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1.
王文福 《天文学报》1995,36(2):225-227
本文讨论了超弦理论中的宇宙波函数,使用Vilenkin的边界条件,我们得到了膨胀子场D的值给定时宇宙标度因子a的几率分布。我们还得到了宇宙自发成核时,经典宇宙的标度因子的最小值为Planck长度的数量级,这说明量子效应能阻止宇宙塌缩到奇点。  相似文献   

2.
本文利用Hartle和Hawking的方法,讨论了具有旋量场的量子宇宙学,得到了相应的Wheeler-De Witt方程。求出了具有旋量场的宇宙波函数。从波函数可以看出,当标度因子α很小时,旋量场的影响很强,具体的形式与初始条件有关,而当标度因子α很大时,旋量场的行为和标量场一样。  相似文献   

3.
我们利用含αR~2+γR_(μv)R~(μv)项的宇宙理论同带有一个标量场φ的Einstein理论之间的等价性,讨论了该宇宙的暴涨行为.结果表明,在D维空时(D>2)中,存在指数型的暴涨解.  相似文献   

4.
沈有根  程宗颐 《天文学报》1996,37(3):278-284
本文将Wheeler—DeWitt方程的平方根形式用于具有辐射场源的Bianchi—Ⅰ型宇宙组成的微超空间模型,由此导出一个具有守恒流和正定几率密度的宇宙波函数.本文探讨了Bianchi型宇宙的3次量子化,把类似于弯曲时空中量子场论程序应用到各向异性的Bianchi—Ⅲ型宇宙中,给出了Wheeler—DeWitt方程所满足的宇宙波函数解.把波函数作为微超空间中宇宙场算符看待后,不仅能解决量子宇宙学中几率解释的困难,而且也能得到宇宙多次产生的结论.同时估算了各种宇宙从“无”产生平均数目,给出了宇宙生成的分布,发现它遵从Planck分布.  相似文献   

5.
本在诱生引力理论中探讨了量子虫洞和宇宙量子场论,在黑格斯场ψ的真空期待值附近,我们求解了Wheeler-De Witt方程,得到了虫洞波函数的严格解,并且探讨了三次最子化问题,我们发现宇宙创生服务Planch分布。  相似文献   

6.
本文讨论了宇宙常数Λ≠0时的平面引力波问题。在弱场近似下,得到了平面引力波传播方程及色散方程。通过对Kretschmann曲率标量的讨论发现,不同于Λ=0时h_(μv)仅有横场这一众所周知的结果,Λ<0时不存在一个坐标系,使h_(μv)的标量场、纵场、混合场分量全为零。最后讨论引力波辐射,结论是与Λ=0时无偶极辐射这一结果不同,Λ<0时,混合场的辐射有偶极辐射。  相似文献   

7.
本文从粒子分布函数所满足的带有规则电场的准线性方程出发,得到了包含有规则电场与湍动起伏场相互耦合作用在内的等效动量空间扩散系数,提出了太阳质子耀斑中性片中的规则电场与湍动起伏场的联合加速机制。根据太阳质子耀斑的物理条件,计算表明荷电粒子在中性片中可以被有效地加速,能量可以达到~20MeV,甚至~1GeV。本文证明了离子声湍动起伏场与规则电场的联合加速机制有效地使质子和其它重离子注入到Langmuir湍动加速区中去;并且表明,在Langmuir湍动起伏场与规则电场联合加速的情形下,可以得到与观测事实符合得较好的高能质子的谱以及高能电子的幂律分布的谱。  相似文献   

8.
通过矢量暴涨理论,研究了与之相关的问题,特别是粒子生成对慢滚过程、相图以及各向异性的影响.计算结果表明,粒子生成对标量场的影响使得相图上出现一个峰,峰的方向不受初始条件和质量改变的影响.而对于矢量场,情况则不同,粒子生成对应的峰其方向会改变,这与质量的变化有关.相应地,体系的各向异性也会随之增强或减弱.各向异性的程度不仅决定于慢滚过程,还决定于慢滚后的粒子生成过程.粒子生成可以成为宇宙各向同性化的原因.  相似文献   

