AR6659光球色球的磁场速度场的演化特征及其与大耀斑的关系

ＡＲ６６５９是２２周以来最重要的一个活动区，它爆发了２２周最强大的高能事件。本文用云南天文台的光球、色球精细结构照片和北京天文台怀柔站的磁场速度场资料，分析了该活动区磁场速度场的二维位形和大耀斑期间的演化特征，本文分析的４个大耀斑均爆发在中性线附近的Ｎ极区磁场梯度大的地方及色球速度场的红移区，偏带观测也显示耀斑物质是向红端移动的。耀斑波沿横场传播在离本黑子群几万至十几万公里的地方激起感生耀斑，在原     

AR6659光球色球的磁场速度场的演化特征及其与大耀斑的关系

ＡＲ６６５９是２２周以来最重要的一个活动区，它爆发了２２周最强大的高能事件。本文用云南天文台的光球、色球精细结构照片和北京天文台怀柔站的磁场速度场资料，分析了该活动区磁场速度场的二维位形和大耀斑期间的演化特征。本文分析的４个大耀斑均爆发在中性线附近的Ｎ极区磁场梯度大的地方及色球速度场的红移区。偏带观测也显示耀斑物质是向红端移动的。耀斑波沿横场传播在离本黑子群几万至十几万公里的地方激起感生耀斑，在原生耀斑与感生耀斑之间往往有耀斑环相连。此外，本文还从演化特征出发分析了耀斑爆发前活动区等离子体的宏观不稳定性。     

1989年8月17日耀斑后环系速度场分析

本文给出了１９８９ 年８ 月１７ 日耀斑后环的观测视向速度场,在环内物质在太阳重力、磁场梯度和大气压力梯度联合作用下沿环腿螺旋上升和环内物质密度由环腿向环顶和环足线性递增的假设下,理论上计算了该环系的视向速度场,理论计算和观测结果基本相符,似乎为耀斑物质由色球蒸发作上升运动的观点提供了间接的例证     

太阳宁静区磁元的空间结构

利用怀柔太阳磁场望远镜,我们对太阳宁静区光球和色球磁场进行了观测。日面中心到边缘的观测表明,太阳宁静区中的小尺度磁结构在从光球到色球的扩展过程中变化不大。日面边缘的观测表明,小尺度磁结构的水平分量在光球和色球都不大。对极区和赤道边缘纵向磁场的比较发现,极区磁场与赤道边缘磁场有着不同的磁结构特性     

1993年5月日面AR7500中暗条的动力学特征

本文利用光球磁场、色球Hα单色像和Hβ速度场等观测资料，分析了1993年5月日面AR7500中3个暗条的演化和动力学行为，得出4个结论(1)3个暗条中两个是右旋暗条，一个是左旋暗条。(2)暗条附近两侧的色球纤维和光球横场几乎平行于暗条长轴，暗条端点处的黑子没有呈现明显的涡旋结构。(3)尖角处因为轴向场取向不同，一直没有发生暗条合并，即使其中一个右旋暗条消失后又重新形成也如此。(4)几天持续存在的左旋暗条，在两天的观测中未出现扰动激活，其中部为杂乱而不明显的运动图案。本文还讨论了可以用暗条的扭曲磁流绳模型来解释暗条的这些动力学行为，以及一些尚待进一步澄清的问题。     

1993年5月日面AR7500中暗条的动力学特征

本文利用光球磁场、色球Hα单色像和Hβ速度场等观测资料，分析了1993年5月日面AR7500中3个暗条的演化和动力学行为，得出4个结论：（1）3个暗条中两人是右旋暗条，一个是左旋暗条。（2）暗条附近两侧的色球纤维和光球横场几乎平行于暗条长轴，暗条端点处的黑子没有呈现明显的涡旋结构。（3）尖角处因为轴向场取向不同，一直没有发生暗条合并，即使其中一个右旋暗条消失后又重新形成也如此。（4）几天持续存在的左旋暗条，在两天的观测中未出现扰动激活，其中部为杂乱而不明显的运动因素。本文还讨论了可以用暗条的扭曲磁流绳模型来解释暗条的这些动力学行为，以及一些尚待进一步澄清的问题。     

1988年3月黑子磁场的演化(英文)

