孤立脉冲星的X射线光度

本文提出一种物理机制得了到了孤立静冲星的Ｘ射线光度与其自转能损失的理论关系式，它与孤立静脉星的Ｘ射线观测数据是完全符合的。     

射电脉冲星的磁层与辐射机制理论

在本文中简介强磁场中一些特殊理过程的特性，在此基础上综述了射电脉冲星的磁层与辐射机理理论。关于磁层，主要由ＧＪ模型了发，从斜转子磁层、加速区机制及回路问题三方面总结前人对磁层问题的认识。     

谱线形成深度的理论及其应用（I）：贡献函数和谱线形成深度

本系列文章中给出了谱线形成深度理论的发展特别是其最新进展，分别叙述了与此理论相联系的贡献函数和响应函数的演化过程，讨论了此理论的应用特别是用于太阳矢量磁场空间三维结构的推导。在这第一篇文章中，叙述了与贡献函数相关的理论，指出了应用此理论的局限性，并讨论了唯一性问题。     

太阳射电尖峰辐射的电子回旋脉泽增长率

本文在Ｍｅｌｒｏｓｅ和Ｄｕｌｋ新发展的准线性理论基础上，继续作者前面所做的工作，对ｓｐｉｋｅ辐射的ＥＣＭ增长率做进一步的分析．     

激变变星的多波段研究（II）

本文继续介绍变变星在紫外，极端紫外（ＥＵＶ），以及Ｘ射线波段的辐射特征。我们仍然从观测现象和理论解释两个方面来介绍。激变变星在这些波段有很强的辐射，因而有丰富观测理，这对于我们更好的认识这类吸积系统有重要意义。     

不稳定性和频谱演化──再论等离子体辐射与其它辐射机制的关系

本文力图阐明的一个基本观点是:由等离子体不稳定性所激发的电磁波幅度的增长从本质上揭示了辐射过程内部的波粒相互作用对辐射频谱演化的贡献。因此,等离子体辐射理论是建立在经典电动力学的辐射理论的基础之上,并以各种基本辐射过程(如轫致辐射、回旋及同步辐射等)的平衡态为初始条件,从而发展起来的动态辐射理论。     

脉冲星磁偶极辐射模型的修正

本文讨论了脉冲星磁偶极辐射模型所取得的成就和存在的困难，针对不足之处对磁偶极模型进行修正。从统计上得到修正因子与周期变率的幂律关系。由修正后的磁场强度得出其衰减时标大于１０８年，这与有关的理论研究结果一致。修正后的磁偶极模型给出周期变率和周期的新关系为р∝Ｐ－３，这恰好和р－Ｐ图中加速线以上的资料的统计拟合方程一致。     

用斯托克斯轮廓推导太阳矢量磁场和热力学参量的三维结构

一种根据斯托克斯轮廓分析推导太阳矢量磁场和热力学参量的空间三维结构的新方法在本文中提出．在不考虑散射和原子偏振的假设下，该方法由三个具有不同功能的操作分别作用于太阳大气中一层或二层斯托克斯轮廓组成．这三个操作构成一个运行单元．将此单元运用到从表面到光球底层所划分的大气层格点，然后对扫描区所有的点应用同样的程序便可获得太阳上观察区的矢量磁场和热力学参量的空间三维结构．文中给出了相应的流程图和三个操作的详细描述，并用简化了的程序对理论轮廓进行了拟合．结果表明此方法能较满意地导出矢量磁场尤其是磁场强度的三维空间结构，而热力学参量结构的推导还需进一步改进．     

自引力辐射体系的熵与引力坍缩

本文利用李立新和刘辽导出的黑洞视界附近的辐射态方程，计算了约束在一个球形盒子中的目引力辐射体系的墙（不含中心黑洞和含有中心黑洞两种情况）．与Sorkin等人的计算比较，本文的结果不会出现发散困难，而且体系的总摘（包括中心黑洞的墙）的上阳正好等于坍缩后形成的同质量的黑洞嫡．作者认为，自引力辐射体系坍绩的合理模式是先形成中心黑洞，然后中心黑洞逐渐长大直至整个体系全部坍缩为黑洞．在坍缩过程中，任一中间态的媳总是比末态的黑洞墙小，到坍缩过程结束总熵才等于对应的黑洞摘．这一结果为黑洞滴的起源提供了一个合理的解释．     

