International program of observations of selected minor planets: first results     

Yulia A. Chernetenko 《Celestial Mechanics and Dynamical Astronomy》2001,80(3-4):185-194

International programs of observations of selected minor planets have lasted about 50 years and the last one comes to the end in 2000. The main aim of these observational programs consists in obtaining the orientation of the stellar reference frame with respect to the dynamical one using observations of the bright minor planets. The observations are also useful for the orbital improvements of the asteroids themselves. They are available from the author via e-mail at the address .During the above mentioned period more than 23 000 observations of minor planets, referred to different reference star catalogues, have been obtained. The reduction procedure of observations to the PPM star catalogue is described. The orientation parameters are given and discussed.  相似文献   

Theoretical estimates of intrinsic galaxy alignment     

Jonathan Mackey  Martin White  Marc Kamionkowski 《Monthly notices of the Royal Astronomical Society》2002,332(4):788-798

It has recently been argued that the observed ellipticities of galaxies may be determined at least in part by the primordial tidal gravitational field in which the galaxy formed. Long-range correlations in the tidal field could thus lead to an ellipticity–ellipticity correlation for widely separated galaxies. We present a new model relating ellipticity to angular momentum, which can be calculated in linear theory. We use this model to calculate the angular power spectrum of intrinsic galaxy shape correlations. We show that, for low-redshift galaxy surveys, our model predicts that intrinsic correlations will dominate correlations induced by weak lensing, in good agreement with previous theoretical work and observations. We find that our model produces ' E -mode' correlations enhanced by a factor of 3.5 over B -modes on small scales, making it harder to disentangle intrinsic correlations from those induced by weak gravitational lensing.  相似文献   

平阳矾山明矾石矿床岩石学特征及其成因浅析     

王福生  兰翔  梁祥济 《浙江国土资源》1997,(1)

在野外地质工作的基础上，通过对浙江平阳研山明矾石矿床的岩石学及地球化学特征进行认真的研究，进一步证实了矾山明矾山矿床是酸性火山气热液与中酸性火山碎屑岩内的碱性长石的交代中形成的。为了解释矿床的均一性，成矿的周期性和矿床单向依变分带等重要特征，我们重点研究了矿床中明矾石化和叶蜡石化的热力学性质，得出了K 活度和pH值是控制交代产物的重要因素的新结论，提出了该矿床交代成矿作用的新模型，并据此成功地解释了矿床的一些重要特征。  相似文献   

Wolf-Rayet stars     

K. A. van der Hucht 《Astronomy and Astrophysics Review》1992,4(2):123-159

Summary Recent literature on Population I Wolf-Rayet star research extending from the Milky Way to blue compact dwarf galaxies is reviewed, broken down into inventory, basic parameters and galactic distribution, atmospheres, binaries, intrinsic variability, mass loss, enrichment and evolution. Also the incidence of Wolf-Rayet stars with variable non-thermal radio emission, excess X-ray fluxes, and episodic/periodic IR excesses is reviewed. These phenomena appear to be associated with wind-wind interaction in wide long-period WR+OB binaries and with wind-compact object interaction in WR+c binaries, with orbit sizes of the order of magnitude of the WR radio photosphere sizes or larger.  相似文献   

瞬变电磁法在断层含水性评价中的应用          下载免费PDF全文

郁万彩 《山东国土资源》2001,17(1):52-55

本文介绍了瞬变电磁法在煤矿水文地质勘探中的具体应用效果.采用瞬变电磁法对落差较大断层的含(导)水性进行测量,不仅可有效地控制断层的空间位置,而且可定性地判断断层的富水性,其测量结果与已知水文地质资料吻合较好.  相似文献   

The 2dF QSO Redshift Survey – VI. Measuring Λ and β from redshift-space distortions in the power spectrum     

P.J. Outram  Fiona Hoyle  T. Shanks  B.J. Boyle  S.M. Croom  N.S. Loaring  L. Miller  R.J. Smith 《Monthly notices of the Royal Astronomical Society》2001,328(1):174-184

