束－等离子体不稳定性直接放大电磁波及其对太阳Ⅲ型爆的解释

弱磁化相对论电子束注入等离子体时，由非共振波粒相互作用激发的束－等离子体不稳定性可以直接放大电磁波，计算结果表明：在偏离共振条件的区域，电磁波仍可在较宽的频率范围被放大，并在每个共振峰下形成平台结构。随着谐波数的增高，增长率峰值逐渐变小，峰宽也变窄。本文还分析了电磁波的增长率随背景参数ω＿（ｐｅ）／Ω＿ｅ及高能电子的入射方向和辐射方向的变化规律，在典型的日冕条件下，此类不稳定性所放大的电磁波的增长率大小、带宽、方向性、偏振及谐波等性质，可以用来解释太阳Ⅲ型射电爆发现象，本文的研究亦可用来解释其他天体等离子体辐射。     

太阳运动IV型射电爆发的相干辐射模型

为解释太阳运动IV型射电爆发的相干辐射机制提出一个理论模型．从耀斑中产生的高能电子，可以被扩展上升的太阳磁流管俘获．在磁流管顶部，这些高能电子的速度分布形成为类束流速度分布，激发束流等离子体的不稳定性，并且主要直接放大O模电磁波．不稳定性增长率敏锐地依赖了日冕等离子体参数，fpe／fce和射束温度Tb，这能定性解释在太阳运动IV型射电爆发中观测到的高亮温度和高偏振度，以及宽频谱的特性．     

太阳运动Ⅳ型射电爆发的相干辐射模型

为解释太阳运动Ⅳ型射电爆发的相干辐射机制提出一个理论模型.从耀斑中产生的高能电子,可以被扩展上升的太阳磁流管俘获.在磁流管顶部,这些高能电子的速度分布形成为类束流速度分布,激发柬流等离子体的不稳定性,并且主要直接放大O模电磁波.不稳定性增长率敏锐地依赖了日冕等离子体参数fpe/fce和射束温度Tb,这能定性解释在太阳运动Ⅳ型射电爆发中观测到的高亮温度和高偏振度,以及宽频谱的特性.     

束—等离子体不稳定性直接放大电磁波及其对太阳III型爆的解释

弱磁化相对论电子束注入等离子体时，由非共振波粒相互作用激发的束－等离子体不稳定性可以直接放大电磁波。计算结果表明：在偏离共振条件的区域，电磁波仍可在较宽的频率范围被放大，并在每个共振峰下形成平台结构。随着谐波数的增高，增长率峰值逐渐变小，峰宽也变窄。本还分析了电磁波的增长率随背景参数ｗｐｅ／Ｑｅ及高能电子的入射方向和辐射方向的变化规律。在典型的日冕条件下，此类不稳定性所放大的电磁波的增长率大小、     

由束流不稳定性直接激发电磁波来解释太阳射电Ⅲ型爆发

本文在用MHD理论研究等离子体束流不稳定性时发现:在电子等离子体频率附近可以激发出宽频带电磁波,其时间尺度、方向性、相对带宽、偏振特性及谐波结构等理论预期,在典型的日冕参数下,和米波段太阳射电Ⅲ型爆发的观测结果基本吻合.这一机制还可避免经典的等离子体辐射理论中由Langmuir波转换成横电磁波的效率较低的主要困难.     

中等贫金属星的元素丰度分析

给出 １１颗中等贫金属星－１．３ ５［Ｆｅ／Ｈ］ ≤－０．６的观测资料,确定了这些样本星的恒星大气参数,得到了这些星中１４种元素的丰度．讨论了各类元素丰度比随金属丰度的变化。α元素（Ｍｇ、 Ｓｉ、 Ｃａ、 Ｔｉ）相对于铁均表现超丰,每一金属丰度处都存在不同程度的弥散．大部分的铁峰元素（Ｖ、Ｃｒ、Ｎｉ、Ｃｕ）也相对于铁超丰,不随［Ｆｅ／Ｈ］而变化,而［Ｍｎ／Ｆｅ］则随金属丰度的增加而增加．［Ｎａ／Ａｌ］在［Ｆｅ／Ｈ］＞－１．１的样本星中表现超车,在［Ｆｅ／Ｈ］＜－１．１的样本中却明显过贫．     

射电喷流中相对论电子束激发的不稳定性

本文作者用相对论电子束在等离子体中运动时的色散关系讨论了纵向传播的波模的稳定性，发现静电Ｌａｎｇｍｕｉｒ波和Ａｌｆｖｅｎ波是不稳定的，并计算了其增长率，而高频电磁模和硝声模是稳定的。相对论电子束激发的Ｌａｎｇｍｕｉｒ波和Ａｌｆｖｅｎ波的不稳定性可用于解释射电喷流中相间的热斑、粒子再加速、辐射机制以及能量传输问题。     

