Parameters of the intense X-ray and gamma-ray radiation from the solar flare of May 20, 2002, as observed from the Coronas-F spacecraft     

A. V. Bogomolov  A. P. Ignat’ev  K. Kudela  S. N. Kuznetsov  Yu. I. Logachev  O. V. Morozov  I. N. Myagkova  S. N. Oparin  A. A. Pertsov  S. I. Svertilov  B. Yu. Yushkov 《Astronomy Letters》2003,29(3):199-204

We consider temporal, spectral, and polarization parameters of the hard X-ray and gamma-ray radiation observed during the solar flare of May 20, 2002, in the course of experiments with the SONG and SPR-N instruments onboard the Coronas-F spacecraft. This flare is one of the most intense gamma-ray events among all of the bursts of solar hard electromagnetic radiation detected since the beginning of the Coronas-F operation (since July 31, 2001) and one of the few gamma-ray events observed during solar cycle 23. A simultaneous analysis of the Coronas-F and GOES data on solar thermal X-ray radiation suggests that, apart from heating due to currents of matter in the the flare region, impulsive heating due to the injection of energetic electrons took place during the near-limb flare S21E65 of May 20, 2002. These electrons produced intense hard X-ray and gamma-ray radiation. The spectrum of this radiation extends up to energies ≥7 MeV. Intense gamma-ray lines are virtually unobservable against the background of the nonthermal continuum. The polarization of the hard X-ray (20–100 keV) radiation was estimated to be ≤15–20%. No significant increase in the flux of energetic protons from the flare under consideration was found. At the same time, according to ACE data, the fluxes of energetic electrons in interplanetary space increased shortly (～25 min) after the flare.  相似文献   

Building blocks in hierarchical clustering scenarios and their connection with damped Lyα systems     

Sofía A. Cora  Patricia B. Tissera †  Diego G. Lambas ‡  Mirta B. Mosconi 《Monthly notices of the Royal Astronomical Society》2003,343(3):959-970

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The fundamental plane of ellipticals – I. The dark matter connection     

Annamaria Borriello  Paolo Salucci  Luigi Danese 《Monthly notices of the Royal Astronomical Society》2003,341(4):1109-1120

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Lithium Abundances in the Atmospheres of SLR C-Giants WZ Cas and WX Cyg from Resonance and Subordinate Li I Lines     

Larisa A. Yakovina  Yakiv V. Pavlenko  Carlos Abia 《Astrophysics and Space Science》2003,288(3):279-286

Lithium abundances in the atmospheres of the super Li-rich C-giants WZ Cas and WX Cyg are derived by the spectral synthesis technique using the Li I resonance line at λ670.8 nm and three subordinate lines at λλ 812.6, 610.4 and 497.2 nm. The differences between the Li abundances derived from the λ670.8 nm line and the λλ 497.2, 812.6 nm lines do not exceed ±0.5 dex. The lithium line at λ610.4 nm provides typically lower abundances than the resonance line (by ≈ 1 dex). The mean LTE and NLTE Li abundances from three Li I lines (excluding λ610.4 nm) are 4.7, 4.9 for WZ Cas, and 4.6, 4.8 for WX Cyg, respectively. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

格网DEM中基于坡度信息的粗差检测与剔除方法试验     

韩玲 《地球科学与环境学报》2003,25(1):74-75

提出了一种基于格网DEM的粗差检测及剔除方法,其基本思想是对每个表面上的点,在坡度上,高程或突变量引起的形状不连续,可能被怀疑有误差,通过坡度上每个点,应用坡度逼近或改变量来计算,考虑坡度变化的相对值,并以这些相对值计算一个统计值为判断该点合法性的阈值,使计算结果更为可靠。  相似文献   

Detailed comparison of the structures and kinematics of simulated and observed barred galaxies     

J. K. O'Neill  John Dubinski 《Monthly notices of the Royal Astronomical Society》2003,346(1):251-264

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卫星星座与编队飞行问题综述   总被引：3，自引：0，他引：3  

胡松杰  王歆  刘林 《天文学进展》2003,21(3):231-240

卫星应用的日益发展需要由多颗卫星组成的卫星系统(形成各种类型的星座)来替代单颗卫星，这就给卫星轨道力学的应用增加了一些新内容。重点阐述了卫星星座整体结构的演化、卫星星座编队飞行中的星-星相对几何构形及其保持问题，以及星座卫星定轨所涉及的测控方式和天地基网联合定轨问题。这些内容都是卫星星座轨道力学中的重要组成部分。  相似文献   

Steady-state size distributions for collisional populations:: analytical solution with size-dependent strength     

David P. O'Brien  Richard Greenberg 《Icarus》2003,164(2):334-345

The steady-state population of bodies resulting from a collisional cascade depends on how material strength varies with size. We find a simple expression for the power-law index of the population, given a power law that describes how material strength varies with size. This result is extended to the case relevant for the asteroid belt and Kuiper belt, in which the material strength is described by 2 separate power laws—one for small bodies and one for larger bodies. We find that the power-law index of the small body population is unaffected by the strength law for the large bodies, and vice versa. Simple analytical expressions describe a wave that is superimposed on the large body population because of the transition between the two power laws describing the strength. These analytical results yield excellent agreement with a numerical simulation of collisional evolution. These results will help to interpret observations of the asteroids and KBOs, and constrain the strength properties of those objects.  相似文献   

The shape of the rotation curves of edge-on galaxies     

A. V. Zasov  A. V. Khoperskov 《Astronomy Letters》2003,29(7):437-446

We consider the effects of projection, internal absorption, and gas-or stellar-velocity dispersion on the measured rotation curves of galaxies with edge-on disks. Axisymmetric disk models clearly show that the rotational velocity in the inner galaxy is highly underestimated. As a result, an extended portion that imitates nearly rigid rotation appears. At galactocentric distances where the absorption is low (i.e., it does not exceed 0.3–0.5^m kpc^?1), the line profiles can have two peaks, and a rotation curve with minimum distortions can be obtained by estimating the position of the peak that corresponds to a higher rotational velocity. However, the high-velocity peak disappears in high-absorption regions and the actual shape of the rotation curve cannot be reproduced from line-of-sight velocity estimates. In general, the optical rotation curves for edge-on galaxies are of little use in reconstructing the mass distribution in the inner regions, particularly for galaxies with a steep velocity gradient in the central region. In this case, estimating the rotation velocities for outer (transparent) disk regions yields correct results.  相似文献   

The Orion nebula (M42) Herbig–Haro object, HH 201, within the tip of a molecular finger     

M. F. Graham  J. Meaburn  M. P. Redman 《Monthly notices of the Royal Astronomical Society》2003,343(2):419-426

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