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。     

进动不规则性对SS433短周期现象的影响

本文在文献［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。     

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。     

Hale-Bopp 彗星喷流结构的周期变化

通过对上海天文台佘山观测基地１９９７年３月至５月初期间所得到的Ｈａｌｅ－Ｂｏｐｐ彗 星喷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．     

Her X-1 35天开关周期是由于中子星的自由进动产生的吗?(英文)

一些作者提出Her X-1的35天开关周期是由中子星的自由进动引起的。对这个模型我们进行了理论计算,并将理论结果和观测资料进行了比较,我们发现: (1)Hcr X-1的35天周期的光变曲线的理论值与观测(Jones ＆ Forman,1976)不符。 (2)在这个模型中脉冲宽度和强度随35天周期有很大的变化(见图4和图5),也与观测不符(如Gruber等人1980年的观测)。 (3)Parmar等人(1985)报道他们没有发现预期的Her X-1的X射线辐射35天周期的变化,这也同中子星自由进动的模型不一致。 Pravdo等(1977)建议观测到的X射线脉冲是由产生于中子星表面附近的、对称的辐射束经汤姆逊散射而形成。我们用强磁场中的汤姆逊散射理论所作的分析表明,该模型可以较好地与观测相符。     

α吸积盘与河外喷流的进动

本文考虑黑洞在其周围吸积盘驱使下进动的机制,得出进动周期对吸积率的依赖关系。这个结果与河外喷流的观测资料符合较好。     

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．     

平谱射电类星体B30307+380的15GHz射电光变分析

欧文斯谷射电天文台(Owens Valley Radio Observatory, OVRO)的长时间监测数据显示,平谱射电类星体B3 0307+380的15 GHz射电光变曲线中表现出多个爆发过程。基于双指数函数拟合12个爆发过程,得到了每个爆发过程的光变幅度和上升、下降时标,进而估算了亮温度T_b和光变多普勒因子δ_V。多普勒因子范围为(9.12±0.58)～(35.38±3.34),平均值■为18. 65±7. 11 (sd)。这个结果表明,此源的射电辐射存在明显的聚束效应,支持主流的相对论性喷流模型。利用Lomb-Scargle周期图方法和加权小波分析方法,探讨了B3 0307+380是否存在周期性光变,发现存在一个较高置信度( 99%)的约244天的周期,并简要讨论了周期存在的可能原因。     

费米耀变体的伽马辐射与发射线辐射的相关分析（英文）

在活动星系核的标准模型中,中心有一个超大质量黑洞,黑洞周围是一个吸积盘,喷流处在垂直于吸积盘的平面上。理论研究表明,喷流和吸积盘之间存在一定的联系,许多学者利用射电(或伽马)辐射与发射线辐射之间的相关性研究这种关系。然而,耀变体的射电或伽马辐射具有强烈的成束效应,使得在讨论喷流-吸积盘的联系时,应该考虑成束效应。收集了202个FERMI/LAT耀变体的宽发射线数据研究喷流与吸积的关系。202个源中,66个具有多普勒因子。对整个样本和平谱射电类星体与蝎虎座BL型天体2个子样本,分别研究了去除红移影响和成束放大效应时,伽马射线与宽发射线以及射电波段与宽发射线的相关关系,得到整个样本202个源的伽马射线与宽发射线以及射电波段与宽发射线之间存在强的正相关,而且这种相关性在去除红移效应之后仍然存在。对于66个有多普勒因子的源,在去除多普勒因子的影响之后,伽马射线与宽发射线以及射电波段与宽发射线之间仍然存在正相关。分析结果表明:(1)整个样本和各个子类的伽马射线与宽发射线之间都存在强相关。这些相关性在红移效应去除后仍然存在,并且证实了文献中他们所研究的结果。(2)对于66个有多普勒因子的耀变体,宽发射线与多普勒因子之间存在强的相关性,伽马射线与宽发射线在去除多普勒因子的影响之后存在相关性。在射电和宽发射线之间也得到了类似的结果。(3)吸积过程与喷流之间存在强关联性。     

