Emission lines of Fe xv in spectra obtained with the Solar Extreme-Ultraviolet Research Telescope and Spectrograph     

F. P. Keenan  K. M. Aggarwal  R. O. Milligan  R. S. I. Ryans  D. S. Bloomfield  V. Srigengan  M. G. O'Mullane  K. D. Lawson  A. Z. Msezane  J. W. Brosius  J. M. Davila  R. J. Thomas 《Monthly notices of the Royal Astronomical Society》2005,356(4):1592-1598

Recent R-matrix calculations of electron impact excitation rates in Mg-like Fe  xv are used to derive theoretical emission-line ratios involving transitions in the 243–418 Å  wavelength range. A comparison of these with a data set of solar active region, subflare and off-limb spectra, obtained during rocket flights by the Solar Extreme-Ultraviolet Research Telescope and Spectrograph (SERTS), reveals generally very good agreement between theory and observation, indicating that most of the Fe  xv emission lines may be employed with confidence as electron density diagnostics. In particular, the 312.55-Å  line of Fe  xv is not significantly blended with a Co  xvii transition in active region spectra, as suggested previously, although the latter does make a major contribution in the subflare observations. Most of the Fe  xv transitions which are blended have had the species responsible clearly identified, although there remain a few instances where this has not been possible. We briefly address the long-standing discrepancy between theory and experiment for the intensity ratio of the  3s^2 1S–3s3p ³P₁  intercombination line at 417.25 Å  to the  3s^2 1S–3s3p ¹P  resonance transition at 284.16 Å.  相似文献   

中国人居环境研究的总体特征及其知识图谱可视化分析   总被引：1，自引：0，他引：1  

王毅  陆玉麒  朱英明  丁正山 《热带地理》2020,40(3):498-514

基于CNKI、CSCD文献搜索引擎，以及文献计量可视化工具，采用传统文献研究与知识图谱相结合的方法，对1992—2017年中国人居环境研究的总体特征与知识图谱进行了定量识别和全景式展现。结果发现：1）近25年来，中国人居环境研究发文数量显著增长，《建筑学报》《城市规划》《城市发展研究》等期刊是学者的主要科研阵地；2）研究的优势机构和团队主要集中在中国科学院地理与资源研究所，以及辽宁师范大学、清华大学等其他建筑、规划类和师范类院校；3）研究经费多元化趋势明显，国家级基金是最主要的来源。4）在研究热点方面，人居环境、居住环境、宜居城市、人类环境、可持续发展、居住空间等是学者长期重点关注的热点词汇。5）在研究主题与知识基础方面，相关研究内容广泛，主题尚不集中，城市人居环境、宜居城市、居住环境、农村人居环境、自然适宜性、居住生活满意度、人居环境科学、人口发展是受到关注较多的8个热点主题，其知识基础建立在31篇经典文献之上。6）在具体演进轨迹方面，相关研究的知识结构呈连续发展且彼此联系紧密的态势，发展脉络较为清晰，并具有较强的问题导向性和政策导向性；社会经济发展的阶段性和动态性，问题或政策的学科发展导向，以及学者间的合作交流、学科间的交叉融合、技术方法的革新与应用等是其演进的主要驱动力。  相似文献   

Polarized radio emission from a magnetar     

M. Kramer  B. W. Stappers  A. Jessner  A. G. Lyne  C. A. Jordan 《Monthly notices of the Royal Astronomical Society》2007,377(1):107-119

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A systematic survey for infrared star clusters with |b| < 20° using 2MASS     

D. Froebrich  A. Scholz  C. L. Raftery 《Monthly notices of the Royal Astronomical Society》2007,374(2):399-408

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Periodic nulls in the pulsar B1133+16     

Jeffrey L. Herfindal  Joanna M. Rankin 《Monthly notices of the Royal Astronomical Society》2007,380(2):430-436

Numerous studies of the brightest Cambridge pulsar, B1133+16, have revealed little order in its individual pulses, apart from a weak 30-odd-rotation-period fluctuation feature and that some 15 per cent of the star's pulsars are 'nulls'. New Arecibo observations confirm this fluctuation feature and that it modulates all the emission, not simply the 'saddle' region. By replacing each pulse with a scaled version of the average profile, we were able to quench all subpulse modulation and thereby demonstrate that the star's 'null' pulses exhibit a similar periodicity. A subbeam carousel model with a sparse and irregular 'beamlet' population appears to be compatible with these characteristics.  相似文献   

Reflections on reflexions – I. Light echoes in Type Ia supernovae     

Ferdinando Patat 《Monthly notices of the Royal Astronomical Society》2005,357(4):1161-1177

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Intragroup diffuse light in compact groups of galaxies: HCG 79, 88 and 95     

C. Da Rocha  C. Mendes de Oliveira 《Monthly notices of the Royal Astronomical Society》2005,364(3):1069-1081

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The discovery of a massive supercluster at  z= 0.9  in the UKIDSS Deep eXtragalactic Survey     

A. M. Swinbank  A. C. Edge  Ian Smail  J. P. Stott  M. Bremer  Y. Sato  C. van Breukelen  M. Jarvis  I. Waddington  L. Clewley  J. Bergeron  G. Cotter  S. Dye  J. E. Geach  E. Gonzalez-Solares  P. Hirst  R. J. Ivison  S. Rawlings  C. Simpson  G. P. Smith  A. Verma  T. Yamada 《Monthly notices of the Royal Astronomical Society》2007,379(4):1343-1351

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Scale transformations, tree-level perturbation theory and the cosmological matter bispectrum     

Jun Pan  Peter Coles  István Szapudi 《Monthly notices of the Royal Astronomical Society》2007,382(4):1460-1464

Soon after the discovery of radio pulsars in 1967, the pulsars are identified as strongly magnetic (typically 10¹² G) rapidly rotating (∼10²− 0.1 Hz) neutron stars. However, the mechanism of particle acceleration in the pulsar magnetosphere has been a longstanding problem. The central problem is why the rotation power manifests itself in both gamma-ray beams and a highly relativistic wind of electron–positron plasmas, which excites surrounding nebulae observed in X-ray. Here we show with a three-dimensional particle simulation for the global axisymmetric magnetosphere that a steady outflow of electron–positron pairs is formed with associated pair sources, which are the gamma-ray emitting regions within the light cylinder. The magnetic field is assumed to be a dipole, and to be consistent, the pair creation rate is taken to be small, so that the model might be applicable to old pulsars such as Geminga. The pair sources are charge-deficient regions around the null surface, and we identify them as the outer gap. The wind mechanism is the electromagnetic induction which brings about fast azimuthal motion and eventually trans-field drift by radiation drag in the close vicinity of the light cylinder and beyond. The wind causes loss of particles from the system. This maintains charge deficiency in the outer gap and pair creation. The model is thus in a steady state, balancing loss and supply of particles. Our simulation implies how the wind coexists with the gamma-ray emitting regions in the pulsar magnetosphere.  相似文献   

A comparison of hydrodynamic techniques for modelling collisions between main-sequence stars     

Hy Trac  Alison Sills  Ue-Li Pen 《Monthly notices of the Royal Astronomical Society》2007,377(3):997-1005

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