024黑子(S.G.D编号为4964)是1988年3月份太阳上最大、磁场最强的黑子群。在日面上出现的半个月里,始终有耀斑产生。北京天文台怀柔太阳磁场望远镜对这个活动区作了常规观测,并获得了磁场和速度场资料。 024活动区是由一个偶极黑子和δ黑子组成的。12日01~h49~mUT,黑子刚从东部出现时就有耀斑和活动日珥产生。从速度场与H_β色球单色像对比来看,耀斑内有物质向里流动,而暗条中有物质向外抛射。024活动区的磁场十分复杂,S极、N极磁场互相包含、渗入、剪切,形成许多海湾结构。可能这就是产生了许多各种形状的耀斑的缘故。本文对磁场的形态作了描述。     

1989年1月18日白光耀斑的研究

本文利用色球Ｈα单色光序列照相资料，Ｈα光谱扫描资料，黑子精细结构照相资料和日面纵向磁场观测资料，分析了１９８９年１月１８日ＷＬＦ所在活动区ＮＯＡＡ／ＵＳＡＦ：５３１２的磁场结构，黑子结构及该ＷＬＦ的演化特征，求出了视向速度场，并以理论计算的Ｈα谱线轮廓作为诊断工具，探讨了该ＷＬＦ可能的能量传输机制和动力学过程。     

1989年1月14日AR5312活动区中的耀斑和磁场的关系(英文)

1989年1月14日AR5312(怀柔编号89009)活动区,产生了一个2B级耀斑。该活动区经纬度为L306、S32,黑子群磁场分类为δ型。耀斑开始时间为0202UT,结束为0534UT,持续了3个多小时。北京天文台磁场望远镜,得到了一系列较完整的高分辨磁场及速度场资料,包括光球5324A的矢量磁场图和色球4861A的纵向磁场图(图1、2)。从耀斑前后的磁图得到以下结果: 1、耀斑初始亮点位于纵向磁场中性线附近高度剪切区域(见图1B区)、新浮磁流区(图2D区)以及双极磁结构对消区。前两种区域均能形成电流片,并且引起磁流体不稳定性,从而激发耀斑,但对消区和耀斑的关系不是很清楚,有待于理论工作者进一步探讨。 2、耀斑极大时间过后,光球和色球H_(11)=0线附近纵场梯度均有明显下降。 3、在强剪切区域(图1B区),5324A横向磁场和H_(11)=0线之间的夹角在耀斑极大时间过后有明显增大,该现象表明磁能释放后,磁场剪切缓解。 4、耀斑初始亮点产生后磁场高度剪切区、新浮磁流区和双极对消区,其触发耀斑的作用和周围的磁场环境有密切关系,特别是象具有磁海湾结构这样的活动区,似乎更容易产生耀斑。 5. 该活动区色球磁场位形,较光球磁场位形复杂,主要表现在:色球的纵场出现了一些磁弧岛结构,其原因可能是光球之上的磁力线高度剪切区及扭绞所致。0411     

色球磁场极性反转结构的某些观测特征

利用怀柔太阳观测站的300余对光球(FeIλ5324.19A)和色球(H_βλ4861.34A)的观测磁图,分析得出色球极性反转结构是存在于太阳大气中的真实物理现象的结论.根据对活动区两个层次上的磁场精细结构的分析,发现色球磁场反转结构可能有4种不同的存在形式.     

Bianchi type-II,VIII, and IX cosmological models with matter and electromagnetic fields

We present analytic solutions of the Einstein-Maxwell equations for cosmological models of LRS Bianchi type-II, VIII, and IX. The solutions represent anisotropic universes with source-free electromagnetic fields and perfect fluids matter satisfying the equation of state that is a function of the cosmic-time. Some physical properties of the models have been discussed.     