Peculiar nature of hard X-ray eclipse in SS433 from INTEGRAL observations

The analysis of hard X-ray INTEGRAL observations (2003–2008) of superaccreting Galactic microquasar SS433 at precessional phases of the source with the maximum disc opening angle is carried out. It is found that the shape and width of the primary X-ray eclipse are strongly variable, suggesting additional absorption in dense stellar wind and gas outflows from the optical A7I component and the wind–wind collision region. The independence of the observed hard X-ray spectrum on the accretion disc precessional phase suggests that hard X-ray emission (20–100 keV) is formed in an extended, hot, quasi-isothermal corona, probably heated by interaction of relativistic jet with inhomogeneous wind outflow from the precessing supercritical accretion disc. A joint modelling of X-ray eclipsing and precessional hard X-ray variability of SS433 revealed by INTEGRAL by a geometrical model suggests the binary mass ratio   q = m_x / m _v ≃  0.25–0.5. The absolute minimum of joint orbital and precessional  χ²  residuals is reached at   q ≃ 0.3  . The found binary mass ratio range allows us to explain the substantial precessional variability of the minimum brightness at the middle of the primary optical eclipse. For the mass function of the optical star   f _v = 0.268 M_⊙  as derived from Hillwig & Gies data, the obtained value of   q ≃ 0.3  yields the masses of the components   m_x ≃ 5.3 M_⊙, m _v ≃ 17.7 M_⊙  , confirming the black hole nature of the compact object in SS433.     

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.     

Relativistic dispersion effects on SS433 jets

We here investigate the dispersion properties of radiation in the SS433 relativistic jets. We assume that the jet is composed of cold electron-proton plasma immersed in a predominantly parallel magnetic field to the jet axis. We find that for the mildly relativistic source SS433 (for which 〈ψ〉≃79°), the bulk velocity is too small (v≃0.26c) to produce significant changes in the dispersion properties of the medium. Nonetheless, in the rarefied outer regions of the jets, where radio emission dominates, even a weak magnetic field has some influence on the dispersion properties and there appear two different electromagnetic branches that are slightly sensitive to the bulk relativistic motion. In the inner, X-ray region, the magnetic field is much stronger, but in this region the high electron density preserves the isotropic character of the local plasma and no branch separation occurs. In the region of the jet where the IR and optical emission dominates, the cold plasma may be also considered isotropic, i.e., neither the magnetic field nor the bulk velocity is able to affect the propagation of the radiation. Finally, we find that the Doppler line displacement in SS433 is affected by plasma dispersion only in a narrow frequency range in the far IR. As a consequence, although the shift (z) modulation due to precession of the SS433 jets is well described by previous work, it has to be corrected by plasma dispersion effects in the far-IR range.     

Superbroad component in emission lines of SS 433

We have detected new components in stationary emission lines of SS 433; these are the superbroad components that are low-contrast substrates with a width of 2000–2500 km s^?1 in He I λ4922 and Hβ and 4000–5000 kms^?1 in He II λ4686. Based on 44 spectra taken during four years of observations from 2003 to 2007, we have found that these components in the He II and He I lines are eclipsed by the donor star; their behavior with precessional and orbital phases is regular and similar to the behavior of the optical brightness of SS 433. The same component in Hβ shows neither eclipses nor precessional variability. We conclude that the superbroad components in the helium and hydrogen lines are different in origin. Electron scattering is shown to reproduce well the superbroad component of Hβ at a gas temperature of 20–35 kK and an optical depth for Thomson scattering τ ≈ 0.25?0.35. The superbroad components of the helium lines are probably formed in the wind from the supercritical accretion disk. We have computed a wind model based on the concept of Shakura-Sunyaev supercritical disk accretion. The main patterns of the He II line profiles are well reproduced in this model: not only the appearance of the superbroad component but also the evolution of the central two-component part of the profile of this line during its eclipse by the donor star can be explained.     