活动星系核中相对论电子束的物理效应

本文研究了Ｂｌａｚａｒ天体的辐射性质，提出一种新的喷流模型，即具有幂律分布的极端相对论电子团从中心核注入喷流等离子体中，它在一定的注入速度下，不仅能在喷流等离子体中激发等离子体湍动，产生电磁波的相干辐射，而且能产生强的同步辐射。利用等离子体的弱湍理论，我们研究了极端相对论电子团在喷流等离子体中的辐射过程，并详细研究了它在解释Ｂｌａｚａｒ天体辐射特性中的应用，本文认为，Ｂｌａｚａｒ天体的不稳定辐射与极端相对论电子团的无规注入、喷流等离子体的物理环境瞬息变化有关。Ｂｌａｚａｒ中快速变化的辐射偏振角摆动。产生于相对论电子团在湍动等离子体中的同步辐射过程。另外，Ｘ选和射电选的ＢＬＬａｃ天体之间的区别取决于喷流等离子体的运动状态和物理环境。     

The effectiveness of the Kozai mechanism in the Galactic Centre

I examine the effectiveness of Kozai oscillations in the centres of galaxies and in particular the Galactic Centre (GC) using standard techniques from celestial mechanics. In particular, I study the effects of a stellar bulge potential and general relativity on Kozai oscillations, which are induced by stellar discs. Löckmann et al. recently suggested that Kozai oscillations induced by the two young massive stellar discs in the GC drive the orbits of the young stars to large eccentricity  ( e ≈ 1)  . If some of these young eccentric stars are in binaries, they would be disrupted near pericentre, leaving one star in a tight orbit around the central supermassive black hole and producing the S-star population. I find that the spherical stellar bulge suppresses Kozai oscillations, when its enclosed mass inside a test body is of the order of the mass in the stellar disc(s). Since the stellar bulge in the GC is much larger than the stellar discs, Kozai oscillations due to the stellar discs are likely suppressed. Whether Kozai oscillations are induced from other non-spherical components to the potential (e.g. a flattened stellar bulge) is yet to be determined.     

Physics of solar-like oscillations

The physics of solar and stellar oscillations determines their observable properties: frequencies, amplitudes, lifetimes, line asymmetries and phase relations. In the solar case these quantities have been measured, often with high precision, and much has been learned about the properties of the solar interior, and the properties of the oscillations. With recent advances in observational techniques, such seismic investigations are now being extended to solar-like oscillations in distant stars. I provide a brief overview of the basic properties of stellar oscillations, and of the information about stellar properties that may be inferred from them, concentrating mostly on the low-degree modes for which information may be expected for distant stars. In addition, I consider the current state of investigations of solar-like oscillations in other stars, and the prospects for an improved understanding of the physics of such oscillations.     

The YNEV stellar evolution and oscillation code

We have developed a new stellar evolution and oscillation code YNEV,which calculates the structures and evolutions of stars,taking into account hydrogen and helium burning.A nonlocal turbulent convection theory and an updated overshoot mixing model are optional in this code.The YNEV code can evolve low-and intermediate-mass stars from the pre-main sequence to a thermally pulsing asymptotic branch giant or white dwarf.The YNEV oscillation code calculates the eigenfrequencies and eigenfunctions of the adiabatic oscillations for a given stellar structure.The input physics and numerical scheme adopted in the code are introduced.Examples of solar models,stellar evolutionary tracks of low-and intermediate-mass stars with different convection theories(i.e.mixing-length theory and nonlocal turbulent convection theory),and stellar oscillations are shown.     

Propagating Linear Waves in Convectively Unstable Stellar Models: A Perturbative Approach

Linear time-domain simulations of acoustic oscillations are unstable in the stellar convection zone. To overcome this problem it is customary to compute the oscillations of a stabilized background stellar model. The stabilization affects the result, however. Here we propose to use a perturbative approach (running the simulation twice) to approximately recover the acoustic wave field while preserving seismic reciprocity. To test the method we considered a 1D standard solar model. We found that the mode frequencies of the (unstable) standard solar model are well approximated by the perturbative approach within 1 μHz for low-degree modes with frequencies near 3 mHz. We also show that the perturbative approach is appropriate for correcting rotational-frequency kernels. Finally, we comment that the method can be generalized to wave propagation in 3D magnetized stellar interiors because the magnetic fields have stabilizing effects on convection.     