球状星团NGC4147基于依巴谷系统的自行和空间运动

王家骥等［１］曾得到球状星团ＮＧＣ４１４７的绝对自行为（－２．８２±０．４９,２．３７±０．４３）ｍａｓ／ｙｒ．但是,其中所用的参考星表是Ｂｒｏｓｃｈｅ等［２］１９８５年发表的结果,含有ＡＧＫ３星表的系统误差．在Ｄａｕｐｈｏｌｅ等［３］给出的２６个球状星团轨道远银心距（ａｐｏｇａｌａｃｔｉｃｄｉｓｔａｎｃｅ）与金属度［Ｆｅ／Ｈ］的关系图上,ＮＧＣ４１４７处于一个特殊的位置,即按照它的远银距（５２ｋｐｃ）,它的金属度［Ｆｅ／Ｈ］应该大于－２．０,但实际上只有－１．８３［４］．类似的问题在文［１］的…     

射电活动星系核相对论性束流Doppler因子的决定(I)3C273

目前决定射电活动星系核Ｄｏｐｐｌｅｒ因子δ的方法,主要是用均匀球状源模型的同步自康普顿机制（ＳＳＣ）关联射电和Ｘ射线（或光学）波段各一点的流量来定出δ．观测表明,此方法有较大的不足．本文发展了一种新方法,一方面将ＳＳＣ机制推广到非均匀情况,另一方面是用谱拟合代替点计算．我们首次用这种方法对３Ｃ２７３的Ｄｏｐｐｌｅｒ因子进行了推算．计算结果表明,３Ｃ２７３的多普勒因子δ～３１３．在假设喷流中非均匀成分和喷流整体的运动速度相同时,得到相对论性束流运动方向与视向的夹角θ～１５°．根据δ定出源的内禀亮温度约为５０×１０１０Ｋ,缓解了“康普顿灾变”的困难．由于非均匀模型比均匀模型更接近射电活动星系核中心致密子源的真实物理图象,有关参数由３Ｃ２７３的同时性和准同时性多波段观测定出,观测结果对ＳＳＣ机制提供了较好的支持,故理论和观测相符,由此确定的多普勒因子是更可信的．     

贫金属星的重元素丰度Ⅱ.细致的光谱分析

本文确定了贫金属矮星和亚巨星的重元素丰度，基于高分辨率高信噪比光谱得到２７颗样本星的锶，钇，锆，钡，镧，铈和铕丰度，主要结果为：（１）第一峰区元素锶－钇－锆显示了奇偶效应，在晕族星中钇相对于锶和锆过贫。（２）对［Ｆｅ／Ｈ］＞－２．５的恒星钇丰度为常数。（３）［Ｆｅ／Ｈ］＜１．７的样本星，随金属丰度减小钡过贫增加。（４）镧和铈相对于铁过贫。（５）在金属丰度－１．０＞［Ｆｅ／Ｈ］＞－２．０区间，铕表现     

A survey of orbits of co-orbitals of Mars

Many asteroids with a semimajor axis close to that of Mars have been discovered in the last several years. Potentially some of these could be in 1:1 resonance with Mars, much as are the classic Trojan asteroids with Jupiter, and its lesser-known horseshoe companions with Earth. In the 1990s, two Trojan companions of Mars, 5261 Eureka and 1998 VF₃₁, were discovered, librating about the L₅ Lagrange point, 60° behind Mars in its orbit. Although several other potential Mars Trojans have been identified, our orbital calculations show only one other known asteroid, 1999 UJ₇, to be a Trojan, associated with the L₄ Lagrange point, 60° ahead of Mars in its orbit. We further find that asteroid 36017 (1999 ND₄₃) is a horseshoe librator, alternating with periods of Trojan motion. This asteroid makes repeated close approaches to Earth and has a chaotic orbit whose behavior can be confidently predicted for less than 3000 years. We identify two objects, 2001 HW₁₅ and 2000 TG₂, within the resonant region capable of undergoing what we designate “circulation transition”, in which objects can pass between circulation outside the orbit of Mars and circulation inside it, or vice versa. The eccentricity of the orbit of Mars appears to play an important role in circulation transition and in horseshoe motion. Based on the orbits and on spectroscopic data, the Trojan asteroids of Mars may be primordial bodies, while some co-orbital bodies may be in a temporary state of motion.     

Equation of state and anisotropy of pressure of magnetars

Magnetars are the neutron stars with the highest magnetic fields up to 10¹⁵–10¹⁶ G. It has been proposed that they are also responsible for a variety of extra-galactic phenomena, ranging from giant flares in nearby galaxies to fast radio bursts. Utilizing a relativistic mean field model and a variable magnetic field configuration, we investigate the effects of strong magnetic fields on the equation of state and anisotropy of pressure of magnetars. It is found that the mass and radius of low-mass magnetars are weakly enhanced under the action of the strong magnetic field, and the anisotropy of pressure can be ignored. Unlike other previous investigations, the magnetic field is unable to violate the mass limit of the neutron stars.     