9.
通过矢量暴涨理论,研究了与之相关的问题,特别是粒子生成对慢滚过程、相图以及各向异性的影响.计算结果表明,粒子生成对标量场的影响使得相图上出现一个峰,峰的方向不受初始条件和质量改变的影响.而对于矢量场,情况则不同,粒子生成对应的峰其方向会改变,这与质量的变化有关.相应地,体系的各向异性也会随之增强或减弱.各向异性的程度不仅决定于慢滚过程,还决定于慢滚后的粒子生成过程.粒子生成可以成为宇宙各向同性化的原因.  相似文献   

10.
星系的红移巡天是观测宇宙学中最基本的工作,有关宇宙大尺度结构研究中的许多关键问题,例如宇宙中最大结构的尺度,宇宙中大尺度结构的拓扑特征,以及有关宇宙物质分布的密度场和速度场的许多基本性质的研究,都依赖于覆盖面积足够大、极限星等足够暗的完备的星系红移大样本.通过对巡天的覆盖天区、巡天深度、选样方法、巡样率等方面的分析,比较了最近已完成的一些红移巡天(IRAS、CfA、SSRS、ORS和LCRS等)并对计划中的2dF和SDSS巡天计划作了简要介绍.  相似文献   

11.
Rozelot  J.P.  Godier  S.  Lefebvre  S. 《Solar physics》2001,198(2):223-240
In this paper we first emphasize why it is important to know the successive zonal harmonics of the Sun's figure with high accuracy: mainly fundamental astrometry, helioseismology, planetary motions and relativistic effects. Then we briefly comment why the Sun appears oblate, going back to primitive definitions in order to underline some discrepancies in theories and to emphasize again the relevant hypotheses. We propose a new theoretical approach entirely based on an expansion in terms of Legendre's functions, including the differential rotation of the Sun at the surface. This permits linking the two first spherical harmonic coefficients (J 2 and J 4) with the geometric parameters that can be measured on the Sun (equatorial and polar radii). We emphasize the difficulties in inferring gravitational oblateness from visual measurements of the geometric oblateness, and more generally a dynamical flattening. Results are given for different observed rotational laws. It is shown that the surface oblateness is surely upper bounded by 11 milliarcsecond. As a consequence of the observed surface and sub-surface differential rotation laws, we deduce a measure of the two first gravitational harmonics, the quadrupole and the octopole moment of the Sun: J 2=−(6.13±2.52)×10−7 if all observed data are taken into account, and respectively, J 2=−(6.84±3.75)×10−7 if only sunspot data are considered, and J 2=−(3.49±1.86)×10−7 in the case of helioseismic data alone. The value deduced from all available data for the octopole is: J 4=(2.8±2.1)×10−12. These values are compared to some others found in the literature. Supplementary material to this paper is available in electronic form at http://dx.doi.org/10.1023/A:1005238718479  相似文献   

12.
13.
A two-component theoretical model of the physical libration of the Moon in longitude is constructed with account taken of the viscosity of the core. In the new version, a hydrodynamic problem of motion of a fluid filling a solid rotating shell is solved. It is found that surfaces of equal angular velocity are spherical, and a velocity field of the fluid core of the Moon is described by elementary functions. A distribution of the internal pressure in the core is found. An angular momentum exchange between the fluid core and solid mantle is described by a third-order differential equation with a right-hand side. The roots of a characteristic equation are studied and the stability of rotation is proved. A libration angle as a function of time is found using the derived solution of the differential equation. Limiting cases of infinitely large and infinitely small viscosity are considered and an effect of lag of a libration phase from a phase of action of an external moment of forces is ascertained. This makes it possible to estimate the viscosity and sizes of the lunar fluid core from data of observations.  相似文献   

