进动不规则性对SS433短周期现象的影响

本在献［１］的基础上考虑进动不规则性，采用改进的阻尼正弦模型来计算ＳＳ４３３短周期变化的振幅、周期和多普勒频移残差分布轮廓的理论曲线，并将此曲线和残差分布轮廓作方差分析进行比较。结果表明：（１）在进动不规则性情形下，短周期变化的周期没有变化，振幅有微小变化；（２）理论曲线和残差分布轮廓吻合较好，这说明残差分布轮廓与进动不规则性有关；（３）短周期现象中的拍仍然存在，只不过受到不同程度的畸变影响。     

SS433短周期变化中的拍现象

本文用喷流模型计算SS433短周期变化的周期和振幅值。讨论短周期变化叠加成拍的条件。用此条件判断,很自然地得出:在短周期变化中可能存在拍现象。对于喷流模型,在一个进动周期内其拍频为2。 文中还利用了Margon,B·等人的SS433多普勒频移图作SS433多普勒频移的残差分布图。在分布图中,某些进动周期内显示出分布轮廓有双峰结构,分析产生双峰的原因,正是与章动有关的、短周期变化中的拍现象。因此,在SS433的163天多普勒频移图上,观测点始终存在10％的弥散,乃是163天进动曲线与不能消除的短周期中的拍叠加的结果。 这样,本文从理论和实测分析上都证认了SS433短周期变化中存在拍现象的可能性。     

盾牌座δ型变星4CVn的多重非径向脉动振幅变化

对非径向脉动δＳｃｕｔｉ（盾牌座δ）型变星４ＣＶｎ的最新光电测光观测，证实了其振幅和周期的长期缓慢变化．两种多重频率分析方法都一致确认出已知７个频率中的５个（ｆ１，ｆ２，ｆ３，ｆ５，ｆ７）．观测还发现三个可疑频率．目前主频的振幅和十几年前的一样，基本保持不变，可能正处于向最大振幅变化的增加阶段或者处于刚过极大的下降段．其它四个频率的振幅都不同程度地变大．ｆ２，ｆ３和ｆ５的振幅增幅分别为６３％，２５％和１２０％，尤其是ｆ７，从上次的０变为０．００９ｍａｇ．频率分析显示除主频ｆ１几乎未变外，其它频率缓慢变化：ｆ２和ｆ７约减小０．０８％；ｆ３减小０．１４％；ｆ５增加０．０３％．用Ｂｌａｚｈｋｏ效应和不同非径向脉动模式之间的共振解释振幅和周期变化的合理性，尚需进一步从观测上检验．     

活动双星AR Lac的周期研究

用Ｋａｌｉｍｅｒｉｓ等人提出的分析周期新方法对ＲＳＣＶｎ型双星系统ＡＲＬａｃ的ＯＣ曲线进行分析,结果表明这颗食双星的轨道周期在长期减小的同时也含有周期为４７年、振幅为１．５６×１０－５天的周期性变化．对引起轨道周期变化（非周期性变化和周期性变化）的各种物理机制进行了分析研究,并求出了它们的关键性物理参量．研究表明该系统轨道周期的变化可能是由于次子星周期性的磁场活动和由磁滞引起的角动量损失引起     

华盛顿海军天文台天顶筒纬度观测残差与厄尼诺,南方涛动现象的相关性

厄尼诺、南方涛动是地球大气、海洋系统年际变化中最为显著的一种地球动力学运动。现在通常采用Ｔａｈｉｔｉ（１４８°Ｗ，１８°Ｓ）和Ｄａｒｗｉｎ（１３１°Ｅ，１２°Ｓ）两地海平面气压之差这一定量指标来刻划这一种大气、海洋系统的运动，简称为南方涛动指数ＳＯＩ。本文分析华盛顿海军天文台天顶筒１９３２－１９９１年间纬度观测的残差，证实它与ＳＯＩ在年际变化的频段内显著相关：最大相关系数达到０．６－０．７以上，但纬度残差的变化要滞后ＳＯＩ约２年时间。这很可能是一个证据，说明陆地部分的铬垂线变化与大气、海洋系统的大规模运动有关联。     