恒星物质的不透明度

简介介绍了恒星物质的透明性质在恒星结构、演化、振动等许多恒星物理基本问题研究中的重要性和决定恒星物质不透明度的物理过程,回顾了第一代不透明度数据ＬＡＯＬ的发展历程与存在的问题,介绍了新一代不透明度数据ＯＰＡＬ的发展和目前观测与理论之间依然不一致的地方。     

Multisite campaign on the open cluster M67 – II. Evidence for solar-like oscillations in red giant stars

Measuring solar-like oscillations in an ensemble of stars in a cluster, holds promise for testing stellar structure and evolution more stringently than just fitting parameters to single field stars. The most-ambitious attempt to pursue these prospects was by Gilliland et al. who targeted 11 turn-off stars in the open cluster M67 (NGC 2682), but the oscillation amplitudes were too small (<20 μmag) to obtain unambiguous detections. Like Gilliland et al. we also aim at detecting solar-like oscillations in M67, but we target red giant stars with expected amplitudes in the range 50–  500 μmag  and periods of 1 to 8 h. We analyse our recently published photometry measurements, obtained during a six-week multisite campaign using nine telescopes around the world. The observations are compared with simulations and with estimated properties of the stellar oscillations. Noise levels in the Fourier spectra as low as  27 μmag  are obtained for single sites, while the combined data reach  19 μmag  , making this the best photometric time series of an ensemble of red giant stars. These data enable us to make the first test of the scaling relations (used to estimate frequency and amplitude) with an homogeneous ensemble of stars. The detected excess power is consistent with the expected signal from stellar oscillations, both in terms of its frequency range and amplitude. However, our results are limited by apparent high levels of non-white noise, which cannot be clearly separated from the stellar signal.     

Pulsar radiation belts and transient radio emission

It is proposed that radiation belts similar to the ones in the planetary magnetosphere can exist for a pulsar with a relatively long period and a strong magnetic field. In the belts located in the closed field line region near the light cylinder relativistic pairs are trapped and maintained at a density substantially higher than the local Goldreich–Julian corotation density. The trapped plasma can be supplied and replenished by either direct injection of relativistic pairs from acceleration of externally supplied particles in a dormant outer gap or in situ ionization of the accreted neutral material in the trapping region. The radiation belts can be disrupted by waves that are excited in the region as the result of plasma instabilities or emitted from the surface due to starquakes or stellar oscillations. The disruption can cause an intermittent particle precipitation towards the star producing radio bursts. It is suggested that such bursts may be seen as rotating radio transients.     

Oscillations de l'atmosphère de l'étoile pulsante

Résumé On étudie les oscillations non-adiabatiques d'une atmosphère stellaire sous l'approximation du premier ordre, en déduisant les solutions générales des équations différentielles. On confirme les conditions aux limites de la pulsation d'étoile. Pour les étoiles variables des supergéantes rouges l'onde progressive est possible dans l'atmosphère, avec l'oscillation stationnaire.

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Non-adiabatic linear oscillations of the stellar atmosphere are studied by deriving the general solution of the equation of the problem. Boundary conditions which we obtained at the stellar surface are confirmed for the pulsation of the cepheid variables. It is shown that the progressive wave coupling with the stellar pulsation is possible in the atmospheres of red supergiants.

     

Solar models with low opacity

Solar Physics - Evolutionary models of the present Sun with standard and artifically low opacity of stellar matter are obtained and adiabatic nonradial oscillations of the models are computed. The...     

Space and Ground Based Data for Asteroseismology

Measuring eigenfrequencies and identifying eigenmodes provide the observational basis for a significant improvement in our understanding of stellar evolution and structure.Development throughout the last few years show that we may be at the dawn of a `Golden Age'for Asteroseismology. For this to become a reality we only need two things:Better data and better models. In this paper I describe some aspectsof how one detects stellar oscillations.