A test of general relativity from the three-dimensional orbital geometry of a binary pulsar.

Binary pulsars provide an excellent system for testing general relativity because of their intrinsic rotational stability and the precision with which radio observations can be used to determine their orbital dynamics. Measurements of the rate of orbital decay of two pulsars have been shown to be consistent with the emission of gravitational waves as predicted by general relativity, but independent verification was not possible. Such verification can in principle be obtained by determining the orbital inclination in a binary pulsar system using only classical geometrical constraints. This would permit a measurement of the expected retardation of the pulse signal arising from the general relativistic curvature of space-time in the vicinity of the companion object (the 'Shapiro delay'). Here we report high-precision radio observations of the binary millisecond pulsar PSR J0437-4715, which establish the three-dimensional structure of its orbit. We see the Shapiro delay predicted by general relativity, and we determine the mass of the neutron star and its white dwarf companion. The determination of such masses is necessary in order to understand the origin and evolution of neutron stars.     

Formation of the black-hole binary M33 X-7 through mass exchange in a tight massive system

The X-ray source M33 X-7 in the nearby galaxy Messier 33 is among the most massive X-ray binary stellar systems known, hosting a rapidly spinning, 15.65M(⊙) black hole orbiting an underluminous, 70M(⊙) main-sequence companion in a slightly eccentric 3.45-day orbit (M(⊙), solar mass). Although post-main-sequence mass transfer explains the masses and tight orbit, it leaves unexplained the observed X-ray luminosity, the star's underluminosity, the black hole's spin and the orbital eccentricity. A common envelope phase, or rotational mixing, could explain the orbit, but the former would lead to a merger and the latter to an overluminous companion. A merger would also ensue if mass transfer to the black hole were invoked for its spin-up. Here we report simulations of evolutionary tracks which reveal that if M33 X-7 started as a primary body of 85M(⊙)-99M(⊙) and a secondary body of 28M(⊙)-32M(⊙), in a 2.8-3.1-d orbit, its observed properties can be consistently explained. In this model, the main-sequence primary transfers part of its envelope to the secondary and loses the rest in a wind; it ends its life as a ～16M(⊙) helium star with an iron-nickel core that collapses to a black hole (with or without an accompanying supernova). The release of binding energy, and possibly collapse asymmetries, 'kick' the nascent black hole into an eccentric orbit. Wind accretion explains the X-ray luminosity, and the black-hole spin can be natal.     

BL Lac天体OJ 287的光学光变周期研究

从大量文献中收集了BL Blac天体OJ 287光学V波段30多年的观测数据,分析了光变周期。用两种不同的方法分析周期光变(功率谱方法及小波分析法),发现其光变曲线中存在7.06年和13.5年的周期,预期2020年秋将再次爆发。     

A test of general relativity using radio links with the Cassini spacecraft

According to general relativity, photons are deflected and delayed by the curvature of space-time produced by any mass. The bending and delay are proportional to gamma + 1, where the parameter gamma is unity in general relativity but zero in the newtonian model of gravity. The quantity gamma - 1 measures the degree to which gravity is not a purely geometric effect and is affected by other fields; such fields may have strongly influenced the early Universe, but would have now weakened so as to produce tiny--but still detectable--effects. Several experiments have confirmed to an accuracy of approximately 0.1% the predictions for the deflection and delay of photons produced by the Sun. Here we report a measurement of the frequency shift of radio photons to and from the Cassini spacecraft as they passed near the Sun. Our result, gamma = 1 + (2.1 +/- 2.3) x 10(-5), agrees with the predictions of standard general relativity with a sensitivity that approaches the level at which, theoretically, deviations are expected in some cosmological models.     

A young massive planet in a star-disk system

There is a general consensus that planets form within disks of dust and gas around newly born stars. Details of their formation process, however, are still a matter of ongoing debate. The timescale of planet formation remains unclear, so the detection of planets around young stars with protoplanetary disks is potentially of great interest. Hitherto, no such planet has been found. Here we report the detection of a planet of mass (9.8+/-3.3)M(Jupiter) around TW Hydrae (TW Hya), a nearby young star with an age of only 8-10 Myr that is surrounded by a well-studied circumstellar disk. It orbits the star with a period of 3.56 days at 0.04 au, inside the inner rim of the disk. This demonstrates that planets can form within 10 Myr, before the disk has been dissipated by stellar winds and radiation.     

视广义相对论及新广义相对论为广义引力理论特殊情况的研究

根据广义引力理论的基本公式导出了广义相对论和新广义相对论的引力场方程和粒子运动方程．结果表明了广义相对论和新广义相对论均是广义引力理论的特殊情况．阐述了这种方法在理论上和运算上的一些优点．     

量子理论和广义相对论的统一

首先简要介绍了量子引力理论中的超引力和环量子引力.其次基于量子理论和广义相对论的基本原理、主要特征等探讨了某些新的统一理论.进而提出广义相对论形式、算符形式和二者的结合等具体的数学方程及6个结果.最后讨论了一些统一的新方案,如量子理论中可能存在的类似宇宙项,各种相互作用粒子的质量关系,标准模型某些可能的发展等.       

广义相对论中的同时性定义

按照广义相对论时-空间隔的特性,同时性定义被严格地推广到广义相对论.同时性定义原是狭义相对论中的重要问题,过去一些文献将它推广到广义相对论时,忽视了广义相对论与狭义相对论在时空特性上的差别,因而在推广的过程中,出现了一些概念上或计算上的混乱和错误,影响了对广义相对论的正确理解.通过严格的论证,指出了这些混乱和错误,并予以了改正.     