极移振幅和相位的时—频域统计分析

极移的各种周期变化与地球上的许多现象，如地震等，有某种紧密的联系。研究这些周期变化及其成因是相当重要的。利用新的观点来分析这 一经典问题。首先将复小波变换引入极移的研究之中，了解极移的复小波变换及各种周期变化。提出小波变换对数幅相图的概念，并对小波变换的振幅和相位的变化分别进行了分析。结果表明：极移的模值以及小波变换的模值都有某种周期的变化。小波变换尺度比较小时，可以描述短周期的变化；小波变换尺度大时可以描述较长周期的变化。     

Hale—Bopp彗星喷流结构的周期变化

通过对上海天台佘山观测基地１９９７年３月３至５月 初期间所得到的Ｈale－Ｂｏｐ ｐ彗星喷流观测流观测资料的处理和分析，发现该彗星的喷流结构有周期性变化，其周期为８－９天，这种周期变化可能与彗星的自转轴在空间的进动周期有关。     

日长年际变化的主要激发源

将年际时间尺度上的△ＬＯＤ序列（１９５８．０－１９９８．０）与大气角动量变化（纬向风）风的激发和ＳＯＩ等作比较,表明大气动力学过程是年际时间尺度△ＬＯＤ变化的重要激发源,在实测△ＬＯＤ、纬向风激发和ＳＯＩ中存在的一些相近的频率分量,但是,在实测△ＬＯＤ中有若干很强的信号（如平均周期约６．３年,平均振幅约０．１３ｍｓ的主要分量,以及平均周期约９．０年,平均振幅约０．０７ｍｓ的分量）在纬向风激发和ＳＯ     

地球自转极移近120天准周期变化的小波分析及其大气激发机制

本文利用小波变换这一新的频谱分析方法研究了地球自转极移近１２０天准周期变化的时频特征，证实了在极移序列中存在显著的近１２０天准周期振荡，得到了极移准周期变化的周期与振幅随时间变化的规律．以地球自转动力学为基础，在时域内分析了大气变化对自转极移季节内变化的激发．表明大气激发在本文所研究的频段内是极移短周期变化的主要激发源。并发现在极移近１２０天准周期振荡平静时期，发生ＥＬＮｉｎｏ事件，同时日长变化近１２０天准周期变化增强．     

地球自转速率的短周期项、大气环流和太阳活动

本文用AR谱分析方法分析了1976—1980年地球自转速率的资料和大气环流的资料,以及用调和分析计算了各周期项的振幅及相位,并计算了大气环流的激发函数。其结果说明:两者存在相应的周期项;北半球的大气环流对自转速率周年项的激励约为60％,对半年项及其他短周期项的贡献约为15％以上。本文对自转速率的不规则变化和太阳耀斑大爆发的关系作了定性的比较。     

On the precession of accretion discs in X-ray binaries

In this Letter, recent results on the nodal precession of accretion discs in close binaries are applied to the discs in some X-ray binary systems. The ratio between the tidally forced precession period and the binary orbital period is given, as well as the condition required for the rigid precession of gaseous Keplerian discs. Hence the minimum precessional period that may be supported by a fluid Keplerian disc is determined. It is concluded that near-rigid body precession of tilted accretion discs can occur and generally reproduce observationally inferred precession periods, for reasonable system parameters. In particular, long periods in SS 433, Her X-1, LMC X-4 and SMC X-1 can be fitted by the tidal model. It is also found that the precession period that has been tentatively put forward for Cyg X-2 cannot be accommodated by a tidally precessing disc model for any realistic choice of system parameters.     

