共查询到19条相似文献，搜索用时 312 毫秒
1.
对于配置光子计数探测器的低纬子午环，在其观测数据的归算过程中应该加以考虑的星径曲率改正包括三种改正量：卯酉方向记录时刻的星径曲率改正；卯酉方向天顶距的星径曲率改正；子午方向天顶距的星径曲率改正。结合测微器的新视栅形式，本文给出了一种旨在解决星径曲率改正问题的新思路。 相似文献
2.
低纬子午环用CCD测微器观测时的星径曲率改正 总被引：1，自引：0，他引：1
本文推导了纬子午环彩和ＣＣＤ测微器观测时所得测定值的各种星径曲率改正公式。针对云南天文台具体的地理位置，在不同观测天顶距情况下，给出了ＣＣＤ视场中不同位置的天体通过参考平面（子午平面或卯酉平面）时，星过记录时刻和天顶距测定值的星径曲率改正模拟运算结果。 相似文献
3.
本文推导了低纬子午环采用ＣＣＤ测微器观测时所得测定值的各种星径曲率改正公式。针对云南天文台具体的地理位置（纬度为２５°），在不同观测天顶距情况下，给出了ＣＣＤ视场中不同位置的天体通过参考平面（子午平面或卯酉平面）时，星过记录时刻和天顶距测定值的星径曲率改正模拟运算结果。结果表明：对于偏离ＣＣＤ芯片相对中心的天体，其星径曲率改正值比较大，且随天体偏离距离的增加而增大。 相似文献
4.
本文用投影椭圆的方法推导了子午方向的天顶距测定值应加的星径曲率改正、以及星过仪器卯酉方向的时刻和天顶距测定值的相应改正;还推导了子午方向观测中由于过任一天体的赤经圈投影与子午面之间夹角的变化对量度坐标x测定值的影响,所有这些都是由于转轴观测和星象偏离芯片相对中心引起的。文章还推导了视场中任一星象相对于芯片相对中心的大气折射和周年光行差较差改正。并给出了以//2(x′-x)和1/2(y′-y)为引数的改正公式,同时还得出,对于天顶距大于15°的观测,量度坐标x的大气折射较差改正可以忽略不计。 相似文献
5.
本文利用解球面三角形和视场平面投影相结合的方法,推导出了卯酉方向记录时刻中星径曲率改正的表达式。并以给定的纬度和单边准直差为例,计算了改正值。对于转轴观测,在天顶距较小的情况下,这种改正值比丹容等高仪的星径曲率改正大几百倍。由于这种方法能根据需要导出高次项改正的表达式,作为一种推导的途径,可以满足不同数量改正值推导的要求。文中还给出了验算公式。 相似文献
6.
蒋虎 《中国科学院上海天文台年刊》1998,(19):51-57
在献[1],[2]中,我们已经推得云南天台低纬子午环观测的星径曲率改正公式。本以定性方法论述和分析了昨径曲率改正,与以前的有关章相比,我们对星径曲率改正的部分计算作了校正,为便于进行定性分析,本给出了对应于云南天台地理位置的星径曲率计算公式的特性曲线图,最后,我们认为：中给出的星径曲率改正公式对观测天顶距大于25°的天体是比较有效的,在编制低纬子午环观测纲要时应当充分考虑这一点。 相似文献
7.
本文叙述了在卯酉方向作转轴观测时,由于转轴前后的观测都是偏离于卯酉圈的观测,在仪器具有较大方位差,及一颗星从卯圈方向到酉圈方向观测过程中,存在水平差变化的情况下,转轴观测不能完全消除准直差,方位差的测定值需加几项二次项改正。文章中用给定的方位差及水平差变化对二次项改正作了数值估算,得出改正值与卯酉方向观测星的天顶距有关的结果,天顶距越小的星,改正值越大,天顶距大于40°的星,改正值可以忽略不计。文章还就卯酉方向观测时,周日光行差和蒙气差的影响作了估算,结果看出这两种影响都基本上可以忽略不计。 相似文献
8.
本文利用把三角函数展开成级数的方法,严格推导了卯酉方向视天顶距测定值中星径曲率改正的表达式。这种方法,虽然只能准确到二级小量,但比视场平面投影的近似推导法更精确。 相似文献
9.
为了满足低纬子午环绝对测定方法的要求,即在子午方向同时测定天体中天时刻和天顶距;在卯酉方向记录恒星通过卯酉圈的时刻。本文从视栅倾斜的影响出发,讨论了低纬子午环可采用的测微器的视栅形式——垂直狭缝和斜狭缝组合视栅,并对在卯酉方向测定视天顶距的方法作了讨论。 相似文献
10.
本文讨论了在利用卯酉圈观测方法绝对测定观测点瞬时纬度的过程中,仪器定向误差、周日光行差和大气折射的高次项对所得结果的影响。研究结果表明,仪器定向误差的高次项影响在可观测天顶距范围内都是比较大的,必须在结果中加以改正。而周日光行差和大气折射的影响一般不大,在精度要求的范围内可以忽略。 相似文献
11.
