Fundamental Physics and astronomy Texas A&M UniversityCollege StationTX 77843USA

Stars with initial masses in the range of 8-2. solar masses are thought to end their lives as hydrogen-rich supernovae(SNeⅡ).Based on the pre-explosion images of Hubble space telescope(HST)and Spitzer space telescope,we place tight constraints on the progenitor candidate of type IIP SN 2.2.ixf in Messier *** of the spectral energy distribution(SED)of its progenitor with dusty stellar spectral models results in an estimation of the effective temperature as 3091+*** luminosity is estimated as lg(L/L⊙)~4.83,consistent with a red supergiant(RSG)star with an initial mass of 12.1+2.⊙.The derived mass loss rate(6×10^(-6)-9×10^(-6)M⊙yr^(-1))is much lower than that inferred from the flash spectroscopy of the SN,suggesting that the progenitor experienced a sudden increase in mass loss when approaching the final *** the infrared bands,significant deviation from the range of regular RSGs in the color-magnitude diagram and period-luminosity space of the progenitor star indicates enhanced mass loss and dust *** with new evidence of polarization at the early phases of SN 2.2.ixf,such a violent mass loss is likely a result of binary interaction.

关键词： stellar evolution mass loss red supergiants infrared emission supernovae

在线全文

学校读者我要写书评

暂无评论

SAGE巡天介绍Ⅰ--测光系统和数据处理

天文学进展 2018年第2期36卷 101-121页

作者：范舟赵刚王炜赵景昆郑捷谈克峰刘玉娟何维宋轶晗姜晓军马路中国科学院光学天文重点实验室国家天文台北京100101 中国科学院大学天文与空间科学学院北京100049 中国科学院南美天文中心中智联合天文中心智利圣地亚哥7550000 中国科学院新疆天文台乌鲁木齐830011

SAGE(Stellar Abundance and Galactic Evolution)巡天采用一套对恒星大气参数敏感的独特测光系统,包括uSC,vSAGE,g,r,i,Hα_n,Hα_w和λ_(DDO51)(David Dunlap Observatory,DDO)共8个波段。该系统对恒星大气参数(有效温度T_(eff)、表面重力lg g和金属丰度[Fe/H])和星际消光的测量比传统的uvbyβ系统(Str?mgren-Crawford,SC)更敏感。由于g,r,i波段带宽较宽,因而观测效率较高,对恒星大气参数的测量精度和观测效率均超过uvbyβ系统和宽带测光系统。利用美国亚利桑那大学Steward天文台2.3 m Bok望远镜、新疆天文台南山1 m望远镜和乌兹别克斯坦maO(maidanak {2. Observatory)1 m望远镜已展开巡天观测。项目计划在约4年时间内完成所有的巡天观测,北天天区覆盖面积约12.00(~?)~2.高精度测光(信噪比为100σ)深度约15 mag(V波段);5σ探测极限可深至约2. mag(V波段)。最终将探测约5×108颗恒星,并得出其恒星大气参数以及星际消光。该样本比之前的u,v,b,y,β测光巡天,如GCS(Geneva-Copenhagen Survey)巡天和HM(Hauck and Mermilliod 1998)巡天,扩展到更深的区域,即深度达到7～8 mag(V波段)。利用观测得到的大样本恒星测光星表,可以开展如下课题的研究:(1)得到银河系约5×10~8颗恒星大样本的金属丰度分布,并根据恒星演化模型得到其年龄分布;(2.预期搜寻到一批贫金属星候选体,并利用其他望远镜进行下一步观测;(3)结合高质量的uSC波段数据,预期可以找到一批白矮星;(4)结合其他星表,预期找到一批长周期变源以及移动天体;(5)结合uSC波段数据和其他星表,预期可以找到一批类星体。

关键词：测光系统数据处理流量定标天测定标银河系结构