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胜利油气区有机包裹体研究及其在油气勘探中的应用     

李荣西  金奎励  廖永胜 《地球科学与环境学报》1997,(4)

应用显微光度术、显微傅立叶红外光谱（Ｍｉｃｒｏ－ＦＴ．ＩＲ）和飞行时间二次离子质谱（ＴＯＦ－ＳＩＭＳ）等原位微分析技术并结合均一温度测量对胜利油气区下第三系沙河街组沙三段中有机包裹体进行了研究。区分出两类有机包裹体，即原生有机包裹体和次生有机包裹体。结果表明两类有机包裹体特征不同，二者物质组成、有机质成分及化学结构、热演化程度等差别也较大。结合地质分析表明原生有机包裹体是沙三段烃源岩生成烃类运移产物，具“自生自储”特点，而次生有机包裹体是沙四段烃源岩生成的烃类二次运移的产物。沙三段是沙河街组油气运移和聚集的主要层位，因而是寻找油气资源的主要目标层。研究表明，有机包裹体是研究油气生成、运移、聚集和演化等成藏系统最有效的手段之一，在油气勘探中有重要的应用意义。  相似文献   

The SuperCOSMOS Sky Survey – III. Astrometry     

N.C. Hambly  A.C. Davenhall  M.J. Irwin  H.T. MacGillivray 《Monthly notices of the Royal Astronomical Society》2001,326(4):1315-1327

In this, the third in a series of three papers concerning the SuperCOSMOS Sky Survey, we describe the astrometric properties of the data base. We describe the algorithms employed in the derivation of the astrometric parameters of the data, and demonstrate their accuracies by comparison with external data sets using the first release of data, the South Galactic Cap survey. We show that the celestial coordinates, which are tied to the International Celestial Reference Frame via the Tycho–2 reference catalogue, are accurate to better than ±0.2 arcsec at J , R ∼19,18 , rising to ±0.3 arcsec at J , R ∼22,21 , with positional-dependent systematic effects from bright to faint magnitudes at the ∼0.1-arcsec level. The proper motion measurements are shown to be accurate to typically ±10 mas yr⁻¹ at J , R ∼19,18 , rising to ±50 mas yr⁻¹ at J , R ∼22,21 , and are tied to zero using the extragalactic reference frame. We show that the zero-point errors in the proper motions are ≤1 mas yr⁻¹ for R >17 , and are no larger than ∼10 mas yr⁻¹ for R <17 mas yr⁻¹ .  相似文献   

The electron pressure in the outer atmosphere of ε Eri (K2 V)     

C. Jordan  S.A. Sim  A.D. McMurry  M. Aruvel 《Monthly notices of the Royal Astronomical Society》2001,326(1):303-312

Observations of ε Eri (K2 V) have been made with the Space Telescope Imaging Spectrograph on the Hubble Space Telescope . The spectra obtained show a number of emission lines which can be used to determine, or place limits on, the electron density and pressure. Values of the electron pressure are required in order to make quantitative models of the transition region and inner corona from absolute line fluxes, and to constrain semi-empirical models of the chromosphere. Using line flux ratios in Si  iii and O  iv a mean electron pressure of P _e= N _e T _e=4.8×10¹⁵ cm⁻³ K is derived. This value is compatible with the lower and upper limits to P _e found from flux ratios in C  iii , O  v and Fe  xii . Some inconsistencies which may be because of small uncertainties in the atomic data used are discussed.  相似文献   

抗差估计的初值选择     

王振杰  欧吉坤  曲国庆 《大地测量与地球动力学》2001,21(3):32-35

对L1 范估计的平差值和LS估计的平差值作为抗差估计的初值进行了比较 ,指出在 ρ函数是严凸函数时 ,二者无明显的区别。因为LS估计简单且易于计算 ,因此建议用LS估计的平差值作为抗差估计的初值。  相似文献