Ahmad Rami El-Nabulsi 《Astrophysics and Space Science》2010,327(2):167-171
We explore the late-time dynamics of a four-dimensional homogeneous and isotropic universe based on a modified Brans-Dicke scalar tensor theory in the presence of string corrections and Gauss-Bonnet curvature corrections. Many original and attractive cosmological features are revealed and discussed in some details. 相似文献
12.
L. Rezzolla B. J. Ahmedov J. C. Miller 《Monthly notices of the Royal Astronomical Society》2001,322(4):723-740
We present analytic solutions of Maxwell equations in the internal and external background space–time of a slowly rotating magnetized neutron star. The star is considered isolated and in vacuum, with a dipolar magnetic field not aligned with the axis of rotation. With respect to a flat space–time solution, general relativity introduces corrections related both to the monopolar and the dipolar parts of the gravitational field. In particular, we show that in the case of infinite electrical conductivity general relativistic corrections resulting from the dragging of reference frames are present, but only in the expression for the electric field. In the case of finite electrical conductivity, however, corrections resulting from both the space–time curvature and the dragging of reference frames are shown to be present in the induction equation. These corrections could be relevant for the evolution of the magnetic fields of pulsars and magnetars. The solutions found, while obtained through some simplifying assumption, reflect a rather general physical configuration and could therefore be used in a variety of astrophysical situations. 相似文献
13.
Ahmad Rami El-Nabulsi 《Astrophysics and Space Science》2010,325(2):149-152
We investigate the cosmological dynamics of a four-dimensional Friedmann–Robertson–Walker homogenous and isotropic universe from Gauss–Bonnet higher-order curvature corrections, together with nonminimal coupling and with an infrared effective action of gravity based on a second-order gauge formulation for the Lorentz group. We study the evolution of the universe in such a model, identifying its key properties. Many new interesting features are revealed and discussed in some detail. 相似文献
14.
A non-linear gravitational model with a multidimensional geometry and quadratic scalar curvature is considered. For certain
parameter ranges, the extra dimensions are stabilized if the internal spaces have negative constant curvature. As a consequence,
the 4-dimensional effective cosmological constant as well as the bulk cosmological constant become negative. The homogeneous
and isotropic external space is asymptotically AdS4. The connection between the D-dimensional and the 4-dimensional fundamental mass scales sets an additional restriction on
the parameters of the considered non-linear models.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
15.
Ahmad Rami El-Nabulsi 《Astrophysics and Space Science》2010,327(2):161-165
We investigate the cosmological dynamics of a four-dimensional Friedmann–Robertson–Walker homogenous and isotropic universe
from Gauss–Bonnet higher-order curvature corrections, together with nonminimal coupling and with an infrared effective action
of gravity based on a second-order gauge formulation for the Lorentz group. We study the evolution of the universe in such
a model, identifying its key properties. Many new interesting features are revealed and discussed in some detail. 相似文献
16.
OlindoZanotti LucianoRezzolla 《Monthly notices of the Royal Astronomical Society》2002,331(2):376-388
We have solved numerically the general relativistic induction equations in the interior background space–time of a slowly rotating magnetized neutron star. The analytic form of these equations was discussed recently (Paper I), where corrections due to both the space–time curvature and the dragging of reference frames were shown to be present. Through a number of calculations we have investigated the evolution of the magnetic field with different rates of stellar rotation, different inclination angles between the magnetic moment and the rotation axis, as well as different values of the electrical conductivity. All of these calculations have been performed for a constant-temperature relativistic polytropic star and make use of a consistent solution of the initial-value problem which avoids the use of artificial analytic functions. Our results show that there exist general relativistic effects introduced by the rotation of the space–time which tend to decrease the decay rate of the magnetic field. The rotation-induced corrections are however generally hidden by the high electrical conductivity of the neutron star matter, and when realistic values for the electrical conductivity are considered, these corrections become negligible even for the fastest known pulsar. 相似文献
17.
An internal singularity of a string four-dimensional black hole with second order curvature corrections is investigated. A
restriction to a minimal size of a neutral black hole is obtained in the frame of the model considered. Vacuum polarization
of the surrounding space-time caused by this minimal-size black hole is also discussed. 相似文献
18.
An analysis of a spherically symmetric braneworld configuration is performed when the intrinsic curvature scalar is included
in the bulk action. In the case when the electric part of the Weyl tensor is zero, all the exterior solutions are found; one
of them is of the Schwarzschild-(A)dS
4 form, which is matched to a modified Oppenheimer-Volkoff interior solution. In the case when the electric part of the Weyl
tensor is non zero, the exterior Schwarzschild-(A)dS
4 black hole solution is modified receiving corrections from the non-local bulk effects. A non-universal gravitational constant
arises, depending on the density of the considered object and the Newton's law is modified for small and large distances;
however, the conventional limits are easily obtained.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
Equations for the dynamics of a rotating two-component neutron star are derived in the framework of the general theory of
relativity. The density of neutron vortex filaments is expressed in terms of the angular momentum density of the superfluid
neutrons in the “npe” phase of the neutron star. It is shown that a theory of the relaxation of the angular velocity of pulsars
must include corrections associated with the deviation of g00 from unity, which is a consequence of the curvature of space. 相似文献