依巴谷星(104297)相对于伽里略卫星Callisto的CCD位置测量     

彭青玉  李自力 《天文学报》2002,43(1):84-89

１９９７年１１月１４日晚，在中国科学院云南天文台１米望远镜上用新安装的１０２４２ＣＣＤ观测到了木星的两颗伽里略卫星；Ｅｕｒｏｐａ和Ｃａｌｌｉｓｔｏ及一颗依巴谷星（星号为 １０４２９７）．当采用新的 ＪＰＬ ＤＥ４０５和 Ｓａｍｐｓｏｎ－Ｌｉｅｓｋｅ理论（Ｇ５）计算卫星的理论位置并相对于Ｃａｌｌｉｓｔｏ测量恒星位置时，视位置的观测值与计算值之差的平均值在赤经和赤纬方向分别为△α＝－０″０２９±０．″０１２，△δ＝０．″００５± ０．″０１１．这对应于平均观测历元（ＵＴ）：１９９７年１１月１４日１３时４３分５０秒．这一试验结果与 Ｃａｓａｓ等在同一时期内ＣＣＤ观测的结果有着很好的一致性 它反映了依巴谷星表体现的光学参考系与ＤＥ４０５体现的动力学参考系在观测历元具有较好的一致性．单次位置测定的标准误差在赤经赤纬方向分别为±０．″０５２和０．″０４７．这一精度明显优于 Ｃａｓａｓ等人发表的 Ｃａｌｌｉｓｔｏ的处理精度，并与目前国际上最好的伽里略卫星观测精度相当  相似文献   

Importance of soil surface characteristics on water erosion in a small grazed Sahelian catchment     

H. Karambiri  O. Ribolzi  J. P. Delhoume  J. Ducloux  A. Coudrain‐Ribstein  A. Casenave 《水文研究》2003,17(8):1495-1507

This study concerns the problem of water erosion in the Sahel. Surface water and sediment yields (suspended matter and bedload) were monitored for 3 years (1998–2000) at the outlet of a small grazed catchment (1·4 ha) in the northern part of Burkina Faso. The catchment consists of about 64% sandy deposits (DRY soil surface type), which support most of the vegetation, and about 34% of crusted bare soils (ERO soil surface type). The annual solid‐matter export is more than 90% suspended sediment, varying between 4·0 and 8·4 t ha^?1. The bedload represents less than 10% of soil losses. In a single flood event (10 year return period), the sediment yield can reach 4·2 t ha^?1. During the period studied, a small proportion (20 to 32%) of the floods was thus responsible for a large proportion (80%) of the solid transport. Seasonal variation of the suspended‐matter content was also observed: high mean values (9 g l^?1) in June, decreasing in July and stabilizing in August (between 2 and 4 g l^?1). This behaviour may be a consequence of a reorganization of the soil surfaces that have been destroyed by trampling animals during the previous long dry season, vegetation growth (increase in the protecting effect of the herbaceous cover) and, to a lesser extent, particle‐supply limitation (exhaustion of dust deposits during July). The particle‐size distribution in the suspended matter collected at the catchment outlet is 60% made up of clay: fraction ≤2 µ m. The contribution of this clay is maximum when the water rises and its kaolinite/quartz ratio is then close to that of the ERO‐type surfaces. This indicates that these surfaces are the main source of clay within the catchment. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

X-ray bursts from the source A1742-294 in the Galactic-center region     

A. A. Lutovinov  S. A. Grebenev  M. N. Pavlinsky  R. A. Sunyaev 《Astronomy Letters》2001,27(8):501-506

We present observations of the X-ray burster A1742-294 near the Galactic center with the ART-P telescope onboard the Granat observatory. The shape of its persistent spectra was described well by the model of bremsstrahlung from optically thin plasma, and it remained essentially unchanged over ～2.5 years of observations. We show that the mean interval between X-ray bursts from the source is several times shorter than assumed previously and that the burst profile itself depends on the flux during the burst. We analyze in detail the strong X-ray burst detected from this source on October 18, 1990, and construct the evolution curves of its luminosity and radiation temperature.  相似文献   

