Broadening of lines of Be ii, Sr ii and Ba ii by collisions with hydrogen atoms and the solar abundance of strontium   总被引：1，自引：0，他引：1  

P. S. Barklem  B. J. O'Mara 《Monthly notices of the Royal Astronomical Society》2000,311(3):535-540

In a previous paper by the present authors the theory of Anstee and O'Mara for the broadening of spectral lines of neutral atoms by collisions with hydrogen atoms was extended to singly ionized atoms. In this paper we apply the method to the resonance and triplet lines of ionized strontium, the infrared triplet of ionized barium, and the resonance lines of ionized beryllium. Analysis of five lines of ionized strontium, previously regarded as too strong for an abundance analysis, and two lines of neutral strontium results in a solar abundance of strontium of log( N _Sr N _H)+12=2.92±0.05, which is entirely consistent with the meteoritic value.  相似文献   

谱线分析法测定ζAur型系统的 红巨星星风物质损失     

赵定烽 《天文学进展》2000,18(4):344-353

用双星技术（Binary-technique）的谱线分析方法来测定双星系统中的红巨星或红超巨星的星风物质损失率是目前最为精确的。扼要介绍了此类方法的一般原理以及在ζAur/VVCep双星系统的物质损失测量中的应用。同时介绍了该方法的最新进展,并展开与此有关的一些简要讨论。  相似文献   

世界核电工业发展与地理格局的初探   总被引：1，自引：0，他引：1  

郑晓非  张志全 《世界地理研究》2000,9(3):74-76,41

核电工业自本世纪50年代以来发展迅速,其发电量不断上升,且有与火电、水电并行发展的趋势。本文在论述世界核电工业发展的基本情况后,以核电大国法国为典型代表,分析了核电工业的地位和地域分布特点,初浅地总结了核电工业的地理空间格局。  相似文献   

地质灾害发生时间和空间的预测预报   总被引：16，自引：2，他引：14  

许强  黄润秋  向喜琼 《山地学报》2000,18(Z1):112-116

运用非线性科学的理论和方法,提出了一整套地质灾害预测预报的理论和方法,包括探索地质灾害发生前兆的加卸载响应比方法、地质灾害发生时间预测的协同学模型以及地质灾害区域预测评价的神经网络方法,并建立了基于GIS的地质灾害区域评价系统。同时,通过对向家坝水电站库区的崩滑地质灾害的统计分析,提出了地质灾害发生规模与发生频率间的幂律规则。  相似文献   

Optimal Design of TMD Under Long-Term Nonstationary Wave Loading   总被引：3，自引：0，他引：3  

李华军  蒋济同  曹宏生  稽春艳  Tomotsuka TAKAYAMA 《中国海洋工程》2000,14(1):25-32

—Traditionally,the use of a tuned mass damper(TMD)is to improve the surviability of the pri-mary structure under extraordinary loading environment while the design loading condition is describedby either a harmonic function or a stationary random process that can be fully characterized by a powerspectral density(PSD)function.Aiming at prolonging the fatigue life of an offshore platform,this studyconsiders an optimal design of TMD for the platform under long-term nonstationary loading due tolong-term random sea waves characterized by a probabilistic power spectral density(PPSD)function.Inprinciple,a PPSD could be derived based on numerous ordinary PSD functions;and each of them is treat-ed as realization of the corresponding PPSD.This study provides a theoretical development for theoptimal TMD design by minimizing the cost function to be the mean square value of the expectedlong-term response.A numerical example is presented to illustrate the developed design procedure.  相似文献   

一个土墩日珥的D3线光谱分析Ⅰ-D3线特征及其计算     

李可军  顾啸马  李秋莎  李建勇 《天文研究与技术》2000,(1)

198 4年 5月 5日太阳东边缘土墩日珥的Hα单色像和D3线被观测到了。D3发射线由两部分组成 :主成分和致宽成分。本文利用双层模型方法对该土墩日珥的 1 7条D3发射线成功地进行了计算 ,给出了D3线的计算结果。计算结果表明 :日珥的D3发射线主要由热的多普勒致宽和微观湍流致宽所致 ,其它致宽机制的作用可以忽略  相似文献   

Detection of a variable interstellar absorption component towards δ Orionis A     

R. J. Price  I. A. Crawford  M. J. Barlow 《Monthly notices of the Royal Astronomical Society》2000,312(3):L43-L48

Observations of δ Ori A made with the UHRF in its highest resolution mode ( R ≈900 000) have revealed the presence of a cool ( T _k350 K) variable absorption component at a heliocentric velocity of +21.3 km s⁻¹. The component is detected in Na  i D₁, where clear hyperfine splitting is seen, and Ca  ii K. Comparison of our data with existing spectra suggests that the component has consistently increased in strength from 1966 to 1994, and subsequently reduced in intensity by 1999. Following a discussion of the possible origins of this component it is concluded that an interstellar, rather than circumstellar, origin is most likely. This is one of very few detections of variable interstellar absorption reported in the literature, and we suggest an origin within filamentary material associated with the expanding H  i shell surrounding the Orion–Eridanus superbubble.  相似文献   

Theoretical values for the [O iii] 5007/4959 line-intensity ratio and homologous cases     

P. J. Storey  C. J. Zeippen 《Monthly notices of the Royal Astronomical Society》2000,312(4):813-816

The magnetic-dipole probabilities for the ¹D₂–³P₂ and ¹D₂–³P₁ transitions in carbon-like and oxygen-like ions are calculated up to atomic number Z =12, including relativistic corrections to the magnetic dipole operator. The ratio of the probabilities for these two transitions is found to change by up to 5 per cent compared with previous theoretical work, none of which included these relativistic corrections, with the effect being largest for the near neutral ions. The transition probability ratio for the [O  iii ] 5007 and 4959 Å lines is found to be 3.01, implying an intensity ratio of 2.98, in significantly better agreement with the observed ratio than the earlier theoretical work.  相似文献   

Effects of Kerr space–time on spectral features from X-ray illuminated accretion discs     

A. Martocchia  C  V. Karas  G. Matt 《Monthly notices of the Royal Astronomical Society》2000,312(4):817-826

We performed detailed calculations of the relativistic effects acting on both the reflection continuum and the iron line from accretion discs around rotating black holes. Fully relativistic transfer of both illuminating and reprocessed photons has been considered in Kerr space–time. We calculated overall spectra, line profiles and integral quantities, and present their dependences on the black hole angular momentum. We show that the observed EW of the lines is substantially enlarged when the black hole rotates rapidly and/or the source of illumination is near above the hole. Therefore, such calculations provide a way to distinguish between different models of the central source.  相似文献   

The southern active-chromosphere star HD 6628     

L. C. Watson  J. B. Hearnshaw  K. R. Pollard  P. M. Kilmartin  A. C. Gilmore 《Monthly notices of the Royal Astronomical Society》2000,315(1):69-76

The star HD 6628, heretofore classified as a G5 subgiant, is shown to be a chromospherically active single-lined spectroscopic binary with a period of 27.332±0.008 d. From high-resolution spectra, the system is found to consist of a late F-type dwarf and an active G8–K1 bright subgiant, the latter having a rotation period of not more than 14.8±3.8 d derived from the width of metal lines. Further stellar and orbital parameters are derived and presented.  相似文献