Estimation of the Time Scale of Merging of the Components of Contact Binaries of the W UMa Type

Time scales of the transition from contact binary systems of the W UMa type to single stars of the blue straggler type are estimated. A model of one-way mass transfer from the primary component to the companion inside a common envelope (Eggen et al.) and a model of a contact binary lying on the zero-age main sequence with a companion that is losing mass (F. van't Veer) are used to calculate these scales. The merging times of components were calculated for 304 contact systems of the W UMa type from the Catalog of Approximate Photometric and Absolute Elements of Eclipsing Variable Stars on a scale of loss of mass and orbital angular momentum due to magnetic braking, under the assumption of synchronization of the axial rotation and orbital revolution. On the basis of the resulting statistics, the characteristic merging scales are 0.4-0.6 and 0.5-0.7 Gyr, respectively, for the above two models. The results of a comparison with the work of other authors are discussed.     

淮河洪水的可公度性分析

分析了上两个世纪发生在淮河的洪水事件的可公度性，根据其可公度值及其黄金分割点指出1991年与2003年淮河洪水的不可避免，最后讨论了可公度性的局限及淮河洪水可公度值的可能机制。     

Flattening of galaxies of different morphological types in subclusters of Coma

This paper deals with the observed variation in the flattening of galaxies with the density of galaxies in the subclusters of Coma surrounding NGC 4889, NGC 4874, and NGC 4839 based on data from the Abastumani Combined Catalog of Galaxies. The mean values of the observed ratios of the diameters of the galaxies, as well as histograms of their distributions, indicate that in the central, dense regions of the subclusters within a volume of 0.5h ₇₅ ⁻¹ Mpc³, E and S0 type galaxies are close to spheroidal. A significant reduction in the mean values of the diameters of the galaxies in the subclusters is noted, regardless of their morphology relative to the galaxies in the halo of the Coma cluster. In the subclusters, spiral galaxies are found with a hydrogen deficit that is more than 5 times the hydrogen deficit in spirals within the halo of the cluster. According to their 3-D coordinates, most of the galaxies with a hydrogen deficit are located closer to the south-east edge of the subcluster surrounding NGC 4874 near an extended gas filament in the x-ray region. This may indicate that the subcluster is moving toward a central condensation of faint galaxies in the Coma cluster and a possible merger with it. __________ Translated from Astrofizika, Vol. 50, No. 3, pp. 355–368 (August 2007).     

基于STK的寿命末期GEO卫星轨道演化分析

地球同步轨道上的GEO卫星接近寿命末期时,星上的有效载荷和电子元器件等仍能正常应用,此时如果只做东西方向的位置保持,可以大幅度延长卫星的在轨工作寿命。简要介绍了引起GEO卫星轨道变化的主要摄动力,利用STK软件分析寿命末期GEO卫星的运动规律,并给出这类GEO卫星轨道演化的仿真分析流程,用以指导寿命末期GEO卫星的开发应用工作。     

The discovery of Segue 2: a prototype of the population of satellites of satellites

We announce the discovery of a new Milky Way satellite Segue 2 found in the data of the Sloan Extension for Galactic Understanding and Exploration (SEGUE). We followed this up with deeper imaging and spectroscopy on the Multiple Mirror Telescope (MMT). From this, we derive a luminosity of   M _v =−2.5  , a half-light radius of 34 pc and a systemic velocity of  ∼−40 km s⁻¹  . Our data also provide evidence for a stream around Segue 2 at a similar heliocentric velocity, and the SEGUE data show that it is also present in neighbouring fields. We resolve the velocity dispersion of Segue 2 as 3.4 km s⁻¹ and the possible stream as  ∼7 km s⁻¹  . This object shows points of comparison with other recent discoveries, Segue 1, Boo II and Coma. We speculate that all four objects may be representatives of a population of satellites of satellites – survivors of accretion events that destroyed their larger but less dense parents. They are likely to have formed at redshifts   z > 10  and are good candidates for fossils of the reionization epoch.     

Modeling of lightcurves of binary asteroids

We present a numerical method for inverting long-period components of lightcurves of asynchronous binary asteroids. Data of five near-Earth binary asteroids, (175706) 1996 FG₃, (65803) Didymos, (66391) 1999 KW₄, (185851) 2000 DP₁₀₇ and (66063) 1998 RO₁, for two of them from more than one apparition, were inverted. Their mutual orbits' poles and Keplerian elements, size ratios, and ellipsoidal shape axial ratios were estimated via this inversion. The pole solutions and size ratios for 1999 KW₄ and 2000 DP₁₀₇ are in a good agreement with independent estimates from radar measurements. We show that uncertainties of estimates of bulk densities of binary systems can be large, especially when observed on short arcs.     

Investigation of Times of Minima of Selected Early-Type Eclipsing Binaries

New precise times of minimum light for several early-type eclipsing binaries were obtained at three observatories. The changes of period of the following measured binaries are discussed: V1182 Aql, LY Aur, SZ Cam, FZ CMa, QZ Car, LZ Cen, V606 Cen, AH Cep and TU~Mus.