Seismic source representation in orthogonal functions     

D. W. Vasco 《Geophysical Journal International》1990,102(3):531-535

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Broadband X-ray spectrum of XTE J1550-564 during the outburst of 2003     

V. A. Aref’ev  M. G. Revnivtsev  A. A. Lutovinov  R. A. Sunyaev 《Astronomy Letters》2004,30(10):669-674

We present the INTEGRAL and RXTE X-ray observations of XTE J1550-564, a Galactic microquasar and a black hole candidate, during its outburst in the spring of 2003. The source during the outburst was in a canonical hard state, and its spectrum remained constant in both the rise and decay phases.  相似文献   

Observations of the transient X-ray pulsar KS 1947+300 by the INTEGRAL and RXTE observatories     

S. S. Tsygankov  A. A. Lutovinov 《Astronomy Letters》2005,31(2):88-97

We analyze the observations of the X-ray pulsar KS 1947+300 performed by the INTEGRAL and RXTE observatories over a wide (3–100 keV) X-ray energy range. The shape of the pulse profile was found to depend on the luminosity of the source. Based on the model of a magnetized neutron star, we study the characteristics of the pulsar using the change in its spin-up rate. We estimated the magnetic field strength of the pulsar and the distance to the binary.  相似文献   

On the analysis of light curves in asteroseismology     

David L. Mary 《Journal of Astrophysics and Astronomy》2005,26(2-3):283-292

We provide a detailed introduction to the main problems arising when analyzing light curves in asteroseismology. Attention is first paid to the signal model delivered by the pulsating stars and to the noise sources corrupting this model in photometric observations. The main pitfalls and ambiguities occurring in Fourier analysis are summarized and illustrated. Some classical, Least Squares (LS) based methods for spectrum analysis are analyzed and commented on from the point of view of ill-posed problems. The insight that can be gained from such analyses is discussed.  相似文献   

Searches for bright-rimmed clouds with IRAS point sources     

K. Sugitani  K. Ogura 《Astrophysics and Space Science》1995,224(1-2):571-572

We have carried out systematic surveys for small bright-rimmed clouds associated with IRAS point sources in/around HII regions. They are candidate sites for star formation due to radiation-driven implosion.  相似文献   

Cosmic Ray Acceleration Inside Molecular Clouds     

V. A. Dogiel  A. V. Gurevich  Ya. N. Istomin  K. P. Zybin 《Astrophysics and Space Science》2005,297(1-4):201-211

Acceleration of charged particles by neutral gas turbulence in giant molecular clouds is considered. The gamma-ray emission from these clouds is estimated. It is shown that molecular clouds can be the counterparts of some of unidentified sources.  相似文献   

Facies-controlled volcanic reservoirs of northern Songliao Basin, NE China     

WANG Pu-jun  HOU Qi-jun  SHU Ping  HUANG Yu-long  GUO Zhen-hua  LI Jin-long College of Earth Sciences  Jilin University  Changchun  Jilin  China Jilin Petroleum Company  Songyuan  Jilin  China Daqing Petroleum Company  Daqing  HeiLongjiang  China 《东北亚地学研究》2005,(Z1)

Volcanic rocks of the late Mesozoic are very important reservoirs for the commercial natural gases including hydrocarbon, carbon dioxide and rare gases in the northern Songliao Basin. The reservoir volcanic rocks include rhyolite, andesite, trachyte, basalt and tuff. Facies of the volcanic rocks can be classified into 5 categories and 15 special types. Porosity and permeability of the volcanic reservoirs are facies-controlled. Commercial reservoirs were commonly found among the following volcanic subfacies: volcanic neck (I1) , underground-explosive breccia (I3), pyroclastic-bearing lava flow (II3), upper effusive (III3) and inner extrusive ones (IV1). The best volcanic reservoirs are generally evolved in the interbedded explosive and effusive volcanics. Rhyolites show in general better reservoir features than other types of rocks do.  相似文献