Precession instability models of SS433

Several models are available to describe precession instability of SS433: 6- and 7-parameter models, sinusoidal and damped sinusoidal models etc. From the available observation data, it appears that 6- and 7-parameter models are most likely to be incorrect. We have analyzed and compared the sinusoidal and damped sinusoidal models in terms of figures of phase residual, and then proposed and improved a damped sinusoidal model. The data from the three models (sinusoidal, damped sinusoidal, and improved damped sinusoidal model) have been subjected to regression analysis for the purpose of determining the differences among the models.     

SS433研究的新进展

SS433是银河系内一个著名的高能天体,W50是它周围的超新星遗迹,自20世纪70年代末SS433的运动模型建立以来,已经受到了越来越多的关注,取得了丰富的多波段观测资料。但是,直到现在,关于这一系统的一些基本性质和参数还存在相当大的争论。该文介绍了关于SS433研究的某些新进展,主要包括SS433的运动模型和喷流的膨胀冷却模型,SS433的物质损失,各种时标的光变和喷流的结构,并对关于SS433研究的热点问题作了总结与展望。     

Three-dimensional hydrodynamical simulations of the large-scale structure of W50−SS433

We present 3D hydrodynamical simulations of a precessing jet propagating inside a supernova remnant (SNR) shell, particularly applied to the W50−SS433 system in a search for the origin of its peculiar elongated morphology. Several runs were carried out with different values for the mass-loss rate of the jet, the initial radius of the SNR, and the opening angle of the precession cone. We found that our models successfully reproduce the scale and morphology of W50 when the opening angle of the jets is set to 10° or if this angle linearly varies with time. For these models, more realistic runs were made considering that the remnant is expanding into an interstellar medium with an exponential density profile (as H  i observations suggest). Taking into account all these ingredients, the large-scale morphology of the W50−SS433 system, including the asymmetry between the lobes (formed by the jet–SNR interaction), is well reproduced.     

Determining the orientation and spin period of TOPEX/Poseidon satellite by a photometric method

We present the results of photometric observations of the TOPEX/Poseidon satellite performed during 2008–2016. The satellite become space debris after a failure in January, 2006, in a low Earth orbit. In the Laboratory of Space Research of Uzhhorod National University 73 light curves of the spacecraft were obtained. Standardization of photometric light curves is briefly explained. We have calculated the color indices of reflecting surfaces and the spin rate change. The general tendency of the latter is described by an exponential decay function. The satellite spin periods based on 126 light curves (including 53 light curves from the MMT-9 project operating since 2014) were taken into account. In 2016 the period of its own rotation reached its minimum of 10.6 s.A method to derive the direction of the spin axis of an artificial satellite and the angles of the light scattered by its surface has been developed in the Laboratory of Space Research of Uzhhorod National University. We briefly describe the “Orientation” program used for these purposes. The orientation of the TOPEX/Poseidon satellite in mid-2016 is given. The angle of precession β = 45°–50° and period of precession P _pr = 141.5 s have been defined. The reasons for the identified nature of the satellite’s own rotation have been found. They amount to the perturbation caused by a deviation of the Earth gravity field from a central-symmetric shape and the presence of moving parts on the satellite.     

Do superfluid instabilities prevent neutron star precession?

We discuss short wavelength (inertial wave) instabilities present in the standard two-fluid neutron star model when there is sufficient relative flow along the superfluid neutron vortex array. We demonstrate that these instabilities may be triggered in precessing neutron stars, since the angular velocity vectors of the neutron and proton fluids are misaligned during precession. Our results suggest that the standard (Eulerian) slow precession that results for weak drag between the vortices and the charged fluid (protons and electrons) is not seriously affected by the instability. In contrast, the fast precession, which results when vortices are strongly coupled to the charged component, is generally unstable. The presence of this instability renders the standard (solid body) rotation model for free precession inconsistent and makes unsafe conclusions that have recently been drawn regarding neutron star interiors based on observations of precession in radio pulsars.     