Possible origin of the radio emission from SS433 jets

It is shown that radio emission from the jet of the galactic source SS433 as well as the variability of its flux density could be accounted for by the inelastic collision model. Variability in the jet flux is attributed mainly to the variability in the thermal proton number density available in the jet regions.     

The Supercritical Accretion Disk of SS 433

The structure of the SS 433 supercritical accretion disk derived from spectral and photometric data is described. In the disk plane, gas outflows at a velocity of about 100-150 km/s, while above the disk plane, the velocity increases sharply and reaches 1500 km/s at polar angle 60°. The outer parts of the accretion disk are involved in the precessional motion, which means that the slaved disk precession model is correct. There is complex periodic variability in the radial velocities of SS 433. Apart from the well-known precessional and orbital variability, the strongest cycle is 1/7 of the precession period, P7 = 23.228 ± 0.005 days. This is interpreted as evidence for a spiral shock in the accretion disk. The He II 4686 line consists of two components: a stream-formed narrow Gaussian profile and a broad double-peaked one. The latter is completely eclipsed at phase 0.0. Its blue and red peaks are probably emitted in gaseous cocoons around the bases of the relativistic jets. A correct value of the mass function has been found, which shows that the optical star is massive. The relativistic star's mass is estimated to be Mx 6M.     

Numerical simulations of a Mars geodesy network experiment: Effect of orbiter angular momentum desaturation on Mars' rotation estimation

The scientific objectives of a geodetic experiment based on a network of landers, such as NEIGE (NEtlander Ionosphere and Geodesy Experiment) are to improve the current knowledge of Mars' interior and atmosphere dynamics. Such a network science experiment allows monitoring the motions of the Martian rotation axis with a precision of a few centimeters (or milli-arc-seconds (mas)) over annual and sub-annual periods. Thereto, besides radio tracking of a Mars orbiter from the Earth, radio Doppler shifts between this orbiter and several landers at the planet's surface will be performed. From the analysis of these radio Doppler data, it is possible to reconstruct the orbiter motion and Mars' orientation in space. The errors on the orbit determination (position and velocity of the orbiter) have an impact on the geodetic parameters determination from the Doppler shifts and must be removed from the signal in order to achieve a high enough accuracy. In this paper, we perform numerical simulations of the two Doppler signals involved in such an experiment to estimate the impact of the spacecraft angular momentum desaturations on the determination of Mars' orientation variations. The attitude control of the orbiter needs such desaturation maneuvers regularly repeated. They produce velocity variations that must be taken into account when determining the orbit. For our simulations, we use a priori models of the Martian rotation and introduce the spacecraft velocity variations induced by each desaturation event. By a least-squares adjustment of the simulated Doppler signals, we then estimate the orbiter velocity variations and the parameters of the Mars' rotation model. We show that these velocity variations are ill resolved when the spacecraft is not tracked, therefore requiring a near-continuous tracking from the Earth to accurately determine the orbit. In such conditions we show that only 15- of lander-orbiter tracking per week allows recovering Mars' orientation parameters with a precision of a few mas over a period of 1 Martian year.     

Understanding ULX nebulae in the framework of supercritical accretion

For a long time, the well-known supercritically accreting binary SS433 is being proposed as a prototype for a class of hypothetical bright X-ray sources that may be identified with the so-called Ultraluminous X-ray sources (ULXs) in nearby galaxies or at least with part of them. Like SS433, these objects should be associated with optical nebulae, powered by both radiation of the central source and its wind or jet activity. Indeed, around many ULXs, bright optical nebulae (ULX Nebulae, ULXNe) are found. Here, we use SS433 as a prototype for the power source creating the nebulae around ULXs. Though many factors are important such as the structure of the host star-forming region and the possible supernova remnant formed together with the accreting compact object, we show that most of the properties of ULXNe may be explained by an SS433-like system evolving for up to about one million years in a constant-density environment. The basic stages of evolution of a ULX Nebula include a non-spherical HII-region with a central cavity created by non-radiative shock waves, an elongated or bipolar shock-powered nebula created by jet activity and a large-scale quasi-spherical bubble.