普通物理相对论教学的几点思考

X相对论作为前沿内容已引入了高中物理新教材。基于这一现实,重新思考了普通物理相对论的教学——认为普通物理相对论教学应强调科学哲学、渗透科学方法、联系物理学史、了解前沿进展、关注多元理解。     

关于广义相对论的Brown-York与Quadratic Spinor作用量

广义相对论希尔伯特作用量在类空无穷远发散．如果要在类空无穷远得到收敛,则需要在希尔伯特作用量加上边界修正项．比较在类空无穷远收敛的Brown—York作用量,以及二次方旋量场（Quadratic Spinor）作用量．发现当狄拉克（Dirac）旋量场在边界超曲面上满足Witten方程时,二次方旋量场作用量在渐进类空无穷远等于Brown—York作用量．     

工程装备通用自动测试系统设计

为了提高自动测试系统的通用性能,将自动测试技术和虚拟仪器技术相结合,设计并实现了一种基于"PXI模块化仪器 程控仪器 连接器-适配器"结构的工程装备通用自动测试系统.系统根据各待测单元的信号频率和功能特征设计标准阵列接口连接器ICA(interface connector assembly);在仪器控制方面为了弥补可互换虚拟仪器ⅣⅠ(interchangeable virtual instruments)规范的不足,采用ⅣⅠ类仪器模型的基本思想,建立了系统的"ATS(automatic test system)资源模型",利用IVI规范配置仪器无关性系统;软件平台让用户根据待测单元的测试需求完成TPS(test program set)的开发,使在此软件平台上开发出的TPS完全独立于测试资源.工程应用表明,该系统具有良好的实用性和扩展性.     

通用中考成绩管理信息系统的设计与实现

讨论了中考成绩信息管理的特点及要求，介绍了一种通用中考管理信息软件设计技术及实际使用情况。     

Gravitational redshift of galaxies in clusters as predicted by general relativity

The theoretical framework of cosmology is mainly defined by gravity, of which general relativity is the current model. Recent tests of general relativity within the Lambda Cold Dark Matter (ΛCDM) model have found a concordance between predictions and the observations of the growth rate and clustering of the cosmic web. General relativity has not hitherto been tested on cosmological scales independently of the assumptions of the ΛCDM model. Here we report an observation of the gravitational redshift of light coming from galaxies in clusters at the 99 per cent confidence level, based on archival data. Our measurement agrees with the predictions of general relativity and its modification created to explain cosmic acceleration without the need for dark energy (the f(R) theory), but is inconsistent with alternative models designed to avoid the presence of dark matter.     

二元会话类型系统中演进特性研究

提出了一个保持演进特性的二元同步会话类型系统,分析了进程通信中可能发生的死锁情形;同时结合会话类型的子类型概念和松弛对偶关系,定义了类型一致性等法则,确保了类型系统中进程通信一旦发生,合式进程在通道上不会发生死锁的情形.此外,还定义了递归会话类型的子类型和松弛对偶关系,提高了类型系统的灵活性.     

相对论中的一个矛盾问题及分析

在由洛仑兹变换推证动量守恒定律在不同惯性系中具有相同的数学形式过程中，提出了一个推导中的矛盾，通过对这一矛盾的分析，说明同一物体不仅运动时的质量与静止时的质量不同，而且不同情况下的静止质量也是不同的。进而对几种情况下物体的静止质量做了说明，强调在相对论中，对静质量的处理，不能一概而论，必须具体问题具体分析。     

RR-Lyrae-type pulsations from a 0.26-solar-mass star in a binary system

RR Lyrae pulsating stars have been extensively used as tracers of old stellar populations for the purpose of determining the ages of galaxies, and as tools to measure distances to nearby galaxies. There was accordingly considerable interest when the RR Lyrae star OGLE-BLG-RRLYR-02792 (referred to here as RRLYR-02792) was found to be a member of an eclipsing binary system, because the mass of the pulsator (hitherto constrained only by models) could be unambiguously determined. Here we report that RRLYR-02792 has a mass of 0.26 solar masses M[symbol see text] and therefore cannot be a classical RR Lyrae star. Using models, we find that its properties are best explained by the evolution of a close binary system that started with M[symbol see text] and 0.8M[symbol see text]stars orbiting each other with an initial period of 2.9 days. Mass exchange over 5.4 billion years produced the observed system, which is now in a very short-lived phase where the physical properties of the pulsator happen to place it in the same instability strip of the Hertzsprung-Russell diagram as that occupied by RR Lyrae stars. We estimate that only 0.2 per cent of RR Lyrae stars may be contaminated by systems similar to this one, which implies that distances measured with RR Lyrae stars should not be significantly affected by these binary interlopers.     

转动潮汐变形双星表面重力加速度的数值模拟

转动和潮汐效应是影响双星结构演化非常重要的物理因素。在转动双星系统中,根据考虑转动潮汐变形的高阶扰动势数值计算了主星表面的重力加速度的分布,并与洛希模型计算的表面重力加速度分布做了对比。结果发现:转动和潮汐对恒星表面的重力加速度的大小和分布有重要影响,采用本文中的初始参数进行演化计算,最大影响可达到103～104 cm/s2。因此在讨论恒星结构和演化时,转动和潮汐变形是不可忽略的重要因素。