The influence of large-scale structures on halo shapes and alignments

Alignments of galaxy clusters (the Binggeli effect), as well as of galaxies themselves have long been studied both observationally and theoretically. Here, we test the influence of large-scale structures and tidal fields on the shapes and alignments of cluster-size and galaxy-size dark matter haloes. We use a high-resolution N -body simulation of a Λ cold dark matter (ΛCDM) universe, together with the results of Colberg, Krughoff & Connolly, who identified filaments connecting pairs of clusters. We find that cluster pairs connected by a filament are strongly aligned with the cluster–cluster axis, whereas unconnected ones are not. For smaller, galaxy-size haloes, there also is an alignment signal, but its strength is independent of whether the halo is part of an obvious large-scale structure. Additionally, we find no measurable dependence of galaxy halo shape on membership of a filament. We also quantify the influence of tidal fields and find that these do correlate strongly with alignments of haloes. The alignments of most haloes are thus caused by tidal fields, with cluster-size haloes being strongly aligned through the added mechanism of infall of matter from filaments.     

Method for analyzing the spatial distribution of galaxies on gigaparsec scales. II. Application to a grid of the HUDF-FDF-COSMOS-HDF surveys

The initial principles of a method for analyzing the spatial distribution of visible matter in the universe with structures on size scales of thousands of Mpc are discussed. This method is based on analyzing the distribution N(z) of the photometric redshifts of galaxies in deep fields using large bins Δ z=0.1–0.3. Fluctuations in the numbers of galaxies in these bins in terms of redshifts are caused by Poisson noise, correlated structures, and systematic errors in estimating photo-z. This method involves covering a sufficiently large region of the celestial sphere with a grid of deep multi-band surveys with a cell size on the order of 10o×10o, with deep fields of size ∼10'×10' observed with 3-10 meter telescopes at its nodes. The distribution of the photometric redshifts of the galaxies within each deep field will yield information on the radial extent of superlarge structures, while comparing the radial distributions in neighboring fields will yield information on the tangential extent of these structures. A necessary element of this method is an analysis of possible distortions in the radial distributions of the galaxies associated with the technique for evaluating the photometric redshifts.     

Method for analyzing the spatial distribution of galaxies on gigaparsec scales. I. initial principles

The initial principles of a method for analyzing the spatial distribution of visible matter in the universe with structures on size scales of thousands of Mpc are discussed. This method is based on analyzing the distribution N(z) of the photometric redshifts of galaxies in deep fields using large bins Δ z=0.1–0.3. Fluctuations in the numbers of galaxies in these bins in terms of redshifts are caused by Poisson noise, correlated structures, and systematic errors in estimating photo-z. This method involves covering a sufficiently large region of the celestial sphere with a grid of deep multi-band surveys with a cell size on the order of 10º×10º, with deep fields of size ～10'×10' observed with 3-10 meter telescopes at its nodes. The distribution of the photometric redshifts of the galaxies within each deep field will yield information on the radial extent of superlarge structures, while comparing the radial distributions in neighboring fields will yield information on the tangential extent of these structures. A necessary element of this method is an analysis of possible distortions in the radial distributions of the galaxies associated with the technique for evaluating the photometric redshifts.     

The 3D skeleton: tracing the filamentary structure of the Universe

The skeleton formalism, which aims at extracting and quantifying the filamentary structure of our Universe, is generalized to 3D density fields. A numerical method for computing a local approximation of the skeleton is presented and validated here on Gaussian random fields. It involves solving equation     , where  ∇ρ  and     are the gradient and Hessian matrix of the field. This method traces well the filamentary structure in 3D fields such as those produced by numerical simulations of the dark matter distribution on large scales, and is insensitive to monotonic biasing.
Two of its characteristics, namely its length and differential length, are analysed for Gaussian random fields. Its differential length per unit normalized density contrast scales like the probability distribution function of the underlying density contrast times the total length times a quadratic Edgeworth correction involving the square of the spectral parameter. The total length-scales like the inverse square smoothing length, with a scaling factor given by  0.21 (5.28 + n )  where n is the power index of the underlying field. This dependency implies that the total length can be used to constrain the shape of the underlying power spectrum, hence the cosmology.
Possible applications of the skeleton to galaxy formation and cosmology are discussed. As an illustration, the orientation of the spin of dark haloes and the orientation of the flow near the skeleton is computed for cosmological dark matter simulations. The flow is laminar along the filaments, while spins of dark haloes within 500 kpc of the skeleton are preferentially orthogonal to the direction of the flow at a level of 25 per cent.     