The proximity of Mercury's spin to Cassini state 1 from adiabatic invariance

In determining Mercury's core structure from its rotational properties, the value of the normalized moment of inertia, C/MR², from the location of Cassini 1 is crucial. If Mercury's spin axis occupies Cassini state 1, its position defines the location of the state, where the axis is fixed in the frame precessing with the orbit. Although tidal and core-mantle dissipation drive the spin to the Cassini state with a time scale O(¹⁰⁵) years, the spin might still be displaced from the Cassini state if the variations in the orbital elements induced by planetary perturbations, which change the position of the Cassini state, cause the spin to lag behind as it attempts to follow the state. After being brought to the state by dissipative processes, the spin axis is expected to follow the Cassini state for orbit variations with time scales long compared to the 1000 year precession period of the spin about the Cassini state because the solid angle swept out by the spin axis as it precesses is an adiabatic invariant. Short period variations in the orbital elements of small amplitude should cause displacements that are commensurate with the amplitudes of the short period terms. The exception would be if there are forcing terms in the perturbations that are nearly resonant with the 1000 year precession period. The precision of the radar and eventual spacecraft measurements of the position of Mercury's spin axis warrants a check on the likely proximity of the spin axis to the Cassini state. How confident should we be that the spin axis position defines the Cassini state sufficiently well for a precise determination of C/MR²? By following simultaneously the spin position and the Cassini state position during long time scale orbital variations over past 3 million years [Quinn, T.R., Tremaine, S., Duncan, M., 1991. Astron. J. 101, 2287-2305] and short time scale variations for 20,000 years [JPL Ephemeris DE 408; Standish, E.M., private communication, 2005], we show that the spin axis will remain within one arcsec of the Cassini state after it is brought there by dissipative torques. In this process the spin is located in the orbit frame of reference, which in turn is referenced to the inertial ecliptic plane of J2000. There are no perturbations with periods resonant with the precession period that could cause large separations. We thus expect Mercury's spin to occupy Cassini state 1 well within the uncertainties for both radar and spacecraft measurements, with correspondingly tight constraints on C/MR² and the extent of Mercury's molten core. Two unlikely caveats for this conclusion are: (1) an excitation of a free spin precession by an unknown mechanism or (2) a displacement by a dissipative core mantle interaction that exceeds the measurement uncertainties.     

Photometry of an active Algol-type binary HP Aur

The short period Algol-type binary HP Aur has been studied on the basis ofUBV photometric observations. Its colour indexes were found to be (U-B)=0.14, (B-V)=0.70, and light curves show non-symmetrical and obvious photometric disturbances. Autoregressive spectral analysis and harmonic analysis for its light variations were made. The results indicate its brightness variations have the multiplet quasi-periods and low amplitudes. Its photometric solutions have been obtained using the Wilson-Devinney method. Its mass ratio is 0.5631, orbital inclination is 85.0 and it is a detached system. Its basic model has been discussed briefly.     

古气候记录指示的天文周期分析

利用西峰市以西16km处的巴家嘴黄土剖面的上新世以来的（6.2-2.5MaB.P.）磁化率和粒重及太平洋深海沉积物资料，用不同的数据分析方法，不仅得到地球轨道主要参数中（对应于偏心率、交角和气候岁差）的0.1Ma、0.041Ma和0.023Ma几个天文周期，而且还得到了0.20Ma、0.15Ma、0.08Ma和0.06Ma其他周期，它们都在80%置信度水平以上，此外，通过小波变换表明，所有这些周期呈现出时变特性，随不同的地质年代增强或逐渐消失，这说明古气候的变化受多种古环境的影响所致，近来提出0.1Ma周期变化不但和地球轨道偏心率有关，而且可能和星际尘埃粒子沉降速率和青藏高原的隆升有着密切的关系。因此，地球轨道参数变化影响气候长期变化只是其中一种因素。