3C345中视超光速节点运动轨道的数学描述

本提出一种数学方法来描述类星体３Ｃ３４５中视超光速节点的运动轨道,它既可以描述内部节点的螺旋运动,又可以描述外产节点的直线运动。这种统一的描述方法可能对描述其它致密射电源中视超光速节点的 有用的,并有助于研究流量的内聚变化 。     

类星体3C345中的VLBI核心在运动吗?

在视超光速源3C345(类星体)中,有5个VLBI节点被观测到有视超光速运动,特别是其中靠近核心的两个节点C_4和C_5沿着不同的弯曲轨道运动.本文考虑这种双轨道运动是由于射电核心运动造成的可能性.利用现有资料,把观测到的C_4和C_5的运动,分解成射电核心的运动和它们沿着一条共同的轨道运动.结果表明,这种分解可以很好地拟合现有关于节点C_4和C_5的观测结果.对进一步的观测检验和模型的物理涵义作了扼要的讨论。     

视超光速射电节点的频谱演化:持续供能的喷流—激波模型

本文提出一个持续供能的喷流—激波模型来解释视超光速射电节点频谱演化的普遍特性．理论计算指出，射电爆发频谱的反转频率νm和频谱极大流量Sm之间的关系具有典型的3阶段演化方式，并且与类星体3C345中观测到的视超光速节点C4的演化行为相当好地符合．令Sm∝ν，则在上升阶段ζ≤3；在平坦变化阶段ζ≈0，而在衰减阶段ζ≈1．爆发幅度和流量极大的迟后时间对频率的关系△Smax（ν）和△t（ν），都具有Blazar天体中观测到的射电爆发的普遍形式．本文提出的激波模型，考虑到驱动气体的持续注入和激波后等离子体的绝热膨胀．因此提供了对相对论喷流中激波形成和演化的物理原因更深入的理解．并对Blazar天体中视超光速节点频谱演化提出了新的解释．     

视超光速运动的一个统计检验

本文利用文川提供的视超光速运动数据，对标准宇宙模型、相对论束模型及同步加速自康普顿散射机制在视超光速运动计算方面是否相容的问题进行统计检验．结果表明，理论预言与实际数据相吻合，上述诸理论是相容的，并且它们对视超光速运动的综合解释是合理的．     

视超光速源3C345中节点C4的内禀变化

本文利用新的相对论理论模型研究了视超光速源3C345中节点C4的内禀变化。     

M 87大尺度喷流的多波段研究

射电星系M87的大尺度喷流在射电、光学和X波段都已经具备高分辨率的成像观测和频谱观测。其各个节点的宽波段连续谱目前被认为是同步辐射主导的。文章采用相对论性电子同步辐射的Kardashev-Pacholczyk模型,对各节点的多波段连续谱进行了独立的最佳拟和,从而得到相应的多普勒因子。此外进一步结合各节点的视超光速运动的观测数据,导出了不同节点整体运动的Lorentz因子和对观测者的视角。计算结果表明,M87的大尺度喷流具有一定程度的弯曲,其整体动力学行为是减速的。     

量子远程通讯与超光速问题

论述量子远程通讯的最新成就很可能意味着自然界存在超光速的信息联系，狭义相对论又面临新的考验，若考虑虚数“i”的作用，狭义相对论可与物质的超光速运动相容，而且不违反因果律，即使自然界存在超光速的物质运行也不可能动摇狭义相对论，建议设计实验测量德布罗意波的相速度并深入研究波粒二象性。     

VLBI与视超光速源——(Ⅰ)观测手段与结果

类星体和活动星系核结构的变化及其中的视超光速运动,被认为是用VLBI方法所揭示的最重大的天体物理现象之一。十余年来积累了大量观测资料,迄今已经观测证实了不少于25个视超光速源,更广泛的监测和搜寻计划正在进行中。 本文从观测手段和结果两个方面,综述对视超光速源探测的方法及现状。在另一篇文章中将总结视超光速源的观测特征,以及为解释这些特征所作的有代表性而又较广为接受的理论探讨。     

百秒差距尺度上的4C39.25

通过主要在短厘米波长的全球VLBI观测,已经发现强射电类星体4C39.25在十秒差距尺度结构中的视超光速运动,其运动学图景表明该源是一个很特殊的视超光速源.近几年已提出了若干模型,试图解释这特殊的运动图景.报道不多的百秒差距尺度的VLBI观测,很可能有助于检验提出的模型.本文介绍用欧洲网及上海25m天线,在18cm波长对4C39.25所作的VLBI 成象观测的初步结果,显示百秒差距尺度复杂结构及可能存在的视超光速运动.     

视超光速运动的相对论超光速模型

从相对论出发，在视超光速源质心相对于观测者静止的条件下，推导出两个向相反方向运动的视超光速子源之间的视速度方程，这一方程包含了相对论射束模型的表现横向速度公式，且对高、低速不同条件均为适用。     

Determination of 3D Trajectories of Knots in Solar Prominences Using MSDP Data

In this paper we present a new method of restoration of the true three-dimensional (3D) trajectories of prominence knots using ground-based observations taken with a single telescope that is equipped with a Multi-Channel Subtractive Double Pass imaging spectrograph. Our method allows us to evaluate the true 3D trajectories of the prominence knots without any assumptions concerning the shape of the trajectories or the dynamics of the motion. The reconstructed trajectories of several knots observed in three prominences are presented.     