Simulations of jet formation from a magnetized accretion disk

Axisymmetric magnetohydrodynamic (MHD) simulations have been made of the formation of jets from a Keplerian disk threaded by a magnetic field. The disk is treated as a boundary condition, where matter with high specific entropy is ejected with a Keplerian azimuthal speed and a poloidal speed less than the slow magnetosonic velocity, and where boundary conditions on the magnetic fields correspond to a highly conducting disk. Initially, the space above the disk, the corona, is filled with high specific entropy plasma in the thermal equilibrium in the gravitational field of the central object. The initial magnetic field is poloidal and is represented by the superposition of the fields of monopoles located below the plane of the disk.The rotation of the disk twists the initial poloidal magnetic field lines, and this twist propagates into the corona pushing matter into jet-like outflow in a cylindrical region. After the first switch-on wave, which originates during the first rotation period of the inner radius of the disk, the matter outflowing from the disk starts to flow and accelerate in thez-direction owing to both the magnetic and pressure gradient forces. The flow accelerates through the slow magnetosonic and Alfvén surfaces and at larger distances through the fast magnetosonic surface. The flow velocity of the jet is approximately parallel to thez-axis, with the collimation mainly a result of the pinching force of the toroidal magnetic field. The energy flux of the flow increases with increasing magnetic field strength on the disk. Some of the cases studied have been run for long times, 60 rotation periods of the inner radius of the disk, and show indications of approaching a stationary state.     

Instabilities and Formation of Coherent Structures

This tutorial paper is devoted to theoretical aspects of the coherent electrostatic structures that have been encountered in various space plasmas. These structures, called solitary waves, electrostatic shocks or double layers have been observed in the solar wind, the Earth bow shock, the auroral zones and the magnetotail. Most of these structures can be interpreted in terms of electron or ion phase space holes. Their1D structure, their emergence from plasma instabilities, their mutual interactions, their bidimensional stability, and their ability to create large scale electric fields are discussed in this paper. This revised version was published online in July 2006 with corrections to the Cover Date.     

Theory of superdense matter and degenerate stellar configurations

During the last two decades the theory of degenerate stellar configurations has been developed in works by Ambartsumian and Sahakian, as well as in some other papers. This article is further progress in this direction. Systematic investigations of thermodynamic properties of the ground and metastable states of degenerate plasma have been carried out over the total range of pressures. It was found that in the range of densities 3×10¹⁰???3×10¹⁴ g cm^?3 there exists a pionization effect which plays an important role in the thermodynamics of degenerate plasma. The pion condensate present in nuclear matter promotes the existence of metastable nuclear clusters with the nuclear numberA?10⁶. The equation of state of degenerate stellar matter has been notably revised and, accordingly, the neutron star parameters have been calculated anew. The role of the pion condensate in generating strong magnetic fields observed in the pulsars is discussed.     

Latitudinal drift of solar magnetic field imbalance

The latitudinal drift of the imbalance flow of magnetic fields as a whole and the latitudinal drift of the imbalance flow components with certain significant rotation periods are determined. Comparison of these two drift types is performed for different ranges of magnetic field strength using the data of a 26-year observation period. The mathematical model of representation of the imbalance as a steady-state random process is used. As a result of analysis the following facts are established: (i) structures rotating with the same significant period are observed in a wide latitude range, (ii) there exist several significant periods in the power spectrum for one latitude, (iii) the character of the latitudinal drift of the imbalance flow of magnetic fields as a whole and the imbalance structures rotating with significant periods is the same for fields with close strengths, and (iv) for fields with each of the considered strengths there exists a latitude band in which a drift along the meridian is absent.     

RADIO MAPS OF THE SOLAR WIND TRANSITION REGION

Occultation studies of near-Sun plasmas using several natural sources simultaneously result in large-scale patterns, radio maps of the solar wind flow. Large radio telescopes of the P.N. Lebedev Physical Institute, Pushino, were used. Previously it had been shown that the plasma acceleration and traverse of the sound barrier proceed in an extended region, the transition region of the solar wind, located at radial distances of about 10–40 solar radii from the Sun. The 1989–1994 experiments showed that the evolution of the transition region geometry is very close to that of the optical corona. On the other hand, the plasma flow structures characteristic of the transition region persist in the course of the 11-year cycle, which demonstrates the existence of some specific mechanism of the solar wind acceleration, independent of wide variations of the general solar activity state. These experimental facts are discussed in connection with the existing theoretical approaches.