14.
We calculate the so-called convective term, which shows up in the expression for the angular velocity of the elastic Earth, within the Andoyer formalism. The term emerges due to the fact that the elasticity-caused perturbation depends not only on the instantaneous orientation of the Earth but also on its instantaneous angular velocity. We demonstrate that this term makes a considerable contribution into the overall angular velocity. At the same time the convective term turns out to be automatically included into the correction to the nutation series due to the elasticity, if the series is defined by the perturbation of the figure axis (and not of the rotational axis) in accordance with the current IAU resolution. Hence it is not necessary to take the effect of the convective term into consideration in the perturbation of the elastic Earth as far as the nutation is related to the motion of the figure axis.  相似文献   

15.
Range of values of the Sun's mass quadrupole moment of coefficient J2 arising both from experimental and theoretical determinations enlarge across literature on two orders of magnitude, from around 10-7 until to 10-5. The accurate knowledge of the Moon's physical librations, for which the Lunar Laser Ranging data reach an outstanding precision level, prove to be appropriate to reduce the interval of J2 values by giving an upper bound of J2. A solar quadrupole moment as high as 1.1 10-5 given either from the upper bounds of the error bars of the observations, or from the Roche's theory, is not compatible with the knowledge of the lunar librations accurately modeled and observed with the LLR experiment. The suitable values of J2 have to be smaller than 3.0 10-6. As a consequence, this upper bound of 3.0 10-6 is accepted to study the impact of the Sun's quadrupole moment of mass on the dynamics of the Earth-Moon system. Such as effect (with J2 = 5.5±1.3 × 10-6) has been already tested in 1983 by Campbell & Moffat using analytical approximate equations, and thus for the orbits of Mercury, Venus, the Earth and Icarus. The approximate equations are no longer sufficient compared with present observational data and exact equations are required. As if to compute the effect on the lunar librations, we have used our BJV relativistic model of solar system integration including the spin-orbit coupled motion of the Moon. The model is solved by numerical integration. The BJV model stems from general relativity by using the DSX formalism for purposes of celestial mechanics when it is about to deal with a system of n extended, weakly self-gravitating, rotating and deformable bodies in mutual interactions. The resulting effects on the orbital elements of the Earth have been computed and plotted over 160 and 1600 years. The impact of the quadrupole moment of the Sun on the Earth's orbital motion is mainly characterized by variations of , , and . As a consequence, the Sun's quadrupole moment of mass could play a sensible role over long time periods of integration of solar system models. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

16.
By means of a simple relation between the velocity v of the fluid particle and the velocity vf of the photospheric footpoint of the magnetic field line vz and Bz being respectively the components of v and the magnetic field B normal to the photospheric surface, it is shown formally that through the phtospheric surface the transport of all the quantities attributed to the magnetic field, such as the magnetic flux, the magnetic energy and the helicity, is independent of vz, and vf is the only kinematical quantity on which the transport depends. In addition, in the neighborhood of the neutral line the velocity vl of the moving curve of constant Bz is found to be equal approximately to the component of v or vf in the direction of vl. Since vl can be measured or extimated, so can the components of v and vf near the neutral line.  相似文献   

17.
When the K-corona is formed by the scattering of photospheric radiation from free electrons, the Fraunhofer lines are greatly broadened by the thermal motions of the hot electrons. This paper discusses the possibility of measuring the coronal electron temperature from the residual depressions in the K-coronal spectrum. If the ratio of the intensities at 4100 Å and 3900 Å can be measured to an accuracy of ±1%, the coronal temperature can be inferred to an accuracy of ±0.2 MK. The temperature of a coronal inhomogeneity may also be measured by this method, provided the position angle is known.Now at Fraunhofer Institute, Freiburg, Germany.  相似文献   

18.
Using the well-known equation for the normal component of the current which exist near the tangential discontinuity in the plasma in the case of the frozen-in magnetic field, and supposing that the current closes in the ionosphere in the auroral oval in the region 1, one calculates and compares with the data of observations the dependence of the density of the field-aligned current at the level of the ionosphere on the local time.  相似文献   

19.
The classical method of determination of the absolute azimuth (or Bessel's parameter n) can secure sufficiently precision for RA from observations of stars at high geographical latitudes during polar night only.  相似文献   

20.
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