Is the VLBI core of 3C 345 moving?

In the superluminal source quasar 3C 345, five VLBI knots have been observed to have superluminal motion and, in particular, the two knots C₄ and C₅ move along different curved orbits. This paper examines the possibility that this pair of orbits are due to the motion of the radio core. Using the available data, the motions of C₄ and C₅ are resolved as a superposition of a motion of the core and a motion along a common orbit. The results show that such a resolution can fit well the observations. A brief discussion is made on further test of the model and its physical implications.     

Motions in a loop prominence

Motions of loop prominence knots have been studied on H-line filtergrams. By making use of contours of equal photographic density for entire cinegram it has been possible to significantly decrease the error in determining the locations of the knots. The method of mean velocities has been developed, which has permitted for the first time accurate determination of the laws of knot motion with sufficient accuracy. Two types of falling knots are distinguished: (1) those with a constant acceleration that is always below the gravitational acceleration, and (2) those with a constant velocity. The initial velocity of the falling knots is always different from zero. The gasdynamic theory has been developed to explain the deceleration of the two types of knots due to: the work done against the pressure force; pileup plasma raking; and shock-wave generation. The shock mechanism imparts a constant velocity to the motion. The temperature along the knot trajectories has been estimated. The ratio of the densities in the knots to the surrounding medium has been found.The aim of the present work is to gain new insight into the known observations of the motions in active prominences, in particular in the loop prominences, and to understand the reasons for the observed motions.A number of studies of prominence knot motions have been made using filter photographs (cinefilms). It seems to us, however, that the velocities (and especially acceleration) of individual knots have been determined within insufficient accuracy. It will be noted first of all that values of V(t) have been determined with a low accuracy by some authors even for high velocities (V 100 km s^–1). In fact, to achieve at least 10% accuracy in determining V by comparing two photographs obtained with a 30 s interval, it is necessary to measure the location of knots to 0.5 accuracy. The problem is the more complicated as the size of the knots can often reach 5 × 10. This is why the temporal dependence of the velocity of prominence knot motion is represented with a complicated curve.     

Proper motion measurements in various young stellar object jets in Taurus

We present proper motion measurements for a number of knots in the jets and bow shocks of the outflows from DG Tau, DG Tau B, T Tau, CoKu Tau 1, FS Tau, and FS Tau B in the nearby Taurus-Auriga star forming region. From these measurements and the available radial velocity data we derive tangential velocities, spatial velocities, angles of the outflows with respect to the plane of the sky, and in a couple of cases the pattern motions of the knots relative to the flow speed.     

Kinematics of a twisted surge

Using the H-alpha solar filtergrams taken at Kandilli Observatory, we have studied the motion of a twisted surge, from the kinematic point of view. We applied the Palu (1972) method to two knots of the twisted surge occurred at 10 November, 1967. The results are discussed.     

On the motion around the centre of mass of a viscously elastic sphere in the restricted elliptic three-body problem

In the restricted three-body problem we consider the motion of a viscously elastic sphere (planet) with its centre of mass moving in a conditionally-periodic orbit. The approximate equations describing the rotational motion of the sphere in terms of the Andoyer variables are obtained by the method of the separation of motion and averaging; the evolution of the motion is also analysed.     

Evidence for deceleration in the radio jets of GRS 1915+105?

There is currently a clear discrepancy in the proper motions measured on different angular scales in the approaching radio jets of the black hole X-ray binary GRS 1915+105. Lower velocities were measured with the Very Large Array (VLA) prior to 1996 than were subsequently found from higher resolution observations made with the Very Long Baseline Array and the Multi-Element Radio Linked Interferometer Network. We initiated an observing campaign to use all three arrays to attempt to track the motion of the jet knots from the 2006 February outburst of the source, giving us unprecedented simultaneous coverage of all angular scales, from milliarcsecond scales out to arcsecond scales. The derived proper motion, which was dominated by the VLA measurements, was found to be 17.0 mas d⁻¹, demonstrating that there has been no significant permanent change in the properties of the jets since 1994. We find no conclusive evidence for deceleration of the jet knots, unless this occurs within 70 mas of the core. We discuss possible causes for the varying proper motions recorded in the literature.     

Spectral study of the object HH12

Spectral studies of one of the brightest Herbig-Haro objects, HH12, using a multiaperture (multi-pupil) spectrograph are reported. We identify nine knots (densification nodes) in intensity diagrams. Hα emission mainly predominates in this object, except in two of the knots (C and M) which have a lower excitation level, given their high [SII] line intensity. The average electron temperature across the object is 6700 K. It is shown that the radial velocity of the object as a whole is low, i.e., its motion is mostly in the celestial plane. The excitation source for HH12 is also discussed. __________ Translated from Astrofizika, Vol. 49, No. 1, pp. 71–79 (February 2006).