恒星的初始—终止质量关系

本研究了星族ＩＲＧＢ／ＡＧＢ星外壳结合能为零时的核质量与其初始质量的关系，发现此关系与Ｗｅｉｄｅｍａｎｎ和Ｋｏｅｓｔｅｒ得到的初始－终止质量关系的相符，并与Ｚｈａｎｇ和Ｋｗｏｋ得到的行星状星云核质量分布的观测结果相符合，采用相同的假设，本还得到了星族Ⅱ恒星的初始－终止质量关系，对于相同的初始质量，星族Ⅱ恒星的终止质量比星族Ｉ的大－１０－２０％。     

钡星的形成机制(Ⅱ)Monte Carlo分析

本文对文章Ⅰ所建立的钡星形成的完备模型进行了ＭｏｎｔｅＣａｒｌｏ分析,并同观测结果作了比较．结果表明,大部分强钡星可能产生于星风吸积过程、星风暴露过程和稳定的洛希瓣物质交流过程,而大部分中等钡星可能产生于星风吸积过程和星风暴露过程．银河系中钡星的数量、轨道周期分布和质量函数分布在本文各种模型计算结果范围之内．模型还预言钡星轨道周期与污染因子相关．模型给出,银河系中钡星的诞生率为００２／年左右,亮于１０个星等的钡星大约有６０００颗,强钡星的平均质量为１８Ｍ⊙左右,而钡星的白矮星伴星平均质量为０６０Ｍ⊙．另外,结果还显示,星族ＩＡＧＢ星热脉动开始较早,星风有潮汐增强效应存在（Ｂ～５００）,ｓ过程最大恒星质量为２Ｍ⊙左右．     

钡星的形成机制(I)完备模型

本文系统地研究了钡星的形成,提出了钡星形成的四种机制：星风吸积、星风暴露、稳定的洛希瓣物质交流和公共包层的抛射,从而建立了钡星形成的完备模型     

中等质量恒星在赫罗图中由E-AGB星进入TP-AGB星的分界点

通过对3～10 M_☉恒星在赫罗图上演化轨迹的研究,分析恒星内部氦壳层燃烧峰值处能量、密度、温度、氦壳层表面光度与恒星表面光度比及恒星半径的变化,给出了中等质量恒星由早期AGB星演化至热脉冲AGB星阶段在赫罗图上的分界点,与119颗碳星的观测结果吻合得相当好.同时提出:在恒星演化至该分界点之后,其星风物质损失公式可能需要引入一个与表面光度无关的量以主导超星风的形成.在此基础上,通过对考虑湍流压效应下5 M_☉恒星的结构和演化及星风物质损失率的分析,发现湍流压在热脉冲AGB星阶段对星风物质损失影响较大,从而使得热脉冲AGB星的湍流压不可忽略,进而提出了影响热脉冲AGB星星风物质损失的可能的物理因素.     

湍流压对中小质量恒星后期演化的影响（II）湍流区对内部结构和演化…

本研究了２．８Ｍ⊙和７Ｍ⊙恒星由于主序到红巨星和ＡＧＢ星阶段的演化,结果发现,湍流压的存在质量较大的７Ｍ⊙恒星的内部结构有较大的影响,它将使氢燃烧壳屋明显变厚并较早地消失,使恒星中心的温度降低,使ＨＲ图中的演化轨迹向温度降低和光度减小的方向变化,使氢壳层燃烧出现周期性脉动,氦壳层的热脉动周期变短等等。但是,对于质量较小的２．８Ｍ⊙恒星,湍流压的效应很微小。     

湍流压对中小质量恒星后期演化的影响(Ⅲ)红巨星和AGB星产生强大星风物质损失的机理研究

本文提供了一个判别红巨星和ＡＧＢ星对流外壳中是否会产生动力学非稳定性的条件．根据这个条件和对２８Ｍ及７Ｍ恒星从主序到巨星阶段和ＡＧＢ阶段的演化计算,可以证明,湍流压效应是导致红巨星和ＡＧＢ星靠近表面区域产生动力学非稳定性,从而造成物质向外喷流的原因．并认为它就是造成红巨星和ＡＧＢ星表面温度很低（因而辐射压很低）从而产生强大星风物质损失的物理原因．     

中等质量富金属AGB长周期变星的振动研究

本采用恒星演化计算与恒星振动计算相结合的方法，对中等质量富金属恒星演化到渐近巨星分支时的振动性质进行了分析研究，从理论上得出这类恒星的振动方式是处于一阶谐频振动，而振动的激发则是在氢电离区和氦的二次电离区由多种机制共同作用造成的，同时提出很长周期的ＡＧＢ长周期变星只能是由中等质量恒星演化到ＡＧＢ阶段形成的。我们的理论计算结果还比较支持在ＡＧＢ顶端存在巨大星风物质损失的观点，且这种星风物质损失很可     

湍流压对中小质量恒星后期演化的影响(I)湍流压对内部结构和演化的影响

本文研究了２８Ｍ⊙和７Ｍ⊙恒星由主序到红巨星和ＡＧＢ星阶段的演化．结果发现,湍流压的存在对质量较大的７Ｍ⊙恒星的内部结构有较大的影响,它将使氢燃烧壳层明显变厚并较早地消失;使恒星中心的温度降低;使ＨＲ图中的演化轨迹向温度降低和光度减小的方向变化;使氢壳层燃烧出现周期性脉动;氦壳层的热脉动周期变短等等．但是,对于质量较小的２８Ｍ⊙恒星,湍流压的效应很微小．     

湍流压对中小质量恒星后期演化的影响（Ⅲ）红巨星和AGB星产生强？…

本提供了一个判别红巨星和ＡＧＢ星对流外壳中是否会产生动力学非稳定性的条件。根据这个条件和对２．８Ｍ⊙及７Ｍ⊙恒星从主序列到巨星阶段和ＡＧＢ阶段的演化计算,可以证明,湍流压效应是导致红居星和ＡＢＧ星靠近表达区域产生动力学非稳定性,从而造成质向外喷流的原因,并认为它就是造成红巨星和ＡＧＢ星表面温度很低（因而辐射压很低）从而产生强大星风物质损失的物理原因。     

年轻星天体的质量

质量是恒星最基本、最重要的物理量之一,它在恒星形成和演化过程中起着至关重要的作用.年轻星天体的形成机制以及早期演化过程是彻底解决恒星形成问题的关键所在,而年轻星天体形成过程中的物质下落、质量吸积以及外流等物理过程都与年轻星天体的质量密切相关.该文介绍了确定年轻星天体质量的一些常用方法,包括利用开普勒定律的动力学方法、赫罗图方法、年轻星天体脉动方法和磁层吸积方法等.并对这些方法的适用范围及测量精度进行了评述,还综述了各种方法的研究进展及未来可能的发展.     

Mass Loss in Young Stellar Objects

Various aspects of mass loss associated with Young Stellar Objects are reviewed. The classification of the driving sources of the outflows is presented, and the properties of the youngest sources, the Class 0 protostars, are given. The observed properties of the molecular, atomic, and neutral components of the bipolar flows are discussed and critically compared with the most recent theoretical models. This revised version was published online in July 2006 with corrections to the Cover Date.     

同等质量下盘状星系的颜色-尺度关系

挑选Sloan数字巡天第7次释放数据(SDSS DR7)的主星系样本中近邻的、面向的盘状星系作为星系样本,统计研究了在恒星总质量相等的情况下盘状星系的颜色和尺度之间的相关性,并对相关性的真实性进行了检验.发现对于同等质量的盘状星系,u-r颜色与尺度相关性很弱,而g-r、r-i、r-z颜色与尺度负相关,即星系的尺度越大,颜色越蓝.该结果意味着盘状星系的质量分布对其恒星形成历史影响很大,物质分布越延展的星系,其演化越慢.     

Stellar Winds and Mass Loss in A-Type Supergiants

We examine the relationship between the surface escape velocities and wind terminal velocities of A-type supergiants according to the radiation-driven wind theory. This revised version was published online in July 2006 with corrections to the Cover Date.     

Mechanism of Mass Loss of Stellar Wind for Medium-mass Stars

Along with the considerations of the effect of constraint of gravitation on the matter loss of stellar wind and the disturbances of the radiation pressure and turbulent pressure on it, by introducing the mechanism of compressible flow, the effect of promotion of the convective region in stellar outer shell on the matter loss of stellar wind is investigated. Hence a new formula of matter loss of stellar wind is established. After this and via the computation of the rate of mass loss of stellar wind in the theoretical model of 3∼5M? stars, the following is revealed. From the main sequence up to the stage of termination of central helium-core burning, the rate of mass loss of stellar wind calculated with the new formula agrees almost completely with that given by the classical formula. But in the TP-AGB stage the stellar model calculated with the new formula of mass loss of stellar wind is not affected by luminosity and gives rise to the persistent and large matter loss of stellar wind. This rather well agrees with the results of actual observations.     

恒星级黑洞的观测证认研究进展

具有不同质量的恒星在耗尽其热核能源后,最终可能会坍缩成为性质完全不同的致密天体,如白矮星、中子星或者黑洞。从20世纪30年代起,黑洞的观测及其证认一直是天体物理学的研究热点之一。首先简要地回顾了恒星级黑洞的形成及其候选天体的研究历史;然后介绍了如何从观测上证认恒星级黑洞:接着详细讨论了恒星级黑洞的质量和自转参数的测量方法;最后介绍恒星级黑洞观测及其证认的最新研究进展,并做出结论:目前已经有充分的证据宣告在部分吸积X射线双星中存在恒星级黑洞。     

A Numerical Simulation Study of Mass Segregation in Embedded Stellar Clusters

The initial condition of the formation of massive stars is still unclear at present. In particular, it is still debatable whether or not massive stars are formed in the cluster center. Some people considered from the viewpoint of time scale and thought that the mass segregation phenomena in embedded clusters means that the massive stars can only be born in the cluster center. In this paper we used the Monte Carlo method to make numerical simulation of the dynamical evolution of embedded clusters and the result is compared with the observations. It is assumed that at the initial time massive stars are randomly distributed. It was found that, due to the random motions of massive stars, temporary mass segregation may exist at certain times in the course of evolution of a given embedded cluster, and this phenomenon may be very prominent in some of them. It is pointed out that massive star formation in the center is not the only explanation for mass segregation in embedded clusters. In addition, dynamical friction from the gas can effectively reduce the time scale of the dynamical mass segregation. In consequence, the probability of temporary mass segregation is increased.     

Unresolved Binaries and the Initial Mass Function

In the area of binary stars the important contribution of GAIA will be towards statistical studies of the binary star distribution functions. On the other hand, from the GAIA observations, more than 10 000 masses accurate to 1% can be expected. This improves accuracy of the stellar initial mass function (IMF) still poorly known, particularly for the low-mass stars. A goal of the present study is to simulate a solar vicinity model with 100% binaries for predicting observational distributions. Under the assumption that star formation rate is constant, a random pairing of objects drawn from a pre-assumed single star power-law IMF is generated. Stellar evolution and selection effects are taken into account. Orbital parameters are assumed to be spread according to the common distributions. It is shown that under given assumptions the power-law IMF does lead to quasi-lognormal turnovers for the resulting observational mass function. The described model can be used to estimate, under reasonable assumptions on the IMF shape, the number of binaries of the different types that can be observed with GAIA. This revised version was published online in July 2006 with corrections to the Cover Date.     

疏散星团M67的初始质量函数

本文利用合理的成员判定方法对典型年老疏散星团Ｍ６７进行了成员判定，直接得到了该团存在空间和速度空间质量分层效应的结论。在研究ＰＤＬＦ和ＰＤＭＦ时，我们还合理地作了由分析样本天区不完备而带来的修正。最后，从理论上提出了一种动力学演化对疏散星团ＩＭＰ影响的简易而普适的修正方法，利用该方法得到了Ｍ６７在０．７Ｍ⊙≤Ｍ≤１．３Ｍ⊙间ＩＭＦ的斜率为－１．６７±０．０９，与Ｍｉｌｌｅｒ和Ｓｃａｌｏ场星ＩＭＦ斜率较相符，并对该值的合理性进行了讨论。     

The Effect of Method of Constructing the Mass Distribution on Single Stellar Populations

We use two methods of constructing the initial mass distribution, the traditional way and Monte Carlo simulation, to obtain integrated U - B, B - V, V-R and V-I colours and absorption-line indices denned by the Lick Observatory image dissector scanner (referred to as Lick/IDS), for instantaneous burst solarmetallicity single stellar populations with ages in the range 1-15 Gyr. We find that the evolutionary curves of all colours obtained by the traditional method are smoother than those by Monte Carlo simulation, that the U - B and B - V colours obtained by the two methods agree with one another, while the V - R and V - I colours by the traditional method are bluer than those by Monte Carlo simulation. A comparison of the Lick/IDS absorption-line indices shows that the variations in all the indices by the traditional method are smoother than that for the Monte Carlo simulation, and that all the indices except for TiO1 and TiO2 are consistent with those for the Monte Carlo simulation.